PHP - How to pass a global variable to a function

Question

I have a function that populates an array that was created before the function is launched. To make the population work, I used 'global' in my function. Everything is working fine with the here below situation:

$parameter = 'something'; 
$listOne = array();
my_function($parameter);
function my_function($para) {
 global $listeOne;
 ...some code 
 $listeOne[0] = 'john';
 $listeOne[1] = 'lugano';
}

What I would like is to pass the array that is supposed to be used in the function when calling the function. The idea would be to do something like this:

$parameter = 'something'; 
$listOne = array();
$listTwo = array();
my_function($listOne, $parameter);
...some code
my_function($listTwo, $parameter);
function my_function($list, $para) {
 ...some code
 $list[0] = 'john';
 $list[1] = 'lugano';
}

In addition according to what I read, using global is maybe not the best thing to do... I saw some people using the & sign somewhere and saying it is better. But I don't get it and not find information about that 'method'... Hope I am clear. Thank you in advance for your replies. Cheers. Marc

Answer 1

It's called referencing:

$listOne = array();
function my_function(&$list, $para) {
 ...some code
 $list[0] = 'john';
 $list[1] = 'lugano';
}
my_function($listOne, $parameter);
print_r($listOne); // array (0 => 'john', 1 => 'lugano');

Now the omitted array will be changed.

• Marc: Helo Dan. Thanks for trying to help. How is this & sign called in that situation and how does it work? And when calling the function do I have to put the & sign as well?
• Shakti Singh: @Marc: why not read the manual, he left a link to direct there
• dan-lee: In my message referencing is linked, anyway the exact term for this occasion here is Passing by reference
• Marc: Thak you Dan. I am on my way to read what is behind that link. Thank you for your help...

Answer 2

Maybe you need some thing like "parameters by reference" http://www.php.net/manual/en/functions.arguments.php

Answer 3

Using & means to pass by reference.

For example:

$x = '123';
function changeX(&$data){
 $data = '1';
}
echo $x; //x should print out as 1.

In your case, you could use:

$parameter = 'something'; 
$listOne = array(); 
$listTwo = array(); 
my_function($listOne, $parameter); 
my_function($listTwo, $parameter); 
function my_function(&$list, $para) { 
 $list[0] = 'john'; 
 $list[1] = 'lugano'; 
} 

Answer 4

you can write your function like this:

$listOne = array();
my_function($list = array())
{
array_push($list, 'john');
array_push($list, 'lugano');
return $list;
} 
$listOne = my_function($listOne);
print_r($listOne);