Implement Custom strcmp function

Code

#include <stdio.h>

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

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