Are you trying to modify the project? If that's so, you should use more up-to-date CInSim and InSim.h. Rather than trying to exhume this ancient VS 6.0 project it might be easier to create a new VS 2015 project and add these files to it.
Just in case you simply want to use the program, in folder \insim_simplex_v2\Debug is a compiled .exe
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I tried with codeblocks ("import VS project") and gcc compiler, it worked.
The code itself is ok.
What is the error?
Is it something with the pthread libary / sched.h file?
(That is what I am trying to figure out currently too , on my other computer. )
/edit:
Ah.
You mean "/ ZI and / Gy" - As in the commandline options?
Try turning them off, somewhere in settings.