what does two back to back $ behind a variable means. Like this $$id
where can I find more information on that Thanks
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*(reference)* http://de3.php.net/manual/en/language.variables.variable.php – Gordon May 06 '10 at 07:18
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In PHP, $$ means you are about to inflict years of pain and suffering on at least one maintenance programmer. Note that you might wind up being that maintenance programmer.
It is a variable variable. Imagine this:
$quux = 'bar';
$foo[$quux] = "baz";
echo $foo['bar']; //prints baz
if there was no such thing as arrays, you might try something like this:
$quux = 'bar';
$$quux = "baz";
echo $bar; //prints baz
luckily we do have arrays so please don't use variable variables unless you are doing something convoluted and magical* and have no other choice.
*: Please don't do convoluted magical things, either.
Carson Myers
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You can make anything look convoluted with undescriptive variable names like that. Variable variables are just as maintainable as regular ones when named properly. – Lotus Notes May 06 '10 at 06:20
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the foo, bar, baz, etc variables are very common when demonstrating a language feature. Obviously proper use of naming is a must in any language, but I'm talking about the maintainability of variable variables, not of dummy names -- I think they take much effort to use in a way that is not evil, so I'm okay with presenting them in a way that would make a novice programmer approach them with caution. – Carson Myers May 06 '10 at 08:36
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These are called variable variables.
$foo = 'bar';
$id = 'foo';
echo $id; // prints foo
echo $$id; // prints bar
codaddict
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in the PHP manual of course
http://www.php.net/manual/en/language.variables.variable.php
note that it's obsolete and senseless syntax and you should always use arrays instead.
Your Common Sense
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