Implement Custom strcmp function

Code

#include <stdio.h>
#include <stdlib.h> 
int custom_strcmp(const char *a, const char *b) {

        do{
            if(!(*a==*b))
            return *a-*b;
        }while(*a++!='\0' && *b++!='\0');
    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