When I add
#include
and try to use
std::ifstream (i.e. std::ifstream ifile(pDest))
in my lib
for anyone like me that this answer did not ring helpful, a second option is to go to: Project Properties->Configuration Properties->General->Project Defaults->.NET Target Framework Version and set it to v4.0
https://connect.microsoft.com/VisualStudio/feedbackdetail/view/806238/unwarranted-linker-errors-using-stl-filestream-class-in-managed-classes-in-c-11-cli has an obscure answer from Microsoft team that fixed my issue.
I also added this answer to another version of the same problem.