Strange results using references - or is it?

[NigelRel3]

I'm working with something where I use references to allow me to modify arrays - and the reference on a field seems to 'stick'.

The code I've cut down to show this is...

<?php
$tableName = "BinType";
$fields = [ 
		[ 
				"name" => "binTypeID"
		],
		[ 
				"name" => "description"
		]
];
foreach ( $fields as $field ) {
	echo " name1='" . $field ['name'] . "' ";
}
$fieldNames = array ();
foreach ( $fields as &$field ) {
	echo " name2='" . $field ['name'] . "' ";
	$fieldNames [] = $field ['name'];
}
foreach ( $fields as $field ) {
	echo " name3='" . $field ['name'] . "' ";
}

Which gives as the output...

name1='binTypeID' name1='description' name2='binTypeID' name2='description' name3='binTypeID' name3='binTypeID'

So it seems that the reference in the middle foreach seems to be still in place for the last foreach.
Can someone shed some light on this or do I just do what I did and rename the last $field to $field1 and ignore the problem?

 

Thanks

( PHP - PHP Version 7.0.15 )

[cyberRobot]

When you are done with a reference variable, you can unset it.

http://php.net/manual/en/language.references.unset.php

[Psycho]

Here is what I believe is happening:

 

At the end of the second foreach() loop you have a "$field" variable that is a reference. Then on the first iteration of the third loop the "$fields as $field" within the foreach is taking the first value of the array $fields and setting it as the value of the variable $field - which is still a reference to the second element in the array. So, on that third foreach loop, I think it is actually displaying the value for the second element on both iterations - but you are seeing the first value because it was overwritten on the first instance.

 

Think of it this way for the logic on the last foreach loop:

 

Take the next value from the $fields array and assign it to the 2nd element of $fields. Then display the value of the 2nd element.

[requinix]

So many people have reported that behavior as a bug in PHP that we added a big red warning in the documentation.

 

It still amazes me how many people don't RTFM.

[NigelRel3]

Thanks - it makes sense if the value persists beyond the scope of the foreach.  I was under the impression that this value is only valid inside the foreach block and therefore would be forgotten after each loop :-/

 

[Jacques1]

PHP doesn't have block scope. Statements like foreach, if etc. do not introduce a new variable scope (like they would in Java or C).

[NigelRel3]

My problem is that I've done more Java than PHP and so I was erroneously making that assumption about scope, I will now unscrew my head and make the appropriate adjustments