This is always a hot topic at this time of year. It’s been a while since we did procedures, parameters, byVal, Byref & Data Flow

From Shawlands Acc

Data flow within a program is handled by parameters

A parameter is a value or a variable which is passed into or out from a subroutine

The parameters used in a procedure call are ACTUAL parameters

The parameters used in a procedure definition are called FORMAL parameters

A parameter is passed BY REFERENCE if it is to by passed into and back out of a procedure

A parameter is passed BY VALUE if it is to by passed into but NOT back out of a procedure

Arrays are ALWAYS passed by reference

The use of parameters means that variables can be kept local to subroutines

This leads to programs being more reliable and robust