C++ program to find the area of a circle

In this C++ program tutorial our task is to:

• Write a C++ program to find the area of the circle

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C++ program to calculate the area of a circle

Given below is the C++ code where we take radius of the circle as an input  and the area of the circle is given as the output.

#include<iostream>
#define pi 3.14       //macros where the value of pi is defined
using namespace std;
int main()
{
    float radius,areaOfCircle;
    cout<<"Enter the value of the radius"<<endl;
    cin>>radius;
    areaOfCircle = pi * radius * radius;      //Calculating the area of the circle
    cout<<"Area of the circle\n"<<areaOfCircle<<endl;
    return 0;
}

OUTPUT : 

Enter the value of the radius

2

Area of the circle

12.56

 

A macros is defined in the above program (#define pi 3.14). Macros are defined so that the program run faster and is very efficient while doing competitive programming.

EXPLANATION:

• In the above program the compiler first compiling from the main function (here int main()).
• Then two 4(assuming 32/64-bit system) bits memory space are created for the two float variable .
• Then it takes in the input for the radius and goes to the calculation part.
• It then searches for the value of "pi" which has been defined as a macros.
• After that the value get saved in the areaOfCircle

 

You can see the above code execution and output in codeblocks IDE: