Understand PHP's return references and local static variables, php local static variables_PHP tutorial

Understand PHP's return references and local static variables, php local static variables

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:
Copy code The code is as follows:
function &returns_reference()
{
$someref = 0;
Return $someref;
}

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

For more information about citations, check out the explanation of citations.

Let’s take a look at a single instance registration model that many open source codes like to use
Copy code 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 re-initialize the 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' : '';

http://www.bkjia.com/PHPjc/1011953.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/1011953.htmlTechArticleUnderstand PHP’s return references and local static variables. PHP local static variables read the manual first ======= === Returning a reference from a function must be done when the function is declared and the return value is assigned to a variable...