PHP: is_bool - Manual (original) (raw)

(PHP 4, PHP 5, PHP 7, PHP 8)

is_bool — Finds out whether a variable is a boolean

Description

Parameters

value

The variable being evaluated.

Examples

Example #1 is_bool() examples

<?php $a = false; <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>b</mi><mo>=</mo><mn>0</mn><mo separator="true">;</mo><mi mathvariant="normal">/</mi><mi mathvariant="normal">/</mi><mi>S</mi><mi>i</mi><mi>n</mi><mi>c</mi><mi>e</mi></mrow><annotation encoding="application/x-tex">b = 0;// Since </annotation></semantics></math>b=0;//Sincea is a boolean, it will return true if (is_bool($a) === true) { echo "Yes, this is a boolean\n"; }// Since $b is not a boolean, it will return false if (is_bool($b) === false) { echo "No, this is not a boolean\n"; } ?>

Found A Problem?

Julio Marchi ¶

6 years ago

To check if a variable is boolean is one thing, to evaluate if the value of a variable represents a boolean condition (true or false) is another.

Here is a simple function that checks the status of the received variable in regard to boolean equivalencies (case-insensitive).

<?php
/** 
 * Check "Booleanic" Conditions :)
 *
 * @param  [mixed]  $variable  Can be anything (string, bol, integer, etc.)
 * @return [boolean]           Returns TRUE  for "1", "true", "on" and "yes"
 *                             Returns FALSE for "0", "false", "off" and "no"
 *                             Returns NULL otherwise.
 */
function is_enabled($variable)
{
    if (!isset($variable)) return null;
    return filter_var($variable, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);
}
?>

Of course, it is a simplistic approach, but for the majority of cases it will do the job right.

And, just to put the thing from the right perspective, here's a real function that does what Phill disclosed:

<?php
/** 
 * Convert $variable to boolean (adapted from Phill answer)
 *
 * @param  [mixed]  $variable  Can be anything
 * @return [boolean]           Returns the booelan equivalent to $variable based on Zend Enegine interpretation
 */
function to_bool($variable) 
{ 
    return (bool)$variable;
}
?>

I hope it helps someone. Happy coding.

phil ¶