# exchange() Function in C++ 14

• Difficulty Level : Basic
• Last Updated : 28 Jun, 2022

The exchange() function is a built-in function in C++ 14 defined in the <utility> header. The exchange() function copies new value to old value and it will return the old value.

Syntax:

`exchange(old, new)`

Parameters: The function needs two parameters.

1. The parameter needs to be set.
2. The parameter with which we wanted to set our parameter 1

Return Value: It returns the old value which means the parameter that needs to be set

Example 1:

## C++14

 `// C++ Program to demonstrate` `// exchange()` `#include ` `#include ` `using` `namespace` `std;`   `int` `main()` `{` `    ``int` `x = 10;` `    ``int` `y = 20;`   `    ``// Setting value of y to x` `    ``exchange(x, y);`   `    ``cout << ``"Value of x:"` `<< x << ``'\n'` `         ``<< ``"Value of y:"` `<< y << endl;` `    ``int` `a = 40;` `    ``int` `b = 30;`   `    ``// Setting value of b to a and copying a to b` `    ``b = exchange(a, b);`   `    ``cout << ``"Value of a:"` `<< a << ``'\n'` `         ``<< ``"Value of b:"` `<< b << endl;`   `    ``return` `0;` `}`

Output

```Value of x:20
Value of y:20
Value of a:30
Value of b:40```

Example 2:

## C++14

 `// C++ Program to demonstrate` `// exchange()` `#include ` `#include ` `#include ` `using` `namespace` `std;`   `int` `main()` `{` `    ``// We can also set one vector` `    ``// values to another vector` `    ``vector<``int``> v1 = { 2, 4, 6, 8 };` `    ``vector<``int``> v2 = { 1, 3, 5, 7 };` `    ``v2 = exchange(v1, v2);` `    ``cout << ``"Values of v1 after exchange:"` `<< endl;` `    ``for` `(``auto` `ele : v1) {` `        ``cout << ele << ``" "``;` `    ``}` `    ``cout << endl;` `    ``cout << ``"Values of v2 after exchange:"` `<< endl;` `    ``for` `(``auto` `ele : v2) {` `        ``cout << ele << ``" "``;` `    ``}` `    ``return` `0;` `}`

Output

```Values of v1 after exchange:
1 3 5 7
Values of v2 after exchange:
2 4 6 8 ```

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