Do–while loop in C - Mini Project: Build & Apply

Do-while loop in C

📖 Scenario: You are creating a simple program that repeatedly asks a user to enter a number until they enter zero. This is like asking a friend to keep giving you numbers until they say stop by entering zero.

🎯 Goal: Build a C program that uses a do-while loop to keep asking for numbers and stops when the user enters zero.

📋 What You'll Learn

Create an integer variable called number

Use a do-while loop to ask the user to enter a number

Inside the loop, read the number from the user using scanf

The loop should continue as long as number is not zero

After the loop ends, print "Done"

💡 Why This Matters

🌍 Real World

Do-while loops are useful when you want to run a block of code at least once and then repeat it based on a condition, like menus or repeated user input.

💼 Career

Understanding loops like do-while is essential for programming jobs where you handle user input, data processing, or repetitive tasks.

1

Create the variable to store the number

Create an integer variable called number and set it to 0.

C

#include 

int main() {
    int number = 0;  // Your code here

    return 0;
}

Need a hint?

Think about how to create a variable to hold a number in C.

2

Set up the do-while loop structure

Write a do block followed by a while condition that checks if number is not equal to 0. Leave the do block empty for now.

C

#include 

int main() {
    int number = 0;

    do {
        // Your code here
    } while (number != 0);

    return 0;
}

Need a hint?

Remember the syntax of a do-while loop in C: do { ... } while(condition);

3

Add input reading inside the loop

Inside the do block, add a printf statement to ask the user to "Enter a number (0 to stop): ", then use scanf to read the integer into number.

C

#include 

int main() {
    int number = 0;

    do {
        // Your code here
    } while (number != 0);

    return 0;
}

Need a hint?

Use printf to show the message and scanf to read the number into the variable.

4

Print "Done" after the loop ends

After the do-while loop, write a printf statement to print "Done\n".

C

#include 

int main() {
    int number = 0;

    do {
        printf("Enter a number (0 to stop): ");
        scanf("%d", &number);
    } while (number != 0);

    // Your code here

    return 0;
}

Need a hint?

Use printf("Done\n"); to show the message after the loop.