How provide indexing to any array in php - php

Question

i am trying to compare two arrays using php intersect function.
I am using following code
$input_array=array();
$input_array=explode("," , $_POST['list']);
$array = array();
$result1 =mysql_query("SELECT b_no FROM abc");
while($fetch_array=mysql_fetch_array($result1)){
$array[] = $fetch_array['b_no'];
}
$result=array_intersect($input_array,$array);
echo"<pre>";
print_r($result);
echo"</pre>";
and result is like this:
Array
(
[4] => 443829
[5] => 952040
)
The resultant array have not their own indexing. Is possible to provide indexing?

Answer 1

It is possible to provide indexing, but you will need to specify which indexing you want.
If the resulting indexing is not what you expected, please note that array_intersect() only compares the values of each array, and it retains the index or key from the first array of each match.
If your requirement is to also match on the keys of an associative array (although I am inferring you are not judging from your example) you can use array_intersect_assoc().
If you want to simply 'reset' the indexing you can use array_values(). For example:
<?php
$a = [2 => 1, 2, 3];
$b = [2, 3, 4];
$intersect = array_intersect($a, $b);
print_r($intersect);
// Original keys are retained:
//
// Array
// (
// [3] => 2
// [4] => 3
// )
print_r(array_values($intersect));
// Original keys are discarded:
//
// Array
// (
// [0] => 2
// [1] => 3
// )
On the other hand, if you had a specific set of keys you wanted to use, say for example ['foo', 'bar'] you can use array_combine() - it accepts two arrays, one as keys and the other as values, to explicitly define a new set of indexes or keys for an array. For example:
$keys = ['foo', 'bar'];
print_r(array_combine($keys, $intersect);
// Array
// (
// [foo] => 2
// [bar] => 3
// )
$indexes = [100, 200];
print_r(array_combine($indexes, $intersect));
// Array
// (
// [100] => 2
// [200] => 3
// )
Please note, array_combine() requires that the length of both arrays are the same. I cannot really provide any more detail unless you update your question but I hope this helps :)