#include <string.h>
#include <stdlib.h>

#define SLMAX 100

char * alloc_build_string(const char *ss[])
{
	size_t total_len = 1;
	size_t slens[SLMAX]; /* should be enough */
	int ns = 0;
	for (int i = 0; ss[i] != NULL; i++) {
		if (ns >= SLMAX)
			return NULL;
		size_t l = strlen(ss[i]);
		slens[ns] = l;
		ns++;
		total_len += l;
	}
	char *res = malloc(total_len);
	size_t cur = 0;
	for (int i = 0; i < ns; i++) {
		memcpy(res+cur, ss[i], slens[i]);
		cur += slens[i];
	}
	res[cur] = 0;
	return res;
}