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 not necessary…
if ($show_separators == TRUE) {
echo «<hr>\n»;
}
// …because instead, this can be used:
if ($show_separators) {
echo «<hr>\n»;
}
?>
Warning-1 is considered TRUE, like any other non-zero (whether negative or positive) number!
<?php
var_dump((bool) ""); // bool(false)
var_dump((bool) 1); // bool(true)
var_dump((bool) -2); // bool(true)
var_dump((bool) "foo"); // bool(true)
var_dump((bool) 2.3e5); // bool(true)
var_dump((bool) array(12)); // bool(true)
var_dump((bool) array()); // bool(false)
var_dump((bool) "false"); // bool(true)
?>