Example of php static variables, phpstatic_PHP tutorial-PHP Tutorial-php.cn

Example of php static variables, phpstatic_PHP tutorial

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Release： 2016-07-13 10:13:54

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Examples of php static variables, phpstatic

class test
{
public static function a(){}
public function b(){}
}
$obj = new test;

Call code

test::a();
$obj->a();
$obj->b();

Example demonstrates the need for static variables

class myobject {
public static $mystaticvar = 0;

function mymethod() {
// :: Scope limiting operator
// Use self scope instead of $this scope
// Because $this only represents the current scope of the class instance, and self:: expresses the class itself
self::$mystaticvar += 2;
echo self::$mystaticvar . "
";
}
}

$instance1 = new myobject();
$instance1->mymethod(); // Display 2

$instance2 = new myobject();
$instance2->mymethod(); // Display 4

class myobject {
public static $myvar = 10;
}

echo myobject::$myvar;

// Result: 10
?>

This function is not very useful because it will set the value of $w3sky to 0 and output "0" every time it is called. Increasing the variable $w3sky++ by one has no effect, because the variable $w3sky does not exist once this function exits. To write a counting function (www.111cn.net) that will not lose this count value, define the variable $w3sky as static:

Example Example of using static variables

function test()
{
static $w3sky = 0;
echo $w3sky;
$w3sky++;
}
?>
Now, each time the test() function is called, the value of $w3sky will be output and incremented by one.

Look at an example

class foo
{
public static $my_static = 'foo';
public function staticvalue() {
return self::$my_static;
}
}
class bar extends foo
{
public function foostatic() {
return parent::$my_static;
}
}
print foo::$my_static . "n";
$foo = new foo();
print $foo->staticvalue() . "n";
print $foo->my_static . " n"; // undefined "property" my_static
print $foo::$my_static . "n";
$classname = 'foo';
print $classname::$my_static . "n"; // After php 5.3.0, you can dynamically call
print bar::$my_static . "n";
$bar = new bar();
print $bar->foostatic() . "n ";
?>

from:http://www.111cn.net/phper/php/php-static.htm