Help with programming Functions in PHP

[Ocean]

I have a section of code that needs to be present in multiple places in one of vB's PHP files. Rather than duplicating the code, I thought that I would just make that common section into a function - and just call that function from the various places within the PHP file.

However, I don't seem to have done it properly. To test the process with just one of the locations, this is what I did:


I effectively started out with this:




if ($_REQUEST['do'] == 'custom_action')
{

// Common code was here

}




...and I made it this:




function custom_function()
{

// Common Code is now here

}



if ($_REQUEST['do'] == 'custom_action')
{

custom_function();

}





However, that doesn't seem to work. Can someone help me to understand what I did wrong?

Thanks! :)

[AN-net]

r u sure your returning something?

[Ocean]

r u sure your returning something?

Ah, perhaps that's the problem. I wasn't looking to return anything - I was simply looking to execute code.

Perhaps functions are not what I need then...


Is there another way I can re-use the same section of code without needing to have two sets of it?

In other words, I'm trying to avoid this:





if ($testvariable == true)
{

// Common Section of Code

}

if ($_REQUEST['do'] == 'custom_action')
{


// Unique Code goes here


// Duplicate of Common Section of Code


// More Unique Code goes here

}

[CarCdr]

It's probably a scoping problem. Scoping in PHP is, well, lacking. In your function, if you want to reference a variable outside the function, such as $DB_site, or $bbuserinfo, or whatever, you have to declare it as global. You would do so using something like the following inside your function:

global $DB_site, $bbuserinfo;

[Ocean]

It's probably a scoping problem. Scoping in PHP is, well, lacking. In your function, if you want to reference a variable outside the function, such as $DB_site, or $bbuserinfo, or whatever, you have to declare it as global. You would do so using something like the following inside your function:

global $DB_site, $bbuserinfo;


Does that need to work in both directions? In other words, do I have to do that for variables created inside the function if I need to reference them outside of the function?

Also, that process is not insignificant in size for a function that references/uses many variables. Is there any way I can easily state that I want ALL variables within the function to be Global?

[Colin F]

Does that need to work in both directions? In other words, do I have to do that for variables created inside the function if I need to reference them outside of the function?

Also, that process is not insignificant in size for a function that references/uses many variables. Is there any way I can easily state that I want ALL variables within the function to be Global?
If you want values calculated in the function to be available after, you'd probably want to do this by returning them.

then you'll have

function foo()
{
global $DB_site, $bbuserinfo;
$fooreturn = $bbuserinfo['usergroupid'];

return $fooreturn;
}

You'd then use it like this:

if ($_REQUEST['do'] == "foo-it")
{

$foooutput = foo();
echo $foooutput;
}


If you want to return multiple values, return an array.

[Natch]

You can use global to globalise variables from inside and outside: if you global $foo; inside a function then define an array $foo inside the function, you can then reference the array $foo[bar] etc outside the function, but only after the function has been called.

[Ocean]

You can use global to globalise variables from inside and outside: if you global $foo; inside a function then define an array $foo inside the function, you can then reference the array $foo[bar] etc outside the function, but only after the function has been called.



Makes sense, and works perfectly. Thanks!

[Ocean]

If you want values calculated in the function to be available after, you'd probably want to do this by returning them.



I would think that echoing them only makes them useable only at that moment. If I'm wrong, than is there a reason you would recommend that method over globalising them from inside the function? Or would they be interchangeable in results?

[Colin F]

I would think that echoing them only makes them useable only at that moment. If I'm wrong, than is there a reason you would recommend that method over globalising them from inside the function? Or would they be interchangeable in results?
I'm not sure what you mean by "only at that moment".
The data is saved in the variable and this is usable like any other variable.

[Ocean]

I'm not sure what you mean by "only at that moment".
The data is saved in the variable and this is usable like any other variable.


I thought "echo" was an immediate output function - so that if you ran the following...



<?

$i = 10;

echo ($i);

?>




...you would have "10" displayed on screen.

Was I mistaken?

[Colin F]

I thought "echo" was an immediate output function - so that if you ran the following...



<?

$i = 10;

echo ($i);

?>




...you would have "10" displayed on screen.

Was I mistaken?
Oh of course :)

I just wrote the echo line to show that the variable can be used normally. You don't have to echo it, you can use it like any other variable.

[Ocean]

Oh of course :)

I just wrote the echo line to show that the variable can be used normally. You don't have to echo it, you can use it like any other variable.


My mistake. :)


Well, that being the case - I'm still curious - is there any difference in function or performance between returning the values or globalising the variables? Or are there no significant differences or merits to using one as opposed to the other?

[Natch]

Globalising a variable is useful IMO when you have a lot of data you wanna pass back in many different variables, whereas a small function for a sepcific purpose might just return one value or array, in which case returning the variable and keeping it out of the $GLOBALS array may be more suitable.

Two examples:

- passing a number to a function to return a ordinalised string (1, 2, 3 => 1st, 2nd, 3rd) would be better simply to have $parsed_string = ordinalise($number); and function ordinalize($num)
{
if (!is_numeric($num))
return $num;

if ($num >= 11 and $num <= 19) return $num."th";
elseif ( $num % 10 == 1 ) return $num."st";
elseif ( $num % 10 == 2 ) return $num."nd";
elseif ( $num % 10 == 3 ) return $num."rd";
else return $num."th";
}
NOTE: I know this could be switched, but this is just an example)

- If you are trying to test for or generate a data caches, you might be better off globalising them at the start of the function, then you wont have to create a multi-dimensional array of the values you want to return, then list($cacheone, $cachetwo, $cache_three) = caching_function(); afterwards...

I hope that makes sense?

[Ocean]

Globalising a variable is useful IMO when you have a lot of data you wanna pass back in many different variables, whereas a small function for a sepcific purpose might just return one value or array, in which case returning the variable and keeping it out of the $GLOBALS array may be more suitable.



I think I understand. :)

[Natch]

I think I understand. :)
If I can clarify in more detail, or give you seom more detailed examples of where I have/would use global variables and where I have/would return values, just PM me and I can give you a look at some of the apps I've written...

[Ocean]

If I can clarify in more detail, or give you seom more detailed examples of where I have/would use global variables and where I have/would return values, just PM me and I can give you a look at some of the apps I've written...



Thanks, Natch. I truly appreciate your help, as well as the help offered by everyone else.


Thanks, all! :)