Area of Circle (Function / Macros)

#include<iostream.h>
#include<conio.h>

float circle(float);

void main()
{
    float r, k;
    clrscr();

    cout<<"Enter radius of circle: ";
    cin>>r;

    k = circle(r);

    cout<<"Area of circle is : "<<k;
}

float circle(float m)
{
    float area;

    area = 3.142 * m * m;

    return area;
}



Using MACROS

#include<iostream.h>
#include<conio.h>

#define PI    3.142

float circle(float);

void main()
{
    float r, k;
    clrscr();

    cout<<"Enter radius of circle: ";
    cin>>r;

    k = circle(r);

    cout<<"Area of circle is : "<<k;
}

float circle(float m)
{
    float area;

    area = PI * m * m;

    return area;

}