Regarding PHP reference in loop scope

Question

I'm wondering why this code is working like this. Why changing variable name makes difference ? Shouldn't $t be available just in foreach scope ?

$types = [
    ['name'=>'One'],
    ['name'=>'Two']
];

foreach($types as &$t){
    if ($t['name']=='Two') $t['selected'] = true;
}

// now put that selection to top of the array
// I know this is not a good way to sort, but that's not the point
$_tmp=[];

// Version 1
// foreach($types as $v) if (isset($v['selected'])) $_tmp[] = $v;
// foreach($types as $v) if (!isset($v['selected'])) $_tmp[] = $v;

// Version 2
foreach($types as $t) if (isset($t['selected'])) $_tmp[] = $t;
foreach($types as $t) if (!isset($t['selected'])) $_tmp[] = $t;

print_r($_tmp);
//Version 1 :  Array ( [0] => Array ( [name] => Two [selected] => 1 ) [1] => Array ( [name] => One ) )
//Version 2 :  Array ( [0] => Array ( [name] => One ) [1] => Array ( [name] => One ) )

Once you declare variable in php, it will be available till the end of script. Same thing apply for variables declare in For and Foreach loop. These variables also available till the end of script. So in you case last value stored in $t in foreach loop will be available in rest of the script. — Gokul Shinde
– Gokul Shinde, Commented Mar 31, 2016 at 9:33

Kubber · Accepted Answer · 2016-08-10 13:43:31Z

1

Correct answer is in question comment. "Once you declare variable in php, it will be available till the end of script. Same thing apply for variables declare in For and Foreach loop. These variables also available till the end of script. So in you case last value stored in $t in foreach loop will be available in rest of the script. – Gokul Shinde Mar 31 at 9:33"

answered Aug 10, 2016 at 13:43

Kubber

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Comments

Govinda raj · Accepted Answer · 2016-03-31 10:25:44Z

0

You are using the reference operator (&), due to that

$types = array(
0 => array('name'=>'One'),
1 => array('name'=>'Two'));

array converts to

$types = array(
0 => array('name'=>'One'),
1=> array('name'=>'Two', 'selected' => 1);

foreach($types as $t){
if ($t['name']=='Two') $t['selected'] = true;}

If you remove the & from the for-each the selected key will not reflect from the $types array.

answered Mar 31, 2016 at 10:25

Govinda raj

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1 Comment

Kubber Over a year ago

thanks, I think Gokul Shinde answer is one I was looking for .

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