Lab - Writing Different Types of Loops in C

Overview

In this lab, we'll explore how to write different types of loops in C programming. We'll start with a basic main program and gradually introduce new functions, each implementing a different type of loop: for, while, and do-while. Follow along as we demonstrate these loop constructs with examples.

Step 1 - Setting Up the Main Program

Let's begin with a simple main program that demonstrates the basic structure of C code:

#include <stdio.h>

int main() {

    // Our starting point
    printf("C loop demo program\n");

    return 0;
}

Compile and run the program by clicking the Excecute button in the Jdoodle window.

You should See the following output:

C loop demo program

This is our starting point. Now, let's add functions for different types of loops.

Step 2 - Adding a for Loop

We'll start with the for loop, which is perfect for tasks with a known number of iterations. Here's how you can write a for loop in C:

#include <stdio.h>

// Function to demonstrate a for loop
void demonstrateForLoop() {
    printf("Using a for loop to print numbers from 1 to 5:\n");
    for (int i = 1; i <= 5; i++) {
        printf("%d ", i);
    }
    printf("\n");
}

int main() {
    printf("C loop demo program\n");
    demonstrateForLoop();
    
    return 0;
}

In this example, the demonstrateForLoop function showcases the for loop. It prints numbers from 1 to 5.

Step 3 - Run the Program

Compile and run the program by clicking the Excecute button in the Jdoodle window.

You should See the following output:

C loop demo program
Using a for loop to print numbers from 1 to 5:
1 2 3 4 5

Step 4 - Adding a while Loop

Next, let's introduce the while loop, which is suitable when the number of iterations is not known in advance. Here's how to use a while loop:

#include <stdio.h>

// Function to demonstrate a while loop
void demonstrateWhileLoop() {
    printf("Using a while loop to print numbers from 1 to 5:\n");
    int i = 1;
    while (i <= 5) {
        printf("%d ", i);
        i++;
    }
    printf("\n");
}

// Function to demonstrate a for loop
void demonstrateForLoop() {
    printf("Using a for loop to print numbers from 1 to 5:\n");
    for (int i = 1; i <= 5; i++) {
        printf("%d ", i);
    }
    printf("\n");
}

// Rest of the code remains the same

int main() {
    printf("C loop demo program\n");
    demonstrateForLoop();
    demonstrateWhileLoop();
    
    return 0;
}

In the demonstrateWhileLoop function, we print numbers from 1 to 5 using a while loop. The loop continues as long as the condition i <= 5 is true.

Step 4 - Run the Program

Compile and run the program by clicking the Excecute button in the Jdoodle window.

You should see the following output:

C loop demo program
Using a for loop to print numbers from 1 to 5:
1 2 3 4 5 
Using a while loop to print numbers from 1 to 5:
1 2 3 4 5

Step 5 - Adding a do-while Loop

Finally, let's incorporate the do-while loop, which guarantees that a block of code is executed at least once before checking the condition. Here's how to use a do-while loop:

#include <stdio.h>

// Function to demonstrate a do-while loop
void demonstrateDoWhileLoop() {
    printf("Using a do-while loop to print numbers from 1 to 5:\n");
    int i = 1;
    do {
        printf("%d ", i);
        i++;
    } while (i <= 5);
    printf("\n");
}

// Function to demonstrate a while loop
void demonstrateWhileLoop() {
    printf("Using a while loop to print numbers from 1 to 5:\n");
    int i = 1;
    while (i <= 5) {
        printf("%d ", i);
        i++;
    }
    printf("\n");
}

// Function to demonstrate a for loop
void demonstrateForLoop() {
    printf("Using a for loop to print numbers from 1 to 5:\n");
    for (int i = 1; i <= 5; i++) {
        printf("%d ", i);
    }
    printf("\n");
}

// Rest of the code remains the same

int main() {
    printf("C loop demo program\n");
    demonstrateForLoop();
    demonstrateWhileLoop();
    demonstrateDoWhileLoop();
    
    return 0;
}

In the demonstrateDoWhileLoop function, we print numbers from 1 to 5 using a do-while loop. This loop ensures that the code block runs at least once before checking the condition.

Step 6 - Run the Program

Compile and run the program by clicking the Excecute button in the Jdoodle window.

You should see the following output:

C loop demo program
Using a for loop to print numbers from 1 to 5:
1 2 3 4 5 
Using a while loop to print numbers from 1 to 5:
1 2 3 4 5 
Using a do-while loop to print numbers from 1 to 5:
1 2 3 4 5

Summary

Congratulations! You've successfully learned how to write different types of loops in C programming. We started with a basic main program and gradually introduced for, while, and do-while loops, each implemented within a separate function. Loops are essential tools for controlling program flow and automating repetitive tasks, making your C programs more efficient and versatile.