How to Reverse a String in Place in C++?

In C++, reversing a string is a basic operation in programming that is required in various applications, from simple and complex algorithms. Reversing a string in place involves changing the characters of the string directly without using input-dependent additional storage. In this article, we learn how to reverse a string in place in C++.

For Example,

Input:
myString = "Hello, World!"

Output:
myString = "!dlroW ,olleH"

Reverse a String In-Place in C++

The std::reverse() function provided by the C++ STL library can be used to reverse the string in place. This function takes the iterator to the beginning and the end of the string.

Syntax of std::reverse()

std::reverse(begin, end)

The begin and end can be either an iterator or a pointer.

C++ Program to Reverse a String In-Place

// C++ program to reverse a string in place
#include <algorithm>
#include <iostream>
#include <string>
using namespace std;
int main()
{
    // Initialize the string
    string str = "Hello, World!";
    // Reverse the string
    reverse(str.begin(), str.end());
    // Output the result
    cout << "Reversed string is: " << str << endl;
    return 0;
}

Reversed string is: !dlroW ,olleH

Time Complexity: O(n)
Auxiliary Space: O(1)

Note: In an in-place algorithm, additional space can be used as long as it is not dependent on the input.