Accessing arrays whitout quoting the key

Question

I can access an array value either with $array[key] or $array[\'key\']

Is there a reason to avoid using one over the other?

Answer 1

PHP will raise a warning for the quote-less version ($array[key]) if there's no constant named keydefined, and silently convert it to $array['key']. Consider the trouble you'd have debugging your code if you had something:

$array['foo'] = 'baZ'
echo $array[foo];
echo $array['foo'];
echo "$array[foo]";
echo "{$array['foo']}";
echo "{$array[foo]}";

define('foo', 'baR');
echo $array[foo];
echo $array['foo'];
echo "$array[foo]";
echo "{$array['foo']}";
echo "{$array[foo]}";

Try them out and see, but make sure you've got warnings enabled (error_reporting(E_ALL) and display_errors(1))