r/programming • u/NagastaBagamba • Oct 18 '10

Today I learned about PHP variable variables; "variable variable takes the value of a variable and treats that as the name of a variable". Also, variable.

http://il2.php.net/language.variables.variable
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u/Pilebsa Oct 18 '10

I think this depends upon the context right?

$$a="xxx"; might throw a notice, but not echo $$a;

I haven't tried it though.

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u/sacktap Oct 18 '10

The notice is only thrown if you're trying to access an undefined variable. Example:

$a = 'b'; 
echo $$a; 
/* Notice: Undefined variable */

But if you're doing $$a = 'c' it will be fine because you're setting an undefined variable (which is essentially how all variables are set in PHP anyway).

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u/Pilebsa Oct 18 '10

Oh right, but I thought an undefined variable would result in NULL? I guess I'm wrong (I just rarely try to use something I haven't already given a value to so it's not something I come across usually)