Question about variable scope?

askjames01

php GURUs

ok, here is my story
i have 2 or 3 pages
the first page must have this code below;

page1.php
<?php
$my_variable = "Testing.";
?>

and the second page has this codes below,

page2.php
<?php
echo "$my_variable";
?>

page3.php
<?php
echo "$my_variable"; //the same with page2.php
?>

now what do i do?, to make $my_variable available to all
the pages2.php, pages3.php? how?

and check these out;

private vars; //does php have this command?

and also

public vars: //does php have this command?

and also.

private vars: //does also php have this command?

and lastly.

local vars: //is this also accepted by php?

any bright answers will be very, very appreciated. 🙂

THANK YOU VERY MUCH in advance GURUs...!

-/james/

bradgrafelman

If you want to use variables/functions declared in a PHP script inside of another PHP script, look at [man]include/man'ing or [man]require/man'ing the file with the declarations. For example:

<?PHP // File: page1.php
$myVar = 'Hello World!';

function sayHi() {
     /* globalize the variable, since we're inside the function() scope, and the
     variable we want is actually outside that scope in the global scope. */
     global $myVar;

 echo $myVar;
}
?>

<?PHP // File: page2.php
include_once 'page1.php';

sayHi(); // outputs "Hello world!"
?>

I included two concepts in that code snippet:

Using the [man]include_once/man/[man]require_once/man variation of the include/require statements which does the exact same, though the '_once' change simply tells PHP that if the file was already loaded to memory earlier in the script, in another script, etc., that it should not re-execute the script again. This is a common practice when including scripts that declare functions, as you will get warning messages if you try to declare a function that has already been declared.
Inside of a function scope, you have a "local" scope, meaning that any variable creation/manipulation/deletion/etc. you do will only affect things INSIDE that function. Since I had declared a variable in the global scope of the file (outside any function/class/etc.), we needed to bring that variable inside the function's local scope. The [man]global[/man] statement allows you to do that.

samudasu

You could also use sessions if you're just looking to get the variable value between pages. You'll need to read the docs because there's certain things that you need to know about using sessions.
http://www.php.net/manual/en/ref.session.php

page1.php

<?php
session_start();
$_SESSION['my_variable'] = 'Testing';

page2.php

<?php
session_start();
print $_SESSION['my_variable'];

askjames01

so you mean guys that GLOBAL and SESSION are the only way to make the variable
avaiable onto different pages.

so is this mean that PUBLIC, PRIVATE & LOCAL assignment of variable doesn't exist?

laserlight

so you mean guys that GLOBAL and SESSION are the only way to make the variable
avaiable onto different pages.

Global variables dont necessarily persist across pages. However, the $SESSION and $COOKIE superglobal variables do persist across pages.

so is this mean that PUBLIC, PRIVATE & LOCAL assignment of variable doesn't exist?

I dont understand what you mean.

askjames01

what i mean here is by using global you delcare it like this.

   global $myvar;

but are these not possible in php?

   public $myvar; //is this possible?
   local   $myvar; //is this possible?
   private $myvar; //is this possible?

are these three built in commands with php or not?

samudasu

You could just read the variables section of the php manual. PHP5 has public and private properties when your working with classes but that doesn't really have anything to do with variables persiting across pages. If you want to set a variable to persist across all pages then use sessions or cookies like laserlight mentioned. So i guess the answer to your question is no, the three commands aren't built in at least with procedural coding. And no, sessions or cookies arent' the only way. Bradgrafelman has already told you another way to do it. You really need to read the manual.

bradgrafelman

askjames01 - PHP scripts are executed as a single "program." When they are done executing, the thread that was procesing your script is cleared and made ready for another request.

Going from page to page, there is nothing that is "left over". No variables in memory are kept - the memory space is completely wiped and reallocated for a thread to use again. Using cookies or sessions, however, lets one PHP script save data to disk (either the server's using sesions or the client's using cookies) so that another script can reference the session/cookie previously saved by the other script.