PHP - Manual: is_countable

2024-11-15

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is_countable

(PHP 7 >= 7.3.0, PHP 8)

is_countable — Verify that the contents of a variable is a countable value

说明

is_countable(mixed $value): bool

Verify that the contents of a variable is an array or an object implementing Countable

参数

value: The value to check

返回值

Returns true if value is countable, false otherwise.

更新日志

版本	说明
7.3.0	is_countable() has been added.

范例

示例 #1 is_countable() examples


<?php
var_dump(is_countable([1, 2, 3])); // bool(true)
var_dump(is_countable(new ArrayIterator(['foo', 'bar', 'baz']))); // bool(true)
var_dump(is_countable(new ArrayIterator())); // bool(true)
var_dump(is_countable(new stdClass())); // bool(false)

参见

is_array() - 检测变量是否是数组
is_object() - 检测变量是否是一个对象
is_iterable() - Verify that the contents of a variable is an iterable value
is_bool() - 检测变量是否是布尔值

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User Contributed Notes 6 notes

down

info at arisendrake dot de ¶

3 years ago


If you are unable to upgrade to PHP 7.3 (not released at the time of writing), you can use this simple polyfill:

<?php
if (!function_exists('is_countable')) {
    function is_countable($var) {
        return (is_array($var) || $var instanceof Countable);
    }
}
?>

down

renic ¶

3 years ago


be wary of using is_object($var) and assuming that the object has implemented Countable.  Not all objects are countable directly with count().

down

Anonymous ¶

1 year ago


Fixed polyfill:
<?php
if (! function_exists('is_countable')) {
    /**
      * @param mixed $value The value to check
      * @return bool
      */
    function is_countable($value): bool
    {
        return is_array($value) || (is_object($value) && $value instanceof Countable);
    }
}
?>

down

danmichaelo at gmail dot com ¶

3 years ago


Note that a polyfill for this method is also provided by the symfony/polyfill project.

down

-4

info at ensostudio dot ru ¶

1 year ago


Note: if is_countable() return true is does not guarantee that the it can be calculated recursively and correctly:
<?php
$iterator = new ArrayIterator(['one', 'two', new ArrayIterator(['three', 'four'])]);
var_dump(is_countable($iterator), count($iterator, COUNT_RECURSIVE));
// return TRUE and 3!
?>

down

-12

deoomen ¶

3 years ago


Polyfill written by arisendrake is not quite good. It return FALSE when checking an Simple XML Node but count() works properly on PHP 7.1 and 7.3.
Better is this one:

<?php
if (version_compare(PHP_VERSION, "7.3") < 0 && !function_exists("is_countable")) {
    function is_countable($var): bool
    {
        return (is_array($var) || is_object($var) || is_iterable($var) || $var instanceof Countable);
    }
}
?>

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官方地址：https://www.php.net/manual/en/function.is-countable.php

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is_countable

说明

参数

返回值

更新日志

范例

参见

User Contributed Notes 6 notes