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What does the $$ mean in variables?

Apr 29th, 2001 19:57
Philip Olson, Sheni R. Meledath, harry f, Nathan Wallace,


This is called "a variable variable", the manual entry is here :
  Variable variables                                         :
  ------------------------------------------------------------
  http://www.php.net/manual/en/language.variables.variable.php
Essentially it works like this :  
  $a = 'bear';
  $b = 'a';
  print $$b;   // prints bear
Essentially $$b is like $a.  So :
  print $$b;   // prints bear
  print ${$b}; // prints bear
  print $a;    // prints bear
Take a little time with it, it's not as complicated as it may seem.  
For good measure, here are a couple tutorials on the subject :
  http://phpbuilder.com/columns/robert20000928.php3
  http://devshed.com/Server_Side/PHP/VarVar/
A tip regarding variable variables and arrays, do it like so :
  $var = ${$array_name}[$key];