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Source: Darren's Outpost - http://ahkuan.com
from entry - http://ahkuan.com/weblog/archive/2005/10/16/php-passing-by-reference.html
this code fragment itself - http://ahkuan.com/weblog/20/code/1.html
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--------------- code fragment begin ---------------
// function declaration with default value
function foo($bar = 'default value here'){ ... };
// function declaration with passing by reference
function foo(&$bar){ ... };