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# Program to find Circumference of a Circle

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``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;``} `

## 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`

## 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`

## 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.`

## PHP

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## Javascript

 ``

Output :

`Circumference = 31.415`

Time Complexity: O(1), since there is no loop or recursion.

Auxiliary Space: O(1), since no extra space has been taken.

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