PHP reference

is_bool

Checks whether a value is a boolean.

Syntax

is_bool(mixed $value): bool

Parameter	Type	Description
$value	mixed	The value to check.

bool`true` if the value is `true` or `false`.

A boolean and look-alikes:

<?php
 
var_dump(is_bool(false));
var_dump(is_bool(0));
var_dump(is_bool('true'));

Output:

bool(true)
bool(false)
bool(false)

This is how "nothing found" is told apart from a real value: strpos(), for instance, returns false rather than 0.

Data types — The main PHP data types — strings, numbers, booleans, arrays and null.