Do PHP array keys need to we wrapped in quotes?

Question

Which one below is correct? First code has no quotes in the $_GET array and the second one does, I know you are supposed to have them when it is a string of text but in this case it is a variable, also what about if the key is a number?

no quotes

function arg_p($name, $default = null) {
  return (isset($_GET[$name])) ? $_GET[$name] : $default;
}

with quotes

function arg_p($name, $default = null) {
  return (isset($_GET['$name'])) ? $_GET['$name'] : $default;
}

Answer 1

The first one will use the value of $name as key while the second will use the literal string '$name' as key.

Answer 2

With PHP, $_GET["$name"] and $_GET[$name] are identical, because PHP will evaluate variables inside double-quotes. This will return the key of whatever the variable $name stores.

However, $_GET['$name'] will search for the key of $name itself, not whatever the variable $name contains.

If the key is a number, $_GET[6], $_GET['6'], and $_GET["6"] are all syntactically equal.

Answer 3

• if the key is a variable

  $array[$key];

you don't have to quote it.

• but if it a literal string you must (it is not a string if you don't wrap it in quotes)

  $array['myKey'];

and you will get an notice if you do it like this

$array[mykey];