Understanding While loop in C

While Loop

The while Loop is an entry-controlled loop in C. This loop is used to iterate a part of the code while the given condition remains true. The test takes place before each iteration.

In this C Tutorial, we will explore more about while Loop which will include what is for loop in C, for loop in c programming example, and the syntax of for loop in C. First, we will see What are types of loops in C.

Read More - Top 50 C Interview Questions and Answers

1. For loop
2. While loop
3. Do While loop

But right now we are going to focus on only While Loop, So let's discuss it.

What is a While Loop?

• While loop is nothing but a a pre-tested loop. 
• It allows a part of the code to be executed n number of times depending upon a given boolean condition. 
• The while loop is viewed as a repeating if statement. 
• It is merely used in the case where the number of iterations is not known in advance.

Flowchart 

Syntax

while(test condition){ 
//code to be executed 
} 

• The test condition is checked, if false the loop will be skipped and the program will continue
• If the test condition is true, the body of the loop executes
• The update expression gets updated
• Again the test condition is evaluated
• The process repeats until the test condition becomes true.

Example: While loop in the CCompiler

// Print numbers from 1 to 10
#include <stdio.h>
int main() 
{
 int i = 1;
 while (i <= 10) {
 printf("%d\n", i);
 i++;
 }
 return 0;
}

Explanation:

• In the above code, i is initialized to 1 before the start of the loop.
• The test condition, i<=10 is evaluated. If true, the body of the loop executes.
• If the condition becomes false in the beginning itself, the program control does not even enter the loop once.
• The loop executes until i becomes 10.

Output

1
2
3
4
5
6
7
8
9
10

Infinite while loop:

• In this loop test condition is incorrect.
• And the updation statement is not present.

Example:

#include <stdio.h>

#include <stdlib.h>
 
int main()
{
    int Sch1= 1;
    int Sch2= 1;
 
    while (Sch1< 10) {
 
        Sch2 = Sch2+ 1;
        printf("Welcome to ScholarHat");
    }
    
    return 0;
}

Output

Welcome to ScholarHat
Welcome to ScholarHat
Welcome to ScholarHat