Basic Macro Usage

Create a macro PI to hold the value of pi in a header file constants.h. Use this macro in a main.cpp file to calculate the area of a circle.

Hint

Remember that the formula for the area of a circle is Area = PI * radius * radius.

Answer

constants.h

#pragma once

#define PI 3.14159

main.cpp

#include <iostream>
#include "constants.h"

int main() {
    double radius;

    std::cout << "Enter the radius of the circle: ";
    std::cin >> radius;

    double area = PI * radius * radius;

    std::cout << "The area of the circle is: " << area << std::endl;

    return 0;
}