OpenEuphoria

dictionary binary access

• Posted by Carlos Valdis <cvaldes at NCS.COM> Apr 21, 1998
• 781 views

Some 2 weeks ago there was a discussion on if it was possible to do a
binary access to the dictionary file containing variable length records
(words). Yes, it is possible using some little trick. I am sending the
code sample. It can be posted in the archives if it is considered useful
(if not optimum, for sure).

Carlos Valdes <cvaldes at ncs.com>
Mexico

-- This program adds a first register to the words.txt file
--(why? see next binary access program) and copies the rest
-- You need to rename the output file, again to words.txt
include file.e
include graphics.e
object s
atom f1,f2
--back_color(blue)
f1=open("words.txt","r")
f2=open("words.tyt","w")
    puts(f2,"AAAAAAAAAA\n")
while 1 do
    s=gets(f1)
    if atom(s) then
 exit
    end if
    puts(f2,s)
end while
puts(1,"END of file,FIN de archivo\n")
close(f1)
close(f2)


-- This is the program to do the binary search into the dictionary
--It calculates a new position, reads only part of the register where it
is positioned
--so you need to do a second access to get the whole next register.

include get.e
include sort.e
include file.e
include wildcard.e

integer up,dn,md,tr,f1,x,cc
object ret,da,db,dc
da={}
db={}
dc={}
f1=open("words.txt","r")
while 1 do
    dn=1
    ret=seek(f1,-1)
    if ret!=0 then
 abort(1)
    end if
    up=where(f1)
    md=floor((up-dn)/2)
    tr=0
    puts(1,"\nkey-in word:")
    da=gets(0)
    if length(da)<2 then
 exit
    else
 da=upper(da[1..length(da)-1])
    end if
    while 1 do
 printf(1,"\ndn=%d,md=%d,up=%d\n",{dn,md,up})
 ret=seek(f1,md)
 if ret!=0 then
     exit
 end if
 db=gets(f1)
 db=gets(f1)
 db=db[1..length(db)-1]
 if atom(db) then
     exit
 end if
 x=compare(db,da)
 puts(1,da & ' ')
 puts(1,db & '\n')
 tr=tr+1
 if x=0 then
     printf(1,"found in %d trials",tr)
     exit
 elsif x>0 then
     up=md
 elsif x<0 then
     dn=md
 end if
 x=compare(db,dc)
 if x=0 then
     printf(1,"not found in %d trials",tr)
     dc={}
     ret=seek(f1,1)
     while 1 do
  db=gets(f1)
  if atom(db) then
      exit
  else
      db=db[1..length(db)-1]
      x=compare(db,da)
      if x=0 then
   puts(1,"but it is there.......")
      elsif x>0 then
   puts(1,'\n' & dc & '-' & db & '\n')
   exit
      end if
  end if
  dc=db
     end while
     exit
 end if
 dc=db
 md=floor((up+dn)/2)
    end while
end while
close(f1)
cc=wait_key()