Can't understand the problem in my code

#1

#include<bits/stdc++.h>
using namespace std;
int main() {
string s;
cin>>s;
for(int i=0;i<s.length();i++){
if(s[i]==0)
s[i]==5;

cout<<s[i];
}
return 0;
}// for replace hem all

#2

hi @abhijee0123 s[i] = '5' not s[i] == '5'