From 8a1758bf11c2d741e0cddc761b1dd2cdf564db93 Mon Sep 17 00:00:00 2001
From: Ryan Harrison <rharrison@chromium.org>
Date: Tue, 15 Aug 2017 10:37:59 -0400
Subject: Remove GetAt from string classes

This method duplicates the behaviour of the const [] operator and
doesn't offer any additional safety. Folding them into one
implementation.

SetAt is retained, since implementing the non-const [] operator to
replace SetAt has potential performance concerns. Specifically many
non-obvious cases of reading an element using [] will cause a realloc
& copy.

BUG=pdfium:860

Change-Id: I3ef5e5e5a15376f040256b646eb0d90636e24b67
Reviewed-on: https://pdfium-review.googlesource.com/10870
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
---
 core/fpdfapi/font/cpdf_cidfont.cpp             |  6 +-
 core/fpdfapi/font/cpdf_cmapparser.cpp          | 25 ++++----
 core/fpdfapi/font/cpdf_font.cpp                |  2 +-
 core/fpdfapi/font/cpdf_tounicodemap.cpp        |  4 +-
 core/fpdfapi/render/cpdf_charposlist.cpp       |  2 +-
 core/fpdfdoc/cpdf_filespec.cpp                 | 18 +++---
 core/fpdfdoc/cpdf_variabletext.cpp             | 12 ++--
 core/fpdfdoc/cpvt_generateap.cpp               |  2 +-
 core/fpdftext/cpdf_linkextract.cpp             |  6 +-
 core/fpdftext/cpdf_textpage.cpp                | 30 +++++-----
 core/fpdftext/cpdf_textpagefind.cpp            | 26 ++++-----
 core/fxcrt/cfx_bytestring.cpp                  | 16 +++---
 core/fxcrt/cfx_bytestring.h                    |  5 +-
 core/fxcrt/cfx_bytestring_unittest.cpp         | 79 +++++++++-----------------
 core/fxcrt/cfx_chariter.cpp                    |  2 +-
 core/fxcrt/cfx_string_c_template.h             |  6 +-
 core/fxcrt/cfx_widestring.cpp                  | 12 ++--
 core/fxcrt/cfx_widestring.h                    |  4 +-
 core/fxcrt/cfx_widestring_unittest.cpp         | 77 +++++++++----------------
 core/fxcrt/xml/cxml_parser.cpp                 |  2 +-
 fpdfsdk/javascript/Document.cpp                |  2 +-
 fpdfsdk/javascript/PublicMethods.cpp           | 38 ++++++-------
 fxbarcode/datamatrix/BC_ASCIIEncoder.cpp       |  4 +-
 fxbarcode/datamatrix/BC_Base256Encoder.cpp     | 14 ++---
 fxbarcode/datamatrix/BC_C40Encoder.cpp         |  6 +-
 fxbarcode/datamatrix/BC_DefaultPlacement.cpp   |  2 +-
 fxbarcode/datamatrix/BC_EdifactEncoder.cpp     |  8 +--
 fxbarcode/datamatrix/BC_EncoderContext.cpp     |  8 +--
 fxbarcode/datamatrix/BC_ErrorCorrection.cpp    |  6 +-
 fxbarcode/datamatrix/BC_HighLevelEncoder.cpp   |  8 +--
 fxbarcode/oned/BC_OnedCodaBarWriter.cpp        |  4 +-
 fxbarcode/oned/BC_OnedCode39Writer.cpp         |  6 +-
 fxbarcode/oned/BC_OnedEAN13Writer.cpp          |  2 +-
 fxbarcode/oned/BC_OnedEAN8Writer.cpp           |  2 +-
 fxbarcode/oned/BC_OnedUPCAWriter.cpp           |  4 +-
 fxbarcode/pdf417/BC_PDF417.cpp                 |  2 +-
 fxbarcode/pdf417/BC_PDF417ErrorCorrection.cpp  |  2 +-
 fxbarcode/pdf417/BC_PDF417HighLevelEncoder.cpp | 32 +++++------
 fxbarcode/qrcode/BC_QRCoderEncoder.cpp         | 14 +++--
 xfa/fxfa/cxfa_ffpasswordedit.cpp               |  2 +-
 xfa/fxfa/cxfa_pdffontmgr.cpp                   |  2 +-
 xfa/fxfa/cxfa_textlayout.cpp                   |  4 +-
 xfa/fxfa/cxfa_textparser.cpp                   |  2 +-
 xfa/fxfa/cxfa_widgetacc.cpp                    |  2 +-
 xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp           | 22 +++----
 xfa/fxfa/fm2js/cxfa_fmexpression.cpp           | 18 +++---
 xfa/fxfa/parser/cxfa_dataexporter.cpp          |  6 +-
 xfa/fxfa/parser/cxfa_layoutpagemgr.cpp         |  2 +-
 xfa/fxfa/parser/cxfa_localemgr.cpp             |  7 +--
 xfa/fxfa/parser/cxfa_measurement.cpp           |  2 +-
 xfa/fxfa/parser/cxfa_node.cpp                  | 10 ++--
 xfa/fxfa/parser/cxfa_nodehelper.cpp            |  6 +-
 xfa/fxfa/parser/cxfa_resolveprocessor.cpp      |  4 +-
 xfa/fxfa/parser/cxfa_scriptcontext.cpp         |  2 +-
 xfa/fxfa/parser/cxfa_widgetdata.cpp            |  4 +-
 55 files changed, 271 insertions(+), 324 deletions(-)

diff --git a/core/fpdfapi/font/cpdf_cidfont.cpp b/core/fpdfapi/font/cpdf_cidfont.cpp
index 8cb59de739..9a2261caa9 100644
--- a/core/fpdfapi/font/cpdf_cidfont.cpp
+++ b/core/fpdfapi/font/cpdf_cidfont.cpp
@@ -627,7 +627,7 @@ int CPDF_CIDFont::GlyphFromCharCode(uint32_t charcode, bool* pVertGlyph) {
       if (uni_str.IsEmpty())
         return cid;
 
-      unicode = uni_str.GetAt(0);
+      unicode = uni_str[0];
 #endif
     } else {
       if (cid && m_pCID2UnicodeMap && m_pCID2UnicodeMap->IsLoaded())
@@ -637,7 +637,7 @@ int CPDF_CIDFont::GlyphFromCharCode(uint32_t charcode, bool* pVertGlyph) {
       if (unicode == 0) {
         CFX_WideString unicode_str = UnicodeFromCharCode(charcode);
         if (!unicode_str.IsEmpty())
-          unicode = unicode_str.GetAt(0);
+          unicode = unicode_str[0];
       }
     }
     FXFT_Face face = m_Font.GetFace();
@@ -735,7 +735,7 @@ int CPDF_CIDFont::GlyphFromCharCode(uint32_t charcode, bool* pVertGlyph) {
       if (unicode_str.IsEmpty())
         return -1;
 
-      charcode = unicode_str.GetAt(0);
+      charcode = unicode_str[0];
     }
     return GetGlyphIndex(charcode, pVertGlyph);
   }
diff --git a/core/fpdfapi/font/cpdf_cmapparser.cpp b/core/fpdfapi/font/cpdf_cmapparser.cpp
index cbf693966e..272f8deb34 100644
--- a/core/fpdfapi/font/cpdf_cmapparser.cpp
+++ b/core/fpdfapi/font/cpdf_cmapparser.cpp
@@ -121,7 +121,7 @@ void CPDF_CMapParser::ParseWord(const CFX_ByteStringC& word) {
       }
       m_Status = 0;
     } else {
-      if (word.GetLength() == 0 || word.GetAt(0) != '<') {
+      if (word.GetLength() == 0 || word[0] != '<') {
         return;
       }
       if (m_CodeSeq % 2) {
@@ -140,18 +140,17 @@ uint32_t CPDF_CMapParser::CMap_GetCode(const CFX_ByteStringC& word) {
   if (word.IsEmpty())
     return 0;
   pdfium::base::CheckedNumeric<uint32_t> num = 0;
-  if (word.GetAt(0) == '<') {
-    for (int i = 1; i < word.GetLength() && std::isxdigit(word.GetAt(i)); ++i) {
-      num = num * 16 + FXSYS_HexCharToInt(word.GetAt(i));
+  if (word[0] == '<') {
+    for (int i = 1; i < word.GetLength() && std::isxdigit(word[i]); ++i) {
+      num = num * 16 + FXSYS_HexCharToInt(word[i]);
       if (!num.IsValid())
         return 0;
     }
     return num.ValueOrDie();
   }
 
-  for (int i = 0; i < word.GetLength() && std::isdigit(word.GetAt(i)); ++i) {
-    num =
-        num * 10 + FXSYS_DecimalCharToInt(static_cast<wchar_t>(word.GetAt(i)));
+  for (int i = 0; i < word.GetLength() && std::isdigit(word[i]); ++i) {
+    num = num * 10 + FXSYS_DecimalCharToInt(static_cast<wchar_t>(word[i]));
     if (!num.IsValid())
       return 0;
   }
@@ -162,12 +161,12 @@ uint32_t CPDF_CMapParser::CMap_GetCode(const CFX_ByteStringC& word) {
 bool CPDF_CMapParser::CMap_GetCodeRange(CPDF_CMap::CodeRange& range,
                                         const CFX_ByteStringC& first,
                                         const CFX_ByteStringC& second) {
-  if (first.GetLength() == 0 || first.GetAt(0) != '<')
+  if (first.GetLength() == 0 || first[0] != '<')
     return false;
 
   int i;
   for (i = 1; i < first.GetLength(); ++i) {
-    if (first.GetAt(i) == '>') {
+    if (first[i] == '>') {
       break;
     }
   }
@@ -176,8 +175,8 @@ bool CPDF_CMapParser::CMap_GetCodeRange(CPDF_CMap::CodeRange& range,
     return false;
 
   for (i = 0; i < range.m_CharSize; ++i) {
-    uint8_t digit1 = first.GetAt(i * 2 + 1);
-    uint8_t digit2 = first.GetAt(i * 2 + 2);
+    uint8_t digit1 = first[i * 2 + 1];
+    uint8_t digit2 = first[i * 2 + 2];
     range.m_Lower[i] =
         FXSYS_HexCharToInt(digit1) * 16 + FXSYS_HexCharToInt(digit2);
   }
@@ -185,10 +184,10 @@ bool CPDF_CMapParser::CMap_GetCodeRange(CPDF_CMap::CodeRange& range,
   uint32_t size = second.GetLength();
   for (i = 0; i < range.m_CharSize; ++i) {
     uint8_t digit1 = ((uint32_t)i * 2 + 1 < size)
-                         ? second.GetAt((FX_STRSIZE)i * 2 + 1)
+                         ? second[static_cast<FX_STRSIZE>(i * 2 + 1)]
                          : '0';
     uint8_t digit2 = ((uint32_t)i * 2 + 2 < size)
-                         ? second.GetAt((FX_STRSIZE)i * 2 + 2)
+                         ? second[static_cast<FX_STRSIZE>(i * 2 + 2)]
                          : '0';
     range.m_Upper[i] =
         FXSYS_HexCharToInt(digit1) * 16 + FXSYS_HexCharToInt(digit2);
diff --git a/core/fpdfapi/font/cpdf_font.cpp b/core/fpdfapi/font/cpdf_font.cpp
index 82f9be3361..0fd8b45326 100644
--- a/core/fpdfapi/font/cpdf_font.cpp
+++ b/core/fpdfapi/font/cpdf_font.cpp
@@ -467,7 +467,7 @@ int CPDF_Font::FallbackGlyphFromCharcode(int fallbackFont, uint32_t charcode) {
     return -1;
 
   CFX_WideString str = UnicodeFromCharCode(charcode);
-  uint32_t unicode = !str.IsEmpty() ? str.GetAt(0) : charcode;
+  uint32_t unicode = !str.IsEmpty() ? str[0] : charcode;
   int glyph =
       FXFT_Get_Char_Index(m_FontFallbacks[fallbackFont]->GetFace(), unicode);
   if (glyph == 0)
diff --git a/core/fpdfapi/font/cpdf_tounicodemap.cpp b/core/fpdfapi/font/cpdf_tounicodemap.cpp
index 30bf0317ee..9076f4a737 100644
--- a/core/fpdfapi/font/cpdf_tounicodemap.cpp
+++ b/core/fpdfapi/font/cpdf_tounicodemap.cpp
@@ -147,7 +147,7 @@ void CPDF_ToUnicodeMap::Load(CPDF_Stream* pStream) {
           continue;
         }
         if (len == 1) {
-          m_Map[srccode] = destcode.GetAt(0);
+          m_Map[srccode] = destcode[0];
         } else {
           m_Map[srccode] = GetUnicode();
           m_MultiCharBuf.AppendChar(destcode.GetLength());
@@ -178,7 +178,7 @@ void CPDF_ToUnicodeMap::Load(CPDF_Stream* pStream) {
               continue;
             }
             if (len == 1) {
-              m_Map[code] = destcode.GetAt(0);
+              m_Map[code] = destcode[0];
             } else {
               m_Map[code] = GetUnicode();
               m_MultiCharBuf.AppendChar(destcode.GetLength());
diff --git a/core/fpdfapi/render/cpdf_charposlist.cpp b/core/fpdfapi/render/cpdf_charposlist.cpp
index a87fc3334e..f5882d9944 100644
--- a/core/fpdfapi/render/cpdf_charposlist.cpp
+++ b/core/fpdfapi/render/cpdf_charposlist.cpp
@@ -38,7 +38,7 @@ void CPDF_CharPosList::Load(const std::vector<uint32_t>& charCodes,
     if (pCIDFont)
       charpos.m_bFontStyle = true;
     CFX_WideString unicode = pFont->UnicodeFromCharCode(CharCode);
-    charpos.m_Unicode = !unicode.IsEmpty() ? unicode.GetAt(0) : CharCode;
+    charpos.m_Unicode = !unicode.IsEmpty() ? unicode[0] : CharCode;
     charpos.m_GlyphIndex = pFont->GlyphFromCharCode(CharCode, &bVert);
     uint32_t GlyphID = charpos.m_GlyphIndex;
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
diff --git a/core/fpdfdoc/cpdf_filespec.cpp b/core/fpdfdoc/cpdf_filespec.cpp
index 5ef6f466c5..e34f54e4e1 100644
--- a/core/fpdfdoc/cpdf_filespec.cpp
+++ b/core/fpdfdoc/cpdf_filespec.cpp
@@ -69,13 +69,13 @@ CFX_WideString CPDF_FileSpec::DecodeFileName(const CFX_WideString& filepath) {
   return ChangeSlashToPlatform(filepath.c_str());
 #elif _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
 
-  if (filepath.GetAt(0) != L'/')
+  if (filepath[0] != L'/')
     return ChangeSlashToPlatform(filepath.c_str());
-  if (filepath.GetAt(1) == L'/')
+  if (filepath[1] == L'/')
     return ChangeSlashToPlatform(filepath.c_str() + 1);
-  if (filepath.GetAt(2) == L'/') {
+  if (filepath[2] == L'/') {
     CFX_WideString result;
-    result += filepath.GetAt(1);
+    result += filepath[1];
     result += L':';
     result += ChangeSlashToPlatform(filepath.c_str() + 2);
     return result;
@@ -158,19 +158,19 @@ CFX_WideString CPDF_FileSpec::EncodeFileName(const CFX_WideString& filepath) {
     return CFX_WideString();
 
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
-  if (filepath.GetAt(1) == L':') {
+  if (filepath[1] == L':') {
     CFX_WideString result(L'/');
-    result += filepath.GetAt(0);
-    if (filepath.GetAt(2) != L'\\')
+    result += filepath[0];
+    if (filepath[2] != L'\\')
       result += L'/';
 
     result += ChangeSlashToPDF(filepath.c_str() + 2);
     return result;
   }
-  if (filepath.GetAt(0) == L'\\' && filepath.GetAt(1) == L'\\')
+  if (filepath[0] == L'\\' && filepath[1] == L'\\')
     return ChangeSlashToPDF(filepath.c_str() + 1);
 
-  if (filepath.GetAt(0) == L'\\')
+  if (filepath[0] == L'\\')
     return L'/' + ChangeSlashToPDF(filepath.c_str());
   return ChangeSlashToPDF(filepath.c_str());
 #elif _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
diff --git a/core/fpdfdoc/cpdf_variabletext.cpp b/core/fpdfdoc/cpdf_variabletext.cpp
index 74a5e3adfc..877f8ca01e 100644
--- a/core/fpdfdoc/cpdf_variabletext.cpp
+++ b/core/fpdfdoc/cpdf_variabletext.cpp
@@ -358,11 +358,11 @@ CPVT_WordPlace CPDF_VariableText::InsertText(const CPVT_WordPlace& place,
   CPVT_WordPlace wp = place;
   for (int32_t i = 0, sz = swText.GetLength(); i < sz; i++) {
     CPVT_WordPlace oldwp = wp;
-    uint16_t word = swText.GetAt(i);
+    uint16_t word = swText[i];
     switch (word) {
       case 0x0D:
         if (m_bMultiLine) {
-          if (swText.GetAt(i + 1) == 0x0A)
+          if (swText[i + 1] == 0x0A)
             i += 1;
 
           wp = InsertSection(wp, nullptr, nullptr);
@@ -370,7 +370,7 @@ CPVT_WordPlace CPDF_VariableText::InsertText(const CPVT_WordPlace& place,
         break;
       case 0x0A:
         if (m_bMultiLine) {
-          if (swText.GetAt(i + 1) == 0x0D)
+          if (swText[i + 1] == 0x0D)
             i += 1;
 
           wp = InsertSection(wp, nullptr, nullptr);
@@ -426,11 +426,11 @@ void CPDF_VariableText::SetText(const CFX_WideString& swText) {
     if (m_nCharArray > 0 && nCharCount >= m_nCharArray)
       break;
 
-    uint16_t word = swText.GetAt(i);
+    uint16_t word = swText[i];
     switch (word) {
       case 0x0D:
         if (m_bMultiLine) {
-          if (i + 1 < sz && swText.GetAt(i + 1) == 0x0A)
+          if (i + 1 < sz && swText[i + 1] == 0x0A)
             i++;
           wp.AdvanceSection();
           AddSection(wp, secinfo);
@@ -438,7 +438,7 @@ void CPDF_VariableText::SetText(const CFX_WideString& swText) {
         break;
       case 0x0A:
         if (m_bMultiLine) {
-          if (i + 1 < sz && swText.GetAt(i + 1) == 0x0D)
+          if (i + 1 < sz && swText[i + 1] == 0x0D)
             i++;
           wp.AdvanceSection();
           AddSection(wp, secinfo);
diff --git a/core/fpdfdoc/cpvt_generateap.cpp b/core/fpdfdoc/cpvt_generateap.cpp
index d1abde681d..9b5a82a055 100644
--- a/core/fpdfdoc/cpvt_generateap.cpp
+++ b/core/fpdfdoc/cpvt_generateap.cpp
@@ -123,7 +123,7 @@ bool GenerateWidgetAP(CPDF_Document* pDoc,
       dsBorder = CPVT_Dash(pArray->GetIntegerAt(0), pArray->GetIntegerAt(1),
                            pArray->GetIntegerAt(2));
     }
-    switch (pBSDict->GetStringFor("S").GetAt(0)) {
+    switch (pBSDict->GetStringFor("S")[0]) {
       case 'S':
         nBorderStyle = BorderStyle::SOLID;
         break;
diff --git a/core/fpdftext/cpdf_linkextract.cpp b/core/fpdftext/cpdf_linkextract.cpp
index d795e71639..fb228ec832 100644
--- a/core/fpdftext/cpdf_linkextract.cpp
+++ b/core/fpdftext/cpdf_linkextract.cpp
@@ -152,7 +152,7 @@ void CPDF_LinkExtract::ParseLink() {
 
       if (strBeCheck.GetLength() > 5) {
         while (strBeCheck.GetLength() > 0) {
-          wchar_t ch = strBeCheck.GetAt(strBeCheck.GetLength() - 1);
+          wchar_t ch = strBeCheck[strBeCheck.GetLength() - 1];
           if (ch == L')' || ch == L',' || ch == L'>' || ch == L'.') {
             strBeCheck = strBeCheck.Left(strBeCheck.GetLength() - 1);
             nCount--;
@@ -242,7 +242,7 @@ bool CPDF_LinkExtract::CheckMailLink(CFX_WideString* str) {
   // Check the local part.
   int pPos = aPos;  // Used to track the position of '@' or '.'.
   for (int i = aPos - 1; i >= 0; i--) {
-    wchar_t ch = str->GetAt(i);
+    wchar_t ch = (*str)[i];
     if (ch == L'_' || ch == L'-' || FXSYS_iswalnum(ch))
       continue;
 
@@ -278,7 +278,7 @@ bool CPDF_LinkExtract::CheckMailLink(CFX_WideString* str) {
   int nLen = str->GetLength();
   pPos = 0;  // Used to track the position of '.'.
   for (int i = aPos + 1; i < nLen; i++) {
-    wchar_t wch = str->GetAt(i);
+    wchar_t wch = (*str)[i];
     if (wch == L'-' || FXSYS_iswalnum(wch))
       continue;
 
diff --git a/core/fpdftext/cpdf_textpage.cpp b/core/fpdftext/cpdf_textpage.cpp
index 1470ad700d..a4c8b8fba0 100644
--- a/core/fpdftext/cpdf_textpage.cpp
+++ b/core/fpdftext/cpdf_textpage.cpp
@@ -701,7 +701,7 @@ void CPDF_TextPage::CloseTempLine() {
   CFX_WideString str = m_TempTextBuf.MakeString();
   bool bPrevSpace = false;
   for (int i = 0; i < str.GetLength(); i++) {
-    if (str.GetAt(i) != ' ') {
+    if (str[i] != ' ') {
       bPrevSpace = false;
       continue;
     }
@@ -841,8 +841,7 @@ FPDFText_MarkedContent CPDF_TextPage::PreMarkedContent(PDFTEXT_Obj Obj) {
   CPDF_Font* pFont = pTextObj->GetFont();
   bExist = false;
   for (FX_STRSIZE i = 0; i < nItems; i++) {
-    if (pFont->CharCodeFromUnicode(actText.GetAt(i)) !=
-        CPDF_Font::kInvalidCharCode) {
+    if (pFont->CharCodeFromUnicode(actText[i]) != CPDF_Font::kInvalidCharCode) {
       bExist = true;
       break;
     }
@@ -852,7 +851,7 @@ FPDFText_MarkedContent CPDF_TextPage::PreMarkedContent(PDFTEXT_Obj Obj) {
 
   bExist = false;
   for (FX_STRSIZE i = 0; i < nItems; i++) {
-    wchar_t wChar = actText.GetAt(i);
+    wchar_t wChar = actText[i];
     if ((wChar > 0x80 && wChar < 0xFFFD) || (wChar <= 0x80 && isprint(wChar))) {
       bExist = true;
       break;
@@ -889,7 +888,7 @@ void CPDF_TextPage::ProcessMarkedContent(PDFTEXT_Obj Obj) {
   matrix.Concat(Obj.m_formMatrix);
 
   for (FX_STRSIZE k = 0; k < nItems; k++) {
-    wchar_t wChar = actText.GetAt(k);
+    wchar_t wChar = actText[k];
     if (wChar <= 0x80 && !isprint(wChar))
       wChar = 0x20;
     if (wChar >= 0xFFFD)
@@ -1005,12 +1004,12 @@ void CPDF_TextPage::ProcessTextObject(PDFTEXT_Obj Obj) {
               pTextObj->GetFont()->UnicodeFromCharCode(item.m_CharCode);
           if (wstrItem.IsEmpty())
             wstrItem += (wchar_t)item.m_CharCode;
-          wchar_t curChar = wstrItem.GetAt(0);
+          wchar_t curChar = wstrItem[0];
           if (curChar == 0x2D || curChar == 0xAD)
             return;
         }
         while (m_TempTextBuf.GetSize() > 0 &&
-               m_TempTextBuf.AsStringC().GetAt(m_TempTextBuf.GetLength() - 1) ==
+               m_TempTextBuf.AsStringC()[m_TempTextBuf.GetLength() - 1] ==
                    0x20) {
           m_TempTextBuf.Delete(m_TempTextBuf.GetLength() - 1, 1);
           m_TempCharList.pop_back();
@@ -1053,7 +1052,7 @@ void CPDF_TextPage::ProcessTextObject(PDFTEXT_Obj Obj) {
       CFX_WideString str = m_TempTextBuf.MakeString();
       if (str.IsEmpty())
         str = m_TextBuf.AsStringC();
-      if (str.IsEmpty() || str.GetAt(str.GetLength() - 1) == TEXT_SPACE_CHAR)
+      if (str.IsEmpty() || str[str.GetLength() - 1] == TEXT_SPACE_CHAR)
         continue;
 
       float fontsize_h = pTextObj->m_TextState.GetFontSizeH();
@@ -1164,7 +1163,7 @@ void CPDF_TextPage::ProcessTextObject(PDFTEXT_Obj Obj) {
       }
       if (!bDel) {
         for (int nIndex = 0; nIndex < nTotal; nIndex++) {
-          charinfo.m_Unicode = wstrItem.GetAt(nIndex);
+          charinfo.m_Unicode = wstrItem[nIndex];
           if (charinfo.m_Unicode) {
             charinfo.m_Index = m_TextBuf.GetLength();
             m_TempTextBuf.AppendChar(charinfo.m_Unicode);
@@ -1175,8 +1174,7 @@ void CPDF_TextPage::ProcessTextObject(PDFTEXT_Obj Obj) {
         }
       } else if (i == 0) {
         CFX_WideString str = m_TempTextBuf.MakeString();
-        if (!str.IsEmpty() &&
-            str.GetAt(str.GetLength() - 1) == TEXT_SPACE_CHAR) {
+        if (!str.IsEmpty() && str[str.GetLength() - 1] == TEXT_SPACE_CHAR) {
           m_TempTextBuf.Delete(m_TempTextBuf.GetLength() - 1, 1);
           m_TempCharList.pop_back();
         }
@@ -1225,12 +1223,12 @@ bool CPDF_TextPage::IsHyphen(wchar_t curChar) {
   if (nCount < 1)
     return false;
   int nIndex = nCount - 1;
-  wchar_t wcTmp = strCurText.GetAt(nIndex);
+  wchar_t wcTmp = strCurText[nIndex];
   while (wcTmp == 0x20 && nIndex > 0 && nIndex <= nCount - 1)
-    wcTmp = strCurText.GetAt(--nIndex);
+    wcTmp = strCurText[--nIndex];
   if (0x2D == wcTmp || 0xAD == wcTmp) {
     if (--nIndex > 0) {
-      wchar_t preChar = strCurText.GetAt((nIndex));
+      wchar_t preChar = strCurText[nIndex];
       if (FXSYS_iswalpha(preChar) && FXSYS_iswalpha(curChar))
         return true;
     }
@@ -1268,7 +1266,7 @@ CPDF_TextPage::GenerateCharacter CPDF_TextPage::ProcessInsertObject(
       pObj->GetFont()->UnicodeFromCharCode(item.m_CharCode);
   if (wstrItem.IsEmpty())
     wstrItem += static_cast<wchar_t>(item.m_CharCode);
-  wchar_t curChar = wstrItem.GetAt(0);
+  wchar_t curChar = wstrItem[0];
   if (WritingMode == TextOrientation::Horizontal) {
     if (this_rect.Height() > 4.5 && prev_rect.Height() > 4.5) {
       float top = this_rect.top < prev_rect.top ? this_rect.top : prev_rect.top;
@@ -1357,7 +1355,7 @@ CPDF_TextPage::GenerateCharacter CPDF_TextPage::ProcessInsertObject(
       m_pPreTextObj->GetFont()->UnicodeFromCharCode(PrevItem.m_CharCode);
   if (PrevStr.IsEmpty())
     return GenerateCharacter::None;
-  wchar_t preChar = PrevStr.GetAt(PrevStr.GetLength() - 1);
+  wchar_t preChar = PrevStr[PrevStr.GetLength() - 1];
   CFX_Matrix matrix = pObj->GetTextMatrix();
   matrix.Concat(formMatrix);
 
diff --git a/core/fpdftext/cpdf_textpagefind.cpp b/core/fpdftext/cpdf_textpagefind.cpp
index 3c8e532a7f..55f940cad7 100644
--- a/core/fpdftext/cpdf_textpagefind.cpp
+++ b/core/fpdftext/cpdf_textpagefind.cpp
@@ -110,7 +110,7 @@ bool CPDF_TextPageFind::FindFirst(const CFX_WideString& findwhat,
   m_csFindWhatArray.clear();
   int i = 0;
   while (i < len) {
-    if (findwhatStr.GetAt(i) != ' ')
+    if (findwhatStr[i] != ' ')
       break;
     i++;
   }
@@ -150,7 +150,7 @@ bool CPDF_TextPageFind::FindNext() {
     CFX_WideString csWord = m_csFindWhatArray[iWord];
     if (csWord.IsEmpty()) {
       if (iWord == nCount - 1) {
-        wchar_t strInsert = m_strText.GetAt(nStartPos);
+        wchar_t strInsert = m_strText[nStartPos];
         if (strInsert == TEXT_LINEFEED_CHAR || strInsert == TEXT_SPACE_CHAR ||
             strInsert == TEXT_RETURN_CHAR || strInsert == 160) {
           nResultPos = nStartPos + 1;
@@ -174,16 +174,16 @@ bool CPDF_TextPageFind::FindNext() {
     bool bMatch = true;
     if (iWord != 0 && !bSpaceStart) {
       int PreResEndPos = nStartPos;
-      int curChar = csWord.GetAt(0);
+      int curChar = csWord[0];
       CFX_WideString lastWord = m_csFindWhatArray[iWord - 1];
-      int lastChar = lastWord.GetAt(lastWord.GetLength() - 1);
+      int lastChar = lastWord[lastWord.GetLength() - 1];
       if (nStartPos == nResultPos &&
           !(IsIgnoreSpaceCharacter(lastChar) ||
             IsIgnoreSpaceCharacter(curChar))) {
         bMatch = false;
       }
       for (int d = PreResEndPos; d < nResultPos; d++) {
-        wchar_t strInsert = m_strText.GetAt(d);
+        wchar_t strInsert = m_strText[d];
         if (strInsert != TEXT_LINEFEED_CHAR && strInsert != TEXT_SPACE_CHAR &&
             strInsert != TEXT_RETURN_CHAR && strInsert != 160) {
           bMatch = false;
@@ -192,7 +192,7 @@ bool CPDF_TextPageFind::FindNext() {
       }
     } else if (bSpaceStart) {
       if (nResultPos > 0) {
-        wchar_t strInsert = m_strText.GetAt(nResultPos - 1);
+        wchar_t strInsert = m_strText[nResultPos - 1];
         if (strInsert != TEXT_LINEFEED_CHAR && strInsert != TEXT_SPACE_CHAR &&
             strInsert != TEXT_RETURN_CHAR && strInsert != 160) {
           bMatch = false;
@@ -293,7 +293,7 @@ void CPDF_TextPageFind::ExtractFindWhat(const CFX_WideString& findwhat) {
     int pos = 0;
     while (pos < csWord.GetLength()) {
       CFX_WideString curStr = csWord.Mid(pos, 1);
-      wchar_t curChar = csWord.GetAt(pos);
+      wchar_t curChar = csWord[pos];
       if (IsIgnoreSpaceCharacter(curChar)) {
         if (pos > 0 && curChar == 0x2019) {
           pos++;
@@ -326,12 +326,12 @@ bool CPDF_TextPageFind::IsMatchWholeWord(const CFX_WideString& csPageText,
   int char_count = endPos - startPos + 1;
   if (char_count < 1)
     return false;
-  if (char_count == 1 && csPageText.GetAt(startPos) > 255)
+  if (char_count == 1 && csPageText[startPos] > 255)
     return true;
   if (startPos - 1 >= 0)
-    char_left = csPageText.GetAt(startPos - 1);
+    char_left = csPageText[startPos - 1];
   if (startPos + char_count < csPageText.GetLength())
-    char_right = csPageText.GetAt(startPos + char_count);
+    char_right = csPageText[startPos + char_count];
   if ((char_left > 'A' && char_left < 'a') ||
       (char_left > 'a' && char_left < 'z') ||
       (char_left > 0xfb00 && char_left < 0xfb06) || std::iswdigit(char_left) ||
@@ -348,9 +348,9 @@ bool CPDF_TextPageFind::IsMatchWholeWord(const CFX_WideString& csPageText,
     return false;
   }
   if (char_count > 0) {
-    if (std::iswdigit(char_left) && std::iswdigit(csPageText.GetAt(startPos)))
+    if (std::iswdigit(char_left) && std::iswdigit(csPageText[startPos]))
       return false;
-    if (std::iswdigit(char_right) && std::iswdigit(csPageText.GetAt(endPos)))
+    if (std::iswdigit(char_right) && std::iswdigit(csPageText[endPos]))
       return false;
   }
   return true;
@@ -386,7 +386,7 @@ CFX_WideString CPDF_TextPageFind::MakeReverse(const CFX_WideString& str) {
   str2.clear();
   int nlen = str.GetLength();
   for (int i = nlen - 1; i >= 0; i--)
-    str2 += str.GetAt(i);
+    str2 += str[i];
   return str2;
 }
 
diff --git a/core/fxcrt/cfx_bytestring.cpp b/core/fxcrt/cfx_bytestring.cpp
index 0aba3be12a..cd049dcc5d 100644
--- a/core/fxcrt/cfx_bytestring.cpp
+++ b/core/fxcrt/cfx_bytestring.cpp
@@ -518,6 +518,12 @@ void CFX_ByteString::Format(const char* pFormat, ...) {
   va_end(argList);
 }
 
+void CFX_ByteString::SetAt(FX_STRSIZE index, char c) {
+  ASSERT(index >= 0 && index < GetLength());
+  ReallocBeforeWrite(m_pData->m_nDataLength);
+  m_pData->m_String[index] = c;
+}
+
 FX_STRSIZE CFX_ByteString::Insert(FX_STRSIZE index, char ch) {
   const FX_STRSIZE cur_length = m_pData ? m_pData->m_nDataLength : 0;
   if (index != pdfium::clamp(index, 0, cur_length))
@@ -694,12 +700,6 @@ FX_STRSIZE CFX_ByteString::Replace(const CFX_ByteStringC& pOld,
   return nCount;
 }
 
-void CFX_ByteString::SetAt(FX_STRSIZE index, char c) {
-  ASSERT(index >= 0 && index < GetLength());
-  ReallocBeforeWrite(m_pData->m_nDataLength);
-  m_pData->m_String[index] = c;
-}
-
 CFX_WideString CFX_ByteString::UTF8Decode() const {
   CFX_UTF8Decoder decoder;
   for (FX_STRSIZE i = 0; i < GetLength(); i++) {
@@ -721,10 +721,10 @@ int CFX_ByteString::Compare(const CFX_ByteStringC& str) const {
   int that_len = str.GetLength();
   int min_len = this_len < that_len ? this_len : that_len;
   for (int i = 0; i < min_len; i++) {
-    if ((uint8_t)m_pData->m_String[i] < str.GetAt(i)) {
+    if ((uint8_t)m_pData->m_String[i] < str[i]) {
       return -1;
     }
-    if ((uint8_t)m_pData->m_String[i] > str.GetAt(i)) {
+    if ((uint8_t)m_pData->m_String[i] > str[i]) {
       return 1;
     }
   }
diff --git a/core/fxcrt/cfx_bytestring.h b/core/fxcrt/cfx_bytestring.h
index df31751273..3e8b6619c2 100644
--- a/core/fxcrt/cfx_bytestring.h
+++ b/core/fxcrt/cfx_bytestring.h
@@ -107,14 +107,13 @@ class CFX_ByteString {
   const CFX_ByteString& operator+=(const CFX_ByteString& str);
   const CFX_ByteString& operator+=(const CFX_ByteStringC& bstrc);
 
-  uint8_t GetAt(FX_STRSIZE index) const {
+  const CharType& operator[](const FX_STRSIZE index) const {
     ASSERT(index >= 0 && index < GetLength());
     return m_pData->m_String[index];
   }
 
-  uint8_t operator[](FX_STRSIZE index) const { return GetAt(index); }
-
   void SetAt(FX_STRSIZE index, char c);
+
   FX_STRSIZE Insert(FX_STRSIZE index, char ch);
   FX_STRSIZE InsertAtFront(char ch) { return Insert(0, ch); }
   FX_STRSIZE InsertAtBack(char ch) { return Insert(GetLength(), ch); }
diff --git a/core/fxcrt/cfx_bytestring_unittest.cpp b/core/fxcrt/cfx_bytestring_unittest.cpp
index 680a37e342..35f407f6ec 100644
--- a/core/fxcrt/cfx_bytestring_unittest.cpp
+++ b/core/fxcrt/cfx_bytestring_unittest.cpp
@@ -11,26 +11,8 @@
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/base/stl_util.h"
 
-TEST(fxcrt, ByteStringGetAt) {
-  CFX_ByteString short_string("a");
-  CFX_ByteString longer_string("abc");
-  CFX_ByteString embedded_nul_string("ab\0c", 4);
-
-#ifndef NDEBUG
-  EXPECT_DEATH({ short_string.GetAt(-1); }, ".*");
-#endif
-  EXPECT_EQ('a', short_string.GetAt(0));
-#ifndef NDEBUG
-  EXPECT_DEATH({ short_string.GetAt(1); }, ".*");
-#endif
-  EXPECT_EQ('c', longer_string.GetAt(2));
-  EXPECT_EQ('b', embedded_nul_string.GetAt(1));
-  EXPECT_EQ('\0', embedded_nul_string.GetAt(2));
-  EXPECT_EQ('c', embedded_nul_string.GetAt(3));
-}
-
-TEST(fxcrt, ByteStringOperatorSubscript) {
-  CFX_ByteString abc("abc");
+TEST(fxcrt, ByteStringElementAccess) {
+  const CFX_ByteString abc("abc");
 #ifndef NDEBUG
   EXPECT_DEATH({ abc[-1]; }, ".*");
 #endif
@@ -40,22 +22,35 @@ TEST(fxcrt, ByteStringOperatorSubscript) {
 #ifndef NDEBUG
   EXPECT_DEATH({ abc[3]; }, ".*");
 #endif
-}
 
-TEST(fxcrt, ByteStringSetAt) {
-  // CFX_ByteString includes the NUL terminator for non-empty strings.
-  CFX_ByteString abc("abc");
+  CFX_ByteString mutable_abc = abc;
+  EXPECT_EQ(abc.c_str(), mutable_abc.c_str());
+  EXPECT_EQ('a', mutable_abc[0]);
+  EXPECT_EQ('b', mutable_abc[1]);
+  EXPECT_EQ('c', mutable_abc[2]);
+  EXPECT_EQ(abc.c_str(), mutable_abc.c_str());
+
 #ifndef NDEBUG
-  EXPECT_DEATH({ abc.SetAt(-1, 'd'); }, ".*");
+  EXPECT_DEATH({ mutable_abc.SetAt(-1, 'd'); }, ".*");
+  EXPECT_EQ("abc", abc);
 #endif
-  abc.SetAt(0, 'd');
-  EXPECT_EQ("dbc", abc);
-  abc.SetAt(1, 'e');
-  EXPECT_EQ("dec", abc);
-  abc.SetAt(2, 'f');
-  EXPECT_EQ("def", abc);
+  const char* c_str = abc.c_str();
+  mutable_abc.SetAt(0, 'd');
+  EXPECT_EQ(c_str, abc.c_str());
+  EXPECT_NE(c_str, mutable_abc.c_str());
+  EXPECT_EQ("abc", abc);
+  EXPECT_EQ("dbc", mutable_abc);
+
+  mutable_abc.SetAt(1, 'e');
+  EXPECT_EQ("abc", abc);
+  EXPECT_EQ("dec", mutable_abc);
+
+  mutable_abc.SetAt(2, 'f');
+  EXPECT_EQ("abc", abc);
+  EXPECT_EQ("def", mutable_abc);
 #ifndef NDEBUG
-  EXPECT_DEATH({ abc.SetAt(3, 'g'); }, ".*");
+  EXPECT_DEATH({ mutable_abc.SetAt(3, 'g'); }, ".*");
+  EXPECT_EQ("abc", abc);
 #endif
 }
 
@@ -943,25 +938,7 @@ TEST(fxcrt, ByteStringCMid) {
   EXPECT_EQ(trailing_substring, longer_string.Mid(4, 3));
 }
 
-TEST(fxcrt, ByteStringCGetAt) {
-  CFX_ByteStringC short_string("a");
-  CFX_ByteStringC longer_string("abc");
-  CFX_ByteStringC embedded_nul_string("ab\0c", 4);
-
-#ifndef NDEBUG
-  EXPECT_DEATH({ short_string.GetAt(-1); }, ".*");
-#endif
-  EXPECT_EQ('a', static_cast<char>(short_string.GetAt(0)));
-#ifndef NDEBUG
-  EXPECT_DEATH({ short_string.GetAt(1); }, ".*");
-#endif
-  EXPECT_EQ('c', static_cast<char>(longer_string.GetAt(2)));
-  EXPECT_EQ('b', static_cast<char>(embedded_nul_string.GetAt(1)));
-  EXPECT_EQ('\0', static_cast<char>(embedded_nul_string.GetAt(2)));
-  EXPECT_EQ('c', static_cast<char>(embedded_nul_string.GetAt(3)));
-}
-
-TEST(fxcrt, ByteStringCOperatorSubscript) {
+TEST(fxcrt, ByteStringCElementAccess) {
   // CFX_ByteStringC includes the NUL terminator for non-empty strings.
   CFX_ByteStringC abc("abc");
 #ifndef NDEBUG
diff --git a/core/fxcrt/cfx_chariter.cpp b/core/fxcrt/cfx_chariter.cpp
index b726a7e484..d26dd2df8f 100644
--- a/core/fxcrt/cfx_chariter.cpp
+++ b/core/fxcrt/cfx_chariter.cpp
@@ -29,7 +29,7 @@ bool CFX_CharIter::Next(bool bPrev) {
 }
 
 wchar_t CFX_CharIter::GetChar() {
-  return m_wsText.GetAt(m_nIndex);
+  return m_wsText[m_nIndex];
 }
 
 void CFX_CharIter::SetAt(int32_t nIndex) {
diff --git a/core/fxcrt/cfx_string_c_template.h b/core/fxcrt/cfx_string_c_template.h
index bc0fe1e0a0..99948e90a0 100644
--- a/core/fxcrt/cfx_string_c_template.h
+++ b/core/fxcrt/cfx_string_c_template.h
@@ -119,12 +119,12 @@ class CFX_StringCTemplate {
   FX_STRSIZE GetLength() const { return m_Length; }
   bool IsEmpty() const { return m_Length == 0; }
 
-  UnsignedType GetAt(FX_STRSIZE index) const {
+  const UnsignedType& operator[](const FX_STRSIZE index) const {
     ASSERT(index >= 0 && index < GetLength());
     return m_Ptr.Get()[index];
   }
 
-  CharType CharAt(FX_STRSIZE index) const {
+  const CharType CharAt(const FX_STRSIZE index) const {
     ASSERT(index >= 0 && index < GetLength());
     return static_cast<CharType>(m_Ptr.Get()[index]);
   }
@@ -164,8 +164,6 @@ class CFX_StringCTemplate {
     return CFX_StringCTemplate(m_Ptr.Get() + m_Length - count, count);
   }
 
-  UnsignedType operator[](FX_STRSIZE index) const { return GetAt(index); }
-
   bool operator<(const CFX_StringCTemplate& that) const {
     int result = FXSYS_cmp(reinterpret_cast<const CharType*>(m_Ptr.Get()),
                            reinterpret_cast<const CharType*>(that.m_Ptr.Get()),
diff --git a/core/fxcrt/cfx_widestring.cpp b/core/fxcrt/cfx_widestring.cpp
index c2e1e4877d..01fc8c764e 100644
--- a/core/fxcrt/cfx_widestring.cpp
+++ b/core/fxcrt/cfx_widestring.cpp
@@ -841,12 +841,6 @@ FX_STRSIZE CFX_WideString::Replace(const CFX_WideStringC& pOld,
   return nCount;
 }
 
-void CFX_WideString::SetAt(FX_STRSIZE index, wchar_t c) {
-  ASSERT(index >= 0 && index < GetLength());
-  ReallocBeforeWrite(m_pData->m_nDataLength);
-  m_pData->m_String[index] = c;
-}
-
 // static
 CFX_WideString CFX_WideString::FromLocal(const CFX_ByteStringC& str) {
   return FromCodePage(str, 0);
@@ -886,6 +880,12 @@ CFX_WideString CFX_WideString::FromUTF16LE(const unsigned short* wstr,
   return result;
 }
 
+void CFX_WideString::SetAt(FX_STRSIZE index, wchar_t c) {
+  ASSERT(index >= 0 && index < GetLength());
+  ReallocBeforeWrite(m_pData->m_nDataLength);
+  m_pData->m_String[index] = c;
+}
+
 int CFX_WideString::Compare(const wchar_t* lpsz) const {
   if (m_pData)
     return wcscmp(m_pData->m_String, lpsz);
diff --git a/core/fxcrt/cfx_widestring.h b/core/fxcrt/cfx_widestring.h
index b49e898f32..d57e47c62f 100644
--- a/core/fxcrt/cfx_widestring.h
+++ b/core/fxcrt/cfx_widestring.h
@@ -101,13 +101,11 @@ class CFX_WideString {
 
   bool operator<(const CFX_WideString& str) const;
 
-  wchar_t GetAt(FX_STRSIZE index) const {
+  const CharType& operator[](const FX_STRSIZE index) const {
     ASSERT(index >= 0 && index < GetLength());
     return m_pData->m_String[index];
   }
 
-  wchar_t operator[](FX_STRSIZE index) const { return GetAt(index); }
-
   void SetAt(FX_STRSIZE index, wchar_t c);
 
   int Compare(const wchar_t* str) const;
diff --git a/core/fxcrt/cfx_widestring_unittest.cpp b/core/fxcrt/cfx_widestring_unittest.cpp
index a23763218d..e7206dde06 100644
--- a/core/fxcrt/cfx_widestring_unittest.cpp
+++ b/core/fxcrt/cfx_widestring_unittest.cpp
@@ -10,26 +10,8 @@
 
 #include "testing/gtest/include/gtest/gtest.h"
 
-TEST(fxcrt, WideStringGetAt) {
-  CFX_WideString short_string(L"a");
-  CFX_WideString longer_string(L"abc");
-  CFX_WideString embedded_nul_string(L"ab\0c", 4);
-
-#ifndef NDEBUG
-  EXPECT_DEATH({ short_string.GetAt(-1); }, ".*");
-#endif
-  EXPECT_EQ(L'a', short_string.GetAt(0));
-#ifndef NDEBUG
-  EXPECT_DEATH({ short_string.GetAt(1); }, ".*");
-#endif
-  EXPECT_EQ(L'c', longer_string.GetAt(2));
-  EXPECT_EQ(L'b', embedded_nul_string.GetAt(1));
-  EXPECT_EQ(L'\0', embedded_nul_string.GetAt(2));
-  EXPECT_EQ(L'c', embedded_nul_string.GetAt(3));
-}
-
-TEST(fxcrt, WideStringOperatorSubscript) {
-  CFX_WideString abc(L"abc");
+TEST(fxcrt, WideStringElementAccess) {
+  const CFX_WideString abc(L"abc");
 #ifndef NDEBUG
   EXPECT_DEATH({ abc[-1]; }, ".*");
 #endif
@@ -39,21 +21,34 @@ TEST(fxcrt, WideStringOperatorSubscript) {
 #ifndef NDEBUG
   EXPECT_DEATH({ abc[4]; }, ".*");
 #endif
-}
 
-TEST(fxcrt, WideStringSetAt) {
-  CFX_WideString abc(L"abc");
+  CFX_WideString mutable_abc = abc;
+  EXPECT_EQ(abc.c_str(), mutable_abc.c_str());
+  EXPECT_EQ(L'a', mutable_abc[0]);
+  EXPECT_EQ(L'b', mutable_abc[1]);
+  EXPECT_EQ(L'c', mutable_abc[2]);
+  EXPECT_EQ(abc.c_str(), mutable_abc.c_str());
 #ifndef NDEBUG
-  EXPECT_DEATH({ abc.SetAt(-1, L'd'); }, ".*");
+  EXPECT_DEATH({ mutable_abc.SetAt(-1, L'd'); }, ".*");
+  EXPECT_EQ(L"abc", abc);
 #endif
-  abc.SetAt(0, L'd');
-  EXPECT_EQ(L"dbc", abc);
-  abc.SetAt(1, L'e');
-  EXPECT_EQ(L"dec", abc);
-  abc.SetAt(2, L'f');
-  EXPECT_EQ(L"def", abc);
+  const wchar_t* c_str = abc.c_str();
+  mutable_abc.SetAt(0, L'd');
+  EXPECT_EQ(c_str, abc.c_str());
+  EXPECT_NE(c_str, mutable_abc.c_str());
+  EXPECT_EQ(L"abc", abc);
+  EXPECT_EQ(L"dbc", mutable_abc);
+
+  mutable_abc.SetAt(1, L'e');
+  EXPECT_EQ(L"abc", abc);
+  EXPECT_EQ(L"dec", mutable_abc);
+
+  mutable_abc.SetAt(2, L'f');
+  EXPECT_EQ(L"abc", abc);
+  EXPECT_EQ(L"def", mutable_abc);
 #ifndef NDEBUG
-  EXPECT_DEATH({ abc.SetAt(3, L'g'); }, ".*");
+  EXPECT_DEATH({ mutable_abc.SetAt(3, L'g'); }, ".*");
+  EXPECT_EQ(L"abc", abc);
 #endif
 }
 
@@ -780,25 +775,7 @@ TEST(fxcrt, WideStringCFromVector) {
   EXPECT_EQ(nullptr, cleared_string.raw_str());
 }
 
-TEST(fxcrt, WideStringCGetAt) {
-  CFX_WideStringC short_string(L"a");
-  CFX_WideStringC longer_string(L"abc");
-  CFX_WideStringC embedded_nul_string(L"ab\0c", 4);
-
-#ifndef NDEBUG
-  EXPECT_DEATH({ short_string.GetAt(-1); }, ".*");
-#endif
-  EXPECT_EQ(L'a', static_cast<wchar_t>(short_string.GetAt(0)));
-#ifndef NDEBUG
-  EXPECT_DEATH({ short_string.GetAt(1); }, ".*");
-#endif
-  EXPECT_EQ(L'c', static_cast<wchar_t>(longer_string.GetAt(2)));
-  EXPECT_EQ(L'b', static_cast<wchar_t>(embedded_nul_string.GetAt(1)));
-  EXPECT_EQ(L'\0', static_cast<wchar_t>(embedded_nul_string.GetAt(2)));
-  EXPECT_EQ(L'c', static_cast<wchar_t>(embedded_nul_string.GetAt(3)));
-}
-
-TEST(fxcrt, WideStringCOperatorSubscript) {
+TEST(fxcrt, WideStringCElementAccess) {
   CFX_WideStringC abc(L"abc");
 #ifndef NDEBUG
   EXPECT_DEATH({ abc[-1]; }, ".*");
diff --git a/core/fxcrt/xml/cxml_parser.cpp b/core/fxcrt/xml/cxml_parser.cpp
index 4d9e3dc469..ebd5873b33 100644
--- a/core/fxcrt/xml/cxml_parser.cpp
+++ b/core/fxcrt/xml/cxml_parser.cpp
@@ -171,7 +171,7 @@ void CXML_Parser::SkipLiterals(const CFX_ByteStringC& str) {
   int32_t i = 0, iLen = str.GetLength();
   do {
     while (m_dwIndex < m_dwBufferSize) {
-      if (str.GetAt(i) != m_pBuffer[m_dwIndex++]) {
+      if (str[i] != m_pBuffer[m_dwIndex++]) {
         i = 0;
         continue;
       }
diff --git a/fpdfsdk/javascript/Document.cpp b/fpdfsdk/javascript/Document.cpp
index 77878a53ed..9b821471c2 100644
--- a/fpdfsdk/javascript/Document.cpp
+++ b/fpdfsdk/javascript/Document.cpp
@@ -1018,7 +1018,7 @@ bool Document::documentFileName(CJS_Runtime* pRuntime,
   CFX_WideString wsFilePath = m_pFormFillEnv->JS_docGetFilePath();
   int32_t i = wsFilePath.GetLength() - 1;
   for (; i >= 0; i--) {
-    if (wsFilePath.GetAt(i) == L'\\' || wsFilePath.GetAt(i) == L'/')
+    if (wsFilePath[i] == L'\\' || wsFilePath[i] == L'/')
       break;
   }
   if (i >= 0 && i < wsFilePath.GetLength() - 1) {
diff --git a/fpdfsdk/javascript/PublicMethods.cpp b/fpdfsdk/javascript/PublicMethods.cpp
index bf35a67edc..2996316d79 100644
--- a/fpdfsdk/javascript/PublicMethods.cpp
+++ b/fpdfsdk/javascript/PublicMethods.cpp
@@ -235,7 +235,7 @@ int CJS_PublicMethods::ParseStringInteger(const CFX_WideString& str,
     if (i - nStart > 10)
       break;
 
-    wchar_t c = str.GetAt(i);
+    wchar_t c = str[i];
     if (!std::iswdigit(c))
       break;
 
@@ -254,7 +254,7 @@ CFX_WideString CJS_PublicMethods::ParseStringString(const CFX_WideString& str,
   CFX_WideString swRet;
   nSkip = 0;
   for (int i = nStart, sz = str.GetLength(); i < sz; i++) {
-    wchar_t c = str.GetAt(i);
+    wchar_t c = str[i];
     if (!std::iswdigit(c))
       break;
 
@@ -286,7 +286,7 @@ double CJS_PublicMethods::ParseNormalDate(const CFX_WideString& value,
     if (nIndex > 2)
       break;
 
-    wchar_t c = value.GetAt(i);
+    wchar_t c = value[i];
     if (std::iswdigit(c)) {
       number[nIndex++] = ParseStringInteger(value, i, nSkip, 4);
       i += nSkip;
@@ -373,7 +373,7 @@ double CJS_PublicMethods::MakeRegularDate(const CFX_WideString& value,
     if (bExit)
       break;
 
-    wchar_t c = format.GetAt(i);
+    wchar_t c = format[i];
     switch (c) {
       case ':':
       case '.':
@@ -396,7 +396,7 @@ double CJS_PublicMethods::MakeRegularDate(const CFX_WideString& value,
         int nSkip = 0;
         int remaining = format.GetLength() - i - 1;
 
-        if (remaining == 0 || format.GetAt(i + 1) != c) {
+        if (remaining == 0 || format[i + 1] != c) {
           switch (c) {
             case 'y':
               i++;
@@ -433,12 +433,12 @@ double CJS_PublicMethods::MakeRegularDate(const CFX_WideString& value,
               j += nSkip;
               break;
             case 't':
-              bPm = (j < value.GetLength() && value.GetAt(j) == 'p');
+              bPm = (j < value.GetLength() && value[j] == 'p');
               i++;
               j++;
               break;
           }
-        } else if (remaining == 1 || format.GetAt(i + 2) != c) {
+        } else if (remaining == 1 || format[i + 2] != c) {
           switch (c) {
             case 'y':
               nYear = ParseStringInteger(value, j, nSkip, 4);
@@ -476,13 +476,13 @@ double CJS_PublicMethods::MakeRegularDate(const CFX_WideString& value,
               j += nSkip;
               break;
             case 't':
-              bPm = (j + 1 < value.GetLength() && value.GetAt(j) == 'p' &&
-                     value.GetAt(j + 1) == 'm');
+              bPm = (j + 1 < value.GetLength() && value[j] == 'p' &&
+                     value[j + 1] == 'm');
               i += 2;
               j += 2;
               break;
           }
-        } else if (remaining == 2 || format.GetAt(i + 3) != c) {
+        } else if (remaining == 2 || format[i + 3] != c) {
           switch (c) {
             case 'm': {
               CFX_WideString sMonth = ParseStringString(value, j, nSkip);
@@ -510,7 +510,7 @@ double CJS_PublicMethods::MakeRegularDate(const CFX_WideString& value,
               j += 3;
               break;
           }
-        } else if (remaining == 3 || format.GetAt(i + 4) != c) {
+        } else if (remaining == 3 || format[i + 4] != c) {
           switch (c) {
             case 'y':
               nYear = ParseStringInteger(value, j, nSkip, 4);
@@ -548,7 +548,7 @@ double CJS_PublicMethods::MakeRegularDate(const CFX_WideString& value,
               break;
           }
         } else {
-          if (j >= value.GetLength() || format.GetAt(i) != value.GetAt(j)) {
+          if (j >= value.GetLength() || format[i] != value[j]) {
             bBadFormat = true;
             bExit = true;
           }
@@ -566,7 +566,7 @@ double CJS_PublicMethods::MakeRegularDate(const CFX_WideString& value,
       default:
         if (value.GetLength() <= j) {
           bExit = true;
-        } else if (format.GetAt(i) != value.GetAt(j)) {
+        } else if (format[i] != value[j]) {
           bBadFormat = true;
           bExit = true;
         }
@@ -630,7 +630,7 @@ CFX_WideString CJS_PublicMethods::MakeFormatDate(double dDate,
 
   int i = 0;
   while (i < format.GetLength()) {
-    wchar_t c = format.GetAt(i);
+    wchar_t c = format[i];
     int remaining = format.GetLength() - i - 1;
     sPart = L"";
     switch (c) {
@@ -642,7 +642,7 @@ CFX_WideString CJS_PublicMethods::MakeFormatDate(double dDate,
       case 'M':
       case 's':
       case 't':
-        if (remaining == 0 || format.GetAt(i + 1) != c) {
+        if (remaining == 0 || format[i + 1] != c) {
           switch (c) {
             case 'y':
               sPart += c;
@@ -670,7 +670,7 @@ CFX_WideString CJS_PublicMethods::MakeFormatDate(double dDate,
               break;
           }
           i++;
-        } else if (remaining == 1 || format.GetAt(i + 2) != c) {
+        } else if (remaining == 1 || format[i + 2] != c) {
           switch (c) {
             case 'y':
               sPart.Format(L"%02d", nYear - (nYear / 100) * 100);
@@ -698,7 +698,7 @@ CFX_WideString CJS_PublicMethods::MakeFormatDate(double dDate,
               break;
           }
           i += 2;
-        } else if (remaining == 2 || format.GetAt(i + 3) != c) {
+        } else if (remaining == 2 || format[i + 3] != c) {
           switch (c) {
             case 'm':
               i += 3;
@@ -712,7 +712,7 @@ CFX_WideString CJS_PublicMethods::MakeFormatDate(double dDate,
               sPart += c;
               break;
           }
-        } else if (remaining == 3 || format.GetAt(i + 4) != c) {
+        } else if (remaining == 3 || format[i + 4] != c) {
           switch (c) {
             case 'y':
               sPart.Format(L"%04d", nYear);
@@ -1762,7 +1762,7 @@ bool CJS_PublicMethods::AFExtractNums(CJS_Runtime* pRuntime,
   }
 
   CFX_WideString str = params[0].ToCFXWideString(pRuntime);
-  if (str.GetAt(0) == L'.' || str.GetAt(0) == L',')
+  if (str[0] == L'.' || str[0] == L',')
     str = L"0" + str;
 
   CFX_WideString sPart;
diff --git a/fxbarcode/datamatrix/BC_ASCIIEncoder.cpp b/fxbarcode/datamatrix/BC_ASCIIEncoder.cpp
index de57d81b71..e6b7a2b35b 100644
--- a/fxbarcode/datamatrix/BC_ASCIIEncoder.cpp
+++ b/fxbarcode/datamatrix/BC_ASCIIEncoder.cpp
@@ -37,8 +37,8 @@ void CBC_ASCIIEncoder::Encode(CBC_EncoderContext& context, int32_t& e) {
   int32_t n = CBC_HighLevelEncoder::determineConsecutiveDigitCount(
       context.m_msg, context.m_pos);
   if (n >= 2) {
-    wchar_t code = encodeASCIIDigits(context.m_msg.GetAt(context.m_pos),
-                                     context.m_msg.GetAt(context.m_pos + 1), e);
+    wchar_t code = encodeASCIIDigits(context.m_msg[context.m_pos],
+                                     context.m_msg[context.m_pos + 1], e);
     if (e != BCExceptionNO) {
       return;
     }
diff --git a/fxbarcode/datamatrix/BC_Base256Encoder.cpp b/fxbarcode/datamatrix/BC_Base256Encoder.cpp
index edcd411114..0cbd3fdb10 100644
--- a/fxbarcode/datamatrix/BC_Base256Encoder.cpp
+++ b/fxbarcode/datamatrix/BC_Base256Encoder.cpp
@@ -35,7 +35,7 @@ int32_t CBC_Base256Encoder::getEncodingMode() {
 }
 void CBC_Base256Encoder::Encode(CBC_EncoderContext& context, int32_t& e) {
   CFX_WideString buffer;
-  buffer += (wchar_t)'\0';
+  buffer += L'\0';
   while (context.hasMoreCharacters()) {
     wchar_t c = context.getCurrentChar();
     buffer += c;
@@ -50,7 +50,7 @@ void CBC_Base256Encoder::Encode(CBC_EncoderContext& context, int32_t& e) {
   int32_t dataCount = buffer.GetLength() - 1;
   char buf[128];
   FXSYS_itoa(dataCount, buf, 10);
-  buffer.SetAt(0, wchar_t(*buf) - '0');
+  buffer.SetAt(0, static_cast<wchar_t>(*buf) - '0');
   int32_t lengthFieldSize = 1;
   int32_t currentSize =
       context.getCodewordCount() + dataCount + lengthFieldSize;
@@ -61,10 +61,10 @@ void CBC_Base256Encoder::Encode(CBC_EncoderContext& context, int32_t& e) {
   bool mustPad = (context.m_symbolInfo->dataCapacity() - currentSize) > 0;
   if (context.hasMoreCharacters() || mustPad) {
     if (dataCount <= 249) {
-      buffer.SetAt(0, (wchar_t)dataCount);
+      buffer.SetAt(0, static_cast<wchar_t>(dataCount));
     } else if (dataCount > 249 && dataCount <= 1555) {
-      buffer.SetAt(0, (wchar_t)((dataCount / 250) + 249));
-      buffer.Insert(1, (wchar_t)(dataCount % 250));
+      buffer.SetAt(0, static_cast<wchar_t>((dataCount / 250) + 249));
+      buffer.Insert(1, static_cast<wchar_t>(dataCount % 250));
     } else {
       e = BCExceptionIllegalStateMessageLengthInvalid;
       return;
@@ -79,8 +79,8 @@ wchar_t CBC_Base256Encoder::randomize255State(wchar_t ch,
   int32_t pseudoRandom = ((149 * codewordPosition) % 255) + 1;
   int32_t tempVariable = ch + pseudoRandom;
   if (tempVariable <= 255) {
-    return (wchar_t)tempVariable;
+    return static_cast<wchar_t>(tempVariable);
   } else {
-    return (wchar_t)(tempVariable - 256);
+    return static_cast<wchar_t>(tempVariable - 256);
   }
 }
diff --git a/fxbarcode/datamatrix/BC_C40Encoder.cpp b/fxbarcode/datamatrix/BC_C40Encoder.cpp
index 8edd9eccfe..8a55c922ed 100644
--- a/fxbarcode/datamatrix/BC_C40Encoder.cpp
+++ b/fxbarcode/datamatrix/BC_C40Encoder.cpp
@@ -32,9 +32,9 @@
 namespace {
 
 CFX_WideString EncodeToCodewords(const CFX_WideString& sb, int32_t startPos) {
-  wchar_t c1 = sb.GetAt(startPos);
-  wchar_t c2 = sb.GetAt(startPos + 1);
-  wchar_t c3 = sb.GetAt(startPos + 2);
+  wchar_t c1 = sb[startPos];
+  wchar_t c2 = sb[startPos + 1];
+  wchar_t c3 = sb[startPos + 2];
   int32_t v = (1600 * c1) + (40 * c2) + c3 + 1;
   wchar_t cw[2];
   cw[0] = static_cast<wchar_t>(v / 256);
diff --git a/fxbarcode/datamatrix/BC_DefaultPlacement.cpp b/fxbarcode/datamatrix/BC_DefaultPlacement.cpp
index 405b4f72a1..934d79503c 100644
--- a/fxbarcode/datamatrix/BC_DefaultPlacement.cpp
+++ b/fxbarcode/datamatrix/BC_DefaultPlacement.cpp
@@ -107,7 +107,7 @@ void CBC_DefaultPlacement::module(int32_t row,
     col += m_numcols;
     row += 4 - ((m_numcols + 4) % 8);
   }
-  int32_t v = m_codewords.GetAt(pos);
+  int32_t v = m_codewords[pos];
   v &= 1 << (8 - bit);
   setBit(col, row, v != 0);
 }
diff --git a/fxbarcode/datamatrix/BC_EdifactEncoder.cpp b/fxbarcode/datamatrix/BC_EdifactEncoder.cpp
index c7d6b317c1..7407efb47e 100644
--- a/fxbarcode/datamatrix/BC_EdifactEncoder.cpp
+++ b/fxbarcode/datamatrix/BC_EdifactEncoder.cpp
@@ -38,10 +38,10 @@ CFX_WideString EncodeToCodewords(const CFX_WideString& sb, int32_t startPos) {
   if (len == 0)
     return CFX_WideString();
 
-  wchar_t c1 = sb.GetAt(startPos);
-  wchar_t c2 = len >= 2 ? sb.GetAt(startPos + 1) : 0;
-  wchar_t c3 = len >= 3 ? sb.GetAt(startPos + 2) : 0;
-  wchar_t c4 = len >= 4 ? sb.GetAt(startPos + 3) : 0;
+  wchar_t c1 = sb[startPos];
+  wchar_t c2 = len >= 2 ? sb[startPos + 1] : 0;
+  wchar_t c3 = len >= 3 ? sb[startPos + 2] : 0;
+  wchar_t c4 = len >= 4 ? sb[startPos + 3] : 0;
   int32_t v = (c1 << 18) + (c2 << 12) + (c3 << 6) + c4;
   constexpr int32_t kBuflen = 3;
   wchar_t cw[kBuflen];
diff --git a/fxbarcode/datamatrix/BC_EncoderContext.cpp b/fxbarcode/datamatrix/BC_EncoderContext.cpp
index 404c07d980..eaf3768f49 100644
--- a/fxbarcode/datamatrix/BC_EncoderContext.cpp
+++ b/fxbarcode/datamatrix/BC_EncoderContext.cpp
@@ -36,8 +36,8 @@ CBC_EncoderContext::CBC_EncoderContext(const CFX_WideString& msg,
   CFX_WideString sb;
   FX_STRSIZE c = dststr.GetLength();
   for (FX_STRSIZE i = 0; i < c; i++) {
-    wchar_t ch = static_cast<wchar_t>(dststr.GetAt(i) & 0xff);
-    if (ch == '?' && dststr.GetAt(i) != '?') {
+    wchar_t ch = static_cast<wchar_t>(dststr[i] & 0xff);
+    if (ch == '?' && dststr[i] != '?') {
       e = BCExceptionCharactersOutsideISO88591Encoding;
     }
     sb += ch;
@@ -60,10 +60,10 @@ void CBC_EncoderContext::setSkipAtEnd(int32_t count) {
   m_skipAtEnd = count;
 }
 wchar_t CBC_EncoderContext::getCurrentChar() {
-  return m_msg.GetAt(m_pos);
+  return m_msg[m_pos];
 }
 wchar_t CBC_EncoderContext::getCurrent() {
-  return m_msg.GetAt(m_pos);
+  return m_msg[m_pos];
 }
 
 void CBC_EncoderContext::writeCodewords(const CFX_WideString& codewords) {
diff --git a/fxbarcode/datamatrix/BC_ErrorCorrection.cpp b/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
index 4071602303..2e84df5c59 100644
--- a/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
+++ b/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
@@ -150,7 +150,7 @@ CFX_WideString CBC_ErrorCorrection::encodeECC200(CFX_WideString codewords,
     for (int32_t block = 0; block < blockCount; block++) {
       CFX_WideString temp;
       for (int32_t d = block; d < symbolInfo->dataCapacity(); d += blockCount) {
-        temp += (wchar_t)codewords.GetAt(d);
+        temp += (wchar_t)codewords[d];
       }
       CFX_WideString ecc = createECCBlock(temp, errorSizes[block], e);
       if (e != BCExceptionNO)
@@ -158,7 +158,7 @@ CFX_WideString CBC_ErrorCorrection::encodeECC200(CFX_WideString codewords,
       int32_t pos = 0;
       for (int32_t l = block; l < errorSizes[block] * blockCount;
            l += blockCount) {
-        sb.SetAt(symbolInfo->dataCapacity() + l, ecc.GetAt(pos++));
+        sb.SetAt(symbolInfo->dataCapacity() + l, ecc[pos++]);
       }
     }
   }
@@ -186,7 +186,7 @@ CFX_WideString CBC_ErrorCorrection::createECCBlock(CFX_WideString codewords,
   uint16_t* ecc = FX_Alloc(uint16_t, numECWords);
   memset(ecc, 0, numECWords * sizeof(uint16_t));
   for (int32_t l = start; l < start + len; l++) {
-    uint16_t m = ecc[numECWords - 1] ^ codewords.GetAt(l);
+    uint16_t m = ecc[numECWords - 1] ^ codewords[l];
     for (int32_t k = numECWords - 1; k > 0; k--) {
       if (m != 0 && FACTORS[table][k] != 0) {
         ecc[k] = (uint16_t)(ecc[k - 1] ^
diff --git a/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp b/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
index 6034173ee4..8b8b413c9b 100644
--- a/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
+++ b/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
@@ -174,7 +174,7 @@ int32_t CBC_HighLevelEncoder::lookAheadTest(CFX_WideString msg,
       }
       return C40_ENCODATION;
     }
-    wchar_t c = msg.GetAt(startpos + charsProcessed);
+    wchar_t c = msg[startpos + charsProcessed];
     charsProcessed++;
     if (isDigit(c)) {
       charCounts[ASCII_ENCODATION] += 0.5;
@@ -253,7 +253,7 @@ int32_t CBC_HighLevelEncoder::lookAheadTest(CFX_WideString msg,
         if (intCharCounts[C40_ENCODATION] == intCharCounts[X12_ENCODATION]) {
           int32_t p = startpos + charsProcessed + 1;
           while (p < msg.GetLength()) {
-            wchar_t tc = msg.GetAt(p);
+            wchar_t tc = msg[p];
             if (isX12TermSep(tc)) {
               return X12_ENCODATION;
             }
@@ -280,12 +280,12 @@ int32_t CBC_HighLevelEncoder::determineConsecutiveDigitCount(CFX_WideString msg,
   int32_t len = msg.GetLength();
   int32_t idx = startpos;
   if (idx < len) {
-    wchar_t ch = msg.GetAt(idx);
+    wchar_t ch = msg[idx];
     while (isDigit(ch) && idx < len) {
       count++;
       idx++;
       if (idx < len) {
-        ch = msg.GetAt(idx);
+        ch = msg[idx];
       }
     }
   }
diff --git a/fxbarcode/oned/BC_OnedCodaBarWriter.cpp b/fxbarcode/oned/BC_OnedCodaBarWriter.cpp
index 14ffcdfc35..ecaeb8d656 100644
--- a/fxbarcode/oned/BC_OnedCodaBarWriter.cpp
+++ b/fxbarcode/oned/BC_OnedCodaBarWriter.cpp
@@ -106,7 +106,7 @@ CFX_WideString CBC_OnedCodaBarWriter::FilterContents(
   CFX_WideString filtercontents;
   wchar_t ch;
   for (int32_t index = 0; index < contents.GetLength(); index++) {
-    ch = contents.GetAt(index);
+    ch = contents[index];
     if (ch > 175) {
       index++;
       continue;
@@ -137,7 +137,7 @@ uint8_t* CBC_OnedCodaBarWriter::EncodeImpl(const CFX_ByteString& contents,
   char ch;
   int32_t position = 0;
   for (int32_t index = 0; index < data.GetLength(); index++) {
-    ch = data.GetAt(index);
+    ch = data[index];
     if (((ch >= 'a') && (ch <= 'z'))) {
       ch = ch - 32;
     }
diff --git a/fxbarcode/oned/BC_OnedCode39Writer.cpp b/fxbarcode/oned/BC_OnedCode39Writer.cpp
index b9d594a028..cd87231fdf 100644
--- a/fxbarcode/oned/BC_OnedCode39Writer.cpp
+++ b/fxbarcode/oned/BC_OnedCode39Writer.cpp
@@ -50,7 +50,7 @@ CBC_OnedCode39Writer::~CBC_OnedCode39Writer() {}
 bool CBC_OnedCode39Writer::CheckContentValidity(
     const CFX_WideStringC& contents) {
   for (int32_t i = 0; i < contents.GetLength(); i++) {
-    wchar_t ch = contents.GetAt(i);
+    wchar_t ch = contents[i];
     if ((ch >= (wchar_t)'0' && ch <= (wchar_t)'9') ||
         (ch >= (wchar_t)'A' && ch <= (wchar_t)'Z') || ch == (wchar_t)'-' ||
         ch == (wchar_t)'.' || ch == (wchar_t)' ' || ch == (wchar_t)'*' ||
@@ -67,7 +67,7 @@ CFX_WideString CBC_OnedCode39Writer::FilterContents(
     const CFX_WideStringC& contents) {
   CFX_WideString filtercontents;
   for (int32_t i = 0; i < contents.GetLength(); i++) {
-    wchar_t ch = contents.GetAt(i);
+    wchar_t ch = contents[i];
     if (ch == (wchar_t)'*' && (i == 0 || i == contents.GetLength() - 1)) {
       continue;
     }
@@ -92,7 +92,7 @@ CFX_WideString CBC_OnedCode39Writer::RenderTextContents(
     const CFX_WideStringC& contents) {
   CFX_WideString renderContents;
   for (int32_t i = 0; i < contents.GetLength(); i++) {
-    wchar_t ch = contents.GetAt(i);
+    wchar_t ch = contents[i];
     if (ch == (wchar_t)'*' && (i == 0 || i == contents.GetLength() - 1)) {
       continue;
     }
diff --git a/fxbarcode/oned/BC_OnedEAN13Writer.cpp b/fxbarcode/oned/BC_OnedEAN13Writer.cpp
index 6f1d957a01..85f545c602 100644
--- a/fxbarcode/oned/BC_OnedEAN13Writer.cpp
+++ b/fxbarcode/oned/BC_OnedEAN13Writer.cpp
@@ -64,7 +64,7 @@ CFX_WideString CBC_OnedEAN13Writer::FilterContents(
   CFX_WideString filtercontents;
   wchar_t ch;
   for (int32_t i = 0; i < contents.GetLength(); i++) {
-    ch = contents.GetAt(i);
+    ch = contents[i];
     if (ch > 175) {
       i++;
       continue;
diff --git a/fxbarcode/oned/BC_OnedEAN8Writer.cpp b/fxbarcode/oned/BC_OnedEAN8Writer.cpp
index 9a85f814a7..ae10fe52ef 100644
--- a/fxbarcode/oned/BC_OnedEAN8Writer.cpp
+++ b/fxbarcode/oned/BC_OnedEAN8Writer.cpp
@@ -70,7 +70,7 @@ CFX_WideString CBC_OnedEAN8Writer::FilterContents(
   CFX_WideString filtercontents;
   wchar_t ch;
   for (int32_t i = 0; i < contents.GetLength(); i++) {
-    ch = contents.GetAt(i);
+    ch = contents[i];
     if (ch > 175) {
       i++;
       continue;
diff --git a/fxbarcode/oned/BC_OnedUPCAWriter.cpp b/fxbarcode/oned/BC_OnedUPCAWriter.cpp
index 13514eb53f..fff4184221 100644
--- a/fxbarcode/oned/BC_OnedUPCAWriter.cpp
+++ b/fxbarcode/oned/BC_OnedUPCAWriter.cpp
@@ -43,7 +43,7 @@ CBC_OnedUPCAWriter::~CBC_OnedUPCAWriter() {}
 
 bool CBC_OnedUPCAWriter::CheckContentValidity(const CFX_WideStringC& contents) {
   for (FX_STRSIZE i = 0; i < contents.GetLength(); ++i) {
-    if (contents.GetAt(i) < '0' || contents.GetAt(i) > '9')
+    if (contents[i] < '0' || contents[i] > '9')
       return false;
   }
   return true;
@@ -54,7 +54,7 @@ CFX_WideString CBC_OnedUPCAWriter::FilterContents(
   CFX_WideString filtercontents;
   wchar_t ch;
   for (int32_t i = 0; i < contents.GetLength(); i++) {
-    ch = contents.GetAt(i);
+    ch = contents[i];
     if (ch > 175) {
       i++;
       continue;
diff --git a/fxbarcode/pdf417/BC_PDF417.cpp b/fxbarcode/pdf417/BC_PDF417.cpp
index 9844798b24..3f492f9c10 100644
--- a/fxbarcode/pdf417/BC_PDF417.cpp
+++ b/fxbarcode/pdf417/BC_PDF417.cpp
@@ -523,7 +523,7 @@ void CBC_PDF417::encodeLowLevel(CFX_WideString fullCodewords,
     int32_t pattern = CODEWORD_TABLE[cluster][left];
     encodeChar(pattern, 17, logic->getCurrentRow());
     for (int32_t x = 0; x < c; x++) {
-      pattern = CODEWORD_TABLE[cluster][fullCodewords.GetAt(idx)];
+      pattern = CODEWORD_TABLE[cluster][fullCodewords[idx]];
       encodeChar(pattern, 17, logic->getCurrentRow());
       idx++;
     }
diff --git a/fxbarcode/pdf417/BC_PDF417ErrorCorrection.cpp b/fxbarcode/pdf417/BC_PDF417ErrorCorrection.cpp
index 6f1d7946eb..1d8258e720 100644
--- a/fxbarcode/pdf417/BC_PDF417ErrorCorrection.cpp
+++ b/fxbarcode/pdf417/BC_PDF417ErrorCorrection.cpp
@@ -145,7 +145,7 @@ bool CBC_PDF417ErrorCorrection::generateErrorCorrection(
   std::vector<wchar_t> ech(k);
   int32_t sld = dataCodewords.GetLength();
   for (int32_t i = 0; i < sld; i++) {
-    int32_t t1 = (dataCodewords.GetAt(i) + ech[k - 1]) % 929;
+    int32_t t1 = (dataCodewords[i] + ech[k - 1]) % 929;
     int32_t t2;
     int32_t t3;
     for (int32_t j = k - 1; j >= 1; j--) {
diff --git a/fxbarcode/pdf417/BC_PDF417HighLevelEncoder.cpp b/fxbarcode/pdf417/BC_PDF417HighLevelEncoder.cpp
index f65cfe46ae..c531716e4f 100644
--- a/fxbarcode/pdf417/BC_PDF417HighLevelEncoder.cpp
+++ b/fxbarcode/pdf417/BC_PDF417HighLevelEncoder.cpp
@@ -64,8 +64,8 @@ CFX_WideString CBC_PDF417HighLevelEncoder::encodeHighLevel(
   CFX_WideString msg;
   int32_t len = bytes.GetLength();
   for (int32_t i = 0; i < len; i++) {
-    wchar_t ch = (wchar_t)(bytes.GetAt(i) & 0xff);
-    if (ch == '?' && bytes.GetAt(i) != '?') {
+    wchar_t ch = (wchar_t)(bytes[i] & 0xff);
+    if (ch == '?' && bytes[i] != '?') {
       e = BCExceptionCharactersOutsideISO88591Encoding;
       return CFX_WideString();
     }
@@ -154,7 +154,7 @@ int32_t CBC_PDF417HighLevelEncoder::encodeText(CFX_WideString msg,
   int32_t submode = initialSubmode;
   int32_t idx = 0;
   while (true) {
-    wchar_t ch = msg.GetAt(startpos + idx);
+    wchar_t ch = msg[startpos + idx];
     switch (submode) {
       case SUBMODE_ALPHA:
         if (isAlphaUpper(ch)) {
@@ -216,7 +216,7 @@ int32_t CBC_PDF417HighLevelEncoder::encodeText(CFX_WideString msg,
             continue;
           } else {
             if (startpos + idx + 1 < count) {
-              wchar_t next = msg.GetAt(startpos + idx + 1);
+              wchar_t next = msg[startpos + idx + 1];
               if (isPunctuation(next)) {
                 submode = SUBMODE_PUNCTUATION;
                 tmp += (wchar_t)25;
@@ -247,10 +247,10 @@ int32_t CBC_PDF417HighLevelEncoder::encodeText(CFX_WideString msg,
   for (int32_t i = 0; i < len; i++) {
     bool odd = (i % 2) != 0;
     if (odd) {
-      h = (wchar_t)((h * 30) + tmp.GetAt(i));
+      h = (wchar_t)((h * 30) + tmp[i]);
       sb += h;
     } else {
-      h = tmp.GetAt(i);
+      h = tmp[i];
     }
   }
   if ((len % 2) != 0) {
@@ -313,7 +313,7 @@ void CBC_PDF417HighLevelEncoder::encodeNumeric(CFX_WideString msg,
       bigint = bigint / num900;
     } while (!bigint.isZero());
     for (int32_t i = tmp.GetLength() - 1; i >= 0; i--) {
-      sb += tmp.GetAt(i);
+      sb += tmp[i];
     }
     idx += len;
   }
@@ -343,12 +343,12 @@ int32_t CBC_PDF417HighLevelEncoder::determineConsecutiveDigitCount(
   int32_t len = msg.GetLength();
   int32_t idx = startpos;
   if (idx < len) {
-    wchar_t ch = msg.GetAt(idx);
+    wchar_t ch = msg[idx];
     while (isDigit(ch) && idx < len) {
       count++;
       idx++;
       if (idx < len) {
-        ch = msg.GetAt(idx);
+        ch = msg[idx];
       }
     }
   }
@@ -360,13 +360,13 @@ int32_t CBC_PDF417HighLevelEncoder::determineConsecutiveTextCount(
   int32_t len = msg.GetLength();
   int32_t idx = startpos;
   while (idx < len) {
-    wchar_t ch = msg.GetAt(idx);
+    wchar_t ch = msg[idx];
     int32_t numericCount = 0;
     while (numericCount < 13 && isDigit(ch) && idx < len) {
       numericCount++;
       idx++;
       if (idx < len) {
-        ch = msg.GetAt(idx);
+        ch = msg[idx];
       }
     }
     if (numericCount >= 13) {
@@ -375,7 +375,7 @@ int32_t CBC_PDF417HighLevelEncoder::determineConsecutiveTextCount(
     if (numericCount > 0) {
       continue;
     }
-    ch = msg.GetAt(idx);
+    ch = msg[idx];
     if (!isText(ch)) {
       break;
     }
@@ -391,7 +391,7 @@ int32_t CBC_PDF417HighLevelEncoder::determineConsecutiveBinaryCount(
   int32_t len = msg.GetLength();
   int32_t idx = startpos;
   while (idx < len) {
-    wchar_t ch = msg.GetAt(idx);
+    wchar_t ch = msg[idx];
     int32_t numericCount = 0;
     while (numericCount < 13 && isDigit(ch)) {
       numericCount++;
@@ -399,7 +399,7 @@ int32_t CBC_PDF417HighLevelEncoder::determineConsecutiveBinaryCount(
       if (i >= len) {
         break;
       }
-      ch = msg.GetAt(i);
+      ch = msg[i];
     }
     if (numericCount >= 13) {
       return idx - startpos;
@@ -411,12 +411,12 @@ int32_t CBC_PDF417HighLevelEncoder::determineConsecutiveBinaryCount(
       if (i >= len) {
         break;
       }
-      ch = msg.GetAt(i);
+      ch = msg[i];
     }
     if (textCount >= 5) {
       return idx - startpos;
     }
-    ch = msg.GetAt(idx);
+    ch = msg[idx];
     if ((*bytes)[idx] == 63 && ch != '?') {
       e = BCExceptionNonEncodableCharacterDetected;
       return -1;
diff --git a/fxbarcode/qrcode/BC_QRCoderEncoder.cpp b/fxbarcode/qrcode/BC_QRCoderEncoder.cpp
index cad70b81c5..f779ed4b95 100644
--- a/fxbarcode/qrcode/BC_QRCoderEncoder.cpp
+++ b/fxbarcode/qrcode/BC_QRCoderEncoder.cpp
@@ -426,9 +426,10 @@ void MergeString(std::vector<ModeStringPair>* result,
 void SplitString(const CFX_ByteString& content,
                  std::vector<ModeStringPair>* result) {
   int32_t index = 0;
-  while (index < content.GetLength() &&
-         ((content[index] >= 0xA1 && content[index] <= 0xAA) ||
-          (content[index] >= 0xB0 && content[index] <= 0xFA))) {
+  while (index < content.GetLength()) {
+    uint8_t c = static_cast<uint8_t>(content[index]);
+    if (!((c >= 0xA1 && c <= 0xAA) || (c >= 0xB0 && c <= 0xFA)))
+      break;
     index += 2;
   }
   if (index)
@@ -438,9 +439,10 @@ void SplitString(const CFX_ByteString& content,
 
   int32_t flag = index;
   while (GetAlphaNumericCode(content[index]) == -1 &&
-         index < content.GetLength() &&
-         !((content[index] >= 0xA1 && content[index] <= 0xAA) ||
-           (content[index] >= 0xB0 && content[index] <= 0xFA))) {
+         index < content.GetLength()) {
+    uint8_t c = static_cast<uint8_t>(content[index]);
+    if (((c >= 0xA1 && c <= 0xAA) || (c >= 0xB0 && c <= 0xFA)))
+      break;
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
     bool high = !!IsDBCSLeadByte(content[index]);
 #else
diff --git a/xfa/fxfa/cxfa_ffpasswordedit.cpp b/xfa/fxfa/cxfa_ffpasswordedit.cpp
index e0d9f33428..df2ea99cde 100644
--- a/xfa/fxfa/cxfa_ffpasswordedit.cpp
+++ b/xfa/fxfa/cxfa_ffpasswordedit.cpp
@@ -52,7 +52,7 @@ void CXFA_FFPasswordEdit::UpdateWidgetProperty() {
   CFX_WideString wsPassWord;
   m_pDataAcc->GetPasswordChar(wsPassWord);
   if (!wsPassWord.IsEmpty())
-    pWidget->SetAliasChar(wsPassWord.GetAt(0));
+    pWidget->SetAliasChar(wsPassWord[0]);
   if (m_pDataAcc->GetHorizontalScrollPolicy() != XFA_ATTRIBUTEENUM_Off)
     dwExtendedStyle |= FWL_STYLEEXT_EDT_AutoHScroll;
   if (m_pDataAcc->GetAccess() != XFA_ATTRIBUTEENUM_Open ||
diff --git a/xfa/fxfa/cxfa_pdffontmgr.cpp b/xfa/fxfa/cxfa_pdffontmgr.cpp
index 6e7a2ede4b..af94ee8c82 100644
--- a/xfa/fxfa/cxfa_pdffontmgr.cpp
+++ b/xfa/fxfa/cxfa_pdffontmgr.cpp
@@ -162,7 +162,7 @@ bool CXFA_PDFFontMgr::PsNameMatchDRFontName(const CFX_ByteStringC& bsPsName,
         return false;
 
       bool bMatch = false;
-      switch (bsPsName.GetAt(iPsLen - 1)) {
+      switch (bsPsName[iPsLen - 1]) {
         case 'L': {
           if (bsDRName.Right(5) == "Light") {
             bMatch = true;
diff --git a/xfa/fxfa/cxfa_textlayout.cpp b/xfa/fxfa/cxfa_textlayout.cpp
index 25bbe45e1b..9c4e36739d 100644
--- a/xfa/fxfa/cxfa_textlayout.cpp
+++ b/xfa/fxfa/cxfa_textlayout.cpp
@@ -796,7 +796,7 @@ bool CXFA_TextLayout::LoadRichText(
                      (m_pLoader->m_dwFlags & XFA_LOADERCNTXTFLG_FILTERSPACE)) {
             m_pLoader->m_dwFlags &= ~XFA_LOADERCNTXTFLG_FILTERSPACE;
           } else if (wsText.GetLength() > 0 &&
-                     (0x20 == wsText.GetAt(wsText.GetLength() - 1))) {
+                     (0x20 == wsText[wsText.GetLength() - 1])) {
             m_pLoader->m_dwFlags |= XFA_LOADERCNTXTFLG_FILTERSPACE;
           } else if (wsText.GetLength() != 0) {
             m_pLoader->m_dwFlags &= ~XFA_LOADERCNTXTFLG_FILTERSPACE;
@@ -885,7 +885,7 @@ bool CXFA_TextLayout::AppendChar(const CFX_WideString& wsText,
 
   int32_t iLength = wsText.GetLength();
   for (int32_t i = iChar; i < iLength; i++) {
-    wchar_t wch = wsText.GetAt(i);
+    wchar_t wch = wsText[i];
     if (wch == 0xA0)
       wch = 0x20;
 
diff --git a/xfa/fxfa/cxfa_textparser.cpp b/xfa/fxfa/cxfa_textparser.cpp
index 7e16202b16..659ec9cc6d 100644
--- a/xfa/fxfa/cxfa_textparser.cpp
+++ b/xfa/fxfa/cxfa_textparser.cpp
@@ -498,7 +498,7 @@ bool CXFA_TextParser::GetEmbbedObj(CXFA_TextProvider* pTextProvider,
     CFX_WideString wsAttr = pElement->GetString(L"xfa:embed");
     if (wsAttr.IsEmpty())
       return false;
-    if (wsAttr.GetAt(0) == L'#')
+    if (wsAttr[0] == L'#')
       wsAttr.Delete(0);
 
     CFX_WideString ws = pElement->GetString(L"xfa:embedType");
diff --git a/xfa/fxfa/cxfa_widgetacc.cpp b/xfa/fxfa/cxfa_widgetacc.cpp
index 92d00e5ba9..30b1eca3e7 100644
--- a/xfa/fxfa/cxfa_widgetacc.cpp
+++ b/xfa/fxfa/cxfa_widgetacc.cpp
@@ -828,7 +828,7 @@ void CXFA_WidgetAcc::CalculateTextContentSize(CFX_SizeF& size) {
   }
 
   wchar_t wcEnter = '\n';
-  wchar_t wsLast = wsText.GetAt(wsText.GetLength() - 1);
+  wchar_t wsLast = wsText[wsText.GetLength() - 1];
   if (wsLast == wcEnter)
     wsText = wsText + wcEnter;
 
diff --git a/xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp b/xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp
index 9028642b76..5912d26a99 100644
--- a/xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp
+++ b/xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp
@@ -3488,17 +3488,17 @@ CFX_WideString CXFA_FM2JSContext::EncodeURL(const CFX_ByteString& szURLString) {
       int32_t iIndex = 0;
       if (iLen % 2 != 0) {
         strEncode[1] = '0';
-        strEncode[2] = strTmp.GetAt(iLen - 1);
+        strEncode[2] = strTmp[iLen - 1];
         iIndex = iLen - 2;
       } else {
-        strEncode[1] = strTmp.GetAt(iLen - 1);
-        strEncode[2] = strTmp.GetAt(iLen - 2);
+        strEncode[1] = strTmp[iLen - 1];
+        strEncode[2] = strTmp[iLen - 2];
         iIndex = iLen - 3;
       }
       wsResultBuf << strEncode;
       while (iIndex > 0) {
-        strEncode[1] = strTmp.GetAt(iIndex);
-        strEncode[2] = strTmp.GetAt(iIndex - 1);
+        strEncode[1] = strTmp[iIndex];
+        strEncode[2] = strTmp[iIndex - 1];
         iIndex -= 2;
         wsResultBuf << strEncode;
       }
@@ -3994,8 +3994,8 @@ void CXFA_FM2JSContext::Replace(CFXJSE_Value* pThis,
   std::ostringstream resultString;
   int32_t iFindIndex = 0;
   for (int32_t u = 0; u < oneString.GetLength(); ++u) {
-    char ch = static_cast<char>(oneString.GetAt(u));
-    if (ch != static_cast<char>(twoString.GetAt(iFindIndex))) {
+    char ch = static_cast<char>(oneString[u]);
+    if (ch != static_cast<char>(twoString[iFindIndex])) {
       resultString << ch;
       continue;
     }
@@ -4003,8 +4003,8 @@ void CXFA_FM2JSContext::Replace(CFXJSE_Value* pThis,
     int32_t iTemp = u + 1;
     ++iFindIndex;
     while (iFindIndex < iFindLen) {
-      uint8_t chTemp = oneString.GetAt(iTemp);
-      if (chTemp != twoString.GetAt(iFindIndex)) {
+      uint8_t chTemp = oneString[iTemp];
+      if (chTemp != twoString[iFindIndex]) {
         iFindIndex = 0;
         break;
       }
@@ -4246,13 +4246,13 @@ void CXFA_FM2JSContext::Stuff(CFXJSE_Value* pThis,
   std::ostringstream resultString;
   int32_t i = 0;
   while (i < iStart) {
-    resultString << static_cast<char>(sourceString.GetAt(i));
+    resultString << static_cast<char>(sourceString[i]);
     ++i;
   }
   resultString << insertString.AsStringC();
   i = iStart + iDelete;
   while (i < iLength) {
-    resultString << static_cast<char>(sourceString.GetAt(i));
+    resultString << static_cast<char>(sourceString[i]);
     ++i;
   }
   resultString << '\0';
diff --git a/xfa/fxfa/fm2js/cxfa_fmexpression.cpp b/xfa/fxfa/fm2js/cxfa_fmexpression.cpp
index c6b5814d6d..e323a330dc 100644
--- a/xfa/fxfa/fm2js/cxfa_fmexpression.cpp
+++ b/xfa/fxfa/fm2js/cxfa_fmexpression.cpp
@@ -72,7 +72,7 @@ bool CXFA_FMFunctionDefinition::ToJavaScript(CFX_WideTextBuf& javascript) {
   for (const auto& identifier : m_pArguments) {
     if (bNeedComma)
       javascript << L", ";
-    if (identifier.GetAt(0) == L'!') {
+    if (identifier[0] == L'!') {
       CFX_WideString tempIdentifier =
           EXCLAMATION_IN_IDENTIFIER +
           identifier.Right(identifier.GetLength() - 1);
@@ -128,7 +128,7 @@ CXFA_FMVarExpression::~CXFA_FMVarExpression() {}
 bool CXFA_FMVarExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"var ";
   CFX_WideString tempName(m_wsName);
-  if (m_wsName.GetAt(0) == L'!') {
+  if (m_wsName[0] == L'!') {
     tempName =
         EXCLAMATION_IN_IDENTIFIER + m_wsName.Right(m_wsName.GetLength() - 1);
   }
@@ -152,7 +152,7 @@ bool CXFA_FMVarExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
 bool CXFA_FMVarExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L"var ";
   CFX_WideString tempName(m_wsName);
-  if (m_wsName.GetAt(0) == L'!') {
+  if (m_wsName[0] == L'!') {
     tempName =
         EXCLAMATION_IN_IDENTIFIER + m_wsName.Right(m_wsName.GetLength() - 1);
   }
@@ -459,7 +459,7 @@ CXFA_FMForExpression::~CXFA_FMForExpression() {}
 bool CXFA_FMForExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"{\nvar ";
   CFX_WideString tempVariant;
-  if (m_wsVariant.GetAt(0) == L'!') {
+  if (m_wsVariant[0] == L'!') {
     tempVariant = EXCLAMATION_IN_IDENTIFIER +
                   m_wsVariant.Right(m_wsVariant.GetLength() - 1);
     javascript << tempVariant;
@@ -514,7 +514,7 @@ bool CXFA_FMForExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L" = 0;\n";
   javascript << L"{\nvar ";
   CFX_WideString tempVariant;
-  if (m_wsVariant.GetAt(0) == L'!') {
+  if (m_wsVariant[0] == L'!') {
     tempVariant = EXCLAMATION_IN_IDENTIFIER +
                   m_wsVariant.Right(m_wsVariant.GetLength() - 1);
     javascript << tempVariant;
@@ -580,7 +580,7 @@ CXFA_FMForeachExpression::~CXFA_FMForeachExpression() {}
 bool CXFA_FMForeachExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L"{\n";
   javascript << L"var ";
-  if (m_wsIdentifier.GetAt(0) == L'!') {
+  if (m_wsIdentifier[0] == L'!') {
     CFX_WideString tempIdentifier =
         EXCLAMATION_IN_IDENTIFIER +
         m_wsIdentifier.Right(m_wsIdentifier.GetLength() - 1);
@@ -612,7 +612,7 @@ bool CXFA_FMForeachExpression::ToJavaScript(CFX_WideTextBuf& javascript) {
   javascript << L" < ";
   javascript << RUNTIMEBLOCKTEMPARRAY;
   javascript << L".length)\n{\n";
-  if (m_wsIdentifier.GetAt(0) == L'!') {
+  if (m_wsIdentifier[0] == L'!') {
     CFX_WideString tempIdentifier =
         EXCLAMATION_IN_IDENTIFIER +
         m_wsIdentifier.Right(m_wsIdentifier.GetLength() - 1);
@@ -637,7 +637,7 @@ bool CXFA_FMForeachExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L" = 0;\n";
   javascript << L"{\n";
   javascript << L"var ";
-  if (m_wsIdentifier.GetAt(0) == L'!') {
+  if (m_wsIdentifier[0] == L'!') {
     CFX_WideString tempIdentifier =
         EXCLAMATION_IN_IDENTIFIER +
         m_wsIdentifier.Right(m_wsIdentifier.GetLength() - 1);
@@ -668,7 +668,7 @@ bool CXFA_FMForeachExpression::ToImpliedReturnJS(CFX_WideTextBuf& javascript) {
   javascript << L" < ";
   javascript << RUNTIMEBLOCKTEMPARRAY;
   javascript << L".length)\n{\n";
-  if (m_wsIdentifier.GetAt(0) == L'!') {
+  if (m_wsIdentifier[0] == L'!') {
     CFX_WideString tempIdentifier =
         EXCLAMATION_IN_IDENTIFIER +
         m_wsIdentifier.Right(m_wsIdentifier.GetLength() - 1);
diff --git a/xfa/fxfa/parser/cxfa_dataexporter.cpp b/xfa/fxfa/parser/cxfa_dataexporter.cpp
index ff9e981e9f..b502bbdfa7 100644
--- a/xfa/fxfa/parser/cxfa_dataexporter.cpp
+++ b/xfa/fxfa/parser/cxfa_dataexporter.cpp
@@ -58,7 +58,7 @@ CFX_WideString ExportEncodeContent(const CFX_WideStringC& str) {
   CFX_WideTextBuf textBuf;
   int32_t iLen = str.GetLength();
   for (int32_t i = 0; i < iLen; i++) {
-    wchar_t ch = str.GetAt(i);
+    wchar_t ch = str[i];
     if (!IsXMLValidChar(ch))
       continue;
 
@@ -73,13 +73,13 @@ CFX_WideString ExportEncodeContent(const CFX_WideStringC& str) {
     } else if (ch == '\"') {
       textBuf << L"&quot;";
     } else if (ch == ' ') {
-      if (i && str.GetAt(i - 1) != ' ') {
+      if (i && str[i - 1] != ' ') {
         textBuf.AppendChar(' ');
       } else {
         textBuf << L"&#x20;";
       }
     } else {
-      textBuf.AppendChar(str.GetAt(i));
+      textBuf.AppendChar(str[i]);
     }
   }
   return textBuf.MakeString();
diff --git a/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp b/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
index 55851bb34a..e643bc502f 100644
--- a/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
+++ b/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
@@ -160,7 +160,7 @@ CXFA_Node* ResolveBreakTarget(CXFA_Node* pPageSetRoot,
       return nullptr;
 
     bTargetAllFind = false;
-    if (wsExpr.GetAt(0) == '#') {
+    if (wsExpr[0] == '#') {
       CXFA_Node* pNode = pDocument->GetNodeByID(
           ToNode(pDocument->GetXFAObject(XFA_HASHCODE_Template)),
           wsExpr.Right(wsExpr.GetLength() - 1).AsStringC());
diff --git a/xfa/fxfa/parser/cxfa_localemgr.cpp b/xfa/fxfa/parser/cxfa_localemgr.cpp
index 633f4b41fd..833f72c33f 100644
--- a/xfa/fxfa/parser/cxfa_localemgr.cpp
+++ b/xfa/fxfa/parser/cxfa_localemgr.cpp
@@ -1083,10 +1083,9 @@ static uint16_t XFA_GetLanguage(CFX_WideString wsLanguage) {
     return FX_LANG_en_US;
 
   wsLanguage.MakeLower();
-  uint32_t dwIDFirst = wsLanguage.GetAt(0) << 8 | wsLanguage.GetAt(1);
-  uint32_t dwIDSecond = wsLanguage.GetLength() >= 5
-                            ? wsLanguage.GetAt(3) << 8 | wsLanguage.GetAt(4)
-                            : 0;
+  uint32_t dwIDFirst = wsLanguage[0] << 8 | wsLanguage[1];
+  uint32_t dwIDSecond =
+      wsLanguage.GetLength() >= 5 ? wsLanguage[3] << 8 | wsLanguage[4] : 0;
   switch (dwIDFirst) {
     case FXBSTR_ID(0, 0, 'z', 'h'):
       if (dwIDSecond == FXBSTR_ID(0, 0, 'c', 'n'))
diff --git a/xfa/fxfa/parser/cxfa_measurement.cpp b/xfa/fxfa/parser/cxfa_measurement.cpp
index 66b715ec38..1c427209f9 100644
--- a/xfa/fxfa/parser/cxfa_measurement.cpp
+++ b/xfa/fxfa/parser/cxfa_measurement.cpp
@@ -37,7 +37,7 @@ void CXFA_Measurement::SetString(const CFX_WideStringC& wsMeasure) {
     return;
   }
   int32_t iUsedLen = 0;
-  int32_t iOffset = (wsMeasure.GetAt(0) == L'=') ? 1 : 0;
+  int32_t iOffset = (wsMeasure[0] == L'=') ? 1 : 0;
   float fValue = FXSYS_wcstof(wsMeasure.unterminated_c_str() + iOffset,
                               wsMeasure.GetLength() - iOffset, &iUsedLen);
   XFA_UNIT eUnit = GetUnitFromString(
diff --git a/xfa/fxfa/parser/cxfa_node.cpp b/xfa/fxfa/parser/cxfa_node.cpp
index 8497e60a74..2b4bdd22c0 100644
--- a/xfa/fxfa/parser/cxfa_node.cpp
+++ b/xfa/fxfa/parser/cxfa_node.cpp
@@ -76,7 +76,7 @@ int32_t GetCount(CXFA_Node* pInstMgrNode) {
     if (iCount == 0) {
       CFX_WideStringC wsName = pNode->GetCData(XFA_ATTRIBUTE_Name);
       CFX_WideStringC wsInstName = pInstMgrNode->GetCData(XFA_ATTRIBUTE_Name);
-      if (wsInstName.GetLength() < 1 || wsInstName.GetAt(0) != '_' ||
+      if (wsInstName.GetLength() < 1 || wsInstName[0] != '_' ||
           wsInstName.Right(wsInstName.GetLength() - 1) != wsName) {
         return iCount;
       }
@@ -197,7 +197,7 @@ CXFA_Node* GetItem(CXFA_Node* pInstMgrNode, int32_t iIndex) {
     if (iCount == 0) {
       CFX_WideStringC wsName = pNode->GetCData(XFA_ATTRIBUTE_Name);
       CFX_WideStringC wsInstName = pInstMgrNode->GetCData(XFA_ATTRIBUTE_Name);
-      if (wsInstName.GetLength() < 1 || wsInstName.GetAt(0) != '_' ||
+      if (wsInstName.GetLength() < 1 || wsInstName[0] != '_' ||
           wsInstName.Right(wsInstName.GetLength() - 1) != wsName) {
         return nullptr;
       }
@@ -406,7 +406,7 @@ void StrToRGB(const CFX_WideString& strRGB,
   int32_t iIndex = 0;
   int32_t iLen = strRGB.GetLength();
   for (int32_t i = 0; i < iLen; ++i) {
-    wchar_t ch = strRGB.GetAt(i);
+    wchar_t ch = strRGB[i];
     if (ch == L',')
       ++iIndex;
     if (iIndex > 2)
@@ -2736,7 +2736,7 @@ void CXFA_Node::Script_Subform_InstanceManager(CFXJSE_Value* pValue,
        pNode = pNode->GetNodeItem(XFA_NODEITEM_PrevSibling)) {
     if (pNode->GetElementType() == XFA_Element::InstanceManager) {
       CFX_WideStringC wsInstMgrName = pNode->GetCData(XFA_ATTRIBUTE_Name);
-      if (wsInstMgrName.GetLength() >= 1 && wsInstMgrName.GetAt(0) == '_' &&
+      if (wsInstMgrName.GetLength() >= 1 && wsInstMgrName[0] == '_' &&
           wsInstMgrName.Right(wsInstMgrName.GetLength() - 1) == wsName) {
         pInstanceMgr = pNode;
       }
@@ -4664,7 +4664,7 @@ CXFA_Node* CXFA_Node::GetInstanceMgrOfSubform() {
       if (eType == XFA_Element::InstanceManager) {
         CFX_WideStringC wsName = GetCData(XFA_ATTRIBUTE_Name);
         CFX_WideStringC wsInstName = pNode->GetCData(XFA_ATTRIBUTE_Name);
-        if (wsInstName.GetLength() > 0 && wsInstName.GetAt(0) == '_' &&
+        if (wsInstName.GetLength() > 0 && wsInstName[0] == '_' &&
             wsInstName.Right(wsInstName.GetLength() - 1) == wsName) {
           pInstanceMgr = pNode;
         }
diff --git a/xfa/fxfa/parser/cxfa_nodehelper.cpp b/xfa/fxfa/parser/cxfa_nodehelper.cpp
index 547831caca..4f1ed04fe3 100644
--- a/xfa/fxfa/parser/cxfa_nodehelper.cpp
+++ b/xfa/fxfa/parser/cxfa_nodehelper.cpp
@@ -283,7 +283,7 @@ bool CXFA_NodeHelper::CreateNode_ForCondition(CFX_WideString& wsCondition) {
     m_iCreateFlag = XFA_RESOLVENODE_RSTYPE_CreateNodeOne;
     return false;
   }
-  if (wsCondition.GetAt(0) == '[') {
+  if (wsCondition[0] == '[') {
     int32_t i = 1;
     for (; i < iLen; ++i) {
       wchar_t ch = wsCondition[i];
@@ -323,12 +323,12 @@ bool CXFA_NodeHelper::ResolveNodes_CreateNode(
   }
   bool bIsClassName = false;
   bool bResult = false;
-  if (wsName.GetAt(0) == '!') {
+  if (wsName[0] == '!') {
     wsName = wsName.Right(wsName.GetLength() - 1);
     m_pCreateParent = ToNode(
         pScriptContext->GetDocument()->GetXFAObject(XFA_HASHCODE_Datasets));
   }
-  if (wsName.GetAt(0) == '#') {
+  if (wsName[0] == '#') {
     bIsClassName = true;
     wsName = wsName.Right(wsName.GetLength() - 1);
   }
diff --git a/xfa/fxfa/parser/cxfa_resolveprocessor.cpp b/xfa/fxfa/parser/cxfa_resolveprocessor.cpp
index 93b2d86061..9edb3bce81 100644
--- a/xfa/fxfa/parser/cxfa_resolveprocessor.cpp
+++ b/xfa/fxfa/parser/cxfa_resolveprocessor.cpp
@@ -41,7 +41,7 @@ int32_t CXFA_ResolveProcessor::Resolve(CXFA_ResolveNodesData& rnd) {
   if (rnd.m_dwStyles & XFA_RESOLVENODE_AnyChild) {
     return ResolveAnyChild(rnd);
   }
-  wchar_t wch = rnd.m_wsName.GetAt(0);
+  wchar_t wch = rnd.m_wsName[0];
   switch (wch) {
     case '$':
       return ResolveDollar(rnd);
@@ -89,7 +89,7 @@ int32_t CXFA_ResolveProcessor::ResolveAnyChild(CXFA_ResolveNodesData& rnd) {
   CFX_WideString wsCondition = rnd.m_wsCondition;
   CXFA_Node* findNode = nullptr;
   bool bClassName = false;
-  if (wsName.GetAt(0) == '#') {
+  if (wsName[0] == '#') {
     bClassName = true;
     wsName = wsName.Right(wsName.GetLength() - 1);
   }
diff --git a/xfa/fxfa/parser/cxfa_scriptcontext.cpp b/xfa/fxfa/parser/cxfa_scriptcontext.cpp
index 115cd5651e..57caa9981b 100644
--- a/xfa/fxfa/parser/cxfa_scriptcontext.cpp
+++ b/xfa/fxfa/parser/cxfa_scriptcontext.cpp
@@ -340,7 +340,7 @@ void CXFA_ScriptContext::NormalPropertySetter(CFXJSE_Value* pOriginalValue,
         pReturnValue, true, (XFA_ATTRIBUTE)lpAttributeInfo->eAttribute);
   } else {
     if (pObject->IsNode()) {
-      if (wsPropName.GetAt(0) == '#') {
+      if (wsPropName[0] == '#') {
         wsPropName = wsPropName.Right(wsPropName.GetLength() - 1);
       }
       CXFA_Node* pNode = ToNode(pObject);
diff --git a/xfa/fxfa/parser/cxfa_widgetdata.cpp b/xfa/fxfa/parser/cxfa_widgetdata.cpp
index d68a907e18..5b9f62c93f 100644
--- a/xfa/fxfa/parser/cxfa_widgetdata.cpp
+++ b/xfa/fxfa/parser/cxfa_widgetdata.cpp
@@ -1215,7 +1215,7 @@ bool CXFA_WidgetData::GetBarcodeAttribute_StartChar(char* val) {
   CFX_WideStringC wsStartEndChar;
   if (pUIChild->TryCData(XFA_ATTRIBUTE_StartChar, wsStartEndChar)) {
     if (wsStartEndChar.GetLength()) {
-      *val = static_cast<char>(wsStartEndChar.GetAt(0));
+      *val = static_cast<char>(wsStartEndChar[0]);
       return true;
     }
   }
@@ -1227,7 +1227,7 @@ bool CXFA_WidgetData::GetBarcodeAttribute_EndChar(char* val) {
   CFX_WideStringC wsStartEndChar;
   if (pUIChild->TryCData(XFA_ATTRIBUTE_EndChar, wsStartEndChar)) {
     if (wsStartEndChar.GetLength()) {
-      *val = static_cast<char>(wsStartEndChar.GetAt(0));
+      *val = static_cast<char>(wsStartEndChar[0]);
       return true;
     }
   }
-- 
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