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From: "J.O. Aho" <user@example.net>
Newsgroups: comp.lang.php
Subject: Re: Setting & displaying Variables
Date: Sat, 21 Sep 2013 23:55:33 +0200
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On 21/09/13 22:20, Twayne wrote:
> Hi,
>
> Obviously, the issue is around the comments var. It works, but it
> doesn't and I'm hoping someone can explain why.
>
> Both echo strlen($comments);  and   echo $comments;    throw a Notice
> about an undefined variable. But the variable "comments" HAS to have
> been defined in order for the two echo statements to work!
>     The variable 'comments' is also in SESSION data, which will also get
> the same Notice of an undefined variable.
>
> What the heck am I missing? Why do I get the undefined var in those two
> statements?
>
> ===================
> <code>
> echo strlen($_POST["comments"])."<br />"; //WORKS
>
> $commments = $_POST["comments"]; // WORKS but not needed; done elsewhere
> too.

Assuming this is just a typo and it was supposed to be $comment

> // echo strlen($comments);  // GETS Notice: Undefined variable: comments
> in C:\xampp\htdocs... and nothing displays.

Variables ain't super global, with other words if you do something 
inside a function it will not automatically be the same outside the function

$comment = "q";

function b() {
	$comment = "b";
}

b();

echo $comment;

This will result in "q" and not "b", as the $comment inside the function 
is another than the one outside the function.

just to clarify, values will not magically get into functions

$comment = "q";

function b() {
	echo $comment;
}

b();

this will return an empty output (logging undefined variable).


There is a few exception from this, super global variable is one of 
those, like $_POST, $_GET, $_SESSION and so on, thos can be accessed 
anywhere in your code.

You can use global in a function to access variable set outside a 
function (this is really bad coding and you will most likely get in bad 
trouble, so avoid using it).

-- 

  //Aho