Question

It may sound silly but I’m quite php outdated/unexperienced and coming from Java programming back to php, so I mix up the concepts.

If in a php webpage I declare a variable

$debug=TRUE;

and try to access it from below within a function

a(){
    if ($debug){
    echo "I'm here";
    }
}

the variable doesn’t exists or isn’t initiated? The whole file is just simply:

<?php
$debug=TRUE;
a(){
    if ($debug){
        echo "I'm here";
    }
}
?>

Do I need to make a session variable or something else? I’m quite clueless & the same concept is confusing me for the use of other variables within. Also for the further use of variables, I am trying to be forced to pass all the variables I need forward to the function where I use them and a class concept as in Java perhaps would be cleaner but is a kind of too much for this simplicity. Or do I need the functions (it’s a form processor) to be declared as a class?

I know this is silly, but I looked through Google and forums and the problem seems to be so obvious and simple that it’s hard to find a webpage or entry targeting this (or perhaps I’m asking the wrong question).

Answer 1

http://php.net/manual/en/language.variables.scope.php

<?php
$debug = TRUE;

function a() {
    global $debug;
    if($debug === TRUE) {
         echo "I'm here....\n"
    }
}

Better, instead of using globals you can pass it in as a parameter:

<?php
$debug = TRUE;

function a($debug = TRUE) {
  if($debug === TRUE) ....
}    

You can also use the $_GLOBALS array:

<?php
$debug = TRUE;

function a() {
   if($_GLOBALS['debug'] === TRUE) ...
}

You can use constants, which are always in scope:

<?php
define('DEBUG', TRUE);

function a() {
  if(DEBUG === TRUE) ...
}

You can also use a singleton:

function a() {
    if(SingletonClass::get_instance()->debug === TRUE) {
        ...
    }
}

You’ll have to create a singleton class which extends StdClass() to get implicit ->get and ->set methods.

http://www.talkphp.com/advanced-php-programming/1304-how-use-singleton-design-pattern.html