Get value in a 2D array in PHP

Question

I have this array:

$array = array (
    "key1" => "Value 1",
    "key2" => "Value 2",
    "key3" => "Value 3",
    "key4" => "Value 4",
    ...
);

I am submitting a key with a form, so I want to assign a variable the value that belongs to that key, for example:

$key = $_POST['key'];
$value = ?????; //this is what I need

This might be very simple, but I haven't done it in a very long time and I have forgotten how to do it.

Thanks.

For reference: this isn't a 2D array. It's just an associative array you index with a dynamic key. PHP doesn't technically have 2D arrays, but a good-enough equivalent (in most cases) would be an array of arrays -- meaning in PHP's rendition of a 2D array, each of those values would itself be an array. — cHao
– cHao, Commented Jul 31, 2013 at 13:53

Tobias Golbs · Accepted Answer · 2013-07-31 14:09:51Z

1

This should do the trick:

$value = $array[$key];

or without another variable:

$value = $array[$_POST['key']];

If you do receive a Notice: Undefined index ... you should check your array before you try to get the value with:

$value = array_key_exists($_POST['key'], $array) ? $array[$_POST['key']] : null;

This condition checks if the key exists. If so, it gets the value. If not, the value of $value will be null.

edited Jul 31, 2013 at 14:09

answered Jul 31, 2013 at 13:51

Tobias Golbs

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11 Comments

jfha73 Over a year ago

I am trying that, but even though it shows me the results I want, it's also showing this: Notice: Undefined index: $key, by the way I'm using PHP 5.5

Tobias Golbs Over a year ago

@jfha73: Showing what?

jfha73 Over a year ago

check my previous comment, I just hit Enter by mistake, I just edited it.

cHao Over a year ago

@jfha73: That typically means you don't have a POST variable named 'key'. You'll want to make sure $_SERVER['REQUEST_METHOD'] === 'POST' and/or isset($_POST['key']) are true before you use $_POST['key']. Particularly if this code is in a script that handles both GET and POST requests.

cHao Over a year ago

@jfha73: Then there are probably quoting issues. Make sure you don't have $key in single quotes. $array['$key'] will not do what you want.

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