Screen Editing

Discussion in 'C Programming' started by someone, Aug 17, 2006.

  1. Which are the ones running a widely-used non-vt100-compatible terminal?
    Thomas Dickey, Aug 18, 2006
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  2. Widely-used? I don't know. But there exists systems where
    you can access the console thru the serial port---I've seen a
    few of those.

    Tak-Shing Chan, Aug 18, 2006
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  3. [/QUOTE]
    A serial port is a data connection (a wire)
    It doesn't present data (a terminal).

    Again, unless it's widely used, it doesn't add to the "most" category.
    Thomas Dickey, Aug 18, 2006
  4. OK. Let me trim it down to just one item: the Sun console.
    It is certainly still in use today, and it does clear the screen
    with '\f'. But you are absolutely right, this has little
    relevance to ``most terminals''. Perhaps I should s/most/some/g.

    Tak-Shing Chan, Aug 18, 2006
  5. The serial driver doesn't, but the console driver does.
    Fair enough.

    Tak-Shing Chan, Aug 18, 2006
  6. yes - "some". As a colleague pointed out to me (quite a while ago),
    as I was modifying a terminal driver to do form-feeds, _printers_
    do form-feeds, terminals are not expected to do this.
    Thomas Dickey, Aug 18, 2006
  7. someone

    Ian Collins Guest

    Getting rather off topic....
    Ian Collins, Aug 18, 2006
  8. Sorry. I should volunterily ban myself from comp.lang.c
    for a month...

    Tak-Shing Chan, Aug 18, 2006
  9. It says that \f (form feed) "moves the active position to the initial
    position at the start of the next logical page."

    I don't see anything there about clearing the screen.

    I think we all know by now that *some* terminals and terminal
    emulators will clear the screen in response to a formfeed characters,
    and some will not. (It happens that most of the ones I use or have
    access to don't. I suspect my experience in this case is typical; I
    certainly don't claim that it's universal.)

    In my opinion, the statement in question 19.4 of the FAQ that clearing
    the display by printing a formfeed character is "halfway portable" is
    incorrect, or at least over-stated.
    Keith Thompson, Aug 18, 2006
  10. I agree with you vis-a-vis '\f', but my reply above was an
    attempt to paint a larger picture---that it is indeed possible to
    ``edit'' something that is already written on the screen, if not
    by '\f', then by '\r' or '\b' on the current line.

    Tak-Shing Chan, Aug 18, 2006
  11. An interesting discussion. But when I go back to what the OP posted
    it has gone a bit off-topic. And to get more off-topic, I have used
    a full-screen editor that worked across half-duplex lines, so it was
    only when you entered a CR that the base system knew what you had been
    doing. (FSE under NOS/VE on CDC Cybers.)
    Dik T. Winter, Aug 18, 2006
  12. (WRT clearing the "screen")
    How about

    int idx, times=1;
    while( 1 ) {
    for( idx=0; idx < times; idx++ ) {
    putchar( '\n' );
    printf( "Was that enough?\n" );
    if( getc(stdin) == 'n' ) {

    ? This way the programmer can decide when the screen is clear enough,
    assuming of course I haven't made any silly mistakes.
    Christopher Benson-Manica, Aug 18, 2006
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