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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#includeusing namespace std;  #define PI 3.1415  double circumference(double r){    double cir = 2*PI*r;    return cir;}  // driver functionint main(){  double r = 5;  cout << "Circumference = "        << circumference(r);  return 0;}

## Java

 // Java program to find circumference of circleimport 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 functiondef circumference(r):    return (2 * PI * r)    # driver functionprint ('%.3f' % circumference(5))  # This code is contributed by Saloni Gupta

## C#

 // C# program to find circumference of circleusing 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.



## 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.