php function to check variable exist or not outside of function
<p>i am in need of a php function to check that a variable exist or not outside of function, if it does not exists then assign a default value to it.
function will be something like : function if_exist($argument, $default = '') , where $argument will be any variable outside the function it can be a variable's variable, and $default will be the default value of the variable if the variable doesn't exists, many thanks in advance, please help, thanks.</p>

<p>PLEASE AVOID USING GLOBAL SCOPE IN THE FUNCTION, 'cause i heard that it's not good for site's security.</p>
