_ Cdecl and _ stdcal

Lresult is dedicated to longcallback In the callback function. Check the VC/BCB definition VC: windef. h # define callback Pascal // _ Pascal # define winapi cdecl // _ cdecl BCB: windef. h # define callback _ stdcall # define winapi _ stdcall _ cdecl is C/C ++ and MFCProgramYou can also add the _ cdecl keyword when declaring a function by default. When _ cdecl is used, function parameters are pushed to the stack in the order from right to left, and the caller pops up the parameter stack to clear the stack. Therefore, a function that implements variable parameters can only use this call convention. Every function using the _ cdecl Convention must containCodeTherefore, the size of the executable files generated is relatively large. _ Cdecl can be written as _ cdecl. _ Stdcall is used to call Win32 API functions. When _ stdcal is used, function parameters are written to the stack in the order from right to left. The called function clears the stack of the transfer parameter before returning, and the number of function parameters is fixed. Because the function body knows the number of passed parameters, the called function can directly clear the stack of the passed parameters with a RET n command before returning the result. _ Stdcall can be written as _ stdcall. _ Fastcall conventions are used in scenarios with high performance requirements. _ Fastcall: The two DWORD parameters starting from the left of the function are placed in the ECX and EDX registers respectively, the other parameters are still transmitted from the right to the left pressure stack. The called function clears the stack of the transfer parameter before returning. _ Fastcall can be written as _ fastcall. By default, the _ cdecl method is used. Therefore, it can be omitted. winapi is generally used to modify the export function callback in the dynamic link library. Callback is only used to modify the callback function.
 

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