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

Example #1 is_countable() examples

<?php
var_dump
(is_countable([123])); // 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

User Contributed Notes

info at ensostudio dot ru 25-Oct-2020 06:29
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!
?>
Anonymous 25-Oct-2020 04:58
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) && $value instanceof Countable);
    }
}
?>
renic 12-Jun-2019 08:33
be wary of using is_object($var) and assuming that the object has implemented Countable.  Not all objects are countable directly with count().
danmichaelo at gmail dot com 08-Apr-2019 08:33
Note that a polyfill for this method is also provided by the symfony/polyfill project.
deoomen 01-Apr-2019 11:58
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);
    }
}
?>
info at arisendrake dot de 30-Aug-2018 11:10
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);
    }
}
?>
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