how does strcmp work in c code example

Example 1: strcmp c

// use: strcmp(string1, string2);

string a = "words";
string b = "words";

if (strcmp(a, b) == 0)
{
	printf("a and b match");
  	// strcmp returns 0 if both strings match
}

else
{
	printf("a and b don't match");
  	// strcmp returns anything else if the strings dont match
}

Example 2: c strcmp

// strCmp implementation
// string1 < string2 => return a negative integer
// string1 > string2 => return a positive integer
// string1 = string2 => return 0
int strCmp(const char* s1, const char* s2) {
    while(*s1 && (*s1 == *s2)) {
        s1++;
        s2++;
    }
    return *s1 - *s2;
}