simple string comparison program in c

Question

I wrote this simple program to compare two strings ,I think it's working properly I just need to confirm that and also have few advices if possible

#include<stdio.h>
// #include<string.h>

int main(){

    int value, lenght=0, i=0;
    char passwd[11], pass[11]="comptiatar";

    printf("enter ur passwd: ");
    scanf("%s", passwd);

    //value = strcmp(passwd,pass);

    while (passwd[i]!=0){
        lenght++;
        i++;
    }
    
    
    for (i=0;i<=lenght;i++){
        if (passwd[i]==pass[i])
            value=0;
        else {
            value=passwd[i]-pass[i];
            break;
        }
    }
    
    if (value)
        printf("\nwrong password\n\n");
    else
        printf("\nlogin successfully\n\n");
    printf("%d\n", value);

return 0;}

Answer 1

Is it really necesary to "reinvent the wheel"? Instead of this:

while (passwd[i]!=0){
        lenght++;
        i++;
    }

could just use:

lenght=strlen(passwd);

And what the problem with just using strcmp? Also you can exit the for loop as soon passwd[i]!=pass[i].

Also what hapens if somebody type password longer then 10 characters? You should make passwd biger or check the return value of scanf.