Subj : Re: Sorting
To   : borland.public.cpp.borlandcpp
From : "Ed Mulroy [TeamB]" <dont_email_me@bitbuc.ket>
Date : Wed Dec 17 2003 01:34 pm

You indicated that you are using BC++ 5.01 but did not mention if you are
writing for DOS, for 16 bit Windows 3.1x or for 32 bit Windows (Win32).

I had to do that a long time ago with a 17 Meg file (supplied on an array of
50, 360K floppy disks!) on a machine that had 128K (not Meg) of memory.  You
do not need a lot of memory to do such a sort.

There was a single file that had a massive amount of strings.  The sorting
went like this:

open the original file

while not end of file on the original file
    create a new temp1 file
    read some strings from the file
    use qsort to sort them
    write them to the temp1 file
    close the original file

while more than one temp file is left

    while there are temp1 files left
        open two temp1 files
        merge their contents into a new temp2 file
        delete the two temp1 files
        close the file that was used as output

    If a temp1 file is left
        open a temp2 file
        merge the contents with the temp2 file
          into a new temp2 file
        delete the temp1 file
        delete the temp2 file that was used as input
        close the file that was used as output

    while more than two temp2 files are left
        open two temp2 files
        merge the contents into a new temp1 file
        delete the temp2 files
        close the file that was used as output

    if a temp2 file is left
        open a temp1 file
        merge the contents with the temp2 file
            into a new temp1 file
        delete the temp2 file
        delete the temp1 file that was used as input
        close the file that was used as output

rename the one remaining temporary file to the output file name

That looks like a lot until you realize that you need only one function to
do the sort and one function which is used for all the merges.  Except for
the user interface, the source code might be less than 6K.

..  Ed

> Nokomis wrote in message
> news:3FE07E01.EDE85954@radiolink.net...
>
> Anyone know an algorithm for sorting large numbers of
> character strings?
>
> Something like a telephone direcctory - too big for a normal
> array. (5.01)

.