PHP Functions Essential Reference

is_bool

bool is_bool(mixed value) 

Tests whether a value is a boolean.

Returns:

TRUE if the value is a boolean; FALSE otherwise

Description:

is_bool() checks whether value is a boolean. If so, the function returns TRUE. If not, FALSE is returned.

Availability:

UNIX, Windows

Version:

3+, 4+

See also:

gettype() 

Example:

Check whether a value is a boolean

$value = NULL; is_bool ($value) or die ('<b>Exiting Program:</b> Variable $value is not a boolean!');