PHP update array with values and keys from another array

Question

I have two arrays:

$a = [
    36 => 7,
    38 => 9,
    41 => 12,
    42 => 5
];

$b = [
    38 => 9,
    41 => 9,
    42 => 5
];

Array a has one extra key[36] and array b has a different value for key[41].

How do i set a key in a to equal 0 if it is not in b and then how do i update a key in a if it has a different value in b and how do i add new keys to a if it is in b and not in a?

For now i've made this code:

foreach($a as $key => $value){
    if(array_key_exists($key, $b) && $value != $b[$key]){
        $a[$key] = $b[$key];
    } else{
        $a[$key] = 0;
    }
}

if($diff = array_diff_key($b, $a)){
    foreach($diff as $key => $value){
        $a[$key] = $value;
    }
}

ksort($a);
print_r($a);

And it works but i feel like there should be a much easier way :-s

splash58 · Accepted Answer · 2018-09-22 10:49:02Z

2

Update a key in a if it has a different value in b and how do i add new keys to a if it is in b and not in a

$a = array_replace($a, $b);

Set a key in a equal to 0 if it is not in b

foreach(array_diff_key($a, $b) as $k=>$v) {
   $a[$k] = 0;
}

demo

edited Sep 22, 2018 at 10:49

answered Sep 22, 2018 at 10:43

splash58

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4 Comments

Barmar Over a year ago

Why doesn't it work with indexes starting from 0? array_merge() would concatenate the arrays, but array_replace() does what you want.

emma Over a year ago

@Barmar, my keys are actually shoe sizes :D that's why i don't start at 0 :D

Barmar Over a year ago

I learned a new PHP function here. I've known about array_merge, but not array_replace.

splash58 Over a year ago

@Barmar I use it in many cases. More than array_merge, I think

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