Category : Files from Magazines
Archive   : V12N05.ZIP
Filename : NXTKEY.PRG

*********************************************************************
* FUNCTION NxtKeyCod Clipper 5
* Increments a key code of serial number that is made up of
* letters and numerals.
*
* - The characters used in the code are from 0 - 9 and then A - Z
* in ascending order.
* - The previous key code passed to this procedure should have the
* maximum length allowed so that the system can check whether
* the next key code will exceed the limit.
* If so, it returns all "*".
* - Spaces are treated as "0". Trailing spaces are significant and
* replaced by "0", while leading spaces will remain unchanged
*********************************************************************
FUNCTION NxtKeyCod( ckeycode )
LOCAL cchrbank, nkeylen, nct, cwkchr, nwkchrseq
cchrbank = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
nkeylen = LEN( ckeycode)
ckeycode = SUBSTR( TRIM( ckeycode ) + ;
REPLICATE( "0", nkeylen), 1, nkeylen)
FOR nct = 1 TO nkeylen
cwkchr = SUBSTR( ckeycode, -1 *nct, 1 )
cwkchr = IIF( cwkchr = " ", "0", cwkchr )
nwkchrseq = AT( cwkchr, cchrbank )
nwkchrseq = nwkchrseq + 1
nwkchrseq = IIF( nwkchrseq > LEN( cchrbank), 1, nwkchrseq )
cwkchr = SUBSTR( cchrbank, nwkchrseq, 1 )
ckeycode = SUBSTR( ckeycode, 1, nkeylen - nct) + cwkchr +;
SUBSTR( ckeycode, nkeylen -nct +2)
IF nwkchrseq != 1
EXIT
ELSEIF nct = nkeylen
ckeycode = REPLICATE( "*", nkeylen )
ENDIF
NEXT
RETURN ckeycode