PHP: type casting and change of the element in foreach loop

Question

I faced with a strange situation today. I need to change array element in foreach loop. As we know it can be done by using reference.

 foreach((array)$output['subjectComposite'] as &$subjectComposite){
     $subjectComposite['subjectSchemeVersion'] = $cellValue;
 }

But above code doesn't work and 'subjectSchemeVersion' is not set. At the same time if I remove (array) it works:

 foreach($output['subjectComposite'] as &$subjectComposite){
     $subjectComposite['subjectSchemeVersion'] = $cellValue;
 }

Can you explain this behaviour to me?

jornane · Accepted Answer · 2014-09-18 17:18:50Z

3

By casting the $output variable to array, you make a copy of it. The & still works, but it refers to the copy. After the loop, the copy is forgotten/garbage collected, and the original $output was never changed.

You can do the following instead, this will convert $output to an array prior to the loop:

settype($output, 'array');
foreach($output['subjectComposite'] as &$subjectComposite){
    $subjectComposite['subjectSchemeVersion'] = $cellValue;
}

edited Sep 18, 2014 at 17:18

answered Sep 18, 2014 at 17:11

jornane

1,56514 silver badges29 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

jornane Over a year ago

Credit for the example goes to Nick J, he made a suggested edit :-)

Collectives™ on Stack Overflow

PHP: type casting and change of the element in foreach loop

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related