C Program to find the Area Of a Circle

in C Programs, Uncategorized March 2, 2025 Comments Off on C Program to find the Area Of a Circle

C Program to find the Area of a Circle – In this particular article, we will detail in how to find the area of a circle in C Programming. There are multiple ways explained in this piece on how to find the area of a circle.

Check out the suitable examples and the sample programs mentioned to explain the c programming code to calculate the area of a circle. The compiler has been added to help you with the solution for the question of concern.

The ways in which the area of a circle is calculated in this article are as follows:

Using Standard Method
Using Functions
Using Pointers
Using Macros

As we all know, circles are the combination of infinite points forming a locus which is equidistant from a single point. The locus is known as the circumference.

The point which is inside the circle that is equidistant to the circumference is known as the centre of the circle. The distance between the centre of the circle and the circumference is known as the radius of the circle.

A circle looks like this:

As we can see in the image uploaded above, the radius of the circle is 5cm.

Thus, the area of the circle is

Area = 2 * pi * (sq)r = 2 * pi * (sq)5

Area = 50pi = 157.08 sq.cm

Thus, the ways to calculate the area of a circle mentioned are as follows:

Using Standard Method

To calculate the area of a circle, we need the radius.
The value of radius will store into the variable “r”.
By substituting the “r” value in the formula, we will get the area.

#include<stdio.h>
int main()
{
	int r;
	float area;
	printf("enter radius of the circle: ");
	scanf("%d",&r);
	area=(22*r*r)/7;
	printf("AOC: %f\n",area);
	return 0;
}

#include<stdio.h>

int main()

{

int r;

float area;

printf("enter radius of the circle: ");

scanf("%d",&r);

area=(22*r*r)/7;

printf("AOC: %f\n",area);

return 0;

}

Output:

enter radius of the circle: 28
AOC: 2464.000000

1 2	enter radius of the circle: 28 AOC: 2464.000000

Using Functions

We are calling the function as area(r) which is having int type of argument.
The called function float area(int r) will calculate the area and return the value, that will return value assigned to the variable “a”.

#include<stdio.h>
float area(int r)
{
	return (22*r*r)/7;
}
int main()
{
	int r;
	float a;
	printf("enter radius of the circle: ");
	scanf("%d",&r);
        a=area(r); 
	printf("area of the circle: %f\n",a);
	return 0;
}

#include<stdio.h>

float area(int r)

{

return (22*r*r)/7;

}

int main()

{

int r;

float a;

printf("enter radius of the circle: ");

scanf("%d",&r);

a=area(r);

printf("area of the circle: %f\n",a);

return 0;

}

Output:

enter radius of the circle: 7
area of the circle: 154.00

1 2	enter radius of the circle: 7 area of the circle: 154.00

Using Pointers

We are calling the function by passing references as arguments using area(&r,&a).
The called function area(int *r, float *a) will retrieve the values at that given addresses and calculate the area and that area value will be stored into the pointer variable “a”.

#include<stdio.h>
void area(int *r,float *a)
{
	*a=(22*(*r)*(*r))/7;
}
int main()
{
	int r;
	float a=1;
	printf("enter radius of the circle: ");
	scanf("%d",&r);
        area(&r,&a); 
	printf("AOC: %f\n",a);
	return 0;
}

#include<stdio.h>

void area(int *r,float *a)

{

*a=(22*(*r)*(*r))/7;

}

int main()

{

int r;

float a=1;

printf("enter radius of the circle: ");

scanf("%d",&r);

area(&r,&a);

printf("AOC: %f\n",a);

return 0;

}

Output:

enter radius of the circle: 35
AOC: 3850.000000

1 2	enter radius of the circle: 35 AOC: 3850.000000

Using Macros

area(r) is the symbolic name to the expression (22*r*r)/7
area(r)replaced with that expression given at #define.

#include<stdio.h>
#define	area(r) (22*r*r)/7;

int main()
{
	int r;
	float a=1;
	printf("enter radius of the circle: ");
	scanf("%d",&r);
        a=area(r); 
	printf("AOC: %f\n",a);
	return 0;
}

#include<stdio.h>

#define area(r) (22*r*r)/7;

int main()

{

int r;

float a=1;

printf("enter radius of the circle: ");

scanf("%d",&r);

a=area(r);

printf("AOC: %f\n",a);

return 0;

}

Output:

enter radius of the circle: 14
AOC: 616.000000

1 2	enter radius of the circle: 14 AOC: 616.000000

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C Program to find the Area Of a Circle

Using Standard Method

Using Functions

Using Pointers

Using Macros

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