How to display a progress indicator in pure C/C++ (cout/printf)?

c, c++, c++11, io, user-interface

Solution

With a fixed width of your output, use something like the following:

float progress = 0.0;
while (progress < 1.0) {
    int barWidth = 70;

    std::cout << "[";
    int pos = barWidth * progress;
    for (int i = 0; i < barWidth; ++i) {
        if (i < pos) std::cout << "=";
        else if (i == pos) std::cout << ">";
        else std::cout << " ";
    }
    std::cout << "] " << int(progress * 100.0) << " %\r";
    std::cout.flush();

    progress += 0.16; // for demonstration only
}
std::cout << std::endl;

http://ideone.com/Yg8NKj

[>                                                                     ] 0 %
[===========>                                                          ] 15 %
[======================>                                               ] 31 %
[=================================>                                    ] 47 %
[============================================>                         ] 63 %
[========================================================>             ] 80 %
[===================================================================>  ] 96 %

Note that this output is shown one line below each other, but in a terminal emulator (I think also in Windows command line) it will be printed on the same line.

At the very end, don't forget to print a newline before printing more stuff.

If you want to remove the bar at the end, you have to overwrite it with spaces, to print something shorter like for example `"Done."`.

Also, the same can of course be done using `printf` in C; adapting the code above should be straight-forward.

Problem

I'm writing a console program in C++ to download a large file. I know the file size, and I start a work thread to download it. I want to show a progress indicator to make it look cooler. How can I display different strings at different times, but at the same position, in cout or printf?

Original source

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