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Subject: Re: question about local and global variables

Author: Daniel Clausen

Date: 11:53:29 09/03/01

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Hi

On September 02, 2001 at 07:29:12, Uri Blass wrote:

>My question is when it is a good idea to define global variables
>instead of local variables

Ah that's an easy one: define a variable as local if it only has a local
meaning, define it as global, if it has a global meaning. ;) As a rule of thumb,
few variables really have a global meaning.


>I found a trick to make my program slightly faster by defining them
>also as global variable and not using them as local variables in part
>of the cases.

... and next time you change something to the code the speed behaviour can be
different because the 'layout' of your program in memory is slightly different.
On a different platform it may also be completely different. (that is, if you
care for other platforms ;)


>Is there a way to know when it is faster without testing for every variable?

Um.. what speed advantages do you get by messing up with the scope of variables?
:) Are you that interested in that extra 2% speed? Call me stupid but I fail to
see  why anyone would want to decrease the readability of the source code that
much to get a lil speed bonus.

I remember a guy (on the net, not personally) coding in Java who skipped the
explicit bound-check when looping thru an array, but catching the
OutofBound-Exception instead... Yeah it might be slightly faster for big arrays
but I would fire that guy from my company. (if I had one ;)

Regards,

Sargon



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