PHP using variables outside of a function - php

Question

I was wondering if someone could help me out.
I'm writing some PHP functions where I would like to use a variable inside a function and then use the updated variable outside of the function.
eg
$subTotal += $priceToShow * $ct_qty;
adminCharge($subTotal);
function adminCharge($loggedInfoprice, $subTotal){
if (($loggedInfoprice == 5)||($loggedInfoprice == 6)){
$packagingCurrency = "$";
$packagingPrice = "63";
$packagingPricing = $packagingCurrency.$packagingPrice;
}else {
$packagingCurrency = "£";
$packagingPrice = "30";
$packagingPricing = $packagingCurrency.$packagingPrice;
}
if(isset($packagingPrice)){
$subTotal = $subTotal + $packagingPrice;
}
}
<?php echo $subTotal; ?>
The echo'd $subTotal only seems to show the value from before the function.
Is it possible to extract both $subTotal and $packagingPricing from the function?
Thanks in advance.
Updated the function

Answer 1

function adminCharge(&$subTotal){
// do things
}
or
$subTotal = adminCharge($subTotal);
function adminCharge($subTotal){
//do things
return $subTotal;
}
In the first case, you pass $subTotal variable as a reference, so all all changes will be reflected to "outside" variable.
In the second case, you pass it and return new value, so is easy to understand why is working.
Please, pay attention
First solution - however - can lead you to side effect that will be difficult to understand and debug
Update
If you want to "extract" (so return) two variables, you can do the following
list($subTotal,$packagingPrice) = adminCharge($subTotal);
function adminCharge($subTotal){
if(isset($packagingPrice)){
$subTotal = $subTotal + $packagingPrice;
}
return array($subTotal, $packagingPrice);
}

Answer 2

function adminCharge($subTotal, $packagingPrice){
if(isset($packagingPrice)){
$subTotal = $subTotal + $packagingPrice;
}
return $subTotal;
}
Use it like this:
$subTotal = adminCharge($subTotal, $packagingPrice);

Answer 3

You don't return anything, so you could use globals but i wouldn't recommend it.. Take a look though, because that's what your asking for: http://www.php.net/global
In my opinion, change your function:
function adminCharge($subTotal){
global $packagingPrice
if(isset($packagingPrice)){
$subTotal = $subTotal + $packagingPrice;
}
return $subTotal;
}
$subTotal += $priceToShow * $ct_qty;
$subTotal = adminCharge($subTotal);
Also keep in mind you didn't had $packagingPrice in your function, so i added it with global. Otherwise it wouldn't work :)

Answer 4

You have to understand the variable scope read here.
In short, there are 3 options.
Use global keyword:
$a = 0;
function foo(){
global $a;
$a += 1;
}
Use pass by reference:
$a = 0;
function foo(&$b){
$b += 1;
}
foo($a);
Collect return value of the function:
$a = 0;
function foo($b){
return $b + 1;
}
$a = foo($a);

Answer 5

you need to use pass the variable by reference or global
option 1
function adminCharge(&$subTotal){
if(isset($packagingPrice)){
$subTotal = $subTotal + $packagingPrice;
}
return array($subTotal, $packagingPrice);
}
option 2
function adminCharge()
{
global $subTotal;
if(isset($packagingPrice))
{
$subTotal = $subTotal + $packagingPrice;
}
return array($subTotal, $packagingPrice);
}