What is Do While Loop in C?

What is Do While Loop in C?

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Anshuman
Anshuman Singh
Senior Executive - Content
Updated on Jul 3, 2023 17:39 IST

In computer programming, loops play an essential part. Instead of writing hundreds of lines of code that keeps running until a particular condition is met, you can do the exact same work just by writing five or six lines of code with the do while loop. There are mainly three loops in C programming language: for loop, while loop, and do while loop.

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This article will discuss all there is to know regarding the do while loop in the C programming language. But, before we begin exploring do while loop in detail, let’s quickly go over the topics listed under the table of contents (TOC) we will cover in this article.

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Table of Contents (TOC)

What is Do While Loop?

The do while loop is a control flow statement in the C programming language. Using this loop, a piece of code can be executed repeatedly as long as a specific condition is True.

The syntax of the do while loop in C programming language is:

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

Here’s the flowchart:

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The do while loop’sloop’s body is executed once before the test condition is assessed. The do while loop is repeated until the condition remains True, and if the condition becomes False, the loop ends immediately after the first iteration. In order to understand the working of do while loop in a better way, let’s go through some of the examples in the next section of the article.

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Examples of Do While Loop 

Here are some examples of the do while loop in order to help you understand better.

Example 1:

Consider the following code:

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

Explanation:

  • The variable “i” is initialized to 1, and then the code inside the do-while loop is executed.
  • The code inside the do-while loop prints the value of “i” to the console and then increments “i” by 1.
  • The while statement at the end of the loop checks if the value of “i” is less than or equal to 10.
  • If the condition is True, the code inside the do-while loop is executed again.
  • This process continues until the value of “i” is no longer less than or equal to 10.

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Example 2:

Consider the following code:

 
#include
int main() {
int num, i, sum = 0;
printf("Enter a positive integer: ");
scanf("%d", &num);
i = 0;
do {
sum = sum + i;
i++;
} while (i <= num);
printf("Sum: %d", sum);
return 0;
}
Copy code

Explanation:

  • Two variables, n and sum = 0, have been declared in the example code above. The user enters a value for the variable n. The number up to which we want to find the sum of natural numbers will be this value. 
  • Next, the do while loop is employed. The loop’s body will only be executed once, adding the new value to the variable sum and decrementing the value of n by 1. 
  • The test condition n > 0 will only be examined after that. 
  • Again, the loop will execute until the input integer n exceeds 0. The integer n is added to the sum and the value of n decrements by 1 in each iteration. 
  • As soon as n falls below 0, the test condition returns False, the do while loop is terminated, and the sum is printed. 

Yoy can also explore: Understanding Data Structures in C: Types And Operations

Advantages of Using the Do While Loop

Some of the advantages of using the do while loop are:

  • The structure of a do-while loop is simple and easy to understand.
  • The code inside a do while loop is always executed at least once, regardless of the condition.
  • The code inside a do while loop will continue to execute as long as the condition is True. This loop is handy for situations where you must repeatedly execute a code until a specific condition is met.

Disadvantages of Using the Do While Loop

Some of the disadvantages of using the do while loop are:

  • If the exit condition is not well defined in the do while loop, it might lead to bugs or unexpected results in the program.
  • The loop will never exit if the condition in the while statement is always True. Because of this, the program will run indefinitely, resulting in an infinite loop.

Conclusion

A do while loop is useful when you must ensure that a piece of code is executed at least once. It especially comes in handy when executing a piece of code repeatedly until a specific condition is met. However, when using do while loop, be cautious of infinite loops and carefully define the exit conditions as they can create a severe problem.

In this article, we have discussed all there is to know about the do while loop and its advantages and disadvantages. If you have any queries related to the topic, please feel free to send your queries through a comment. We will be happy to help.

Happy Learning!!

FAQs

Can I nest a "do-while" loop within another loop?

Yes, you can nest a "do-while" loop within another loop, or nest any type of loop within another loop in C. This allows you to create more complex looping structures to solve specific programming problems.

What is the difference between a "do-while" loop and other loops in C?

The primary difference between a "do-while" loop and other loops (such as "for" and "while" loops) is that a "do-while" loop guarantees that the loop body is executed at least once, even if the condition is initially false. In contrast, the other loops check the condition before executing the loop body, so they may not execute the loop body at all if the condition is false from the start.

When should I use a "do-while" loop?

Use a "do-while" loop when you want to ensure that a block of code is executed at least once, regardless of the condition. This can be useful in situations where you need to perform an action and then check a condition to determine if further iterations are required.

About the Author
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Anshuman Singh
Senior Executive - Content

Anshuman Singh is an accomplished content writer with over three years of experience specializing in cybersecurity, cloud computing, networking, and software testing. Known for his clear, concise, and informative wr... Read Full Bio