Converting to boolean
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:
the boolean FALSE itself
the integer 0 (zero)
the float 0.0 (zero)
the empty string, and the string "0"
an array with zero elements
an object with zero member variables
the special type NULL (including unset variables)
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
echo gettype((bool) ""); // bool(false)
echo gettype((bool) 1); // bool(true)
echo gettype((bool) -2); // bool(true)
echo gettype((bool) "foo"); // bool(true)
echo gettype((bool) 2.3e5); // bool(true)
echo gettype((bool) array(12)); // bool(true)
echo gettype((bool) array()); // bool(false)
?>
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