PHP while Loop Statement


Suppose you want to calculate gross salaries of 20 different persons or take a list of maximum and minimum temperatures of a certain month or a year, the while loop is ideal to solve these types of cases.

The while statement is simple, it executes the statement(s) repeatedly as long as the condition is true. The condition is checked every time at the beginning of the loop.


while ( condition is true )
execute this statement ;
The general form of while statement :
        initialize loop counter;
while (test loop counter using condition)
execute the statement
increment loop counter

Example :

The following example print "Increment Number" with $x1 value as well as "Hello world" five times.

while ($x1<=5)
echo "Increment Number : $x1 <br />";>
echo "Hello World <br />";

Output :

Increment Number : 1 
Hello World 
Increment Number : 2 
Hello World 
Increment Number : 3 
Hello World 
Increment Number : 4 
Hello World
Increment Number : 5 
Hello World

View the example in the browser

Pictorial representation of while loop


See also

do while, for statement

Previous: if else elseif statement
Next: do-while statement

PHP: Tips of the Day

Getting all defined constants

To get all defined constants including those created by PHP use the get_defined_constants function:


$constants = get_defined_constants();
var_dump($constants); // pretty large list


array(2250) {
  resource(1) of type (stream)
  resource(2) of type (stream)
  resource(3) of type (stream)

To get only those constants that were defined by your app call the function at the beginning and at the end of your script (normally after the bootstrap process):

$constants = get_defined_constants();
define("HELLO", "hello");
define("WORLD", "world");
$new_constants = get_defined_constants();
$myconstants = array_diff_assoc($new_constants, $constants);


array (
  'HELLO' => 'hello',
  'WORLD' => 'world',

It's sometimes useful for debugging