C Programming - Library Functions - Discussion

g = strcmp(s1, s2); returns 0 when the strings are equal, a negative integer when s1 is less than s2, or a positive integer if s1 is greater than s2, that strcmp() not only returns -1, 0 and +1, but also other negative or positive values(returns difference between the first non-matching pair of characters between s1 and s2).

A possible implementation for strcmp() in "The Standard C Library".

int strcmp (const char * s1, const char * s2)
{                
	for(; *s1 == *s2; ++s1, ++s2) 
	{
		if(*s1 == 0)
			return 0;
	}
	return *(unsigned char *)s1 < *(unsigned char *)s2 ? -1 : 1;
}