gamedevlists-general

[GD-General] Variables scope

[CAVEY G. <GER...@sg...>]

Hi there

Few days ago i switched to Visual c++ 6.0 and this is what i =
discovered.
The compiler accept the following C++ code :

//first loop
	for(unsigned long b=3D0;b<MeshesArray[current].VerticesCount;b++)
		{
		...//processing
		}
//second loop=20
		for( b=3D0;b<not_used*3;b++)
		{
		...
		}

But i thiink i should write the second FOR like this "for(unsigned long
b=3D0;b<not_used*3;b++)" (i mean i should redeclare 'b' because it came =
out of
scope)
When i tried the compiler answered me "error redefinition ..." !!!
Did i forget to set an option ;it is a bit strange isn t it?

Greetings=20
GC=20


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RE: [GD-General] Variables scope

[Jamie F. <ja...@qu...>]

that's just the way msvc6 is and always has been (i think maybe they added
an option at some point to switch the behaviour?), its scoping of variables
declared in for statements just violates the standard because microsoft
(obviously!) know better. Fortunately they recovered in msvc7.

jamie


-----Original Message-----
From: gam...@li...
[mailto:gam...@li...]On Behalf Of
CAVEY GERARD
Sent: 04 February 2004 09:11
To: 'gam...@li...'
Subject: [GD-General] Variables scope


Hi there

Few days ago i switched to Visual c++ 6.0 and this is what i discovered.
The compiler accept the following C++ code :

//first loop
	for(unsigned long b=0;b<MeshesArray[current].VerticesCount;b++)
		{
		...//processing
		}
//second loop
		for( b=0;b<not_used*3;b++)
		{
		...
		}

But i thiink i should write the second FOR like this "for(unsigned long
b=0;b<not_used*3;b++)" (i mean i should redeclare 'b' because it came out of
scope)
When i tried the compiler answered me "error redefinition ..." !!!
Did i forget to set an option ;it is a bit strange isn t it?

Greetings
GC


*************************************************************************
Ce message et toutes les pieces jointes (ci-apres le "message") sont
confidentiels et etablis a l'intention exclusive de ses destinataires.
Toute utilisation ou diffusion non autorisee est interdite.
Tout message electronique est susceptible d'alteration.
SG Asset Management et ses filiales declinent toute responsabilite au titre
de ce message s'il a ete altere, deforme ou falsifie.

Découvrez l'offre et les services de SG Asset Management sur le site
www.sgam.fr

				********

This message and any attachments (the "message") are confidential and
intended solely for the addressees.
Any unauthorised use or dissemination is prohibited.
E-mails are susceptible to alteration.
Neither SG Asset Management nor any of its subsidiaries or affiliates shall
be liable for the message if altered, changed or falsified.

*************************************************************************





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Re: [GD-General] Variables scope

[Jorrit T. <Jor...@uz...>]

CAVEY GERARD wrote:

>Hi there
>
>Few days ago i switched to Visual c++ 6.0 and this is what i discovered.
>The compiler accept the following C++ code :
>
>//first loop
>	for(unsigned long b=0;b<MeshesArray[current].VerticesCount;b++)
>		{
>		...//processing
>		}
>//second loop 
>		for( b=0;b<not_used*3;b++)
>		{
>		...
>		}
>
>But i thiink i should write the second FOR like this "for(unsigned long
>b=0;b<not_used*3;b++)" (i mean i should redeclare 'b' because it came out of
>scope)
>When i tried the compiler answered me "error redefinition ..." !!!
>Did i forget to set an option ;it is a bit strange isn t it?
>
>Greetings 
>GC 
>  
>

The best way to avoid this bug in VC 6 is to put 'unsigned long b' 
before the first
loop like this:

    unsigned long b;
    for (b = 0 ; ...)
    ...
    for (b = 0 ; ...)

We had the same problem in Crystal Space.

Greetings,

Re: [GD-General] Variables scope

[<ke...@ac...>]

The way I've worked around this in the past has been by redefining for as
follows:
#define for if (false) {} else for

Yes, it's a hideously ugly hack, but so is the problem in the first place.
I've never had any problems because of it.

// Kristoffer

From: "Jorrit Tyberghein" <Jor...@uz...>
> CAVEY GERARD wrote:
>
> >Hi there
> >
> >Few days ago i switched to Visual c++ 6.0 and this is what i discovered.
> >The compiler accept the following C++ code :
> >
> >//first loop
> > for(unsigned long b=0;b<MeshesArray[current].VerticesCount;b++)
> > {
> > ...//processing
> > }
> >//second loop
> > for( b=0;b<not_used*3;b++)
> > {
> > ...
> > }
> >
> >But i thiink i should write the second FOR like this "for(unsigned long
> >b=0;b<not_used*3;b++)" (i mean i should redeclare 'b' because it came out
of
> >scope)
> >When i tried the compiler answered me "error redefinition ..." !!!
> >Did i forget to set an option ;it is a bit strange isn t it?
> >
> >Greetings
> >GC
> >
> >
>
> The best way to avoid this bug in VC 6 is to put 'unsigned long b'
> before the first
> loop like this:
>
>     unsigned long b;
>     for (b = 0 ; ...)
>     ...
>     for (b = 0 ; ...)
>
> We had the same problem in Crystal Space.
>
> Greetings,
>

Re: [GD-General] Variables scope

[Jorrit T. <Jor...@uz...>]

Kristoffer Grönlund wrote:

>The way I've worked around this in the past has been by redefining for as
>follows:
>#define for if (false) {} else for
>
>Yes, it's a hideously ugly hack, but so is the problem in the first place.
>I've never had any problems because of it.
>  
>
Hmm... sounds like an ugly solution for something that is more simply 
solved by just
declaring the loop counter outside the for.

Greetings,

Re: [GD-General] Variables scope

[Jorrit T. <Jor...@uz...>]

Javier Arevalo wrote:

>When you have a large codebase in the "proper" style, and suddenly need to
>use it in a non-compliant compiler (like VC6), a hack may be worth a
>thousand changes.
>
>  
>
True enough.

Greetings,