Booleans on PHP

This is the simplest type. A boolean expresses a truth value. It can be either TRUE or FALSE.
Note: The boolean type was introduced in PHP 4.

Syntax
To specify a boolean literal, use the keywords TRUE or FALSE. Both are case-insensitive.


<?php
$foo = True; // assign the value TRUE to $foo
?>


Typically, some kind of operator which returns a boolean value, and the value is passed on to a control structure.


<?php
// == is an operator which test
// equality and returns a boolean
if ($action == "show_version") {
echo "The version is 1.23";
}

// this is…