# Swap Two Variables in One Line

We have discussed different approaches to swap two integers without the temporary variable. How to swap into a single line without using the library function?
1) Python: In Python, there is a simple and syntactically neat construct to swap variables, we just need to write “x, y = y, x”.
2) 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 behavior (the compiler is free to behave in any way). The reason is, modifying a variable more than once in an expression causes undefined behavior 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);```

3) Java: In Java, rules for subexpression evaluations are clearly defined. The left-hand operand is always evaluated before the right-hand operand. 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 the left operand or right operand is executed by any operator (See this for more details).

4) JavaScript: Using destructing assignment, we can simply achieve swapping using this one line.

`[x,y]=[y,x]`

## 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);` `    ``}` `}`

## 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

 ``

## Javascript

 ``

Output

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

Alternate Solutions:

1. Using swap(): C++ library function
2. b = (a + b) – (a = b);
3. a += b – (b = a);
4. a = a * b / (b = a)
5. a = a ^ b ^ (b = a)

Time complexity : O(1)
Auxiliary Space : O(1)

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