Is the comparator function right? - String sort

#1

#include<bits/stdc++.h>
using namespace std;

bool compare_rev(string a, string b){
if(a.compare(b)){
for(int i=0; i<b.length(); i++){
if(b[i]!=a[i]){
return a<b;
}
}
return b>a;
}
else if(b.compare(a)){
for(int i=0; i<a.length(); i++){
if(a[i]!=b[i]){
return a<b;
}
}
return a>b;
}

}
int main() {
int n;
cin>>n;
cin.get();
string s[n];
for(int i=0; i<n; i++){
getline(cin,s[i]);
}
sort(s,s+n,compare_rev);
for(int i=0; i<n; i++){
cout<<s[i]<<"\n";
}
return 0;
}

#2

Hello @alien,

  1. How does a.compare(b) and b.compare(a) are different?
    Both of them will produce 0 if they a and b are same strings.

  2. if(b[i]!=a[i]) and if(a[i]!=b[i]) have same functonality.

  3. the condition after for loop doesn’t make any sense because that statement will execute only when all characters of both the string match completely i.e. a[i]==b[i] i.e. both are same strings.
    But, if they are the same strings, they would never satisfy the condition referred to in point 1.

Correct approach:

Hope, this would help.

#3

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