Last Updated : 03 Apr, 2024
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Given two variables, x, and y, swap two variables without using a third variable.
Method 1 (Using Addition and subtraction)
The idea is to get a sum in one of the two given numbers. The numbers can then be swapped using the sum and subtraction from the sum.
C++
// C++ Program to swap two numbers without
// using temporary variable
#include <bits/stdc++.h>
using namespace std;
int main()
{
int x = 10, y = 5;
// Code to swap 'x' and 'y'
x = x + y; // x now becomes 15
y = x - y; // y becomes 10
x = x - y; // x becomes 5
cout << "After Swapping: x =" << x << ", y=" << y;
}
// This code is contributed by mohit kumar.
C
#include <stdio.h>
int main()
{
int x = 10, y = 5;
// Code to swap 'x' and 'y'
x = x + y; // x now becomes 15
y = x - y; // y becomes 10
x = x - y; // x becomes 5
printf("After Swapping: x = %d, y = %d", x, y);
return 0;
}
Java
// Java Program to swap two numbers without
// using temporary variable
import java.io.*;
class Geeks {
public static void main(String a[])
{
int x = 10;
int y = 5;
x = x + y;
y = x - y;
x = x - y;
System.out.println("After swapping:"
+ " x = " + x + ", y = " + y);
}
}
// This code is contributed by Mayank Tyagi
Python3
x = 10
y = 5
# Code to swap 'x' and 'y'
# x now becomes 15
x = x + y
# y becomes 10
y = x - y
# x becomes 5
x = x - y
print("After Swapping: x =", x, " y =", y)
# This code is contributed
# by Sumit Sudhakar
C#
// Program to swap two numbers without
// using temporary variable
using System;
class GFG {
public static void Main()
{
int x = 10;
int y = 5;
x = x + y;
y = x - y;
x = x - y;
Console.WriteLine("After swapping: x = " + x
+ ", y = " + y);
}
}
// This code is contributed by Sam007
Javascript
<script>
// Javascript program to swap two
// numbers without using temporary
// variable
let x = 10, y = 5;
// Code to swap 'x' and 'y'
// x now becomes 15
x = x + y;
// y becomes 10
y = x - y;
// x becomes 5
x = x - y;
document.write("After Swapping: x =" + x + ", y=" + y);
// This code is contributed by mukesh07
</script>
PHP
<?php
// PHP Program to swap two
// numbers without using
// temporary variable
$x = 10; $y = 5;
// Code to swap 'x' and 'y'
$x = $x + $y; // x now becomes 15
$y = $x - $y; // y becomes 10
$x = $x - $y; // x becomes 5
echo "After Swapping: x = ",
$x, ", ", "y = ", $y;
// This code is contributed by m_kit
?>
Output
After Swapping: x =5, y=10
Time Complexity: O(1).
Auxiliary Space: O(1).
Method 2: (Using Multiplication and division)
Multiplication and division can also be used for swapping.
C++
// C++ Program to swap two numbers without using temporary
// variable
#include <bits/stdc++.h>
using namespace std;
int main()
{ // NOTE - for this code to work in a generalised sense, y
// !- 0 to prevent zero division
int x = 10, y = 5;
if (y == 0) {
y = x;
x = 0;
}
else if (x == 0) {
x = y;
y = 0;
}
// Code to swap 'x' and 'y'
else {
x = x * y; // x now becomes 50
y = x / y; // y becomes 10
x = x / y; // x becomes 5
}
cout << "After Swapping: x =" << x << ", y=" << y;
}
// This code is contributed by Aditya Kumar (adityakumar129)
C
// C Program to swap two numbers without using temporary
// variable
#include <stdio.h>
int main()
{
int x = 10, y = 5;
if (y == 0) {
y = x;
x = 0;
}
else if (x == 0) {
x = y;
y = 0;
}
// Code to swap 'x' and 'y'
else {
x = x * y; // x now becomes 50
y = x / y; // y becomes 10
x = x / y; // x becomes 5
}
printf("After Swapping: x = %d, y = %d", x, y);
return 0;
}
// This code is contributed by Aditya Kumar (adityakumar129)
Java
// Java Program to swap two numbers without using temporary
// variable
import java.io.*;
class GFG {
public static void main(String[] args)
{
int x = 10;
int y = 5;
if (y == 0) {
y = x;
x = 0;
}
else if (x == 0) {
x = y;
y = 0;
}
// Code to swap 'x' and 'y'
else {
x = x * y; // x now becomes 50
y = x / y; // y becomes 10
x = x / y; // x becomes 5
}
System.out.println("After swapping:"
+ " x = " + x + ", y = " + y);
}
}
// This code is contributed by Aditya Kumar (adityakumar129)
Python3
# Python3 program to
# swap two numbers
# without using
# temporary variable
x = 10
y = 5
# code to swap
# 'x' and 'y'
if y == 0:
y = x
x = 0
elif x == 0:
x = y
y = 0
else:
x = x * y
y = x // y
x = x // y
print("After Swapping: x =",
x, " y =", y)
# This code is contributed
# by @ajit
C#
// C# Program to swap two
// numbers without using
// temporary variable
using System;
class GFG {
static public void Main()
{
int x = 10;
int y = 5;
if (y == 0) {
y = x;
x = 0;
}
else if (x == 0) {
x = y;
y = 0;
}
// Code to swap 'x' and 'y'
else {
x = x * y; // x now becomes 50
y = x / y; // y becomes 10
x = x / y; // x becomes 5
}
Console.WriteLine("After swapping:"
+ " x = " + x + ", y = " + y);
}
}
// This code is contributed by ajit.
Javascript
<script>
// Javascript program to swap two numbers
// without using temporary variable
var x = 10;
var y = 5;
// Code to swap 'x' and 'y'
if (y == 0)
{ y = x; x = 0; }
else if (x == 0) { x = y; y = 0; }
// Code to swap 'x' and 'y'
else
{x = x * y; // x now becomes 50
y = x / y; // y becomes 10
x = x / y; // x becomes 5
}
document.write("After swapping:" + " x = " +
x + ", y = " + y);
// This code is contributed by shikhasingrajput
</script>
Output
After Swapping: x =5, y=10
Time Complexity: O(1).
Auxiliary Space: O(1).
Method 3: (Using Bitwise XOR)
The bitwise XOR operator can be used to swap two variables. The XOR of two numbers x and y returns a number that has all the bits as 1 wherever bits of x and y differ. For example, XOR of 10 (In Binary 1010) and 5 (In Binary 0101) is 1111, and XOR of 7 (0111) and 5 (0101) is (0010).
C++
// C++ code to swap using XOR
#include <bits/stdc++.h>
using namespace std;
int main()
{
int x = 10, y = 5;
// Code to swap 'x' (1010) and 'y' (0101)
x = x ^ y; // x now becomes 15 (1111)
y = x ^ y; // y becomes 10 (1010)
x = x ^ y; // x becomes 5 (0101)
cout << "After Swapping: x =" << x << ", y=" << y;
return 0;
}
// This code is contributed by mohit kumar.
C
// C code to swap using XOR
#include <stdio.h>
int main()
{
int x = 10, y = 5;
// Code to swap 'x' (1010) and 'y' (0101)
x = x ^ y; // x now becomes 15 (1111)
y = x ^ y; // y becomes 10 (1010)
x = x ^ y; // x becomes 5 (0101)
printf("After Swapping: x = %d, y = %d", x, y);
return 0;
}
Java
// Java code to swap using XOR
import java.io.*;
public class GFG {
public static void main(String a[])
{
int x = 10;
int y = 5;
// Code to swap 'x' (1010) and 'y' (0101)
x = x ^ y; // x now becomes 15 (1111)
y = x ^ y; // y becomes 10 (1010)
x = x ^ y; // x becomes 5 (0101)
System.out.println("After swap: x = "
+ x + ", y = " + y);
}
}
// This code is contributed by Mayank Tyagi
Python3
# Python3 code to swap using XOR
x = 10
y = 5
# Code to swap 'x' and 'y'
x = x ^ y; # x now becomes 15 (1111)
y = x ^ y; # y becomes 10 (1010)
x = x ^ y; # x becomes 5 (0101)
print ("After Swapping: x = ", x, " y =", y)
# This code is contributed by
# Sumit Sudhakar
C#
// C# program to swap using XOR
using System;
class GFG {
public static void Main()
{
int x = 10;
int y = 5;
// Code to swap 'x' (1010)
// and 'y' (0101)
// x now becomes 15 (1111)
x = x ^ y;
// y becomes 10 (1010)
y = x ^ y;
// x becomes 5 (0101)
x = x ^ y;
Console.WriteLine("After swap: x = " + x + ", y = " + y);
}
}
// This code is contributed by ajit
Javascript
<script>
// Javascript code to swap using XOR
let x = 10, y = 5;
// Code to swap 'x' (1010) and 'y' (0101)
x = x ^ y; // x now becomes 15 (1111)
y = x ^ y; // y becomes 10 (1010)
x = x ^ y; // x becomes 5 (0101)
document.write("After Swapping: x =" +
x + ", y=" + y);
// This code is contributed by Mayank Tyagi
</script>
PHP
<?php
// Driver Code
$x = 10;
$y = 5;
// Code to swap 'x' (1010)
// and 'y' (0101)
// x now becomes 15 (1111)
$x = $x ^ $y;
// y becomes 10 (1010)
$y = $x ^ $y;
// x becomes 5 (0101)
$x = $x ^ $y;
echo "After Swapping: x = ", $x,
", ", "y = ", $y;
// This code is contributed by aj_36
?>
Output
After Swapping: x =5, y=10
Time Complexity: O(1).
Auxiliary Space: O(1).
Problems with the above methods
1) The multiplication and division-based approach doesn’t work if one of the numbers is 0 as the product becomes 0 irrespective of the other number.
2) Both Arithmetic solutions may cause an arithmetic overflow. If x and y are too large, addition and multiplication may go out of the integer range.
3) When we use pointers to variable and make a function swap, all the above methods fail when both pointers point to the same variable. Let’s take a look at what will happen in this case if both are pointing to the same variable.
// Bitwise XOR based method
x = x ^ x; // x becomes 0
x = x ^ x; // x remains 0
x = x ^ x; // x remains 0
// Arithmetic based method
x = x + x; // x becomes 2x
x = x – x; // x becomes 0
x = x – x; // x remains 0
Let us see the following program.
C++
#include <bits/stdc++.h>
using namespace std;
void swap(int* xp, int* yp)
{
*xp = *xp ^ *yp;
*yp = *xp ^ *yp;
*xp = *xp ^ *yp;
}
// Driver code
int main()
{
int x = 10;
swap(&x, &x);
cout << "After swap(&x, &x): x = " << x;
return 0;
}
// This code is contributed by rathbhupendra
C
#include <stdio.h>
void swap(int* xp, int* yp)
{
*xp = *xp ^ *yp;
*yp = *xp ^ *yp;
*xp = *xp ^ *yp;
}
int main()
{
int x = 10;
swap(&x, &x);
printf("After swap(&x, &x): x = %d", x);
return 0;
}
Java
class GFG {
static void swap(int[] xp, int[] yp)
{
xp[0] = xp[0] ^ yp[0];
yp[0] = xp[0] ^ yp[0];
xp[0] = xp[0] ^ yp[0];
}
// Driver code
public static void main(String[] args)
{
int[] x = { 10 };
swap(x, x);
System.out.println("After swap(&x, &x): x = " + x[0]);
}
}
// This code is contributed by Aditya Kumar (adityakumar129)
Python3
def swap(xp, yp):
xp[0] = xp[0] ^ yp[0]
yp[0] = xp[0] ^ yp[0]
xp[0] = xp[0] ^ yp[0]
# Driver code
x = [10]
swap(x, x)
print("After swap(&x, &x): x = ", x[0])
# This code is contributed by SHUBHAMSINGH10
C#
// C# program to implement
// the above approach
using System;
class GFG {
static void swap(int[] xp, int[] yp)
{
xp[0] = xp[0] ^ yp[0];
yp[0] = xp[0] ^ yp[0];
xp[0] = xp[0] ^ yp[0];
}
// Driver code
static void Main()
{
int[] x = { 10 };
swap(x, x);
Console.WriteLine("After swap(&x,"
+ "&x): x = " + x[0]);
}
}
// This code is contributed by divyeshrabadiya07
Javascript
<script>
function swap(xp,yp)
{
xp[0] = xp[0] ^ yp[0];
yp[0] = xp[0] ^ yp[0];
xp[0] = xp[0] ^ yp[0];
}
// Driver code
let x=[10];
swap(x, x);
document.write("After swap(&x, &x): x = "
+ x[0]);
// This code is contributed by unknown2108
</script>
PHP
<?php
function swap(&$xp, &$yp)
{
$xp = $xp ^ $yp;
$yp = $xp ^ $yp;
$xp = $xp ^ $yp;
}
// Driver Code
$x = 10;
swap($x, $x);
print("After swap(&x, &x): x = " . $x);
// This code is contributed
// by chandan_jnu
?>
Output
After swap(&x, &x): x = 0
Time Complexity: O(1).
Auxiliary Space: O(1).
Swapping a variable with itself may be needed in many standard algorithms. The above problem can be avoided by putting a condition before swapping.
C++
#include <bits/stdc++.h>
using namespace std;
void swap(int* xp, int* yp)
{
// Check if the two addresses are same
if (xp == yp)
return;
*xp = *xp + *yp;
*yp = *xp - *yp;
*xp = *xp - *yp;
}
// Driver Code
int main()
{
int x = 10;
swap(&x, &x);
cout << "After swap(&x, &x): x = " << x;
return 0;
}
// This code is contributed by rathbhupendra
C
#include <stdio.h>
void swap(int* xp, int* yp)
{
if (xp == yp) // Check if the two addresses are same
return;
*xp = *xp + *yp;
*yp = *xp - *yp;
*xp = *xp - *yp;
}
int main()
{
int x = 10;
swap(&x, &x);
printf("After swap(&x, &x): x = %d", x);
return 0;
}
Java
// Java program of above approach
class GFG {
static void swap(int xp, int yp)
{
if (xp == yp) // Check if the two addresses are same
return;
xp = xp + yp;
yp = xp - yp;
xp = xp - yp;
}
// Driver code
public static void main(String[] args)
{
int x = 10;
swap(x, x);
System.out.println("After swap(&x, &x): x = " + x);
}
}
// This code is Contributed by Code_Mech.
Python3
# Python3 program of above approach
def swap(xp, yp):
# Check if the two addresses are same
if (xp[0] == yp[0]):
return
xp[0] = xp[0] + yp[0]
yp[0] = xp[0] - yp[0]
xp[0] = xp[0] - yp[0]
# Driver Code
x = [10]
swap(x, x)
print("After swap(&x, &x): x = ", x[0])
# This code is contributed by SHUBHAMSINGH10
C#
// C# program of above approach
using System;
class GFG {
static void swap(int xp, int yp)
{
if (xp == yp) // Check if the two addresses are same
return;
xp = xp + yp;
yp = xp - yp;
xp = xp - yp;
}
// Driver code
public static void Main()
{
int x = 10;
swap(x, x);
Console.WriteLine("After swap(&x, &x): x = " + x);
}
}
// This code is Contributed by Code_Mech.
Javascript
<script>
function swap(xp, yp)
{
// Check if the two addresses are same
if (xp == yp)
return;
xp[0] = xp[0] + yp[0];
yp[0] = xp[0] - yp[0];
xp[0]= xp[0] - yp[0];
}
// Driver Code
x = 10;
swap(x, x);
document.write("After swap(&x , &x) : x = " + x);
//This code is contributed by simranarora5sos
</script>
PHP
<?php
function swap($xp, $yp)
{
// Check if the two addresses
// are same
if ($xp == $yp)
return;
$xp = $xp + $yp;
$yp = $xp - $yp;
$xp = $xp - $yp;
}
// Driver Code
$x = 10;
swap($x, $x);
echo("After swap(&x, &x): x = " . $x);
return 0;
// This code is contributed
// by Code_Mech.
Output
After swap(&x, &x): x = 10
Time Complexity: O(1).
Auxiliary Space: O(1).
Method 4 (A mixture of bitwise operators and arithmetic operators)
The idea is the same as discussed in Method 1 but uses Bitwise addition and subtraction for swapping.
Below is the implementation of the above approach.
C++
// C++ program to swap two numbers
#include <bits/stdc++.h>
using namespace std;
// Function to swap the numbers.
void swap(int& a, int& b)
{
// same as a = a + b
a = (a & b) + (a | b);
// same as b = a - b
b = a + (~b) + 1;
// same as a = a - b
a = a + (~b) + 1;
}
// Driver Code
int main()
{
int a = 5, b = 10;
// Function Call
swap(a, b);
cout << "After swapping: a = " << a << ", b = " << b;
return 0;
}
// This code is contributed by Aditya Kumar (adityakumar129)
C
// C program to swap two numbers
#include <stdio.h>
// Function to swap the numbers.
void swap(int a, int b)
{
// same as a = a + b
a = (a & b) + (a | b);
// same as b = a - b
b = a + (~b) + 1;
// same as a = a - b
a = a + (~b) + 1;
printf("After swapping: a = %d , b = %d ",a,b);
}
// Driver Code
int main()
{
int a = 5, b = 10;
// Function Call
swap(a, b);
return 0;
}
// This code is contributed by Aditya Kumar (adityakumar129)
Java
// Java program to swap two numbers
import java.io.*;
class GFG {
public static void swap(int a, int b)
{
// same as a = a + b
a = (a & b) + (a | b);
// same as b = a - b
b = a + (~b) + 1;
// same as a = a - b
a = a + (~b) + 1;
System.out.print("After swapping: a = " + a + ", b = " + b);
}
public static void main(String[] args)
{
int a = 5, b = 10;
// Function Call
swap(a, b);
}
}
// This code is contributed by Aditya Kumar (adityakumar129)
Python3
# Python3 program to swap two numbers
# Function to swap the numbers
def swap(a, b):
# Same as a = a + b
a = (a & b) + (a | b)
# Same as b = a - b
b = a + (~b) + 1
# Same as a = a - b
a = a + (~b) + 1
print("After Swapping: a = ", a, ", b = ", b)
# Driver code
a = 5
b = 10
# Function call
swap(a, b)
# This code is contributed by bunnyram19
C#
// C# program to swap two numbers
using System;
class GFG {
static void swap(int a, int b)
{
// same as a = a + b
a = (a & b) + (a | b);
// same as b = a - b
b = a + (~b) + 1;
// same as a = a - b
a = a + (~b) + 1;
Console.Write("After swapping: a = " + a
+ ", b = " + b);
}
static void Main()
{
int a = 5, b = 10;
// Function Call
swap(a, b);
}
}
// This code is contributed by divyesh072019
Javascript
<script>
// Javascript program to swap two numbers
function swap(a, b)
{
// same as a = a + b
a = (a & b) + (a | b);
// same as b = a - b
b = a + (~b) + 1;
// same as a = a - b
a = a + (~b) + 1;
document.write("After swapping: a = " + a + ", b = " + b);
}
let a = 5, b = 10;
// Function Call
swap(a, b);
// This code is contributed by suresh07.
</script>
PHP
<?php
// Driver Code
$a = 5;
$b = 10;
echo("Before swap(a and b) " . $a . "and". $b."<br>");
// same as a = a + b
$a = ($a & $b) + ($a | $b);
// same as b = a - b
$b = $a + (~$b) + 1;
// same as a = a - b
$a = $a + (~$b) + 1;
echo("After swap(a and b) " . $a. "and". $b);
return 0;
?>
Output
After swapping: a = 10, b = 5
Time Complexity: O(1)
Auxiliary Space: O(1), since no extra space has been taken.
Method 5 (One Line Expression)
We can write only one line to swap two numbers.
- x = x ^ y ^ (y = x);
- x = x + y – (y = x);
- x = (x * y) / (y = x);
- x , y = y, x (In Python)
C++
#include <iostream>
using namespace std;
int main(){
int x = 10, y = 5;
x = (x * y) / (y = x);
cout << x << " " << y;
return 0;
}
// This code is contributed by isha307
C
#include <stdio.h>
int main() {
int x = 10, y = 5;
x = (x * y) / (y = x);
printf("After Swapping: x = %d, y = %d", x, y);
return 0;
}
// This code is contributed by isha307
Java
/*package whatever //do not write package name here */
import java.io.*;
class GFG {
public static void main(String[] args)
{
int x = 10;
int y = 5;
x = (x * y) / (y = x);
System.out.println("After swapping:"
+ " x = " + x + ", y = " + y);
}
}
// This code is contributed by isha307
Python3
# Python3 program to swap two numbers
# Function to swap the numbers
def swap(x, y):
x , y = y, x
print("After Swapping: x = ", x, ", y = ", y)
# Driver code
x = 10
y = 5
# Function call
swap(x, y)
# This code is contributed by kothavvsaakash
C#
// C# program to swap two numbers
using System;
public class GFG
{
static public void Main ()
{
int x = 10;
int y = 5;
x = (x * y) / (y = x);
Console.Write("After swapping:" + " x = " + x + ", y = " + y);
}
}
// This code is contributed by kothavvsaakash
Javascript
<script>
// Javascript program to swap two
// numbers without using temporary
// variable
let x = 10, y = 5;
// Code to swap 'x' and 'y'
x = (x * y)/(x = y);
document.write("After Swapping: x =" + x + ", y=" + y);
// This code is contributed by Abhijeet Kumar(abhijeet19403)
</script>
Output
5 10
Time Complexity: O(1)
Auxiliary Space: O(1)
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