OpenEuphoria

Re: How do I open, read and print files?

• Posted by Derek Parnell <ddparnell at bigpond.com> Jun 22, 2007
• 496 views

Dave Bunch wrote:
> 
> I can't seem to find basic examples of how one goes about opening, 
> selecting lines of text from, and then either displaying the lines 
> and/or printing them to a new file. Any suggestions about where 
> this info is found in the documentation and/or examples would be 
> greatly appreciated.
> 

You need to know about the open(), gets() and puts() routines.

Here is an annotated example:

-- This routine copies the lines from 'FileIn' to 'FileOut'.
-- 'FileIn' must exist.
-- 'FileOut' is created if doesn't exist and replaced if it does exist.
procedure CopyFile(sequence pFileIn, sequence pFileOut)
    integer lInHandle       -- File Handle for input file
    integer lOutHandle      -- File Handle for output file
    object lLine            -- Current line read/written

    -- Open the input file and check that it exists.
    lInHandle = open(pFileIn, "r")  -- "r" means open for text reading.
    if lInHandle = -1 then
        -- N.B. A handle of 1 is always the output one for the console.
        puts(1, "Could not open '" & pFileIn & "'\n")
        abort(1) -- Cancel the program.
    end if

    -- Open the output file and check that it got re/created.
    lOutHandle = open(pFileOut, "w")
    if lOutHandle = -1 then
        close(lInHandle)    -- remembe to close input
        puts(1, "Could not create '" & pFileOut & "'\n")
        abort(1)
    end if


    lLine = gets(lInHandle)     -- Get first line of text (if any)
                                -- If 'gets' returns an atom it means
                                -- that it has reached end-of-file.
    while sequence(lLine) do
        -- copy the line out
        puts(lOutHandle, lLine)
        -- get the next line
        lLine = gets(lInHandle)
    end while

    -- Close both files.
    close(lOutHandle)
    close(lInHandle)
end procedure


procedure main(sequence pArgs)
    -- Validate the command line arguments.
    if length(pArgs) < 4 then
        puts(1, "Usage: <filein> <fileout>\n")
        abort(1)
    end if

    -- The third arguement is the name of the input file.
    -- The fourth arguement is the name of the output file.
    CopyFile(pArgs[3], pArgs[4])

end procedure

-- Start running the program, passing it the command line parameters.
main(command_line())

-- 
Derek Parnell
Melbourne, Australia
Skype name: derek.j.parnell