Loop in C with Examples: For, While, Do..While Loops

Loop in C: An Overview

Are you interested in programming but don't know where to start? Have you ever heard the term loop? Looping is one of the key concepts behind programming, and learning how to use Loop in C can open up a new world of code. Gain the foundational skills from this C tutorial and move to the advanced C Language Free Course thatincludes in-depth coverage of loop and other essential programming concepts.

Read More - Top 50 C Interview Questions and Answers

What are Loop in C?

Loops are a block of code that executes itself until the specified condition becomes false. In this section, we will look in detail at the types of loops used in C programming.

What is the Need for Looping Statements in C?

Here are some uses of loops in C:

• Loops allow the user to execute the same set of statements repeatedly without writing the same code multiple times.
• It saves time and effort and increases the efficiency.
• It reduces the chance of getting errors during compilation.
• Loop makes the code readable and easier to understand, especially when dealing with complex logic or large data sets.
• It promotes code reusability.
• Loops help traverse data structures like arrays or linked lists

1. for loop
2. while loop
3. do while loop

1. for loop in C

A for loop is a control structure that enables a set of instructions to get executed for a specified number of iterations. It is an entry-controlled loop.

for loop Flowchart

Syntax

for(initialization; test condition; update expression){
//code to be executed
}

• Here, the initialization statement is executed first and only once.
• The test condition is checked, if false the loop terminates
• 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 false.

Example: For loop in C Compiler

// Program to print numbers from 1 to 10
#include <stdio.h> 

int main() {
 int i;
 for (i = 0; i < 10; i++)
 {
 printf("%d\n", i+1);
 }
 return 0;
}

The above code prints the numbers from 1 to 10 using a for loop in C.

• We know it will take 10 iterations to print 10 numbers so, we have used the for loop.
• i is initialized to 0.
• The condition i<10 will be checked. It is true, therefore i+1 i.e. 1 gets printed.
• Then i increments to 1 again the condition, i<10 is evaluated.
• The process will repeat until i become 10.

Output

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2. while loop in C

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

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

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

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

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