This is the easiest type. A boolean expresses a truth value. It can be either
TRUE or
FALSE.
Note: The boolean type was introduced in PHP 4.
To specify a boolean literal, use either the keyword
TRUE or
FALSE. Both are case-insensitive.
<?php
$foo = True; // assign the value TRUE to $foo
?>
Usually you use some kind of
operator which returns a boolean value, and then pass it on to a
control structure.
<?php
// == is an operator which test
// equality and returns a boolean
if ($action == "show_version") {
echo "The version is 1.23";
}
// this is not necessary...
if ($show_separators == TRUE) {
echo "<hr>\n";
}
// ...because you can simply type
if ($show_separators) {
echo "<hr>\n";
}
?>
To explicitly convert a value to boolean, use either the
(bool) or the
(boolean) cast. However, in most cases you do not need to use the cast, since a value will be automatically converted if an operator, function or control structure requires a boolean argument.
See also
Type Juggling.
When converting to boolean, the following values are considered
FALSE:
Every other value is considered
TRUE (including any
resource).
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)
?>
