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ToggleIn this blog post, we will checkout the area of circle program in C programming. **The area of a circle is given by the formula ( πr^2 ), where ( r ) is the radius of the circle and (π) (Pi) is a constant approximately equal to 3.14159.** This formula is a cornerstone in geometry and is pivotal in various applications across science and engineering fields. Our focus will be on implementing this formula in a C program to efficiently compute the area, providing a practical approach to understanding mathematical concepts through programming.

**Area of Circle** **Formula**

`Area = `** π** * Radius * Radius

Where value of pie = **3.14159** and radius will be given by the user.

## How to Write Area of Circle Program in C?

To create a C program for finding the area of a circle, you can follow this algorithm and corresponding pseudo code.

**Algorithm:**

**Start**: Begin the process.**Input Radius**: Prompt the user to input the radius of the circle.**Calculate Area**: Use the formula Area =**π*** Radius * Radius to calculate the area of the circle.**Display Area**: Show the calculated area to the user.**End**: Conclude the process.

**Pseudo Code:**

```
BEGIN
DECLARE radius, area AS FLOAT
PRINT "Enter the radius of the circle: "
READ radius
area = π * radius * radius
PRINT "The area of the circle with radius ", radius, " is: ", area
END
```

## C Program to Find Area of Circle

```
#include <stdio.h>
int main() {
double radius, area;
// initializing the value of pi
double pi = 22.0 / 7.0;
// Prompt user and get radius
printf("Enter the radius of the circle: ");
scanf("%lf", &radius); // %lf for reading double
// Calculate area
area = pi * radius * radius; // M_PI is from math.h
// Display the area
printf("The area of the circle with radius %.2lf is: %.2lf\n", radius, area);
return 0; // End of program
}
```

**Output**

In the above program, first, we initialise the variable pi with the value of π and take input for radius then using the area of circle formula calculated the area of the circle.

**Time Complexity: **The time complexity of this program is O(1). This is because the calculation of the area of a circle is achieved through a straightforward arithmetic expression that does not depend on iterative or recursive processes.

**Space Complexity:** The space complexity is also O(1). This is because program uses few variables which doesn’t not grow with the input size.

## Conclusion

- On a plane, a shape’s area is the amount of space it covers.
- When the radius is given, the area of a circle is Area=π∗(radius)2Area=π∗(radius)2
- Using the above we have discussed area of circle program in C.

If you liked this post you can checkout other C Programs.

## FAQ

What is the formula of area of C?

The area of circle can be calculated given either the radius (r) , the diameter (d), using one of the following formulas: **Area = πr^2** Area = (π/4) × d.

Can the same program be used to find the area of a circle with a different programming language?

Yes, the formula and logic for calculating the area of a circle remain the same across different programming languages. All you need is to just change the syntax according to programming language.

Are there any libraries or functions available in C for calculating the area of a circle?

C does not provide built-in functions for calculating the area of a circle