Implement Custom strcmp function

Code

#include <stdio.h>

int custom_strcmp(const char *a, const char *b) {
    // Your logic here
    int diff = 0;
    while(*a != '\0' && *b != '\0'){
        if(*a != *b){
            diff = (int)(*a - *b);
        }
        a = a + 1;
        b = b + 1;
    }
    if(*a != '\0'){
        while(*a != '\0'){
            diff = (int)(*a - '\0');
            a = a + 1;
        }
    }
    if(*b != '\0'){
        while(*b != '\0'){
            diff = (int)('\0' - *b);
            b = b + 1;
        }
    }
    return diff;
}

int main() {
    char a[101], b[101];
    fgets(a, sizeof(a), stdin);
    fgets(b, sizeof(b), stdin);

    // Remove newline
    int i = 0;
    while (a[i]) {
        if (a[i] == '\n') { a[i] = '\0'; break; }
        i++;
    }
    i = 0;
    while (b[i]) {
        if (b[i] == '\n') { b[i] = '\0'; break; }
        i++;
    }

    printf("%d", custom_strcmp(a, b));
    return 0;
}

Solving Approach