PHP - How to modify multi-dimensional array item from within a function?

Question

My problem is as follows. I have a multidimensional array. I declare my array. Then, I run some code that populates my array partially. Then i run a function, which among others is supposed to modify some item in my array from within the function. This is unfortunately not working. So my question is simple. Is it normal? And if yes, how can I overcome this. Thank you very much in advance for your replies. Cheers. Marc.

$list = array([0]=>
                   array(
                         [name]=>'James' 
                         [group]=>''
                         )
             ); 



my_function();
print_r($list); 

function my_function(){
     //some code here
     $list[0]['group'] = 'groupA';
}

I take it your array is taken from print_r, and not actually [0] =>? — Ry-
– Ry- ♦, Commented Apr 14, 2012 at 17:21

Andreas Linden · Accepted Answer · 2012-04-14 17:21:59Z

2

you could pass the array to the function by reference

my_function(&$list) {

    $list[0]['group'] = 'groupA';
}

$list = /*...*/
my_function($list);

or simply return the array from the function

my_function($list) {

    $list[0]['group'] = 'groupA';
    return $list;
}

$list = /*...*/
$list = my_function($list);

or use a global

my_function() {

    global $list;
    $list[0]['group'] = 'groupA';
}

$list = /*...*/
my_function();

answered Apr 14, 2012 at 17:21

Andreas Linden

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Comments

Maxim Krizhanovsky · Accepted Answer · 2012-04-14 17:21:49Z

1

In your case, the array is not changed, because it is in the global scope, and unlike other languages, PHP do not provide automatic access to the global scope from within function. So you have to do:

function my_function(){
     global $list;
     //some code here
     $list[0]['group'] = 'groupA';
}

But even better, pass the array as an argument by reference to the function

function my_function(&$list){
     //some code here
     $list[0]['group'] = 'groupA';
}

answered Apr 14, 2012 at 17:21

Maxim Krizhanovsky

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2 Comments

Marc Over a year ago

Helo Darhazer. Tks a lot. Both soution working great. Why is the second one better?

Maxim Krizhanovsky Over a year ago

Because it will work even if you rename the variable in the global space, or in case you need to perform the same operation to different arrays. Generally, avoid using global variables (because you can accidently override a global variable), and coupling (with global you are working with the exactly one array, and passing it by reference enable you to work with any array)

000 · Accepted Answer · 2012-04-14 17:25:55Z

1

Something like this:

$list = array( 0 =>
                   array(
                         'name'=>'James' 
                         'group'=>''
                         )
             ); 



my_function($list);
print_r($list); 

function my_function(&$list){
     //some code here
     $list[0]['group'] = 'groupA';
}

alternatively:

$list = array(0 =>
                   array(
                         'name'=>'James' 
                         'group'=>''
                         )
             ); 



$list = my_function($list);
print_r($list); 

function my_function($list){
     //some code here
     $list[0]['group'] = 'groupA';
     return $list;
}

edited Apr 14, 2012 at 17:25

answered Apr 14, 2012 at 17:20

000

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1 Comment

Marc Over a year ago

Hello Joe. Thanks for trying to help. Unfortunately, I tried that but it is not working...

Chen Kinnrot · Accepted Answer · 2012-04-14 17:26:36Z

0

add ' in your internal array indexes

 array(
                         'name'=>'James' 
                         'group'=>''
      )

edited Apr 14, 2012 at 17:26

answered Apr 14, 2012 at 17:20

Chen Kinnrot

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