End of a file

End of a file

[comicfanzine]

When the program is launched , it count a excess line .

And that's not a editor problem , the result is the same with severals .

So , there is 30 lines in this source code file .
However , the program count 31 .

Why ?


WITH Ada.Text_IO ;  USE Ada.Text_IO ;

Procedure count_nb_lines is

  this_file : File_type ;

  Last_line : Positive_Count := 1 ;

Begin

    Open
     (File => this_file ,
      Mode => In_file ,
      Name => "count_nb_lines.adb");

   loop
     set_line( this_file , Last_line );

     Last_line := Last_line + 1 ;
   end loop ;

    exception
      when End_Error => null;

   put_line ( "End of this file ? : "&Boolean'image( End_Of_File( this_file ) )  );
   put ( "Total of lines by Ada.Text_IO' s package : "&Positive_Count'Image( Last_line ) );

   Close( this_file );

end count_nb_lines ;

Re: End of a file

[J-P. Rosen]

Le 19/01/2016 06:11, comicfanzine@gmail.com a écrit :
> When the program is launched , it count a excess line .
> 
> And that's not a editor problem , the result is the same with severals .
> 
> So , there is 30 lines in this source code file .
> However , the program count 31 .
> 
> Why ?
> 
If you have 30 lines, set_line (30) is OK. It's set_Line (31) that
raises End_Error...


-- 
J-P. Rosen
Adalog
2 rue du Docteur Lombard, 92441 Issy-les-Moulineaux CEDEX
Tel: +33 1 45 29 21 52, Fax: +33 1 45 29 25 00
http://www.adalog.fr

Re: End of a file

[comicfanzine]

>If you have 30 lines, set_line (30) is OK. It's >set_Line (31) that raises End_Error... 

Ok , then why it's the case here :
" raised ADA.IO_EXCEPTIONS.END_ERROR : a-textio.adb:1900 "

There is only 26 lines , and the loop is suppose to stop at the end of the file . 

WITH Ada.Text_IO ;  USE Ada.Text_IO ;

Procedure count_nb_lines is

  this_file : File_type ;

  Last_line : Positive_Count := 1 ;

Begin

    Open
     (File => this_file ,
      Mode => In_file ,
      Name => "count_nb_lines.adb");

   loop exit when End_Of_File( this_file );
     skip_line( this_file , Last_line );

     Last_line := Last_line + 1 ;
   end loop ;

   put ( "Total of lines by Ada.Text_IO' s package : "&Positive_Count'Image( Last_line ) );

   Close( this_file );

end count_nb_lines ;

Re: End of a file

[Georg Bauhaus]

On 19.01.16 08:20, comicfanzine@gmail.com wrote:
>       skip_line( this_file , Last_line );

How many lines do you wish this call to skip on
each iteration?

-- 
"HOTDOGS ARE NOT BOOKMARKS"
Springfield Elementary teaching staff

Re: End of a file

[comicfanzine]

>How many lines do you wish this call to skip on
>each iteration? 

Edit : Sorry , i posted the wrong code .

It just doesn't make sense , why the program create a extra line ?

The rignt number is 25 lines .

But it print 26 .

WITH Ada.Text_IO ;  USE Ada.Text_IO ;

Procedure count_nb_lines is

  this_file : File_type ;

  count : Positive_Count := 1 ;

Begin

    Open
     (File => this_file ,
      Mode => In_file ,
      Name => "count_nb_lines.adb");

   loop exit when End_Of_File( this_file );
     skip_line( this_file );
     count := count + 1 ;
   end loop ;

   put ( "Total of lines by Ada.Text_IO' s package : "&Positive_Count'Image( count ) );

   Close( this_file );

end count_nb_lines ;

Re: End of a file

[MM]

On Tuesday, 19 January 2016 08:43:09 UTC, comicf...@gmail.com  wrote:
>   count : Positive_Count := 1 ;

Initialise this to zero, not one. Before you have read any lines, the count is zero.

M
-- 

Re: End of a file

[comicfanzine]

MM ,

You're right , it work now .