求圆面积的程序

可以使用以下公式简单地评估圆的面积。

Area = pi * r2
where r is radius of circle 

C++

// C++ program to find area
// of circle
#include 
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 
#include 
#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.

Javascript

 
// 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
 

输出：

Area is 78.550000