Sql2k: Increment Numeric Part In Arbitrary String

CREATE FUNCTION fctisnumericex(@c varchar(1))
RETURNS int AS
BEGIN
RETURN CASE WHEN ASCII(@c)>=ASCII('0') AND ASCII(@c)<=ASCII('9') THEN 1 ELSE 0 END END

CREATE FUNCTION fctstringincrement (@string varchar(255),@maxlen int)
RETURNS varchar(255) AS
BEGIN
DECLARE @@posr int
DECLARE @@posl int
DECLARE @@c varchar(1)
DECLARE @@token1 varchar(255)
DECLARE @@token varchar(255)
DECLARE @@token3 varchar(255)
DECLARE @@i int
/* emulates parts of the behaviour of s_modformatting::substringincrement */
/* 1. find the place where the numeric token starts from the right */
/* if we didn't find any non-numeric part then it might well be that the rightmost digit is already numeric */
IF dbo.fctisnumericex(SUBSTRING(@string,DATALENGTH(@string),1))=1
BEGIN
SELECT @@posr=DATALENGTH(@string)
END ELSE BEGIN
SELECT @@i=DATALENGTH(@string)
SELECT @@c=SUBSTRING(@string,@@i,1)
WHILE dbo.fctisnumericex(@@c)!=1 BEGIN
SELECT @@i=@@i-1
IF @@i<1 BEGIN BREAK END
SELECT @@c=SUBSTRING(@string,@@i,1)
END
SELECT @@posr=@@i
END
/* so have we got any numeric part inside that string? */
IF @@posr>0 BEGIN
/* yep. see how long it lasts */
SELECT @@i=@@posr
SELECT @@c=SUBSTRING(@string,@@i,1)
WHILE dbo.fctisnumericex(@@c)=1 BEGIN
SELECT @@posl=@@i
SELECT @@i=@@i-1
IF @@i<1 BEGIN BREAK END
SELECT @@c=SUBSTRING(@string,@@i,1)
END
/* separate now the parts of the string */
IF @@posl>1 BEGIN SELECT @@token1=SUBSTRING(@string,1,@@posl-1) END ELSE BEGIN SELECT @@token1='' END
SELECT @@token=SUBSTRING(@string,@@posl,@@posr-@@posl+1)
IF @@posr<DATALENGTH(@string) BEGIN SELECT
@@token3=SUBSTRING(@string,@@posr+1,DATALENGTH(@string)-@@posr) END ELSE BEGIN SELECT @@token3='' END
/* increment the numeric part */
SELECT @@token=convert(varchar(255),convert(int,@@token)+1)
END ELSE BEGIN
/* no numeric part at all. start with 1 at the end */
SELECT @@token1=@string
SELECT @@token='1'
SELECT @@token3=''
END
/* recompose the string and trim to max length if necessary */
RETURN SUBSTRING(@@token1+@@token+@@token3,1,@maxlen)
END