How to Calculate the Surface Area of a Cylinder in C

Introduction

In this lab, you will learn how to calculate the surface area of a cylinder using C programming. The lab covers the steps to read the radius and height of the cylinder from the user, and then compute the surface area using the formula 2PIr*(r+h). The program will then print the calculated surface area.

The lab provides a complete step-by-step guide, including the necessary C code, to help you understand the process of computing the surface area of a cylinder. By the end of this lab, you will have a solid understanding of how to perform geometry calculations using C programming.

Read Radius and Height

In this step, you will learn how to read the radius and height of a cylinder using C programming. We'll create a simple program that prompts the user to input these values.

First, let's create a new C file in the project directory:

cd ~/project
nano cylinder_surface_area.c

Now, add the following code to the file:

#include <stdio.h>

int main() {
    float radius, height;

    // Prompt user to enter radius
    printf("Enter the radius of the cylinder: ");
    scanf("%f", &radius);

    // Prompt user to enter height
    printf("Enter the height of the cylinder: ");
    scanf("%f", &height);

    // Print the entered values
    printf("Radius: %.2f\n", radius);
    printf("Height: %.2f\n", height);

    return 0;
}

Let's break down the code:

We use printf() to display prompts for radius and height
scanf() is used to read float values for radius and height
%.2f formats the output to display two decimal places

Compile and run the program:

gcc cylinder_surface_area.c -o cylinder_surface_area
./cylinder_surface_area

Example output:

Enter the radius of the cylinder: 5
Enter the height of the cylinder: 10
Radius: 5.00
Height: 10.00

Compute Surface Area = 2PIr*(r+h)

In this step, you will modify the previous program to calculate the surface area of a cylinder using the formula: Surface Area = 2PIr*(r+h).

Open the existing file and update the code:

cd ~/project
nano cylinder_surface_area.c

Replace the previous code with the following:

#include <stdio.h>
#define PI 3.14159

int main() {
    float radius, height, surface_area;

    // Prompt user to enter radius
    printf("Enter the radius of the cylinder: ");
    scanf("%f", &radius);

    // Prompt user to enter height
    printf("Enter the height of the cylinder: ");
    scanf("%f", &height);

    // Calculate surface area
    surface_area = 2 * PI * radius * (radius + height);

    // Print the results
    printf("Radius: %.2f\n", radius);
    printf("Height: %.2f\n", height);
    printf("Surface Area: %.2f\n", surface_area);

    return 0;
}

Let's break down the changes:

Added #define PI 3.14159 to define a constant for π
Created a surface_area variable to store the calculated result
Used the formula: Surface Area = 2PIr*(r+h)
Added a print statement to display the calculated surface area

Compile and run the program:

gcc cylinder_surface_area.c -o cylinder_surface_area
./cylinder_surface_area

Example output:

Enter the radius of the cylinder: 5
Enter the height of the cylinder: 10
Radius: 5.00
Height: 10.00
Surface Area: 628.32

Print the Surface Area

In this final step, you will enhance the program to provide a more user-friendly output of the cylinder's surface area.

Open the existing file and make final modifications:

cd ~/project
nano cylinder_surface_area.c

Update the code with formatted output:

#include <stdio.h>
#define PI 3.14159

int main() {
    float radius, height, surface_area;

    // Prompt user to enter radius
    printf("Cylinder Surface Area Calculator\n");
    printf("--------------------------------\n");
    printf("Enter the radius of the cylinder: ");
    scanf("%f", &radius);

    // Prompt user to enter height
    printf("Enter the height of the cylinder: ");
    scanf("%f", &height);

    // Calculate surface area
    surface_area = 2 * PI * radius * (radius + height);

    // Print formatted results
    printf("\nCalculation Results:\n");
    printf("--------------------------------\n");
    printf("Radius:        %.2f units\n", radius);
    printf("Height:        %.2f units\n", height);
    printf("Surface Area:  %.2f square units\n", surface_area);

    return 0;
}

Compile and run the program:

gcc cylinder_surface_area.c -o cylinder_surface_area
./cylinder_surface_area

Example output:

Cylinder Surface Area Calculator
--------------------------------
Enter the radius of the cylinder: 5
Enter the height of the cylinder: 10

Calculation Results:
--------------------------------
Radius:        5.00 units
Height:        10.00 units
Surface Area:  628.32 square units

Key improvements:

Added a title for the calculator
Included separators for better readability
Added units to the output
Formatted the results with clear labels

Summary

In this lab, you learned how to read the radius and height of a cylinder using C programming, and then calculate the surface area of the cylinder using the formula: Surface Area = 2PIr*(r+h). The program prompts the user to enter the radius and height, and then calculates and displays the surface area.

The key steps covered in this lab are: 1) reading the radius and height from the user, and 2) computing the surface area using the provided formula.