php教程

is_countable

(PHP 7 >= 7.3.0)

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

说明

is_countable ( mixed $var ) : bool

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

参数

var

The value to check

返回值

Returns TRUE if var 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

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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