C Program to Find area and Circumference of Circle

In this tutorial, we are going to write a C Program to Find Area and Circumference of Circle in C Programming with practical program code and step-by-step full complete explanation.

C Program to Find Area and Circumference of the circle.

```#include <stdio.h>
#include <conio.h>

void main()
{
int r;
float pi=3.14, area, ci;
clrscr();

scanf("%d",&r);

area = pi*r*r;

printf("Area of circle = %f",area);

ci = 2*pi*r;

printf("Circumference= %f", ci);

getch();
}
```

Output

```Enter radius of a circle: 5
Area of Circle = 78.000
Circumference = 31.4
```

Here In the above program first we include the header file and then we start with the main function. after that, we declare variables that we are going to use in our program. we set the pi value to 3.14 and use the clrscr() function to clear the screen before writing the output. after that, we use the printf() function to write a message on the output screen.

And then we use the scanf() function to take the input in the r variable. and then calculate the area of the circle using the formula pi*r*r.

And then we Again use the printf() function to display the Area of the circle and in the same manner we use the 2*pi*r formula to print the Circumference of the Circle on the output screen.