PHP: Using a variable that are inside a function

Question

I have:

include ('functions.php');
check_blocked();
echo $blocked;

in functions.php, check_blocked(); exists. Inside check_blocked I got:

global $blocked;
$blocked = '1234';

I want to echo $blocked variable, that are inside check_blocked().

It doesnt work, no output..

This is an example of my original problem, so please dont say that I could just have the echo inside the function, as I cannot have in my original code.

why are all of you encouraging him to use globals, when he should just return the value from the function?? — dqhendricks
– dqhendricks, Commented Jan 13, 2011 at 19:49
Return $blocked? So that 'echo check_blocked()' actually works? If there are multiple $blocked, then use arrays. Where's the problem? — sh03
– sh03, Commented Jan 13, 2011 at 19:49

Geoffrey Wagner · Accepted Answer · 2011-01-13 19:57:49Z

4

Your code should look like

$blocked = 0;
include('functions.php');
check_blocked();
echo $blocked;

With functions.php looking like

function check_blocked(){
     global $blocked;
     $blocked = 1234;
}

You must define blocked outside of the scope of the function before you global blocked into the function.

edited Jan 13, 2011 at 19:57

answered Jan 13, 2011 at 19:47

Geoffrey Wagner

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5 Comments

Lightness Races in Orbit Over a year ago

+1. Indeed. Otherwise the global $blocked in the function doesn't do anything; it doesn't find a global named $blocked because you did not make one yet!

dqhendricks Over a year ago

@Tomalak Geret'kal upvoting the use of globals? why not just return the value from the function?

Geoffrey Wagner Over a year ago

@charlie If you run it, it will echo 1234 because your now in the proper scope. Had $blocked not been set to zero, then you would see nothing. If $blocked was echoed before the check_blocked(); function was called, then you would see zero.

Lightness Races in Orbit Over a year ago

@dqhendricks That could possibly be a superior approach (depending on the actual scenario behind the testcase). However, this answer is a correct response to the question asked, identifying the specific code mistake committed by the OP.

Geoffrey Wagner Over a year ago

There are 100 ways to skin a cat, this answer actually answers the question asked about scope of variables.

Felix Kling · Accepted Answer · 2011-01-13 19:50:05Z

4

Why not just returning the value?

function check_blocked() {
    $blocked = '1234';
    return $blocked;
}

then

include ('functions.php');
echo check_blocked();

Avoid globales wherever possible.

answered Jan 13, 2011 at 19:50

Felix Kling

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4 Comments

mfonda Over a year ago

+1. Globals should be avoided. This is the correct way to do it.

Lightness Races in Orbit Over a year ago

@mfonda There is no single "correct" way to do anything, and sweeping generalisations don't help.

Lightness Races in Orbit Over a year ago

We don't know enough about the real-life scenario behind his testcase. This may in fact not be appropriate; I feel that you diverged too far from the original testcase. No downvote, though.

Felix Kling Over a year ago

@Tomalak Geret'kal: Well that is why I asked (;)). I agree, to give a more appropriate answer we would need more information. Anyway, it is always good to show other possibilities imo.

Cesar · Accepted Answer · 2011-01-13 19:48:43Z

0

You can change check_blocked() to return $blocked or you can try use:

include ('functions.php');
check_blocked();
global $blocked;
echo $blocked;

answered Jan 13, 2011 at 19:48

Cesar

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1 Comment

Lightness Races in Orbit Over a year ago

-1. Eh? That's already in global scope. Why write global there? What nonsense.

dqhendricks · Accepted Answer · 2011-01-13 19:48:46Z

0

instead, use a return value. globals are bad.

include ('functions.php');
echo check_blocked();

function check_blocked() {
    return '1234';
}

answered Jan 13, 2011 at 19:48

dqhendricks

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3 Comments

Geoffrey Wagner Over a year ago

Though a valid way to do things, doesn't push the point of variable scope and how to actually use a global variable.

dqhendricks Over a year ago

@Geoffrey Wagner he doesn't actually ask anything about globals or scope... the OPs question was how to echo a variable that is created within a function after the function has executed. why not help them to understand the best method?

Geoffrey Wagner Over a year ago

i see your point completely and i am not devaluing, but why not show them the errors of their ways instead of saying, just do it this way?? Teach a man to fish and feed him forever IMO

minichate · Accepted Answer · 2011-01-14 19:15:00Z

0

Unless the variable is declared outside of the check_blocked() function, you can't.

$foo = null;

function check_blocked() {
   global $foo;
   $foo = "Hello";
   // do some stuff
}

global $foo;
echo $foo; // prints "Hello"

If its defined inside the function like:

function check_blocked() {
    global $foo;
    $foo = "Hello";
    // other work
}


global $foo;
echo $foo; // Nothing

then the variable is scoped locally, and is discarded as soon as the function completed.

edited Jan 14, 2011 at 19:15

answered Jan 13, 2011 at 19:47

minichate

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1 Comment

Lightness Races in Orbit Over a year ago

) Happens to us all. If you also add it to the second example, and explain why it no longer works properly (which is what this question is all about), then I will remove my downvote.

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