Why null-terminated strings? Or: null-terminated vs. characters + length storage

Question

I\'m writing a language interpreter in C, and my string type contains a length attribute, like so:

struct String
{
    char* charac         


        

Answer 1

One advantage of nul-terminated strings is that if you are walking through a string character-by-character, you only need to keep a single pointer to address the string:

while (*s)
{
    *s = toupper(*s);
    s++;
}

whereas for strings without sentinels, you need to keep two bits of state around: either a pointer and index:

while (i < s.length)
{
    s.data[i] = toupper(s.data[i]);
    i++;
}

...or a current pointer and a limit:

s_end = s + length;
while (s < s_end)
{
    *s = toupper(*s);
    s++;
}

When CPU registers were a scarce resource (and compilers were worse at allocating them), this was important. Now, not so much.