string not reversed-CodePudding

Whats wrong in this code? The string is not reversed even when I wrote s.reverse(). It is showing the same string without reversing? Can someone help me with this?

#include<iostream>
using namespace std;
int main(){

cout << "Hello world" << endl;;
string s;
cin >> s;
s.reverse();
cout << s;
}

CodePudding user response：

When you examine the reference document, you will see that the reverse method has the following prototype:

void reverse (BidirectionalIterator first, BidirectionalIterator last);

This method reverses the order of the elements in the range [first,last].

Update the line where std::reverse() is called as follows:

#include <algorithm>

std::reverse(s.begin(), s.end());

CodePudding user response：

std::string doesn't have a reverse() method, so calling s.reverse() shouldn't even compile.

You need to use the std::reverse() algorithm instead:

#include <iostream>
#include <string>
#include <algorithm>

int main(){
    std::cout << "Hello world" << std::endl;
    std::string s;
    std::cin >> s;
    std::reverse(s.begin(), s.end());
    std::cout << s;
}

CodePudding user response：

You have used the reserve() function which is different from reverse. To reverse your string modify your code as shown below:

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

int main(){
    cout << "Hello world" << endl;
    string s;
    cin >> s;
    reverse(s.begin(), s.end());
    cout << s;
}