How to remove an array element from compare to other array element?

Question

I have two arrays. I need to remove an element from the first array when the element is included in the second array.

e.g.:

$First = array("apple"=>"7", "orange"=>"8", "strawberry"=>"9", "lemon"=>"10", "banana"=>"11");

$Second = array("orange"=>"1", "lemon"=>"1","banana"=>"1");

$Result = array("apple"=>"7","strawberry"=>"9");

I've used the following code but it is not working:

foreach($Second as $key){
    $keyToDelete = array_search($key, $First);
    unset($First[$keyToDelete]);
}
print_r($First);

Mark · Accepted Answer · 2016-05-04 11:51:18Z

7

Use array_diff_key - http://php.net/manual/en/function.array-diff-key.php

$First = array("apple"=>"7", "orange"=>"8", "strawberry"=>"9", "lemon"=>"10", "banana"=>"11");
$Second = array("orange"=>"1", "lemon"=>"1","banana"=>"1");
$Result = array_diff_key($First, $Second);

edited May 4, 2016 at 11:51

answered May 4, 2016 at 11:46

Mark

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3 Comments

Nirpendra Patel Over a year ago

nice answer. +1 up

Mark Over a year ago

my bad, changed to array_diff_key - checked it right now, result is same as desired by OP

Murad Hasan Over a year ago

also change the top portion

rharvey · Accepted Answer · 2016-05-04 12:47:35Z

2

You're close!

Firstly,

foreach ($Second as $key)

will only give you the value. To get the key you have to do

foreach ($Second as $key => $value)

Loop through the $Second array and then if they key exists (use isset) in $First array remove it using unset. $Second will then be the same as $Results

foreach ($Second as $key => $value) {
    if (isset($First[$key])) {
        unset($First[$key]);
    }
}

Alternatively, if you wanted to keep $First and $Second as they are then you can do the following:

foreach ($Second as $key => $value) {
    if (!isset($First[$key])) {
        $Results[$key] = $value;
    }
}

edited May 4, 2016 at 12:47

answered May 4, 2016 at 11:47

rharvey

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4 Comments

Murad Hasan Over a year ago

if you unset then you lost data.

Ravi Kadia Over a year ago

but in my case data comes from db and i just used for show with remove duplication.

Mark Over a year ago

Maybe it is possible to eliminate duplicates on database level?

rharvey Over a year ago

@fraynekonok I have updated my answer. If the key does not exist then store in $Results

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