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Return references and local static variables in PHP

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2017-12-28 10:24:381097browse

This article mainly introduces the understanding of return references and local static variables in PHP. The general way to write return references is to add & before the method name. Local static variables are also very useful. I hope to be helpful.

Read the manual first
==========
Returning a reference from a function must be done both when the function is declared and when assigning the return value to a variable. Use the reference operator &:

<?php  
function &returns_reference()  
{  
    $someref = 0;  
    return $someref;  
}  
   
$newref = &returns_reference();//相当于 $newref = &$someref;  
?>

For more information about references, see the explanation of references.

Let’s take a look at a single instance registration model that many open source codes like to use

class a{}  
class b{}  
function & aa($name)  
{  
    static $class = array(); //局部静态变量 不随方法的执行结束而消失 而是坚持到整个源程序结束时才结束生命周期  
    if(!$class[$name])       //所以 此处的声明/初始化语句 只在首次声明时起作用  
    {                        //之后再调用此方法时, 静态变量不再重新初始化value  
        $class[$name] = new $name();  
    }  
    return $class[$name];  
}  
$a = & aa(&#39;a&#39;);  
$b = & aa(&#39;b&#39;);  
   
$a2 = & aa(&#39;a&#39;);  
$b2 = & aa(&#39;b&#39;);  
   
echo $a === $a2 ? &#39;$a和$a2是同一个实例化对象<br/>&#39; : &#39;&#39;;  
echo $b === $b2 ? &#39;$b和$b2是同一个实例化对象&#39; : &#39;&#39;;

Related recommendations:

php Quote (&) Usage

php Detailed explanation of reference assignment

php Initialization example of static variables Detailed explanation

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