boolval

To anyone like me who came here looking for a way to turn any value into a 0/1 that will fit into a MySQL boolean (tinyint) field:
<?php
$tinyint = (int) filter_var($valToCheck, FILTER_VALIDATE_BOOLEAN);
?>

tinyint will be 0 (zero) for values like string "false", boolean false, int 0
tinyint will be 1 for values like string "true", boolean true, int 1
Useful if you are accepting data that might be from a language like Javascript that sends string "false" for a boolean false.

boolval('false') returns true.
boolval('False') return true.

<?
// Hack for old php versions to use boolval()
if (!function_exists('boolval')) {
 function boolval($val) {
 return (bool) $val;
 }
}
?>

function is_true($val, $return_null=false){
 $boolval = ( is_string($val) ? filter_var($val, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE) : (bool) $val );
 return ( $boolval===null && !$return_null ? false : $boolval );
}
// Return Values:
is_true(new stdClass); // true
is_true([1,2]); // true
is_true([1]); // true
is_true([0]); // true
is_true(42); // true
is_true(-42); // true
is_true('true'); // true
is_true('on') // true
is_true('off') // false
is_true('yes') // true
is_true('no') // false
is_true('ja') // false
is_true('nein') // false
is_true('1'); // true
is_true(NULL); // false
is_true(0); // false
is_true('false'); // false
is_true('string'); // false
is_true('0.0'); // false
is_true('4.2'); // false
is_true('0'); // false
is_true(''); // false
is_true([]); // false

I believe that the double negation !! can perform the same task with the same result if your PHP is not up2date
var_dump(!!1, !!0, !!"test", !!"");
outputs:
boolean true
boolean false
boolean true
boolean false
May the life be good to you.

<?
// Some way to print boolean value as string
$b = true;
echo ['false', 'true'][$b];
?>