如何在純 C/C++ (cout/printf) 中顯示進度指示器？

Question

我正在 C++ 中編寫一個控制台程序來下載一個大文件。 我知道文件大小，我啟動了一個工作線程來下載它。 我想顯示一個進度指示器，讓它看起來更酷。

如何在不同的時間顯示不同的字符串，但在相同的 position、cout 或 printf 中？

Answer 1

使用固定寬度的輸出，使用如下所示的內容：

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 %

請注意，此輸出顯示在一行下方，但在終端模擬器中（我認為也在 Windows 命令行中）它將打印在同一行上。

最后，不要忘記在打印更多內容之前打印換行符。

如果你想刪除最后的欄，你必須用空格覆蓋它，打印更短的東西，例如"Done." .

同樣，當然可以在 C 中使用printf來完成同樣的工作； 修改上面的代碼應該是直截了當的。

Answer 2

您可以使用不帶換行符 (\\n) 的“回車符”(\\r)，並希望您的控制台能做正確的事情。

Answer 3

對於具有可調進度條寬度的C解決方案，您可以使用以下內容：

#define PBSTR "||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||"
#define PBWIDTH 60

void printProgress(double percentage) {
    int val = (int) (percentage * 100);
    int lpad = (int) (percentage * PBWIDTH);
    int rpad = PBWIDTH - lpad;
    printf("\r%3d%% [%.*s%*s]", val, lpad, PBSTR, rpad, "");
    fflush(stdout);
}

它將輸出如下內容：

 75% [||||||||||||||||||||||||||||||||||||||||||               ]

Answer 4

看一下 boost progress_display

http://www.boost.org/doc/libs/1_52_0/libs/timer/doc/original_timer.html#Class%20progress_display

我認為它可以做你需要的，我相信它是一個只有頭文件的庫所以沒有鏈接

Answer 5

您可以打印回車符 ( \\r ) 以將輸出“光標”移回當前行的開頭。

對於更復雜的方法，請查看類似 ncurses（用於基於控制台文本的界面的 API）之類的東西。

Answer 6

我知道我回答這個問題有點晚了，但我做了一個簡單的類，它完全符合你的要求。 （請記住，在此之前我using namespace std;編寫。）：

class pBar {
public:
    void update(double newProgress) {
        currentProgress += newProgress;
        amountOfFiller = (int)((currentProgress / neededProgress)*(double)pBarLength);
    }
    void print() {
        currUpdateVal %= pBarUpdater.length();
        cout << "\r" //Bring cursor to start of line
            << firstPartOfpBar; //Print out first part of pBar
        for (int a = 0; a < amountOfFiller; a++) { //Print out current progress
            cout << pBarFiller;
        }
        cout << pBarUpdater[currUpdateVal];
        for (int b = 0; b < pBarLength - amountOfFiller; b++) { //Print out spaces
            cout << " ";
        }
        cout << lastPartOfpBar //Print out last part of progress bar
            << " (" << (int)(100*(currentProgress/neededProgress)) << "%)" //This just prints out the percent
            << flush;
        currUpdateVal += 1;
    }
    std::string firstPartOfpBar = "[", //Change these at will (that is why I made them public)
        lastPartOfpBar = "]",
        pBarFiller = "|",
        pBarUpdater = "/-\\|";
private:
    int amountOfFiller,
        pBarLength = 50, //I would recommend NOT changing this
        currUpdateVal = 0; //Do not change
    double currentProgress = 0, //Do not change
        neededProgress = 100; //I would recommend NOT changing this
};

關於如何使用的示例：

int main() {
    //Setup:
    pBar bar;
    //Main loop:
    for (int i = 0; i < 100; i++) { //This can be any loop, but I just made this as an example
        //Update pBar:
        bar.update(1); //How much new progress was added (only needed when new progress was added)
        //Print pBar:
        bar.print(); //This should be called more frequently than it is in this demo (you'll have to see what looks best for your program)
        sleep(1);
    }
    cout << endl;
    return 0;
}

注意：我公開了所有類的字符串，以便可以輕松更改欄的外觀。

Answer 7

另一種方法可能是顯示“點”或您想要的任何字符。下面的代碼將在 1 秒后將進度指示器 [排序加載...] 打印為點。

PS：我在這里使用睡眠。 如果關注性能，請三思。

#include<iostream>
using namespace std;
int main()
{
    int count = 0;
    cout << "Will load in 10 Sec " << endl << "Loading ";
    for(count;count < 10; ++count){
        cout << ". " ;
        fflush(stdout);
        sleep(1);
    }
    cout << endl << "Done" <<endl;
    return 0;
}

Answer 8

這是我制作的一個簡單的：

#include <iostream>
#include <windows.h>

using namespace std;

int barl = 20;

int main() {
   system("color 0e");  
   cout << "[";     
   for (int i = 0; i < barl; i++) {         
      Sleep(100);       
      cout << ":";  
   }
   cout << "]";
}

Answer 9

可能是這段代碼會幫助你 -

#include <iostream>
#include <string>
#include <thread>
#include <chrono>
#include <cmath>

using namespace std;

void show_progress_bar(int time, const std::string &message, char symbol)
{
    std::string progress_bar;
    const double progress_level = 1.42;

    std::cout << message << "\n\n";

    for (double percentage = 0; percentage <= 100; percentage += progress_level)
    {
        progress_bar.insert(0, 1, symbol);
        std::cout << "\r [" << std::ceil(percentage) << '%' << "] " << progress_bar;
        std::this_thread::sleep_for(std::chrono::milliseconds(time));       
    }
    std::cout << "\n\n";
}

int main()
{
    show_progress_bar(100, "progress" , '#');
}

Answer 10

很簡單，你可以只使用字符串的填充構造函數：

#include <iostream> //for `cout`
#include <string>   //for the constructor
#include <iomanip>  //for `setprecision`

using namespace std;

int main()
{
    const int cTotalLength = 10;
    float lProgress = 0.3;
    cout << 
        "\r[" <<                                            //'\r' aka carriage return should move printer's cursor back at the beginning of the current line
            string(cTotalLength * lProgress, 'X') <<        //printing filled part
            string(cTotalLength * (1 - lProgress), '-') <<  //printing empty part
        "] " <<
        setprecision(3) << 100 * lProgress << "%";          //printing percentage
    return 0;
}

哪個會打印：

[XXX-------] 30%

如果你需要純 C

並且您希望能夠在運行時自定義大小和填充字符：

#include <stdio.h>  //for `printf`
#include <stdlib.h> //for `malloc`
#include <string.h> //for `memset`

int main()
{
    const int cTotalLength = 10;
    char* lBuffer = malloc((cTotalLength + 1) * sizeof *lBuffer); //array to fit 10 chars + '\0'
    lBuffer[cTotalLength] = '\0'; //terminating it
    
    float lProgress = 0.3;

    int lFilledLength = lProgress * cTotalLength;
    
    memset(lBuffer, 'X', lFilledLength); //filling filled part
    memset(lBuffer + lFilledLength, '-', cTotalLength - lFilledLength); //filling empty part
    printf("\r[%s] %.1f%%", lBuffer, lProgress * 100); //same princip as with the CPP method

    //or you can combine it to a single line if you want to flex ;)
    //printf("\r[%s] %.1f%%", (char*)memset(memset(lBuffer, 'X', lFullLength) + lFullLength, '-', cTotalLength - lFullLength) - lFullLength, lProgress * 100);

    free(lBuffer);

    return 0;
}

但如果您不需要在運行時自定義它：

#include <stdio.h>  //for `printf`
#include <stddef.h> //for `size_t`

int main()
{
    const char cFilled[] = "XXXXXXXXXX";
    const char cEmpty[]  = "----------";
    float lProgress = 0.3;
    
    size_t lFilledStart = (sizeof cFilled - 1) * (1 - lProgress);
    size_t lEmptyStart  = (sizeof cFilled - 1) * lProgress;

    printf("\r[%s%s] %.1f%%",
        cFilled + lFilledStart, //Array of Xs starting at `cTotalLength * (1 - lProgress)` (`cTotalLength * lProgress` characters remaining to EOS)
        cEmpty  + lEmptyStart,  //Array of -s starting at `cTotalLength * lProgress`...
        lProgress * 100 //Percentage
    );

    return 0;
}

Answer 11

我需要創建一個進度條，這里的一些答案會導致進度條在完成時閃爍或顯示低於 100% 的百分比。 這是一個除了模擬 cpu 工作之外沒有循環的版本，它僅在下一個進度單位遞增時打印。

#include <iostream>
#include <iomanip> // for setw, setprecision, setfill
#include <chrono>
#include <thread> // simulate work on cpu

int main()
{
    int batch_size = 4000;
    int num_bars = 50;
    int batch_per_bar = batch_size / num_bars;

    int progress = 0;

    for (int i = 0; i < batch_size; i++) {
        if (i % batch_per_bar == 0) {    
            std::cout << std::setprecision(3) <<
                      // fill bar with = up to current progress
                      '[' << std::setfill('=') << std::setw(progress) << '>'
                      // fill the rest of the bar with spaces
                      << std::setfill(' ') << std::setw(num_bars - progress + 1)
                      // display bar percentage, \r brings it back to the beginning
                      << ']' << std::setw(3) << ((i + 1) * 100 / batch_size) << '%'
                      << "\r";
            progress++;
        }
        
        // simulate work
        std::this_thread::sleep_for(std::chrono::nanoseconds(1000000));
    }
}