dynamic output; changing without reprinting

This is a discussion on dynamic output; changing without reprinting within the C++ Programming forums, part of the General Programming Boards category; My question is regarding what I call "dynamic output". That is to say, printed characters that are able to change ...

  1. #1
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    Post dynamic output; changing without reprinting

    My question is regarding what I call "dynamic output". That is to say, printed characters that are able to change without reprinting. A few examples might help:

    When downloading a file, such as with wget, the printed text changes while remaining 'static'. The progress bar on wget fills up as the file downloads. The printed percentage (eg 75%) also changes as the download progresses. This is done without the console reprinting the entire paragraph every time the percentage increases--this is what I mean by "dynamic".

    I have been able to find no resources on this, most likely because I don't even have an idea of what it's really called. What I would like to know is: firstly, what this is called; secondly, optionally, links or suggestions for resources on this topic.

    I would describe my knowledge of C++ as basic. If you are expected to be able to figure this out on your own with the use of classes, pointers and simpler things, I have come up quite dry. If it requires a greatly more advanced knowledge of C++, I would still appreciate knowing what it is called.

    Thanks!

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    There is no standard way. Ncurses is the most common library for terminal manipulation.

  3. #3
    C++まいる!Cをこわせ!
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    You may want to state the OS for which you are going to program. Since there's no standard C++ way, you may be forced to use some OS API for this.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  4. #4
    'Allo, 'Allo, Allo
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    The simplest way is with the carriage return on *nix and Windows. Don't know exactly if that's exactly how wget does the progress bar, but it seems like it after a quick check.

    Code:
    #include <iostream>
    
    int main()
    {
        for(unsigned times = 1; times; ++times)
        {
            if((times % 1111) == 0)
            {
                std::cout << "\rI've looped " << times << " times";
            }
        }
        std::cout << "Now, onto more useful work";
    }
    It works as long as what you print stays the same length or gets bigger. If it gets smaller, you have to be a bit smarter to erase the characters left from the longer output.

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    Quote Originally Posted by Elysia View Post
    You may want to state the OS for which you are going to program. Since there's no standard C++ way, you may be forced to use some OS API for this.
    I am programming on/for Linux.

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    Quote Originally Posted by frog View Post
    I am programming on/for Linux.
    Then, for starters, if none of the advice in here works, you should

    Code:
    man 3 ncurses

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