is_countable()

(PHP 7 >= 7.3.0)

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 anarrayor an object implementingCountable

参数

$var

The value to check

返回值

ReturnsTRUEif$varis countable,FALSEotherwise.

更新日志

范例

Example #1is_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型

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);
  }
}
?>

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

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

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);
  }
}
?>