In this tutorial, you learn how about While loop in PHP, its syntax, and how to use it to implement looping of a task, with example programs.

PHP While Loop

PHP While Loop executes a block of statements in a loop as long as the condition is true.

Syntax of While Loop

The syntax of PHP while loop is

while (condition) {
  // while-block statement(s)
}

where

  • while is the keyword.
  • condition evaluates to a boolean value: true or false. condition is wrapped in parenthesis.
  • while-block statement(s) are a block of none, one or more statements. while-block statement(s) are enclosed in flower braces. If there is only one statement for while-block, then the flower braces are optional. But, that is a very rare case.

Examples

1 Print numbers from 0 to 3 using While loop

The following program is a simple example demonstrating the working of While loop for printing numbers from 0 to 3. Here the task is to print the numeric value in the variable, repeatedly in a loop.

PHP Program

<?php
$i = 0;
while ( $i < 4 ) {
    echo "$i <br>";
    $i++;
}
?>

Output

In this program,

  • the condition is $i < 4.
  • while-block has two statements: the echo and increment statements.

Explanation

Let us see the step by step execution of the above program.

  1. Assign 0 to i.
  2. Evaluate the condition $i < 4. 0 < 4 is true. So, execute while-block.
    1. Execute echo statement.
    2. Increment i. Now i is 1.
  3. Evaluate the condition $i < 4. 1 < 4 is true. So, execute while-block.
    1. Execute echo statement.
    2. Increment i. Now i is 2.
  4. Evaluate the condition $i < 4. 2 < 4 is true. So, execute while-block.
    1. Execute echo statement.
    2. Increment i. Now i is 3.
  5. Evaluate the condition $i < 4. 3 < 4 is true. So, execute while-block.
    1. Execute echo statement.
    2. Increment i. Now i is 4.
  6. Evaluate the condition $i < 4. 4 < 4 is false. While loop execution is complete.

2 Print Hello World five times using While loop

In the following program, we repeat the task of printing the string value “Hello World” using While loop.

PHP Program

<?php
$i = 0;
while ( $i < 4 ) {
    echo "Hello World";
    echo "<br>";
    $i++;
}
?>

Conclusion

In this PHP Tutorial, we learned the syntax of PHP While Loop, and its working with the help of example program.