Understand PHP's return references and local static variables_PHP tutorial

Understand PHP’s return references and local static variables

This article mainly introduces understanding of PHP’s return references and local static variables. The general way to write a return reference is to add & before the method name. , local static variables are also very useful, friends in need can refer to it

Read the manual first

　==========

To return a reference from a function, you must use the reference operator & both when declaring the function and assigning the return value to a variable:

The code is as follows:

　function &returns_reference()

　{

$someref = 0;

return $someref;

　}

　$newref = &returns_reference();//Equivalent to $newref = &$someref;

　?>

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

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

The code is as follows:

class a{}

class b{}

Function & aa($name)

　{

　static $class = array(); //Local static variables do not disappear when the execution of the method ends, but persist until the end of the entire source program to end the life cycle

　if(!$class[$name]) //So the declaration/initialization statement here only works when it is first declared

　{ //When this method is called later, the static variable will no longer be re-initialized value

　$class[$name] = new $name();

　}

return $class[$name];

　}

　$a = & aa('a');

　$b = & aa('b');

$a2 = & aa('a');

　$b2 = & aa('b');

echo $a === $a2 ? '$a and $a2 are the same instantiated object
' : '';

echo $b === $b2 ? '$b and $b2 are the same instantiated object' : '';

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