Linking CXX executable welcome2.exe
CMakeFiles/welcome2.dir/objects.a(welcome.cc.obj)：在函数‘main’中：
D:/_work/Welcome_2/welcome.cc:36：对‘WSAStartup@8’未定义的引用
collect2: ld returned 1 exit status
make[2]: *** [welcome2.exe] Error 1
make[1]: *** [CMakeFiles/welcome2.dir/all] Error 2
make: *** [all] Error 2