Add an element to each row of an array of associative arrays [duplicate]

Question

I'm returning an associative array via PDO that has the structure:

Array
(
    [0] => Array
        (
            [pesttopicID] => 42
            [sPestName] => CMSM Trap Surveying and Pest Management
            [quizID] => 609
            [bTier1] => 1
            [sDesc] => Workshop assessment
        )

    [1] => Array
        (
            [pesttopicID] => 34
            [sPestName] => Trap Surveyor
            [quizID] => 451
            [bTier1] => 1
            [sDesc] => Competency for CM OAP
        )
)

I want to add a key-value pair to the "inner" array, but all my attempts of trying to use posted solutions to the generic issue of adding to an associative array:

$results = $statement->fetchAll(PDO::FETCH_ASSOC);
$newkey = 'myNewKey';
$newval = 'myNewValue';
foreach ($results as $row){
  $results[][$newkey] = $newval;
  foreach ($row as $key => $value) {
    ... some reporting stuff
    }
}

...result in the pair being added to the "outer" array e.g.

Array
(
    [0] => Array <---- I want the new pair in this "inner" array
        (  
            [pesttopicID] => 42
            [sPestName] => CMSM Trap Surveying and Pest Management
            [quizID] => 609
            [bTier1] => 1
            [sDesc] => Workshop assessment
        )

    [1] => Array  <---- I want the new pair in this "inner" array
        (  
            [pesttopicID] => 34
            [sPestName] => Trap Surveyor
            [quizID] => 451
            [bTier1] => 1
            [sDesc] => Competency for CM OAP
        )

    [2] => Array
        (
            [myNewKey] => myNewValue
        )
)

Is this possible?

so you want [myNewKey] => myNewValue added to each sub-array? — Death-is-the-real-truth
– Death-is-the-real-truth, Commented Sep 7, 2017 at 9:14
For your future refrence $results[][$newkey] = $newval; the [] means create a new element on the end of $results and add something to it. That's why you had some issues. — IsThisJavascript
– IsThisJavascript, Commented Sep 7, 2017 at 9:16
Read how to access array items using the square brackets syntax. — axiac
– axiac, Commented Sep 7, 2017 at 9:25

Death-is-the-real-truth · Accepted Answer · 2024-12-23 06:17:01Z

3

You have to do it like below:

$newkey = 'myNewKey';
$newval = 'myNewValue';
foreach ($results as &$row) { //use reference variable 
  $row[$newkey] = $newval;// remove the second  foreach if not necessary
  //if second foreach is necessary then add it no problem
}

Or you can do like this also:

$newkey = 'myNewKey';
$newval = 'myNewValue';
foreach ($results as $key => $row){ //use key now 
  $results[$key][$newkey] = $newval;// remove the second  foreach if not necessary
  //if second foreach is necessary then add it no problem
}

edited Dec 23, 2024 at 6:17

answered Sep 7, 2017 at 9:15

Death-is-the-real-truth

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1 Comment

TomBaine Over a year ago

Thank you. And I've also now learnt about the &$row construct - I'd not encountered that in my previous reading around the topic. Cheers/Tom

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