c++ -\r 和\n 或缓冲区刷新问题

Question

我在多个地方读到\n 在使用时不会刷新缓冲区，但是在我的代码中，我将在这个问题的末尾添加，它似乎就是这样做的，或者至少看起来是这样的输出(由于我执行 couts 的方式，可能在后台发生了其他事情？)。

预期输出:

Mining Laser 1 cycle will complete in x seconds...

Mining Laser 2 cycle will complete in x seconds...

Mining Laser 3 cycle will complete in x seconds...

Mining Laser 4 cycle will complete in x seconds...

我在 CLI 中得到的结果:

Mining Laser 1 cycle will complete in x seconds...

Mining Laser 2 cycle will complete in x seconds...

Mining Laser 3 cycle will complete in x seconds...

Mining Laser 4 cycle will complete in x seconds...

Mining Laser 1 cycle will complete in x seconds...

Mining Laser 2 cycle will complete in x seconds...

Mining Laser 3 cycle will complete in x seconds...

Mining Laser 4 cycle will complete in x seconds...

Mining Laser 1 cycle will complete in x seconds...

Mining Laser 2 cycle will complete in x seconds...

Mining Laser 3 cycle will complete in x seconds...

Mining Laser 4 cycle will complete in x seconds...

我希望输出保持原样，就像预期输出示例中的输出一样，并且在我的代码中每次执行时间循环时更新自身。

这是我的代码:

#include <iostream>
#include <Windows.h>
#include <string>
#include <vector>
#include <random>
#include <thread>
#include <future>

using namespace std; //Tacky, but good enough fo a poc D:

class mLaser
{
public:
    mLaser(int clen, float mamt, int time_left)
    {
        mlCLen = clen;
        mlMAmt = mamt;
        mCTime_left = time_left;
    }

    int getCLen()
    {
        return mlCLen;
    }

    float getMAmt()
    {
        return mlMAmt;
    }

    void setMCOld(int old)
    {
        mCTime_old = old;
    }

    void mCycle()
    {
        int mCTime_new = GetTickCount(); //Get current tick count for comparison to mCOld_time

        if (mCTime_old != ((mCTime_new + 500) / 1000)) //Do calculations to see if time has passed since mCTime_old was set
        {
            //If it has then update mCTime_old and remove one second from mCTime_left.
            mCTime_old = ((mCTime_new + 500) / 1000);
            mCTime_left -= 1000;
        }

        cur_time = mCTime_left; 
    }

    int getCTime()
    {
        return cur_time;
    }

    int getCTLeft()
    {
        return mCTime_left;
    }


private:
    int mlCLen; //Time of a complete mining cycle
    float mlMAmt; //Amoung of ore produced by one mining cycle (not used yet)
    int cur_time; //The current time remaining in the current mining cycle; will be removing this as it is just a copy of mCTime_left that I was going to use for another possiblity to make this code work
    int mCTime_left; //The current time remaining in the current mining cycle
    int mCTime_old; //The last time that mCycle was called
};

void sMCycle(mLaser& ml, int i1, thread& _thread); //Start a mining cycle thread

//Some global defines
random_device rd;
mt19937 gen(rd());

uniform_int_distribution<> laser(1, 3); //A random range for the number of mlaser entities to use
uniform_int_distribution<> cLRand(30, 90); //A random time range in seconds of mining cycle lengths
uniform_real_distribution<float> mARand(34.0f, 154.3f); //A random float range of the amount of ore produced by one mining cycle (not used yet)

int main()
{
    //Init some variables for later use
    vector<mLaser> mlasers; //Vector to hold mlaser objects
    vector<thread> mthreads; //Vector to hold threads
    vector<shared_future<int>> futr; //Vector to hold shared_futures (not used yet, might not be used if I can get the code working like this)

    int lasers; //Number of lasers to create
    int cycle_time; //Mining cycle time
    int active_miners = 0; //Number of active mining cycle threads (one for each laser)
    float mining_amount; //Amount of ore produced by one mining cycle (not used yet)

    lasers = laser(gen); //Get a random number
    active_miners = lasers; //Set this to that random number for the while loop later on

    //Create the mlaser objects and push them into the mlasers vector
    for (int i = 0; i < lasers; i++)
    {
        int clength = cLRand(gen);

        mlasers.push_back(mLaser(clength, mARand(gen), (clength * 1000)));
        
        //Also push thread obects into mthreads for each laser object
        mthreads.push_back(thread());
    }

    //Setup data for mining cycles
    for (int i = 0; i < mlasers.size(); i++)
    {
        int mCTime_start = GetTickCount(); //Get cycle start time
        mlasers.at(i).setMCOld(((mCTime_start + 500) / 1000));
    }

    //Print initial display for mining cycles
    for (int i = 0; i < mlasers.size(); i++)
    {
        cout << "Mining Laser " << i+1 << " cycle will complete in " << (mlasers.at(i).getCTLeft() + 500) / 1000 << " seconds...\n";
    }

    while (active_miners > 0)
    {   
        for (int i = 0; i < mlasers.size(); i++)
        {
            //futr.push_back(async(launch::async, [mlasers, i, &mthreads]{return sMCycle(mlasers.at(i), i + 1, mthreads.at(i)); }));
            async(launch::async, [&mlasers, i, &mthreads]{return sMCycle(mlasers.at(i), i + 1, mthreads.at(i)); }); //Launch a thread for the current mlaser object
            //mthreads.at(i) = thread(bind(&mLaser::mCycle, ref(mlasers.at(i)), mlasers.at(i).getCLen(), mlasers.at(i).getMAmt()));
        }

        //Output information from loops
        cout << " \r" << flush; //Return cursor to start of line and flush the buffer for the next info

        for (int i = 0; i < mlasers.size(); i++)
        {
            if ((mlasers.at(i).getCTLeft() != 0) //If mining cycle is not completed
            {
                cout << "Mining Laser " << i + 1 << " cycle will complete in " << (mlasers.at(i).getCTLeft() + 500) / 1000 << " seconds...\n";
            }

            else //If it is completed
            {
                cout << "Mining Laser " << i + 1 << " has completed its mining cycle!\n";
                active_miners -= 1;
            }
        }
    }

    
    /*for (int i = 0; i < mthreads.size(); i++)
    {
        mthreads.at(i).join();
    }*/


    //string temp = futr.get();
    //float out = strtof(temp.c_str(),NULL);

    //cout << out << endl;

    system("Pause");
    return 0;
}

void sMCycle(mLaser& ml, int i1,thread& _thread)
{
    //Start thread
    _thread = thread(bind(&mLaser::mCycle, ref(ml)));
    
    //Join the thread
    _thread.join();
}

根据 Ben Voigt 的说法，\r 似乎不能按照我尝试使用它的方式使用。除了 Matthew 每次更新关闭命令窗口的建议之外，还有其他建议吗？也许是 Boost 中的某些东西或 c++11 的新东西？

谢谢。

Answer 1

您可以尝试在每次执行后清空控制台像 system("cls");这是一个帖子的链接[ How can I clear console