FILTER_VALIDATE_BOOLEAN

FILTER_VALIDATE_BOOLEAN filter can check the variable Boolean or not. We will usevar_dump function to know more about the variable returned. Here is an example.

$var="Off";
var_dump(filter_var($var, FILTER_VALIDATE_BOOLEAN));

Here is a list of outputs we will get for different data stored in variable.

$var="Yes"; // bool(true)
$var="1"; // bool(true)
$var="on"; // bool(true)
$var="True"; // bool(true)

$var="T"; // bool(false)
$var="0"; // bool(false)
$var="False"; // bool(false)
$var=""; // bool(false)
$var="abcd"; // bool(false)
$var="Off"; // bool(false)
$var="no"; // bool(false)

For different value of Boolean variable we will get this output. You can see we get bool(false) for non Boolean value. Now we will add one option FILTER_NULL_ON_FAILURE to get null value for all non Boolean variables. Here is the code

$var="Off";
var_dump(filter_var($var, FILTER_VALIDATE_BOOLEAN,FILTER_NULL_ON_FAILURE));

The output for different value of the variable is listed here for easy understanding.

$var="abcd"; // NULL
$var=""; // NULL
$var="T"; // NULL

$var="1"; // bool(true)
$var="on"; // bool(true)
$var="True"; // bool(true)
$var="Yes"; // bool(true)

$var="False"; // bool(false)
$var="0"; // bool(false)
$var="no"; // bool(false)
$var="Off"; // bool(false)

As you can see we are getting NULL value for all non boolean values.