C Programs to Find the Area of a Circle

C program to find the area of a circle; Through this tutorial, we will learn how to find or calculate the area of a circle using formula, function, and poiter in c programs.

Programs and Algorithm to Find the Area of a Circle

• Algorithm To Find Area Of a Circle
• C Programs to Find the Area of a Circle using Formula
• C Programs to Find the Area of a Circle using Function
• C Programs to Find the Area of a Circle using Pointer

Algorithm To Find Area Of a Circle

Use the following algorithm to write a program to find area of a circle; as follows:

1. START PROGRAM.
2. TAKE RADIUS AS INPUT FROM USER.
3. FIND AREA OF A CIRLCE USING THIS FORMULA AREA=3.14*RADIUS*RADIUS.
4. PRINT “AREA OF CIRCLE = “
5. END PROGRAM.

C Programs to Find the Area of a Circle using Formula

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

The output of the above c program; as follows:

Please enter radius of the circle: 15
The area of circle is: 707.000000

C Programs to Find the Area of a Circle using Function

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

The output of the above c program; as follows:

Please enter radius of the circle: 5
area of the circle: 78.000000

C Programs to Find the Area of a Circle using Pointer

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

The output of the above c program; as follows:

Please enter radius of the circle: 7
The area of circle is: 154.000000

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