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Pascal - How do you check for EOF when using a keyboard input?

+2 votes
asked Aug 11 by Gary Ohm (450 points)
Pascal - How do you check for EOF when using a keyboard input?

Turbo Pascal you would do three things: 1) Place a USES CRT statement after the program heading. 2) Set CheckEOF to True with an assignment statement at the start of the program 3) Press Ctrl-Z when done entering data.

I tried that but no luck getting the program to respond to Ctrl-Z when done with data entry.

1 Answer

0 votes
answered Aug 12 by Peter Minarik (79,800 points)
selected Aug 14 by Gary Ohm
Best answer
<Ctrl>+<Z> is the Windows EOF signal.

However, OnlineGBD is running on a Unix-based system where the end of file signal is <Ctrl>+<D>. See if that works for you.
commented Aug 14 by Gary Ohm (450 points)
That was a good suggestion but it did not work.
commented Aug 14 by Peter Minarik (79,800 points)
Ok, I spent some time on this. Here's a small code sample that works:

program EOF_Test;
var s: string;
        write('Please, enter some text: ');
        writeln('You entered: ', s);
    until eof;

As soon as you add "uses CRT;" it stops working, and EOF (<Ctrl>+<D>) is not recognized anymore.

So if you can go without "uses CRT;", please, do so. Otherwise, try to search the Internet, why this is the case. I am not a Pascal programmer.
commented Aug 14 by Gary Ohm (450 points)
It turns out I was using a READ statement instead of READLN as in your code. It appears that using the READ statement the reading marker never got past <eoln>. Using the READLN put the reading marker past <eoln> and then was able to read the <eof> keyboard entry (Ctl-D). The USES command looks to be for the PC based program only where the PC needed to get info from a CRT library. OnlineGBD does not have that problem. Thanks for you comments.
commented Aug 14 by Gary Ohm (450 points)
edited Aug 14 by Gary Ohm
(* This program shows how to read data until the *)
(* EOF (Ctrl-D) is typed into the keyboard.               *)

Program UsingKeyboard_EOF;

  Sysin : Integer;
  Writeln('Enter data. When done enter Ctrl-D on the keyboard to stop program');
  while not eof do
      while not eoln do
          Write(Sysin, ' ');
      Writeln('End of eoln loop');  { For info only. Status of read data loop }
      Readln;                                        { Set read marker to start of next line    }
  Writeln('eof reached');
commented Aug 14 by Peter Minarik (79,800 points)
I'm glad you're sorted. The last time I spent regular time with Pascal was more than 20 years ago, lol.

Keep on coding!
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