Adding an item to an associative array

Question

//go through each question
foreach($file_data as $value) {
   //separate the string by pipes and place in variables
   list($category, $question) = explode('|', $value);

   //place in assoc array
   $data = array($category => $question);
   print_r($data);

}

This is not working as it replaces the value of data. How can I have it add an associative value each loop though? $file_data is an array of data that has a dynamic size.

score 168 · Answer 1 · edited Sep 12 '18 at 12:22

168

You can simply do this

$data += array($category => $question);

If your're running on php 5.4+

$data += [$category => $question];

edited Sep 12 '18 at 12:22

yourcomputergenius

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answered Sep 08 '14 at 05:52

Mohyaddin Alaoddin

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This is the correct answer to adding items to an associative array. – andreszs Dec 18 '17 at 16:09
9

Add multiple elements, too: $data += ['x' => 1, 'y' => 2]; – split19 Jan 31 '19 at 16:13
this is the way if you do not want to end up with more than one objects inside the array – DragonFire Apr 07 '20 at 08:45
1

Note: this can work if your array hasn't already element with the same key so it's can't overwrite an existing element. – Mohamad Hamouday May 03 '20 at 14:06
wow, how come i've never seen this before. Fixed all my issues – answerSeeker Oct 02 '22 at 04:14

score 111 · Accepted Answer · edited Mar 13 '13 at 11:05

111

I think you want $data[$category] = $question;

Or in case you want an array that maps categories to array of questions:

$data = array();
foreach($file_data as $value) {
    list($category, $question) = explode('|', $value, 2);

    if(!isset($data[$category])) {
        $data[$category] = array();
    }
    $data[$category][] = $question;
}
print_r($data);

edited Mar 13 '13 at 11:05

webvitaly

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answered Mar 21 '11 at 23:13

ThiefMaster

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Other programmers will hate you for typos though as they'll be forced to do them, too, or fix them. – ThiefMaster Mar 22 '11 at 00:01
I was too comfortable with array_push, forgot the basics! Really helpful! – CLOUGH Mar 26 '18 at 09:30

score 35 · Answer 3 · edited Sep 19 '22 at 05:50

35

Before for loop:

$data = array();

Then in your loop:

$data[] = array($catagory => $question);

edited Sep 19 '22 at 05:50

Uwe Keim

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answered Mar 21 '11 at 23:12

moe

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If you do it that way don't forget to init the array first by using $data = array(); or else php will throw a notice – Alex Bailey Mar 21 '11 at 23:14
I think SO caches my answer, as soo as posted it I realized I didnt see it being initialized in his code. So I added it and I saw your comment afterwards, thank you :-) – moe Mar 21 '11 at 23:15
5

This didn't work because it made an array inside the array. Sorry If my question kinda through you off. – Phil Mar 21 '11 at 23:27
PHP 5.4+ you can write a little less code: `$data=[];` `$data[] = [$category => $question];` – Justin Mar 20 '14 at 21:05
`$res = array(); $res[] = array('foo' => $bar); $foo = $res['foo'];` fails with **Undefined index: foo in..**, but below suggested plus sign works. – droid192 Jan 01 '17 at 21:09
4

this is adding to the array but as a seperate object – DragonFire Apr 11 '20 at 07:22

score 12 · Answer 4 · edited Feb 11 '19 at 16:21

12

I know this is an old question but you can use:

array_push($data, array($category => $question));

This will push the array onto the end of your current array. Or if you are just trying to add single values to the end of your array, not more arrays then you can use this:

array_push($data,$question);

edited Feb 11 '19 at 16:21

lasec0203

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answered Jun 29 '17 at 15:54

Mike

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score 6 · Answer 5 · answered Dec 19 '17 at 07:34

For anyone that also need to add into 2d associative array, you can also use answer given above, and use the code like this

 $data[$category]["test"] = $question

you can then call it (to test out the result by:

echo $data[$category]["test"];

which should print $question

Adding an item to an associative array

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