unistd library

[mpo]

I'm compiling with Visual Studio and the compiler give to me the following error:
fatal error C1083: Cannot open include file: 'unistd.h': No such file or directory

I have searched in internet and somewhere i have seen that the library unistd there's only for Unix and not for Windows.
What i have to do? I have tried to download and include it anyway into the project but then i have a lot of new errors.