The Countable interface
(PHP 5 >= 5.1.0)
简介
类实现 Countable 可被用于 count() 函数.
接口摘要
Table of Contents
- Countable::count — 统计一个对象的元素个数
用户评论:
[#1] Anonymous [2011-01-17 06:10:43]
Note that arrays don't implement countable. Therefore you can't force a countable parameter for a function if you want it also to work with native arrays.
[#2] isaac dot z dot foster dot nada at spamporfav dot gmail dot com [2010-06-08 01:18:36]
I just want to point out that your class has to actually implement the Countable interface, not just define a count method, to be able to use count($object) and get the expected results. I.e. the first example below won't work as expected, the second will. (The normal arrow function accessor ($object->count()) will work fine, but that's not the kewl part :) )
<?php
//Example One, BAD :(
class CountMe
{
protected $_myCount = 3;
public function count()
{
return $this->_myCount;
}
}
$countable = new CountMe();
echo count($countable); //result is "1", not as expected
//Example Two, GOOD :)
class CountMe implements Countable
{
protected $_myCount = 3;
public function count()
{
return $this->_myCount;
}
}
$countable = new CountMe();
echo count($countable); //result is "3" as expected
?>