International PHP Conference Berlin 2025

    is_bool

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

    is_bool — 変数が boolean であるかを調べる

    説明

    is_bool(mixed $value): bool

    指定した変数が boolean であるかどうかを調べます。

    パラメータ

    value

    評価する変数。

    戻り値

    value が bool である場合に true 、それ以外の場合に false を返します。

    例

    例1 is_bool() の例

    <?php
    $a     = false;
    $b = 0;

    // $a は boolean なので、これは true となります
    if (is_bool($a) === true) {
    echo     "Yes, this is a boolean";
    }

    // $b は boolean ではないので、これは false となります
    if (is_bool($b) === false) {
    echo     "No, this is not a boolean";
    }
    ?>

    参考

    • is_float() - 変数の型が float かどうか調べる
    • is_int() - 変数が整数型かどうかを検査する
    • is_string() - 変数の型が文字列かどうかを調べる
    • is_object() - 変数がオブジェクトかどうかを検査する
    • is_array() - 変数が配列かどうかを検査する

    Found A Problem?

    Learn How To Improve This Page • Submit a Pull Request • Report a Bug
    ＋add a note

    User Contributed Notes 2 notes

    up
    12
    phil
    5 years ago
    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; }
    up
    11
    Julio Marchi
    5 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.
    ＋add a note
    To Top