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PHP do...while Loop Explained with Syntax & Examples

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Learn how the do...while loop works in PHP. Discover its syntax, how it differs from while, and view practical examples to master this loop construct.

🔄 The do-while Loop in PHP

A do-while loop is very similar to a while loop, but with one key difference: the condition is checked after the loop’s code has been executed. This means the loop always runs at least once, regardless of whether the condition is true or false at the start.

🧠 Key Differences Between do-while and while Loops

  • while Loop: Checks the condition before executing the loop. If the condition is false initially, the loop will never run.
  • do-while Loop: Executes the loop once, then checks the condition. If the condition is false after the first iteration, the loop stops.

✅ Syntax of do-while Loop

do {
    // Code to execute
} while (condition);
  • Code to execute: This block will run at least once.
  • Condition: The loop continues running as long as this condition is true.

📝 Example #1: Basic do-while Loop

<?php
$i = 0;
do {
    echo $i;  // This will print 0
} while ($i > 0);  // The condition is false, so the loop stops after one iteration
?>

Explanation:

  • $i is initially 0.
  • The loop runs once before the condition $i > 0 is checked.
  • Since $i > 0 is false, the loop stops after the first iteration.

📝 Example #2: Looping with do-while

<!DOCTYPE html>
<html lang="en">
<head>
    <title>PHP - Do While Loop Example</title>
</head>
<body>

<?php
$x = 6;  // Set initial value of $x

do {
    echo "The number is: $x <br>";  // Prints $x
    $x++;  // Increments $x
} while ($x <= 5);  // Loop stops because $x is no longer <= 5
?>

</body>
</html>

Output:

The number is: 6

Explanation:

  • The loop executes once with $x = 6, printing “The number is: 6”.
  • The condition $x <= 5 is checked after the first iteration, and since it’s false, the loop stops.

⚡ Key Points:

  • The do-while loop always runs at least once, regardless of the condition.
  • The condition is checked after the code runs, unlike the while loop where the condition is checked first.
  • It’s useful when you want the loop body to run at least once before any checks are made (e.g., user input or menu selection).

further reading: