# Swap two variables in one line

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++

 `// 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; ` `} `

## 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); ` `   ``} ` `}  `

## Python3

 `# 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

 ` `

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]

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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Improved By : jit_t, kongasricharan

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