C Program To Find The Area And Perimeter Of A Rectangle

This article explores how to calculate the area and perimeter of a rectangle using the C programming language. In this article, you will learn to implement a simple C program that takes length and width as input and provides accurate calculations.

Problem Statement

A common mathematical task involves determining the area and perimeter of a rectangle. The area represents the space enclosed within the rectangle, while the perimeter is the total length of its boundary. Accurately calculating these values is crucial in various real-world applications.

Example

Consider a rectangle with a length of 10 units and a width of 5 units. The expected output for this rectangle would be:

• Area: 50 square units
• Perimeter: 30 units

Background & Knowledge Prerequisites

To understand and implement the C program for this task, readers should have a basic understanding of:

• Variables: How to declare and use variables to store data (e.g., float for decimal numbers).
• Input/Output Operations: Using printf() to display output and scanf() to read user input.
• Arithmetic Operators: Performing basic calculations like addition (+), multiplication (*).
• Basic Program Structure: The main() function and including header files like stdio.h.

Use Cases or Case Studies

Calculating the area and perimeter of a rectangle has numerous practical applications:

• Construction and Architecture: Determining the amount of material needed for flooring, painting walls, or fencing a rectangular plot of land.
• Gardening and Landscaping: Planning garden layouts, calculating the size of flowerbeds, or determining the length of edging required.
• Manufacturing and Design: Estimating the surface area of components or the length of material needed to form rectangular parts.
• Computer Graphics and UI Design: Calculating the dimensions and layout of screen elements, windows, or image sizes.
• Education: As a fundamental exercise in learning programming and basic geometry.

Solution Approaches

Basic Calculation with User Input

This approach prompts the user to enter the length and width of the rectangle, then computes and displays the area and perimeter using standard mathematical formulas.

// Calculate Area and Perimeter of a Rectangle
#include <stdio.h> // Required for input/output functions

int main() {
    // Step 1: Declare variables to store length, width, area, and perimeter.
    // Using float allows for non-integer dimensions.
    float length;
    float width;
    float area;
    float perimeter;

    // Step 2: Prompt the user to enter the length of the rectangle.
    printf("Enter the length of the rectangle: ");
    // Step 3: Read the length value from the user.
    scanf("%f", &length);

    // Step 4: Prompt the user to enter the width of the rectangle.
    printf("Enter the width of the rectangle: ");
    // Step 5: Read the width value from the user.
    scanf("%f", &width);

    // Step 6: Calculate the area of the rectangle.
    // Formula: Area = length * width
    area = length * width;

    // Step 7: Calculate the perimeter of the rectangle.
    // Formula: Perimeter = 2 * (length + width)
    perimeter = 2 * (length + width);

    // Step 8: Display the calculated area and perimeter to the user.
    // %.2f formats the float to two decimal places.
    printf("\\nArea of the rectangle: %.2f square units\\n", area);
    printf("Perimeter of the rectangle: %.2f units\\n", perimeter);

    return 0; // Indicate successful program execution
}

Run

Sample Output

Enter the length of the rectangle: 12.5
Enter the width of the rectangle: 8.2

Area of the rectangle: 102.50 square units
Perimeter of the rectangle: 41.40 units

Stepwise Explanation

1. Include Header: The #include line brings in the standard input/output library, necessary for functions like printf() and scanf().
2. Declare Variables: Inside main(), four float variables (length, width, area, perimeter) are declared. float is chosen to handle decimal values for dimensions.
3. Get Length Input: The program uses printf() to ask the user for the rectangle's length and scanf("%f", &length); to read the floating-point value entered by the user and store it in the length variable. The & before length is crucial as it passes the memory address of the variable.
4. Get Width Input: Similarly, the program prompts for and reads the width.
5. Calculate Area: The area is computed using the formula length * width and the result is stored in the area variable.
6. Calculate Perimeter: The perimeter is calculated using the formula 2 * (length + width) and stored in the perimeter variable.
7. Display Results: Finally, printf() statements are used to display the calculated area and perimeter. The %.2f format specifier ensures that the floating-point numbers are displayed with two decimal places, making the output cleaner.
8. Return 0: return 0; indicates that the program executed successfully.

Conclusion

This C program provides a straightforward and efficient method to calculate the area and perimeter of a rectangle. By taking user input for length and width, it performs the necessary arithmetic operations and presents the results clearly. This fundamental example showcases basic input/output, variable handling, and arithmetic in C.

Summary

• A rectangle's area is calculated by multiplying its length by its width (Area = L \* W).
• The perimeter is found by adding all four sides, or using the formula: 2 \* (L + W).
• The C program utilizes printf() for output and scanf() for user input to gather dimensions.
• float data type is used for variables to accommodate non-integer dimensions.
• The stdio.h header file is essential for standard input/output functions.