Programming C in Loop While

Understanding the While Loop in C Programming

Hey, budding coder!
Let’s dive into another type of loop called the While Loop. Imagine you have to keep doing something over and over again, but you don’t know how many times you need to repeat it. In this case, the While Loop is your best friend! It keeps repeating code as long as a certain condition is true.

What is a While Loop?

A While Loop is a way to repeat a block of code as long as a specific condition remains true. Unlike the For Loop, which runs a fixed number of times, the While Loop keeps going until the condition becomes false.

Syntax of While Loop

Here’s how you write a While Loop in C:

while (condition) {
    // Code to be repeated
}

Condition: This is a test that the loop checks before running. If it’s true, the loop runs; if it’s false, the loop stops.
Code: This is the block of code that will repeat as long as the condition is true.

Real-Life Example of a While Loop

Imagine you are filling a bucket with water. You want to keep filling the bucket while it’s not full. Once it’s full, you stop. This is a perfect job for a While Loop!

Let’s write a simple program to count from 1 to 5 using a While Loop:

#include <stdio.h>

int main() {
    int i = 1;  // Initialization

    while (i <= 5) {  // Condition
        printf("%d\n", i);  // Code to repeat
        i++;  // Increment to avoid infinite loop
    }

    return 0;
}

Explanation:

We start with i = 1.
The While Loop checks if i <= 5.
As long as this condition is true, the loop prints i and then increases i by 1.
The loop stops when i becomes greater than 5.

Output:

Flowchart of a While Loop

Here’s how the While Loop works step by step:

Check the Condition: Is it true or false?
If true, run the code inside the loop.
If false, exit the loop.
Repeat the process until the condition becomes false.

       [Start]
          |
 [Check condition (i <= 5)]
        /   \
      Yes   No
      |       |
 [Run code]   [End]
      |
 [Increment i++]
      |
 [Repeat loop]

Programming Example: Sum of Numbers

Let’s write a program that adds numbers from 1 to 10 using a While Loop.

#include <stdio.h>

int main() {
    int i = 1;
    int sum = 0;  // Variable to hold the sum

    while (i <= 10) {
        sum += i;  // Add the current number to sum
        i++;  // Increment the counter
    }

    printf("The sum of numbers from 1 to 10 is %d\n", sum);

    return 0;
}

Explanation:

We start with i = 1 and sum = 0.
The loop keeps adding i to sum as long as i <= 10.
After each loop, i is increased by 1, and the loop stops when i becomes 11.

Output:

The sum of numbers from 1 to 10 is 55

Fun Example: Password Check

Let’s write a program that asks for a password and keeps asking until the correct password is entered.

#include <stdio.h>

int main() {
    int password;

    while (password != 1234) {  // Keep asking until the password is correct
        printf("Enter the password: ");
        scanf("%d", &password);  // Read the password input
    }

    printf("Access granted!\n");

    return 0;
}

Explanation:

The loop keeps asking for the password until the user enters 1234.
Once the correct password is entered, the loop stops, and “Access granted!” is printed.

Output:

Enter the password: 1111
Enter the password: 9999
Enter the password: 1234
Access granted!

Avoiding Infinite Loops

One thing to be careful with While Loops is making sure that the condition eventually becomes false. Otherwise, the loop will run forever, and your program will get stuck in an infinite loop.

For example, this loop would never stop:

#include <stdio.h>

int main() {
    int i = 1;

    while (i <= 5) {
        printf("%d\n", i);
        // Missing i++ causes an infinite loop!
    }

    return 0;
}

Challenge Time!

Try this fun challenge: Write a program that prints the multiplication table for the number 2 using a While Loop.

Here’s how you can do it:

#include <stdio.h>

int main() {
    int i = 1;
    int num = 2;

    while (i <= 10) {
        printf("%d x %d = %d\n", num, i, num * i);
        i++;  // Don't forget to increment i!
    }

    return 0;
}

Output:

2 x 1 = 2
2 x 2 = 4
2 x 3 = 6
...
2 x 10 = 20

Summary

The While Loop runs as long as the condition is true.
It’s perfect for situations where you don’t know exactly how many times the loop should run.
Always make sure your condition eventually becomes false, so you don’t get stuck in an infinite loop!

With the While Loop, you can create powerful programs that repeat tasks until the job is done. Keep practicing, and you’ll master loops in no time!