# 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<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;` `}` |

## 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

`<?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` `?>` |

## Javascript

`<script>` `// Javascript program to find circumference of circle` `function` `circumference(r)` `{` ` ` `let cir = 2*3.1415*r;` ` ` `return` `cir;` `}` `// driver function` ` ` `let r = 5;` `document.write(` `"Circumference = "` ` ` `+ circumference(r));` `//This code is contributed by Manoj` `</script>` |

**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.

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