set_errno missing?

[Ivan Galic]

Hello,

I've searched but I couldn't find the function set_errno(), or  
something equivalent, to set the global errno variable used by the CRT.
Or is there not need to set it directly (currently I want to set it to  
0 to make sure that I don't catch any errors left from other function  
calls)?
For example, the wcstol sets errno to some error value if an error  
occurs. I want to make sure that if errno is set to an error value,  
that it was this function which caused it, and not some call that  
happened who knows when...


Does anyone have any ideas?


Thanks,
Ivan