How to calculate difference between keys and values in php

Question

I have two types of arrays:

1:
$array1["a"][] = "value1";
$array1["a"][] = "value2";
$array1["b"][] = "value3";

2:
$array2["0"] = "a";

What I need now is to somehow find difference between these two arrays. I need to filter out array1 by key, which is located in array2 value. I have tried doing the following:

array_diff(array_keys($array1), array_values($array2));

But I get the following error on that line: ErrorException Array to string conversion

Any ideas?

That line does not produce that error. Are you trying to `echo` that diff…? — deceze, Oct 05 '17 at 14:15

score 0 · Accepted Answer · answered Oct 05 '17 at 14:17

Something like this?

foreach ($array1 as $key => $value)
   if( array_search ($key , $array2 ))
    unset($array1[$key]);

If $array1 needs to have the values, you just need to put the diff in $array1 :

$array1 = array_diff(array_keys($array1), array_values($array2));

score 0 · Answer 2 · answered Oct 05 '17 at 14:33

Depending on how you constructed your arrays, it should work. The following code (based on your question) worked:

<?php
$array1=array("a" => array(),"a" => array(),"b" => array());
$array2=array("0"=>"a");
print_r(array_keys($array1));
echo("<br/>");
print_r(array_values($array2));
echo("<br/>");
print_r(array_diff(array_keys($array1), array_values($array2)));       
>

This results in:

Array ( [0] => a [1] => b )
Array ( [0] => a )
Array ( [1] => b )

How to calculate difference between keys and values in php

2 Answers2