PHP - How to set default value of every index of an array

Question

I am having trouble dealing with arrays. PHP throws an error if I access an index of an array which does not exists and It is getting difficult conditioning for every index. Is there any way I could set default value for every index of an array so even if I access a non-existent index of an array then it returns the default set value?

Define a function to access your arrays, something like this: `function access($array, $key) { return isset($array[$key]) ? $array[$key]:'Default Value'; }` and just use `access($array, 'key')` instead of `$array['key']` — t3chguy, Jul 25 '14 at 10:45
This is one of those things in PHP. You need to get accustomed to checking for the presence of a key that could possibly be missing because there is no syntax to avoid it without issuing an E_NOTICE — Michael Berkowski, Jul 25 '14 at 10:47
possible duplicate of [PHP default array values if key doesn't exist?](http://stackoverflow.com/questions/9555758/php-default-array-values-if-key-doesnt-exist) — Anri, Jul 25 '14 at 10:49
What is "every" index? You mean every possible index you may ever possibly want to access, which is basically infinite many indices? Or do you have only a number of defined keys? Please specify some more context. — deceze, Jul 25 '14 at 11:06

score 1 · Accepted Answer · answered Jul 25 '14 at 11:11

You do not want to set a default value for every index of the array, unless your array is really quite small. It would be a waste of processing and memory.

You can do this:

if (isset($array[$index])) {
    $var = $array[$index]; // the index exists
} else {
    $var = 'default value'; // the index does not exist
}
// now so something with $var

Balázs Édes · Answer 2 · 2014-07-25T11:39:36.700

'Object oriented' method:

You could create your own ArrayAccess implementation, which returns a default value (null for example) if the key you are looking for doesn't exists. The easiest way would be to extend the existing ArrayObject class:

class MyArray extends ArrayObject {
    public function offsetGet($offset) {
        if(!$this->offsetExists($offset)) {
            return null; // or some default value
        }
        return parent::offsetGet($offset);
    }
}

Then use this instead of array() :

$arr = new MyArray();
$arr['y'] = "I'm ok";
echo $arr['x']; // not set, default value (null) is returned.
echo $arr['y']; // prints "I'm ok"

Procedural method:

You could define a method, which safely gets a value from your arrays:

function safeGet($array, $key, $default = null){
    if(!is_array($array) && !$array instanceof ArrayAccess){
        throw new InvalidArgumentException('$array must be an array');
    }
    return isset($array[$key]) ? $array[$key] : $default;
}

Then simply access your values using this method:

$arr = array();
$arr['z'] = "I'm ok";

echo safeGet($arr, 'x'); // tries to access $arr['x']. prints null by default.
echo safeGet($arr, 'y', 'default'); // tries to access $arr['y']. prints 'default'.
echo safeGet($arr, 'z'); // key exists, prints "I'm ok".

PHP - How to set default value of every index of an array

2 Answers2