首先注意链接user32和gdi32，可以自己手动link，当然更方便的是让编译器帮你：
#pragma comment (lib, "user32.lib") #pragma comment (lib, "gdi32.lib")
如果你写main不写WinMain，就要告诉编译器入口是main不是WinMain：
#pragma comment(linker, "/subsystem:"Windows" /entry:"mainCRTStartup"")
/subsystem:"Windows"的意思是不要黑框框，直接放界面。如果你需要命令行的话就去掉。去掉了的话/entry:"mainCRTStartup"就不用写了，会变成默认。
更多/entry的选择见微软文档：https://docs.microsoft.com/en-us/cpp/build/reference/entry-entry-point-symbol?view=vs-2019
| Function name | Default for |
|---|---|
| mainCRTStartup (or wmainCRTStartup) | An application that uses /SUBSYSTEM:CONSOLE; calls main (or wmain) |
| WinMainCRTStartup (or wWinMainCRTStartup) | An application that uses /SUBSYSTEM:WINDOWS; calls WinMain (or wWinMain), which must be defined to use __stdcall |
| _DllMainCRTStartup | A DLL; calls DllMain if it exists, which must be defined to use __stdcall |