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Swap two variables in one line
• Difficulty Level : Easy
• Last Updated : 23 Mar, 2021

We have discussed different approaches to swap two integers without the temporary variable. How to swap in a single line without using library function?
Python: In Python, there is a simple and syntactically neat construct to swap variables, we just need to write “x, y = y, x”.
C/C++: Below is one generally provided classical solution

```// Swap using bitwise XOR (Wrong Solution in C/C++)
x ^= y ^= x ^= y; ```

The above solution is wrong in C/C++ as it causes undefined behaviour (compiler is free to behave in any way). The reason is, modifying a variable more than once in an expression causes undefined behaviour if there is no sequence point between the modifications.
However, we can use a comma to introduce sequence points. So the modified solution is

```// Swap using bitwise XOR (Correct Solution in C/C++)
// sequence point introduced using comma.
(x ^= y), (y ^= x), (x ^= y);```

Java: In Java, rules for subexpression evaluations are clearly defined. The left hand operand is always evaluated before right hand operand (See this for more details). In Java, the expression “x ^= y ^= x ^= y;” doesn’t produce the correct result according to Java rules. It makes x = 0. However, we can use “x = x ^ y ^ (y = x);” Note the expressions are evaluated from left to right. If x = 5 and y = 10 initially, the expression is equivalent to “x = 5 ^ 10 ^ (y = 5);”. Note that we can’t use this in C/C++ as in C/C++, it is not defined whether left operand or right operand is executed for any operator (See this for more details)

## C

 `// C program to swap two variables in single line``#include ``int` `main()``{``    ``int` `x = 5, y = 10;``    ``(x ^= y), (y ^= x), (x ^= y);``    ``printf``(``"After Swapping values of x and y are %d %d"``, x,``           ``y);``    ``return` `0;``}`

## C++

 `// C++ code to swap using XOR``#include ` `using` `namespace` `std;` `int` `main()``{``    ``int` `x = 5, y = 10;``    ``// Code to swap 'x'  and 'y'``    ``// to swap two numbers in one``    ``// line``     ``x = x ^ y, y = x ^ y, x = x ^ y;``    ``// printing the swapped variables``    ``cout << ``"After Swapping: x = "``         ``<< x << ``", y= "` `<< y;``    ``return` `0;``}`

## Java

 `// Java program to swap two variables in a single line``class` `GFG {``    ``public` `static` `void` `main(String[] args)``    ``{``        ``int` `x = ``5``, y = ``10``;``        ``x = x ^ y ^ (y = x);``        ``System.out.println(``            ``"After Swapping values"``            ``+``" of x and y are "` `+ x``            ``+ ``" "` `+ y);``    ``}``}`

## Python

 `# Python program to swap two variables in a single line``x ``=` `5``y ``=` `10``x, y ``=` `y, x``print``(``"After Swapping values of x and y are"``, x, y)`

## C#

 `// C# program to swap two``// variables in single line``using` `System;` `class` `GFG {``    ``static` `public` `void` `Main()``    ``{``        ``int` `x = 5, y = 10;``        ``x = x ^ y ^ (y = x);``        ``Console.WriteLine(``"After Swapping values "``                          ``+ ``"of x and y are "` `+ x + ``" "``                          ``+ y);``    ``}``}` `// This code is contributed by aj_36`

## PHP

 ``

## Javascript

 ``

Output:

`After Swapping values of x and y are 10 5`

Alternate Solutions :

• C++ also provides a library function swap()
• b = (a + b) – (a = b); [Thanks to Rajat Mishra for this]
• a += b – (b = a); [Thanks to Zoran Davidovi? for this]
• a = a * b / (b = a)[Thanks to kongasricharan for this]
• a = a ^ b ^ (b = a)

This article is contributed by Harshit Gupta. 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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