Circumference

C Program To Find Area and Circumference of Circle using Pointer

Lets write a C program to calculate area and circumference or perimeter of a Circle using pointer and function.

Video Tutorial: C Program To Find Area and Circumference of Circle using Pointer

[youtube https://www.youtube.com/watch?v=ekmC25v6TqU]

YouTube Link: https://www.youtube.com/watch?v=ekmC25v6TqU [Watch the Video In Full Screen.]

Source Code: C Program To Find Area and Circumference of Circle using Pointer

#include<stdio.h>

void area_peri(float, float*, float*);

int main()
{
    float radius, area, perimeter;

    printf("Enter radius of Circle\n");
    scanf("%f", &radius);

    area_peri(radius, &area, &perimeter);

    printf("\nArea of Circle = %0.2f\n", area);
    printf("Perimeter of Circle = %0.2f\n", perimeter);

    return 0;
}

void area_peri(float r, float *a, float *p)
{
    *a = 3.14 * r * r;
    *p = 2 * 3.14 * r;
}

Output 1:
Enter radius of Circle
5

Area of Circle = 78.50
Perimeter of Circle = 31.40

Output 2:
Enter radius of Circle
14

Area of Circle = 615.44
Perimeter of Circle = 87.92

Logic To Find Area and Circumference of Circle using Pointer

We ask the user to enter value for radius of a Circle. We pass this value along with address of variables area and perimeter to the function area_peri().

area_peri(radius, &area, &perimeter);

We copy the value of radius to a local variable r and then we take 2 floating point pointer variables *a and *p. *a represents the value present at address a or &area. *p has value present at address p or &perimeter.

Inside area_peri() function we calculate the area and circumference / perimeter of Circle and store it as value present at addresses a and p. Since a points to address of variable area and p points to address of variable perimeter, the values of variable area and perimeter changes too.

*a = 3.14 * r * r;

*p = 2 * 3.14 * r;

Area and Circumference of Circle

We’ve separate video tutorials to calculate area and circumference of a Circle using radius, and without using pointer and function. You can check them out at these links:

Calculate Area of a Circle without using math.h library: C
C Program To Calculate Circumference of Circle

Note: When * is precedes any address, it fetches the value present at that address or memory location.

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C Program To Calculate Surface Area of Cylinder

Given the values for radius and height of a Cylinder, write a C program to calculate Surface Area of the Cylinder.

Formula To Calculate Surface Area of Cylinder

Surface_Area = (2 * PI * radius * height) + (2 * PI * radius * radius);
where PI is approximately equal to 3.14

surface area of Cylinder

Logic of Surface Area of Cylinder Formula

A solid Cylinder has 2 circles. One at the top and one at the bottom. Area of a Circle is PI * radius². Since there are 2 Circles in the Cylinder, we multiply it by 2.

i.e., 2 (PI * radius²)

Next lets cut the cylinder at one end and open it. It forms a rectangle. Now height of the rectangle and height of the Cylinder are same. Width of the rectangle is equal to circumference of the circle, since top and bottom of the Cylinder are circles.

So, area of rectangle = (2 * PI * radius) * height

Therefore, Surface Area of Cylinder is:

SA = ( (2 * PI * radius) * height ) + ( 2 (PI * radius²) );

Expected Output for the Input

User Input:
Enter Radius and Height of the Cylinder
2
5

Output:
Surface Area of Cylinder is 87.920006

Video Tutorial: C Program To Calculate Surface Area of Cylinder

[youtube https://www.youtube.com/watch?v=9GGagAMiMSc]

YouTube Link: https://www.youtube.com/watch?v=9GGagAMiMSc [Watch the Video In Full Screen.]

Source Code: C Program To Calculate Surface Area of Cylinder

#include<stdio.h>

int main()
{
    const float PI = 3.14;
          float r, h, Area;

    printf("Enter Radius and Height of the Cylinder\n");
    scanf("%f%f", &r, &h);

    Area = (2 * PI * r * h) + (2 * PI * r * r);

    printf("Surface Area of Cylinder is %f\n", Area);

    return 0;
}

Output 1:
Enter Radius and Height of the Cylinder
5
10
Surface Area of Cylinder is 471.000031

Output 2:
Enter Radius and Height of the Cylinder
2
13
Surface Area of Cylinder is 188.400009

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For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert

C Program To Calculate Circumference of Circle

Given the radius of a Circle, write a C program to calculate circumference of the Circle.

Formula To Calculate Circumference of Circle

circumference = 2 * PI * radius;
Where PI is approximately equal to 3.14

Related Read:
Basic Arithmetic Operations In C

Expected Output for the Input

User Input:
Enter Radius of the Circle
5

Output:
Circumference of the Circle is 31.400002

Video Tutorial: C Program To Calculate Circumference of Circle

[youtube https://www.youtube.com/watch?v=o2r2bDOuCX4]

YouTube Link: https://www.youtube.com/watch?v=o2r2bDOuCX4 [Watch the Video In Full Screen.]

Source Code: C Program To Calculate Circumference of Circle

#include<stdio.h>

int main()
{
    const float PI = 3.14;
          float r, c;

    printf("Enter Radius of the Circle\n");
    scanf("%f", &r);

    c = 2 * PI * r;

    printf("Circumference of the Circle is %f\n", c);

    return 0;
}

Output 1:
Enter Radius of the Circle
10
Circumference of the Circle is 62.800003

Output 2:
Enter Radius of the Circle
41
Circumference of the Circle is 257.480011

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert