Hi Jeongeun Kim,
Did you download C SDK from PTC support website? https://support.ptc.com/appserver/auth/it/esd/product.jsp?prodFamily=TWS
If so, which version did you downloaded, take an example of the latest C SDK version 1-5-2-1933, we could see there are totally 7 folders under the examples folder:
which do you mean 10 examples? Please explain a little more here.