Associative array with 2 names that are the same? - php

Question

I'm working on a PHP script that updates some tracking numbers based on an uploaded CSV file. The import worked fine for some time, then the exports started having quotation marks around the values. I thought this would be fine, but it started rejecting the files. Doing some debugging and var_dumps, I discovered a very strange situation I have never seen before - An associative array with two indices with the same name. I ran the code setting the fields (shown below) and added a line:
$v['order_id'] = '119205';
After running that line, the var_dump was as follows:
array(15) {
["order_id"]=>
string(6) "119205"
["Tracking Number"]=>
string(22) "6735675476254654756"
["Postage"]=>
string(4) "1.64"
["order_id"]=>
string(6) "119205"
}
Some fields removed for brevity. As you can see, there are two ["order_id"] indices. How is this even possible?
Here is the code that sets the values of the array dumped above:
$v = array();
foreach ($map as $k => $n) {
$v[$n] = #$data[$k];
}
with $map being the CSV header row. Trying to reference $v['order_id'] without running the $v['order_id'] = '119205'; line resulted in this error:
Notice: Undefined index: order_id in /dir/to/php/file/php_file.php</b> on line 29
Manually setting the index worked as expected, pulling the rest of the data from $v without issue.
EDIT:
Dumping the array_keys resulted in:
[0]=>
string(11) "order_id"
and:
[14]=>
string(8) "order_id"
making the first one three characters longer.
var_export still resulted in identical indices.
How can I get rid of these invisible characters? I've already tried $v[trim($n)] = #$data[$k]; in the foreach().

Answer 1

Try var_dump(array_keys($v)). Find the key that looks like order_id and make sure the string's length is exactly 8. I suspect there may be a NUL character in there, which would give it a length of 9 and cause it to not respond to order_id.

Answer 2

Quote:
In the output of var_dump(), the null bytes are not visible.
Technically you can not have two times the same key in PHP in an array. It might be that var_dump is not giving the right keys here (e.g. probably some null-chars or other non-displayable chars are dropped).
Instead you might want to check, what's going on:
var_dump(array_keys($data));
Maybe it helps, the following is a related question which demonstrates when var_dump hides some information:
Array to Object and Object to Array in PHP - interesting behaviour