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cpointerswinapisyntaxtypedef

Trouble understanding a typedef along function pointers


Even after reading some answers here on SO regarding this topic, I'm having a bad time trying to understand what exactly the following syntax does: 

typedef BOOL (WINAPI *DllEntryProc)(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved);

My guess: It defines the DllEntryProc data type as an alias for BOOL, where DllEntryProc is a pointer to a function that takes one HINSTANCE, one DWORD and one LPVOID as arguments and returns a WINAPI?

The code above is part of this article regarding how to load a DLL from memory. The function is then called like this: 

DllEntryProc entry = (DllEntryProc) someValue;
(*entry)((HINSTANCE)baseAddress, DLL_PROCESS_ATTACH, 0);

Returning a BOOL (thanks to that typedef), right?

Solution

  • It defines the DllEntryProc data type as an alias for BOOL, where DllEntryProc is a pointer to a function that takes one HINSTANCE, one DWORD and one LPVOID as arguments and returns a WINAPI BOOL

    typedef BOOL (WINAPI *DllEntryProc)(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved);

    DllEntryProc is a new type like int and you can declare variables of this type just like you can declare variables of type int.

    DllEntryProc somevar;

    Now the value that you can assign to somevar should be of type DllEntryProc which is a pointer to a function of the said type.