Different methods to reverse a string in C/C++

Difficulty Level : Easy
Last Updated : 17 Feb, 2021

Given a string, write a C/C++ program to reverse it.

string-reverse

Write own reverse function by swapping characters: One simple solution is to write our own reverse function to reverse a string in C++.

// A Simple C++ program to reverse a string 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to reverse a string 
void reverseStr(string& str) 
{ 
    int n = str.length(); 
  
    // Swap character starting from two 
    // corners 
    for (int i = 0; i < n / 2; i++) 
        swap(str[i], str[n - i - 1]); 
} 
  
// Driver program 
int main() 
{ 
    string str = "geeksforgeeks"; 
    reverseStr(str); 
    cout << str; 
    return 0; 
} 

Output :

skeegrofskeeg

Using inbuilt “reverse” function: There is a direct function in “algorithm” header file for doing reverse that saves our time when programming.

// Reverses elements in [begin, end]
void reverse (BidirectionalIterator begin, 
BidirectionalIterator end);

// A quickly written program for reversing a string 
// using reverse() 
#include <bits/stdc++.h> 
using namespace std; 
int main() 
{ 
    string str = "geeksforgeeks"; 
  
    // Reverse str[begin..end] 
    reverse(str.begin(), str.end()); 
  
    cout << str; 
    return 0; 
} 

Output :

skeegrofskeeg

Only printing reverse:

// C++ program to print reverse of a string 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to reverse a string 
void reverse(string str) 
{ 
   for (int i=str.length()-1; i>=0; i--) 
      cout << str[i];  
} 
  
// Driver code 
int main(void) 
{ 
    string s = "GeeksforGeeks"; 
    reverse(s); 
    return (0); 
} 

Output:

skeegrofskeeG

Getting reverse of a const string:

// C++ program to get reverse of a const string 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to reverse string and return 
// reverse string pointer of that 
char* reverseConstString(char const* str) 
{ 
    // find length of string 
    int n = strlen(str); 
  
    // create a dynamic pointer char array 
    char *rev = new char[n+1]; 
  
    // copy of string to ptr array 
    strcpy(rev, str); 
  
    // Swap character starting from two 
    // corners 
    for (int i=0, j=n-1; i<j; i++,j--) 
        swap(rev[i], rev[j]);        
      
    // return pointer of the reversed string 
    return rev; 
} 
  
// Driver code 
int main(void) 
{ 
    const char *s = "GeeksforGeeks"; 
    printf("%s", reverseConstString(s)); 
    return (0); 
} 

Output:

skeeGrofskeeG

Reverse string using the constructor : Passing reverse iterators to the constructor returns us a reversed string.

// A simple C++ program to reverse string using constructor  
#include <bits/stdc++.h>  
using namespace std;  
int main(){ 
  
    string str = "GeeksforGeeks"; 
  
    //Use of reverse iterators 
    string rev = string(str.rbegin(),str.rend()); 
  
    cout<<rev<<endl;  
    return 0; 
} 

Output:

skeeGrofskeeG

This article is contributed by Priyam kakati, Ranju Kumari, Somesh Awasthi and improved by Supratik Mitra, Lakshay Bansal. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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