What is the difference between $a and $$a in php? [duplicate]

Question

Possible Duplicate:
What does $$ mean in PHP?

I am new to PHP and I don't know what the difference between $a and $$a is.

Answer 1

If $a = 'b' then $$a is $b.

This is a variable variable. They are evil. Use arrays instead (which do the same thing, but more maintainably and with the ability to use array functions on them).