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Re: variables in common blocks [message #53874 is a reply to message #53873]

Fri, 04 May 2007 08:07

Maarten[1]
Messages: 176
Registered: November 2005

Senior Member

On May 4, 2:42 pm, Lasse Clausen <l...@lbnc.de> wrote:

> If you have an easy solution on how to avoid common blocks, shoot. And
> why are common blocks bad? Is it the same reason "goto" statements are
> bad?

Common variables are really global variables. They allow a function to
have side effects, and make it hard to debug a program. For sanity's
sake try to avoid common blocks, unless you really have a good reason
to use them, and clearly label the variables in them as such, so that
you have a clear warning when dealing with them.

In general is it easier to pass variables as formal parameters.

The book I learnt C from started out with local variables, and only
mentioned that global variables even existed in chapter 6. By that
time I was acustomed to pass variables as function arguments, and
hardly ever used globals, except perhaps as a global program kill
switch in GUI applications. The Mac way of things infected me with
aonther (pseudo)Hungarian notation: all my globals have a name
starting with 'g', all constant start with 'k'. If you use a common
block, make sure you do something similar.

Maarten

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[Message index]

		Re: variables in common blocks By: David Fanning on Fri, 04 May 2007 09:48
		Re: variables in common blocks By: Christopher Thom on Fri, 04 May 2007 09:40
		Re: variables in common blocks By: David Fanning on Fri, 04 May 2007 09:03
		Re: variables in common blocks By: lasse on Fri, 04 May 2007 08:56
		Re: variables in common blocks By: Foldy Lajos on Fri, 04 May 2007 08:36
		Re: variables in common blocks By: David Fanning on Fri, 04 May 2007 08:16
		Re: variables in common blocks By: Maarten[1] on Fri, 04 May 2007 08:07
		Re: variables in common blocks By: lasse on Fri, 04 May 2007 07:42
		Re: variables in common blocks By: David Fanning on Fri, 04 May 2007 07:11
		Re: variables in common blocks By: lasse on Fri, 04 May 2007 07:06
		Re: variables in common blocks By: David Fanning on Fri, 04 May 2007 06:45

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