Category : Databases and related files
Archive : MF-DB102.ZIP
Filename : MFUDK.C
Output of file : MFUDK.C contained in archive : MF-DB102.ZIP
Sample UDK (user-defined key) dll
(compiled under MSC 8.0 (VC++))
You may do whatever you want with this. It's free.
*/
#include
#include
/*
MF.dll will call this function and pass the following parameters:
pass:
val 1 (LPSTR a)
val 2 (LPSTR b)
length (Size of keys to compare)
type (This will be a number >= 100)
the 'type' is the 'type of index' specified when the index's where
created. (i.e. When you called mfCreateDB you passed an array of
index types. One of those 'types' was >= 100. Whatever that
# was, it is now passed to you (as the type). This allows you to
support multiple UDK's in one function.
You should return:
returns:
0 == equal
1 == val 1 > val 2
-1 == val 1 < val 2
Demonstrated in this example is a reverse-sorting for character fields
and a variable length char and INT field. The 'type' passed for
these fields is:
1001 = reverse sorting characters
1002 = variable length char and INT
*/
int FAR PASCAL _export mfUDK(LPSTR a, LPSTR b, int len, int type)
{
int iReturnValue;
switch(type){
case 1001:
// _fmemcmp is a MS-C runtime library routine. (It is actually
// pretty quick, believe it or not...)
// Anycase, it returns the EXACT same parameters we need to
// return from this function...
// NOTE: To show the reverse-sorting, we just switched the
// order of the parameters to fmemcmp. For 'alphabetical'
// we would have put 'a' and then 'b'.
return(_fmemcmp((LPSTR)b, (LPSTR)a, len));
break;
case 1002:
// NOTE: By using the value of 'len' we can make this
// a 'variable' length string routine. e.g. if the user
// made the key an 80 bytes, this routine would still
// work (by comparing the first 78 bytes and then the integer
// tacked onto the end...)
iReturnValue = _fmemcmp((LPSTR)a, (LPSTR)b, len-2);
// We can stop checking now because the keys first set of
// keys (the char[len]) doesn't match, therefore the value
// of the INT is irrelevant)
if (iReturnValue != 0)
return (iReturnValue);
if (*(int FAR *)(a+len-2) < *(int FAR *)(b+len-2))
return (-1);
if (*(int FAR *)(a+len-2) > *(int FAR *)(b+len-2))
return (1);
return(0); // exact match...
break;
}
}
/*----------------------------------------------------------------------
This is required for 'windows' dll's.
Generally, you put any startup code that you might require,
initialize variables, allocate memory, etc...
*/
int FAR PASCAL LibMain(
HANDLE hModule,
WORD wDataSeg,
WORD cbHeapSize,
LPSTR lpszCmdLine
)
{
return 1;
}
Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!
This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/