If you want to pass more than one array or hash into or out of a function and maintain their integrity, you should pass references as arguments. The simplest way to do this is to take your named variables and put a backslash in front of them in the argument list:

@returnlist = ref_conversion(@temps1, @temps2, @temps3);

This sends references to the three arrays to the subroutine (and saves you the step of creating your own named references to send to the function). The references to the arrays are passed to the subroutine as the three-member @_ array. The subroutine will have to dereference the arguments so that the data values may be used.

Returning references is a simple matter of returning scalars that are references. This way, you can return distinct hashes and arrays.