## C++ program to find area of the circle

In this example, you will learn about C++ program to find area of the circle with and without using the function.

Formula to find area of the circle:

`Area_circle = Π * r * r`

where,

mathematical value of Π is 3.14159.

Let’s calculate the are of the circle using two methods.

## Example: C++ program to find area of the circle.

``````//C++ program to calculate area of the circle
#include <iostream>
using namespace std;

int main() {

// take radius as input
cout << "Enter the radius of circle: ";

area_circle = 3.14 * radius * radius;
cout << "Area of circle: " << area_circle << endl;

return 0;
}
``````

Output

```Enter the radius of circle: 5
Area of circle: 78.5```

## Example: C++ program to find area of the circle using function.

``````//C++ program to find area of the circle using function
#include <iostream>
using namespace std;

//function declaration

int main() {

// take radius as input
cout << "Enter the radius of circle: ";

cout << "Area of circle: " << areaOfCircle(radius) << endl;

return 0;
}

// function definition to calculate area of circle
{
float area_circle;
area_circle = 3.14 * radius_circle * radius_circle;

return area_circle; //return area
}
``````

Output

Explanation

In the first program, we have simply calculated area of the circle in the main program.

However, we have used `areaOfCircle( )` function for calculating area of the circle in the second program.