What is the difference between while and do while loop?

The difference between while and do while loop is that in the while loop the condition is checked prior to executing any statements whereas in the case of do while loop, statements are run at least once, and then the condition is verified.

What is the difference between while and do while loops on the basis of the approach followed?

The difference between while and do while loops on the basis of the approach followed is that a while loop follows a top-down approach to execute the loop body. On the other hand, the do while loop uses a bottom-up approach for executing a loop body.

What is the difference between while and do while loops based on loop body execution?

The difference between while and do while loops in terms of loop body execution is that in the do-while loop, the loop body executes exactly once whether the condition is true or false, but in the while loop, the loop body executes only if the condition is true.

Which is a better looping statement between while or do while?

We use do while when we want to execute the body of the at least once. The while loop is used when we do not want to run the loop body even one time before checking the loop condition. A programmer chooses a while or do-while loop based on their requirement.

What is the difference between while and do while loop based on execution speed?

The difference between while and do while loops based on execution speed is that a do while loop runs faster than a while loop. The do-while is faster because it runs the first iteration without checking the loop condition. In contrast, the while loop checks the condition always.

What are the types of iterative statements available in programming languages?

An iterative statement is used to repeatedly execute a section of code. Iterative statements are also called looping statements. Looping statements are of three types: For loop While loop Do-while loop Each loop has a different syntax and uses the keywords for, while, and do while respectively to denote the loop type.

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Difference Between While and Do While Loop in C, C++, Java

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Iterative statements are used to repeat a section of code in the program. While and do while are iterative statements used in C, C++, Java, and other languages. Iterative statements are also called looping statements. The major difference between while and do while loops are that the control statement is executed before the loop body in the while loop whereas the control statement is executed after the loop body in the do while loop.

In this article, we will be learning about the two looping statements that are while and do while and the difference between while and do while loop. Let us check the difference between while and do while loop based on various factors in the coming sections in detail.

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Table of content

1. Difference Between While and Do While Loop
2. What is a While Loop?
3. What is a Do While Loop?

Difference Between While and Do While Loop

Although there exist various similarities between while and do while loops such as both are iterative statements, used to save effort and time of execution of a program but there exists a few difference between while and do while loops. These differences are important to know in order to use the apt loop statement as per our requirement. Now let us see the difference between while and do while loops in reference to the C and C++ languages.

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Key Difference Between While and Do While Loop

While Loop	Do While Loop
The Keyword “while” is used.	The keyword “do while” is used.
The control statement is executed before the loop body.	The control statement is present after the loop body.
The loop body executes when the condition becomes true.	The loop body executes once, even if the condition is true or false.
It follows a top-down approach.	It follows a bottom-up approach.
For single statements, brackets are not required.	Brackets are always required.

What is a While Loop?

As we have seen in the difference between While and Do While Loop. Let us see what is while loop in brief. It provides the mechanism to repeat a statement or block of statements if the condition turns out to be true. It runs until the condition becomes false; if the condition is never updated, then the while loop continues to execute infinite times, which is undesirable.

A while loop is also called a top-checking loop as the control condition is placed at the very first line of the code. If the control condition evaluates to false, then the statements enclosed in the loop are never executed.

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What is a Do While Loop?

It is similar to the while loop the only difference between while and do while loop is that in a do while loop, the test condition is tested at the end of the loop. This implies that the body of the loop is executed at least once without checking the condition.

The do while loop is a bottom-checking loop, as the control statement is placed after the body of the loop. Another difference between while and do-while loops is that the do-while loop executes at least one time.

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