Program to Swap two strings in C++

Written by

Juhi Kamdar

There are three tricks through which we swap the strings in C++;

  • Three Character Array Method
  • Three string method
  • Inbuilt swap function
  1. Three Character Array Method

In this method,

  • We copy the contents of the first string to a temporary array.
  • The, we copy the contents of the second array in the first character array.
  • Next, we copy the contents of the temporary array to second character array.


  • We can use this method to reverse the contents of a numeric array too.
  • We do not need to include string library.


  • High time complexity due to many loops(due to copying array contents).
  • Very tedious time-consuming.
  1. Three string method

In this method, We use the same technique as above, but we use strings here instead of character arrays.

  • We include the string library, and make three objects of String class.
  • We use the inbuilt function strcpy() and follow the naïve method of swapping.


#include <iostream>

#include <cstring> //string library

using namespace std;

int main() { int n; //length of string cin>>n; char s1[n]; char s2[n]; char s3[n]; //temporary string //Input String 1 cin>>s1; //Input String 2 cin>>s2; strcpy(s3,s1); //copy contents of s1 in s3 strcpy(s1,s2); // similar to s1=s2 strcpy(s2,s3); cout<<s1<<"\n"; cout<<s2; return 0; }


  • It is faster than the previous method.


  • We need to use three strings, which is a waste of memory.
  1. Inbuilt swap function

In this method, we use the inbuilt swap function to perform the task.

  • We include the string library and make two string objects.
  • Then, we make use of swap() function and output the strings.


#include <iostream>
#include <string>
using namespace std;

int main() { string str1;

string str2;
//input string 1
//input string 2

str1.swap(str2); //swap contents of str1 and str2

return 0;



  • It is the fastest of all.
  • It uses only two strings to execute the task.


Program to Swap two strings in C++