PHP变量全局和静态

Question

I am new to PHP. I'm studying variables scopes.

A variable declared outside a function has a GLOBAL SCOPE and can only be accessed outside a function.

A variable declared within a function has a LOCAL SCOPE and can only be accessed within that function.

The global keyword is used to access a global variable from within a function.

To do this, use the global keyword before the variables (inside the function)

Normally, when a function is completed/executed, all of its variables are deleted. However, sometimes we want a local variable NOT to be deleted. We need it for a further job.

I need to declare variable within function to be global so I can get access to it from outside the function and to be static at the same time so I can keep the value of the variable after execution of the function and use it again. I tried

global static $x; 

but it doesn't work.

I need to know if I'm thinking in wrong way case I'm new to PHP.

<?php 
$x = 5;
function myTest() {

   echo "x is equal to".$GLOBALS['x']."";
   $GLOBALS['x']++;

} 
myTest();
myText();

?>

it executes only the first myTest(). and the second one display an error Fatal error: Uncaught Error: Call to undefined function myText()

Answer 1

just declare it in global scope then use $GLOBALS[] array or global keyword to use that variable in a function. And as they hold the value even after function execution you don't need static keyword as well.

study $GLOBALS , Variable scope

Answer 2

you can use static or global to keep the value:

function doStuff() {
  $x = null;

  if ($x === null) {
     $x = 'changed';
     echo "changed.";
  }
}
doStuff();
doStuff();

the result would be: changed.changed.

if you use:

function doStuff() {
  static $x = null;

  if ($x === null) {
     $x = 'changed';
     echo "changed.";
  }
}
doStuff();
doStuff();

the result would be changed. because static keeps last value even if you call function in multi times also global have the same result because of it's definition so you can also use:

global $x;

in the function and result would be same: changed.

Answer 3

You have typo problem in your code (second calling of your function):

function myTest() ....

Then you called it:

myTeXt();