What is the meaning of [] [closed]

8
votes

I have a code as below and I am not sure what type of data variable $ACTIVITYGROUPS[] has and how do I read it ?

$ACTIVITYGROUPS[] = saprfc_table_read ($fce, "ACTIVITYGROUPS", $i);

When I did print_r(saprfc_table_read ($fce, "ACTIVITYGROUPS", $i); I got bunch of arrays without any seperator and not sure how to exactract the data. can someone tell me what does it do in above sentences ?

Here is what print_r(saprfc_table_read ($fce, "ACTIVITYGROUPS", $i); result gives me:

Array (
    [AGR_NAME] => Y:SECURITY_DISPLAY
    [FROM_DAT] => 20080813
    [TO_DAT] => 99991231
    [AGR_TEXT] => Security Display - Users & Roles
    [ORG_FLAG] => C
)

Array (
    [AGR_NAME] => Y:SECURITY_ADMIN_COMMON
    [FROM_DAT] => 20080813
    [TO_DAT] => 99991231
    [AGR_TEXT] => Security Administrator
    [ORG_FLAG] => C
)

Array (
    [AGR_NAME] => Y:LOCAL_TRANSPORT
    [FROM_DAT] => 20090810
    [TO_DAT] => 99991231
    [AGR_TEXT] => Transport into target client - DEV system only
    [ORG_FLAG] =>
)
4
phparrays
Please please please put a bit more time into your questions. Then you might actually get some help with this matter. – Bojangles
possible duplicate of Reference - What does this symbol mean in PHP? – Wrikken
@Wrikken: Interestingly enough, there are no square bracket symbols at all on that page! I failed to find any using CTRL+F in Firefox. Looks like it's time to update it. – Wesley Murch
I just saw that, editing as we speak, I blatently assumed it was in there, it's about the default to point to when talking PHP operators. But indeed, not a duplicate of that one... stackoverflow.com/questions/2431629/php-array-push-vs-myarray is one though. – Wrikken

4 Answers

29
votes

[] means push - put the given argument as a new element on the end of the array. That means that $ACTIVITYGROUPS is an array*.

$arr = array();
$arr[] = 1;       // Put 1 in position 0
$arr[] = "a";     // Put "a" in position 1
$arr[] = array()  // Put a new, empty array in position 2

As stated by the PHP docs, array_push has the same effect as [].

* If it's not an array, using [] will give you a syntax error:

Warning: Cannot use a scalar value as an array in test.php on line 4

4
votes

In many languages the [] notation stands for an array. Is the same as php's array_push(): it pushes an element in the variable that has [] at the end.

If the variable is null, you can consider the square brackets like a declaration of an array.

The same notation of push applies to Javascript, for example. When using it like $var[] = 'a'; what happens is the same as array_push() I was talking above. Just finds the next position in the array and adds there your value.

An array can be walked with for, foreach, while, do while and you can check it's contents with print_r() or var_dump() functions.

2
votes

how do I read it ?.

Since saprfc_table_read already returns an array, $ACTIVITYGROUPS will be an array of arrays ([] creates a new array element in array $ACTIVITYGROUPS). To read it, you can iterate over it with foreach:

$ACTIVITYGROUPS[] = saprfc_table_read ($fce,"ACTIVITYGROUPS",$i);

foreach ($ACTIVITYGROUPS as $group) {
    echo $group['AGR_NAME']; // echos Y:SECURITY_DISPLAY on first iteration
    echo $group['FROM_DAT']; // echos 20080813 on first iteration
    // and so on...
}
1
votes

It's an array, but the output you have shows that your nested arrays do not have keys. I'm sure they have the default keys of 0,1,2,3,4...and so on, but if you want to identify them by any meaningful way I'd suggest adjusting the keys of the data within the array. 

print_r($ACTIVITYGROUPS); //this should output the whole array
print_r($ACTIVITYGROUPS[0]); //this should output just the first element of the array, which is also an array
//now you have an 'address' for the array that you understand, now lets output one of the values
foreach($ACTIVITYGROUPS as $key => $item){
    echo $item['ARG_NAME']; // this will output the ARG NAME from each of the arrays, in order
}