Question

I am in need of a PHP function to check that a variable exist or not outside of function. If it does not exist, then assign a default value to it.

The 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 exist.

Please avoid using global scope in the function, because I heard that it’s not good for a site’s security.

Answer 1

You can make $argument pass-by-reference:

function if_exist(&$argument, $default="") {
   if(!isset($argument)) {
       $argument = $default;
       return false;
   }
   return true;
}

DEMO