PHP do-while Loop

Introduction

Php do-while loop is a control structure that allows developers to execute a block of code repeatedly while a specified condition is true. This type of loop is similar to the while loop, with the key difference being that the condition is evaluated at the end of each iteration rather than at the beginning.

This means that the block of code within the loop will always be executed at least once, regardless of the initial value of the condition.

Flowchart of the Do-while Loop

A php do-while loop is a type of loop structure in PHP that executes a block of code repeatedly until a specified condition is met. The syntax of the do-while loop in PHP is as follows:

Explanation
In php do-while loop the code block is executed at least once, even if the condition is false. Run the above code in your editor for a better and clear explanation.

To illustrate the flowchart of the do-while loop in PHP, we can break it down into the following steps:

• The loop starts with the execution of the code block inside the "do" statement.
• After executing the code block, the condition inside the "while" statement is evaluated. If the condition is true, then the loop continues to the next iteration, and the code block is executed again.
• If the condition is false, the loop terminates, and the program continues to execute the next statement after the loop.
• If the condition is true, the loop will continue to execute the code inside the loop until and unless the condition becomes false. Once the condition is false, the loop will be terminated, and the program continues to execute the next statement after the loop.

Syntax

This is the syntax of the do-while loop in PHP:

Explanation
In this loop structure, the code block inside the do statement is executed first, and then the while condition is checked. If the condition is true, then the code block will be executed again until and unless the condition becomes false. Run the above code in your editor for a better and clear explanation.

Examples

Basic Example

Output

Explanation
In this example, we have initialized the variable $i to 1. We then have a do statement that contains a code block, which will be executed at least once. Inside the code block, we are using the echo statement to output the value of $i, concatenated with a string.

Display Odd and Even No of Given Number Using Do-While Loop

Output

Explanation
In the first do-while loop, we are checking if the value of $i is odd. If it is odd, we are using the echo statement to display the value of $i. We are then incrementing the value of $i by 1 inside the loop. Run the above code in your editor for a better and clear explanation.

In the second do-while loop, we are checking if the value of $i is even. If it is even, we are using the echo statement to display the value of $i. We are then incrementing the value of $i by 1 inside the loop.

Difference Between While and Do While Loop in PHP

• The while loop checks the condition first and then executes the code block, whereas the do-while loop executes the code block first and then checks the condition.
• The php do-while loop will not execute the code block if the condition is false, whereas the do-while loop will execute the code block at least once, even if the condition is false.
• The while loop is more appropriate when you want to execute the code block only when the condition is true, whereas the do-while loop is more appropriate when you want to execute the code block at least once, regardless of the condition.
• In the while loop, if the initial value of the variable does not meet the condition, the code block will not be executed at all. In contrast, the do-while loop executes the code block at least once, which guarantees that the code inside the loop will be executed at least once.
• The php do-while loop is a pre-test loop, meaning the condition is tested at the beginning of each iteration, while the do-while loop is a post-test loop, meaning the condition is tested at the end of each iteration.
• In the php do-while loop the code block may never be executed if the condition is initially false, while in the do-while loop, the code block is executed at least once, regardless of the initial condition.