How to check if a string starts with another strin

Question

Is there something like startsWith(str_a, str_b) in the standard C library?

It should take pointers to two strings that end with nullbytes, and tell me whether the first one also appears completely at the beginning of the second one.

Examples:

"abc", "abcdef" -> true
"abcdef", "abc" -> false
"abd", "abdcef" -> true
"abc", "abc"    -> true

Answer 1

Optimized (v.2. - corrected):

uint32 startsWith( const void* prefix_, const void* str_ ) {
    uint8 _cp, _cs;
    const uint8* _pr = (uint8*) prefix_;
    const uint8* _str = (uint8*) str_;
    while ( ( _cs = *_str++ ) & ( _cp = *_pr++ ) ) {
        if ( _cp != _cs ) return 0;
    }
    return !_cp;
}

Answer 2

Optimized:

boolean StartsWith(char *s1, char *s2)
{
  while (*s1++ == *s2++)
  {
  }

  return *s2 == 0;
}

Answer 3

I'd probably go with strncmp(), but just for fun a raw implementation:

_Bool starts_with(const char *restrict string, const char *restrict prefix)
{
    while(*prefix)
    {
        if(*prefix++ != *string++)
            return 0;
    }

    return 1;
}