类中的usort函数 [英] usort function in a class

问题描述

我有一个函数可以对多维数组中的数据进行排序，如下所示:

I have a function which sorts data in a multidimensional array, as shown below:

<?php  
$data = array();  
$data[] = array("name" => "James");  
$data[] = array("name" => "andrew");  
$data[] = array("name" => "Fred");  

function cmp($a, $b)  
{  
    return strcasecmp($a["name"], $b["name"]);  
}  

usort($data, "cmp");  

var_dump($data);  
?>  

当我运行它时，它按预期工作，按名称返回的数据按升序返回.但是，我需要在课堂上使用它.

When i run this, it works as expected, returning the data ordered by name, ascending. However, I need to use this in a class.

<?php
class myClass  
{  
    function getData()  
    {  
        // gets all data
        $this -> changeOrder($data);
    }  

    function changeOrder(&$data)  
    {  
         usort($data, "order_new");
    }

    function order_new($a, $b)  
    {  
        return strcasecmp($a["name"], $b["name"]);  
    }
}
?>

使用此方法时，会收到以下警告:警告:usort()期望参数2为有效的回调，未找到函数'order_new'或无效的函数名称.

When I use this, i get the following warning: Warning: usort() expects parameter 2 to be a valid callback, function 'order_new' not found or invalid function name.

当我将order_new函数放到changeOrder函数中时，它可以正常工作，但是我遇到了致命错误:无法重新声明order_new()的问题，所以我不能使用它.有什么建议吗?

When i put the order_new function in the changeOrder function it works fine, but I have problems with Fatal error: Cannot redeclare order_new(), so i cannot use that. Any suggestions?

推荐答案

order_new是一个类方法，而不是全局函数. 正如 PHP手册建议您在这种情况下可以使用

order_new is a class method not a global function. As the PHP-Manual suggest you can use in this case

usort($data, array($this, "order_new")); 

或声明order_new static并使用

or declare order_new static and use

usort($data, array("myClass", "order_new")); 

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