UA Developer: Clarion FAQ

  MAP
MODULE('RTL')
LoadLibrary(STRING _cLibName),LONG,RAW, |
NAME('Clw$LoadLibrary')
GetProcAddr(LONG _LibHandle,STRING _cProcName),LONG,RAW,PASCAL, |
NAME('GetProcAddress')
END
MODULE('')
dll_CallProc(LONG _ProcAddr,LONG _Param1,*CSTRING _Param2),LONG, |
NAME('dll_CallProc')
END
dll::ProcType(LONG _Param1,*CSTRING _Param2),LONG,RAW,PASCAL,TYPE
CallProc(dll::ProcType _Proc,LONG _Param1,*CSTRING _Param2),LONG, |
NAME('dll_CallProc')
END
csStr  CSTRING(40)
CODE
hLib# = LoadLibrary('MYLIB.DLL<0>')
IF hLib#
ProcAddr# = GetProcAddr(hLib#,'MyFunc<0>')
IF ProcAddr#
csStr = 'Hello!'
a# = dll_CallProc(ProcAddr#,1,csStr)
END
END
RETURN
CallProc PROCEDURE(dll::ProcType _Proc,LONG _Param1,*CSTRING _Param2)
CODE
RETURN(_Proc(_Param1,_Param2))

• declare typed function dll::ProcType, so it must be called from DLL module. It is naturally, if this function work with parameters as usual C-funciton, you should use attribute PASCAL instead C.
• Create function-adapter for calling of DLL-function. Pay your attention, you must use attribute NAME to override name that will be given by Clarion.
• in order to pass into this function-adapter address of wanted function received with help of GetProcAddr, we declare it as external dll_CallProc with any type of parameters.