Re: reading a text file into a string

["Steve" <nospam_steved94@comcast.net>]

Sorry for the blank reply (obese finger)

The easiest way to read an entire file into a string, if you're looking for
speed, is to
use Ada.Direct_Io;

Here is a small working example:

with Ada.Direct_Io;
with Ada.Text_Io;

procedure Demo is

    function Get_File_Size( file_name : String ) return Natural is
        package Direct_Io_Char_File is new Ada.Direct_IO( Character );
        use Direct_Io_Char_File;
        size_file : File_Type;
        result : Natural;
    begin
        Open( size_file, In_File, file_name );
        result := Natural( Size( size_file ) );
        Close( size_file );
        return result;
    end Get_File_Size;

begin
    declare
        File_Size : Natural := Get_File_Size( "demo.txt" );
        subtype File_String is String( 1 .. File_Size );
        package File_Reader is new Ada.Direct_Io( File_String );
        in_file : File_Reader.File_Type;
        file_data : File_String;
    begin
        File_Reader.Open( in_file, File_Reader.In_File, "demo.txt" );
        File_Reader.Read( in_file, file_data );
        File_Reader.Close( in_file );
        -- Do what you will with file_data
        Ada.Text_Io.Put( file_data );
    end;
end Demo;

The basic idea is to first create an instance of direct_io for characters,
just to use the
"size" function to find out how many characters are in the file.  Then
create an instance
of direct_io for a string of the same length as the file, and do one read.

This gives you the content of the file as one raw string.  Which may or may
not be
what you want, but it is what you asked for.

Steve
(The Duck)

"zork" <zork@nospam.com> wrote in message news:40f6bf21@dnews.tpgi.com.au...
> hi, i would like to read a whole text file into a string. I thought of
using
> an unbounded_string for this:
>
> ----------
> c, char: character;
> text : unbounded_string;
> ...
> -- read in text file
> while not end_of_file ( File ) loop
>     Get ( File, c );
>     append ( text, c );
> end loop;
> ...
> put ( to_string ( text ) ); -- display content of unbounded_string
>
> -- process text
> for i in 1 .. length ( text ) loop
>   char := element ( text, i );
>   ...
> end loop;
> -----------
>
> ... is this the general way of going about it? or is there a more prefered
> method of reading in a whole text file (into whatever format) for
> processing?
>
> Thanks again!
>
> cheers,
> zork
>
>