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.
- Assign 0 to
i
. - Evaluate the condition
$i < 4
. 0 < 4 is true. So, execute while-block.- Execute echo statement.
- Increment
i
. Nowi
is 1.
- Evaluate the condition
$i < 4
. 1 < 4 is true. So, execute while-block.- Execute echo statement.
- Increment
i
. Nowi
is 2.
- Evaluate the condition
$i < 4
. 2 < 4 is true. So, execute while-block.- Execute echo statement.
- Increment
i
. Nowi
is 3.
- Evaluate the condition
$i < 4
. 3 < 4 is true. So, execute while-block.- Execute echo statement.
- Increment
i
. Nowi
is 4.
- 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.