Can you solve write a program in c++to print area of circle

Answer 1

#include<iostream.h>
#include<conio.h>
main()
{
int r;
float ar;
cout<<"Enter radius : ";
cin>>r;
ar=(22/7.0)*r*r;
cout<<"\nArea of circle = "<<ar;
getch();
}

Answer 2

#include<iostream>
using namespace std;
int main()
{
float r , area ;

cin >> r ;

cout << " Radius = " << r ;

area = (22/7.0)*r*r ;

cout << "\n Area = " << area ;

return 0;

}

Answer 3

For C++11:

constexpr double pi() {
return std::atan(1) * 4;
}

double circleArea(double radius) {
return pi() * radius * radius;
}