CODEWITHSUNDEEP
php
user1094081
user1094081

Reputation:

add key to associative array if key is not found

Given a PHP associative array like this one:

$a = array(
    'color' => 'red',
    'taste' => 'sweet',
    'shape' => 'round',
    'name'  => 'apple'
);

I want to search a key and, if not found, I want to add 'myKey'=>0. Which is the best way to do such a thing?

Upvotes: 2

Views: 20763

Answers (6)

mickmackusa
mickmackusa

Reputation: 47883

You don't need to "check" if the key exists. Just use the array union operator to attempt the appending of one or more elements to the input array.

The array union assigment operator (+=) is shorthand for $a = $a + $newArray;. Demo

$a = [
    'color' => 'red',
    'taste' => 'sweet',
    'shape' => 'round',
    'name'  => 'apple'
];

$a += ['myKey' => 'foo'];  // this is added because the key doesn't exist

$a += ['shape' => 'bar'];  // this is ignored because the already key exists

$a += ['zero'];            // this is added because the 0 key doesn't exist
$a += ['not zero'];        // this is ignored because the 0 key already exists

var_export($a);

Output:

array (
  'color' => 'red',
  'taste' => 'sweet',
  'shape' => 'round',
  'name' => 'apple',
  'myKey' => 'foo',
  0 => 'zero',
)

Upvotes: 0

Mathieu Dumoulin
Mathieu Dumoulin

Reputation: 12244

You have 2 ways, if you are sure your keys CAN'T have NULLs, then you can use the isset(). isset only returns true when the key is set and its value is different than null.

if(!isset($a['keychecked'])){
    $a['keychecked'] = 0;
}

BUT, if you have NULLS in your array. You HAVE to use array_key_exists() which is longuer to write but not subjet to the isset(NULL) == false rule.

if(!array_key_exists('keychecked', $a)){
    $a['keychecked'] = 0;
}

Upvotes: 8

Roy
Roy

Reputation: 44288

You can use the null coalesce operator if you don't store null values:

$a['myKey'] ??= 0;

Note that if the key myKey already exists with a null value, then the above statement will override that value.

Upvotes: 2

user142162
user142162

Reputation:

You are looking for the array_key_exists function:

if (!array_key_exists($key, $arr)) {
    $arr[$key] = 0;
}

Upvotes: 25

AlexanderZ
AlexanderZ

Reputation: 521

<?php
$a = array( 'color' => 'red',
        'taste' => 'sweet',
        'shape' => 'round',
        'name'  => 'apple');
$key = 'myKey';
if (!array_key_exists($key, $a)) {
    $a[$key] = 0;
}
?>

Upvotes: 2

Niet the Dark Absol
Niet the Dark Absol

Reputation: 324620

if( !isset($a['myKey'])) $a['mkKey'] = 0;

Or

$a['myKey'] = $a['myKey'] ? $a['myKey'] : 0;

Or

$a['myKey'] = (int) $a['myKey']; // because null as an int is 0

Upvotes: 3

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