Thread: How to terminate program when EOF or pressing CRTL-D(linux)?

  1. #1
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    Apr 2005

    How to terminate program when EOF or pressing CRTL-D(linux)?

    The problem form
    How to terminate it when EOF or pressing CRTL-D?

  2. #2
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    Nov 2006
    If you think about it, what you enter can't be -1, because ``-1'' is two characters, and getchar is reading one character at a time. It turns out that the value of EOF as seen within your C program has essentially nothing to do with the keystroke combination you might use to signal end-of-file from the keyboard. EOF is essentially a signal to your program that no more characters will be available from that input, for whatever reason (end of a disk file, user is done typing, network stream has closed, I/O error, etc.).

    Depending on your operating system, you indicate end-of-file from the keyboard using various keystroke combinations, usually either control-D or control-Z. The operating system and stdio library then arrange that your C program receive the EOF value. (Note, however, that there are various translations involved along the way. Under normal circumstances, you should not explicitly check for the control-D or control-Z value yourself, nor will you find that the <stdio.h> macro EOF is defined to be either of these values.)

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  3. #3
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    Apr 2005
    thank KoG.
    If I want to do this
    This is testing text.
    I will press CTRL-D to end of input. [CTRL-D]
    How do I read it?

  4. #4
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    Nov 2006
    Ctrl+D sends EOF to the program. so test for EOF

  5. #5
    and the hat of int overfl Salem's Avatar
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    Aug 2001
    The edge of the known universe
    while ( fgets( buff, sizeof buff, stdin ) != NULL )
    This exits when you enter the EOF sequence.

    As does this
    while ( (ch=getchar()) != EOF )
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  6. #6
    Join Date
    Nov 2003
    ctrl-d is normally defined by stty program on login as meaning EOF - so the effect of particular keystroke(s) is defined on a per-user level.

    A lot of Linux/UNIX command line utilities honor EOF - ones like bc for example.

    Anyway, unless you are guaranteed that ctrl-d does generate EOF, don't put something in your menu that says "enter ctrl-D to exit".

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