Take a look at the following example:
Copy Code code as follows:
<?php
function Test ()
{
$w 3sky = 0;
echo $w 3sky;
$w 3sky++;
}
?>
This function sets the value of $w 3sky to 0 and outputs "0" each time it is invoked. Adding a variable to the $w 3sky++ has no effect, because once the function is exited, the variable $w 3sky does not exist. To write a count function that does not lose the value of this count, define the variable $w 3sky as static (static):
As follows:
Copy Code code as follows:
<?php
function Test ()
{
static $w 3sky = 0;
echo $w 3sky;
$w 3sky++;
}
?>
Every call to test () of this function outputs the value of $w 3sky and adds one.
Static variables also provide a way to handle recursive functions. A recursive function is a method of calling itself. Be careful when writing recursive functions, as there may be infinite recursion, no exits. Be sure to have a way to abort recursion. The following simple function recursive count to 10, using static variable $count to determine when to stop:
Examples of static variables and recursive functions:
Copy Code code as follows:
? Php
function Test ()
{
static $count = 0;
$count + +;
Echo $count;
if ($count < 10) {
Test ();
}
$count--;
}
?>
Note: Static variables can be declared according to the example above. If you assign a value to a declaration using the result of an expression, it can cause a parse error.
Declare a static variable example:
Copy Code code as follows:
? Php
function foo () {
static $int = 0;//correct
static $int = 1+2; Wrong (as it is a expression)
Static $int = sqrt (121); Wrong (as it is a expression too)
$int + +;
Echo $int;
}
?>
