[GD-General] RE: VC6 vs VC7

[Jeff L. <je...@SP...>]

Brian asked:
> Unrelated to this I just found out that Microsoft has the command line
> compiler from VC++ 7.2 available for download. I'd like to 
> test it out,
> but I don't want it to screw up my VC++ 6.0 installation -- has anyone
> downloaded it and used it with VC++ 6 and not had the latter die?

Tweety: replied:
> Works perfectly as long as you don't install them in the same folder and
> keep separate PATH env vars to switch around (this is kinda done for you
> with vdvars32.bat and similar).
> 
> As a side note, vc++ 8, vc# 8 and vb.net 8 beta 1 are also 
> available for
> free download with ide included. I heard they're pretty stable.
> 
> ----------------------------------

Something I found out the hard way was that you can't always mix/match DLLs
compiled with different VC compilers, if you use certain constructs.

You definitely can't *link* .obj files from VC6 with VC70 or VC71 because
the runtime support library for floats changed.

You can't pass FILE* pointers from VC6 to VC7 DLL's; Microsoft do lock
operations on the low-level file descriptors, but the VC6 and VC7 runtimes
use different offsets into a statically allocated table.

This knowledge comes the hard way, from having to compile arx plugins for
AutoCAD 2004 (which requires VC70) and AutoCAD 2002 (which requires VC6).