is_bool

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

is_bool — 检测变量是否是布尔值

说明

is_bool ( mixed $value ) : bool

检查变量是否为布尔值。

参数

value: 要检查的变量。

返回值

如果 value 是布尔值则返回 true，否则返回 false。

范例

Example #1 is_bool() 示例


<?php
$a = false;
$b = 0;

// 因为 $a 是布尔值，所以结果为 true
if (is_bool($a) === true) {
    echo "Yes, this is a boolean";
}

// 因为 $b 不是布尔值，所以结果为 false
if (is_bool($b) === false) {
    echo "No, this is not a boolean";
}
?>

参见

is_float() - 检测变量是否是浮点型
is_int() - 检测变量是否是整数
is_string() - 检测变量是否是字符串
is_object() - 检测变量是否是一个对象
is_array() - 检测变量是否是数组

User Contributed Notes

Julio Marchi 08-Sep-2019 12:32


The function Michael Smith published doesn't do the work as it should.



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 a simple function that checks the status of the received variable in regards 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 thing in 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 10-Jan-2019 06:21


It should be stated that this function returns true if the _type_ of it's argument is boolean. It does not convert or coerce the value to a boolean type, not sure why so many comments focus on how to do this.

However, if you arrived here looking for a solution to convert a value to a boolean type, use this:



to_bool($x) { return (bool)$x; }

Michael Smith 17-Nov-2013 01:17


The function in the last comment also converts the string 'false' to a true boolean. Here's a function that does what I think was intended:



<?php

function toBool($var) {

  if (!is_string($var)) return (bool) $var;

  switch (strtolower($var)) {

    case '1':

    case 'true':

    case 'on':

    case 'yes':

    case 'y':

      return true;

    default:

      return false;

  }

}