This is the simplest type. A bool expresses a truth value. It can be either true
or false
.
To specify a bool literal, use the constants true
or false
. Both are case-insensitive.
<?php $foo = True; // assign the value TRUE to $foo ?>
Typically, the result of an operator which returns a bool value is passed on to a control structure.
<?php // == is an operator which tests // equality and returns a boolean if ($action == "show_version") { echo "The version is 1.23"; } // this is not necessary... if ($show_separators == TRUE) { echo "<hr>\n"; } // ...because this can be used with exactly the same meaning: if ($show_separators) { echo "<hr>\n"; } ?>
To explicitly convert a value to bool, use the (bool)
or (boolean)
casts. However, in most cases the cast is unnecessary, since a value will be automatically converted if an operator, function or control structure requires a bool argument.
See also Type Juggling.
When converting to bool, the following values are considered false
:
false
itself Every other value is considered true
(including any resource and NAN
).
-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) ?>
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Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/language.types.boolean.php