Phytec eGrabber-4plus, Hardware Manual

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Driver Software

PHYTEC Meßtechnik GmbH 2004 L-608e_4
95
5.2.5 Application of the W indows 95/98
TM
/ Windows NT4.0
TM
/
Windows 2000
TM
DLL
In order to use the DLL Gr4CDLL.DLL, the software developer must
define a function pointer for each function that will be used in the
application.
Example:
•
Function to be used: WORD Get_Error(void)
•
Definition of the function pointer:
WORD (PASCAL * lpfn_GetError)(void);
Use GetProcAddress(…) to obtain the relationship between the
function pointer and the DLL.
Example:
lpfn_GetError = (WORD(PASCAL *)(void))
GetProcAddress(handle, „Get_Error“);
The function can now be called with:
WORD Errorstatus;
...
Errorstatus = lpfn_GetError();
Caution:
Check the value of the function pointer (return value from
GetProcAddress) to be sure that it = 0. A value of 0 ensures that the
driver version installed on the user’s computer supports the functions
and will return a valid handle.