Lots of Global Variables. Is this a problem?

**jerseyguy1996** · 11-24-2009, 05:44 PM

I keep reading here and there that global variables are bad. This program that I am writing has a lot going on and many of the variables are used across multiple modules. What are the problems with declaring these variables global?

**Spudley_Jones** · 11-24-2009, 06:04 PM

The only problem I would see would be if you used a variable in a module and did not assign it a value in the beginning of the subroutine.
Hope this helps.

**teylyn** · 11-24-2009, 06:15 PM

There's more to it than that: Romperstomper recommends passing values between routines and explains why global variables should be avoided wherever possible in this post:

Originally Posted by romperstomper

Mostly because they make debugging harder. Because they can be changed from anywhere at any time, it can be difficult to try and follow a logical program flow and see what's going wrong. They also violate the principle of encapsulation - i.e. your routines should be as self-contained as possible - and they have a nasty habit of getting reset if an unhandled error occurs in your code.
Obviously they are not always avoidable, but a good rule of thumb is to give variables the narrowest scope you can.

**shg** · 11-24-2009, 07:50 PM

FWIW, I agree with RomperStomper.

As a minimum, public variables should only be modified in one procedure.

**jerseyguy1996** · 11-24-2009, 11:25 PM

I guess this works then. My program starts out with a form that asks the user to input various pieces of information. That information is assigned to the different global variables and then used in a number of different modules. None of the modules modify the variables, they only use the values in their calculations.