Updating one part of the output (C++ / Cout)

[last2kn0]

I was just wondering how some programs update certain parts of the terminal output.... Like when showing the percentage done. Its hard to explain...

Like if the output was this:

Percentage: [number]

Percentage: [number]

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Where [number] was continuously updated.

How is that done?

Thanks

[daracne]

This code will do what you're asking for, however, I have only tested it in windows. Its behavior may be different under linux/mac.

#include <iostream>
using std::iostream;
 
int main()
{
    for (int i=0; i < 5; i++)
        cout << "Progress: " << i*25 << "%\r";
 
     return 0;
}

#include <iostream>
using std::iostream;

int main()
{
    for (int i=0; i < 5; i++)
        cout << "Progress: " << i*25 << "%\r";

     return 0;
}

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[wysota]

Shouldn't it be:

cout << "\rProgress: " << i*25 << "%";

cout << "\rProgress: " << i*25 << "%";

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?

I guess the difference is minimal... Oh, and don't forget to flush the output or you'll see nothing.

[Michiel]

For completions sake:

#include <iostream>
using namespace std;
 
int main() {
        for (uint i = 0; i <= 100; ++i) {
                cout << "\rProgress: " << i << "%" << flush;
                for (uint j = 0; j < 9999999; ++j); // pause
        }
 
        cout << endl;
 
        return 0;
}

#include <iostream>
using namespace std;

int main() {
        for (uint i = 0; i <= 100; ++i) {
                cout << "\rProgress: " << i << "%" << flush;
                for (uint j = 0; j < 9999999; ++j); // pause
        }

        cout << endl;

        return 0;
}

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\r means carriage return. Without a \n, it just takes the cursor back to the beginning of the current line. flush flushes the buffer.

[last2kn0]

Alright, thanks all.... Its nice to fill in one of those little gaps of knowledge.