Given radius of a circle, write a program to find its circumference.

**Examples :**

Input : 2 Output : Circumference = 12.566 Input : 8 Output : Circumference = 50.264

In a circle, points lie in the boundary of a circle are at same distance from its center. This distance is called radius. Circumference of a circle can simply be evaluated using following formula.

Circumference = 2*pi*r where r is the radius of circle and value of pi = 3.1415.

## C++

`// CPP program to find circumference of circle ` `#include<bits/stdc++.h> ` `using` `namespace` `std; ` ` ` `#define PI 3.1415 ` ` ` `double` `circumference(` `double` `r) ` `{ ` ` ` `double` `cir = 2*PI*r; ` ` ` `return` `cir; ` `} ` ` ` `// driver function ` `int` `main() ` `{ ` ` ` `double` `r = 5; ` ` ` `cout << ` `"Circumference = "` ` ` `<< circumference(r); ` ` ` `return` `0; ` `} ` |

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## Python3

`# Python3 code to find ` `# circumference of circle ` ` ` `PI ` `=` `3.1415` ` ` `# utility function ` `def` `circumference(r): ` ` ` `return` `(` `2` `*` `PI ` `*` `r) ` ` ` ` ` `# driver function ` `print` `(` `'%.3f'` `%` `circumference(` `5` `)) ` ` ` `# This code is contributed by Saloni Gupta ` |

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## Java

`// Java program to find circumference of circle ` `import` `java.io.*; ` ` ` `class` `Geometry { ` ` ` ` ` `// utility function ` ` ` `static` `double` `circumference(` `double` `r){ ` ` ` ` ` `double` `PI = ` `3.1415` `; ` ` ` `double` `cir = ` `2` `*PI*r; ` ` ` `return` `cir; ` ` ` `} ` ` ` ` ` `// driver function ` ` ` `public` `static` `void` `main (String[] args) { ` ` ` ` ` `double` `r = ` `5` `; ` ` ` `double` `result = Math.round(circumference(r) * ` `1000` `) / ` `1000.0` `; ` ` ` `System.out.println(` `"Circumference = "` `+ result); ` ` ` `} ` `} ` ` ` `// This article is contributed by Chinmoy Lenka ` |

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## C#

`// C# program to find circumference of circle ` `using` `System; ` ` ` `class` `GFG { ` ` ` ` ` `// utility function ` ` ` `static` `double` `circumference(` `double` `r){ ` ` ` ` ` `double` `PI = 3.1415; ` ` ` `double` `cir = 2*PI*r; ` ` ` `return` `cir; ` ` ` `} ` ` ` ` ` `// driver function ` ` ` `public` `static` `void` `Main () { ` ` ` ` ` `double` `r = 5; ` ` ` `double` `result = ` ` ` `Math.Round(circumference(r) ` ` ` `* 1000) / 1000.0; ` ` ` ` ` `Console.WriteLine(` `"Circumference = "` ` ` `+ result); ` ` ` `} ` `} ` ` ` `// This article is contributed by anuj_67. ` |

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## PHP

`<?php ` `// PHP program to find ` `// circumference of circle ` ` ` `$PI` `= 3.1415; ` ` ` `function` `circumference(` `$r` `) ` `{ ` ` ` `global` `$PI` `; ` ` ` `$cir` `= 2 * ` `$PI` `* ` `$r` `; ` ` ` `return` `$cir` `; ` `} ` ` ` `// Driver Code ` `$r` `= 5; ` `echo` `"Circumference = "` `, ` `circumference(` `$r` `); ` ` ` `// This code is contributed aj_36 ` `?> ` |

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**Output :**

Circumference = 31.415

This article is contributed by **Saloni Gupta **. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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