Program to find area of a circle

Given the radius of a circle, find the area of that circle.

The area of a circle can simply be evaluated using the following formula.

where r is radius of circle and it maybe in float because value of pie is 3.14 

Approach: Using the given radius, find the area using the above formula: (pi * r * r) and print the result in float.

C++

// C++ program to find area
// of circle
#include <iostream>
const double pi = 3.14159265358979323846;
using namespace std;

// function to calculate the area of circle
float findArea(float r)
{
    return (pi * r * r);
}
// driver code
int main()
{
    float r, Area;
    r = 5;

    // function calling
    Area = findArea(r);
    // displaying the area
    cout << "Area of Circle is :" << Area;
    return 0;
}

C

// C program to find area
// of circle
#include <stdio.h>
#include <math.h>
#define PI 3.142

double findArea(int r)
{
   return PI * pow(r, 2);
}

int main()
{
    printf("Area is %f", findArea(5));
    return 0;
}

Java

// Java program to find area
// of circle

class Test
{
    static final double PI = Math.PI;

    static double findArea(int r)
    {
       return PI * Math.pow(r, 2);
    }

    // Driver method
    public static void main(String[] args)
    {
        System.out.println("Area is " +  findArea(5));
    }
}

Python3

# Python3 program to find Area of a circle

def findArea(r):
    PI = 3.142
    return PI * (r*r);

# Driver method
print("Area is %.6f" % findArea(5));

# This code is contributed by Chinmoy Lenka

C#

// C# program to find area of circle
using System;

class GFG
{
    static double PI = Math.PI;

    static double findArea(int r)
    {
    return PI * Math.Pow(r, 2);
    }

    // Driver method
    static void Main()
    {
        Console.Write("Area is " + findArea(5));
    }
}

// This code is contributed by Sam007.

PHP

<?php
// PHP program to find area
// of circle

function findArea( $r)
{
    $PI =3.142;
    return $PI * pow($r, 2);
}

// Driver Code
echo("Area is ");
echo(findArea(5));
return 0;

// This code is contributed by vt_m.
?>

Javascript

<script>

// Javascript program to find area
// of circle

let pi = 3.14159265358979323846;

// function to calculate the area of circle
function findArea(r)
{
    return (pi * r * r);
}

// Driver code
    let r, Area;
    r = 5;

    // function calling
    Area = findArea(r);

    // displaying the area
    document.write("Area of Circle is :" + Area);

// This code is contributed by Mayank Tyagi

</script>

Output

Area of Circle is :78.5398

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