CODEPAGE ITWIN and DESCEND, strange ......

[Franz]

Hello,

I have a dbf index on "descend(dtos(DATAX))".

It works fine if I don't set codepage, if I set codepage to ITWIN order is not correct.

Why descend is affected by codepage in this case ? dtos return a 10 char string with only number.

See my little sample

function main

   set autopen on

   set date italian

   cls

   YES = "S"

   @ 00,00 Say "Set codepage to ITWIN ? " get YES pict "!" valid YES$("SN")

   read

   if YES = "S"

        

           request HB_CODEPAGE_ITWIN

           hb_setcodepage("ITWIN")

   endif

   request DBFCDX

   crea_db()

   fill_db()

   dbedit(5,5,20,70,{'DATAX','dtos(DATAX)'})

   return nil

function crea_db

  Local aDbf := {}

  AADD (aDbf,{"Datax"      , "D",  8,0})

  dbcreate( "Test", aDbf, 'DBFCDX' )

  aDbf := {}

  use TEST

  index on descend(dtos(TEST->DATAX)) to TEST

  return Nil

function fill_db

   local x

   for x := 1 to 100

      sele test

      append blank

      replace DATAX with date()+x

   next i

   return Nil

[José Quintas]

I create a alternative Descend for codepage.

FUNCTION CPDescend( cText )
   LOCAL cResult, acAscii := {}, nCont
   STATIC cFrom, cTo
   IF cFrom == NIL .OR. cTo == NIL
      FOR nCont = 1 TO 255
         Aadd( acAscii, Chr( nCont ) )
      NEXT
      ASort( acAscii )
      cFrom := cTo := ""
      FOR nCont = 1 TO 255
         cFrom += acAscii[ nCont ]
         cTo   += acAscii[ 256 - nCont ]
      NEXT
   ENDIF
   cResult := hb_StrReplace( cText, cFrom, cTo )
   RETURN cResult

José M. C. Quintas

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[Przemyslaw Czerpak]

On Tue, 08 Apr 2014, Franz wrote:

Hi,

> Hello,
> I have a dbf index on "descend(dtos(DATAX))".
> It works fine if I don't set codepage, if I set codepage to ITWIN order is
> not correct.

DESCEND() function is designed to operate on binary (BYTE) sorting
and gives reverted collation order only for codepages which use
such collation.

> Why descend is affected by codepage in this case ? dtos return a 10 char
> string with only number.

Because DESCEND() converts numbers to characters which have
special order in CP you are using. Look at this list archive
for some easy to create custom DESCEND() replacements which
can be used with non accented Latin based languages like
Lithuanian or Polish ones.

best regards,
Przemek

[Franz]

Thanks José and Przemek 

I have tryed José function and I found that it works in this condition. I will check other istances in my prg.

Ciao

Franz