如何让用户输入的单词退出循环？

Question

我正在开发一个程序，系统会提示用户输入参加比赛的参赛者的姓名和评委的分数。所有这些都在一个带有计数器的 for 循环中，以跟踪参赛者的数量。由于参赛者人数未知，用户应该输入 'Done' 退出循环。

我发现退出循环的所有方法都是使用布尔值，它不适用于 'string' 变量。我想知道是否有办法通过输入单词 'Done'

来退出循环

#include <iostream>
#include <string>   //for name entry of contestants
#include <iomanip>  //rounding and point perceision
#include <fstream>  //write names and averages to a file for storage

using namespace std;

double calcAvgScore(int, int, int, int, int);   //calculates the average after the highest and lowest scores are found 
double findHighest(int, int, int, int, int);    //finds the highest of the 5 scores 
double findLowest(int, int, int, int, int);     //finds the lowest of the 5 scores

int main()
{
    string cName;   //name of the contestant
    int jScore1, jScore2, jScore3, jScore4, jScore5;    //scores of each judge
    double AvgScore;    //average of the scores
    ofstream outFile;

    outFile.open("NamesAndAverage.txt");

    for (int count = 1;; count++)
    {
        if (count = 1)
            cout << "Please enter the name of Contestant #" << count << ". If there are no Contestants enter ""Done""";
        else
            cout << "Please enter the name of Contestant #" << count << ". If there are no more Contestants please enter ""Done""";
        cin >> cName;
    }
}

Answer 1

您可以 break 脱离循环：

for (int count = 1;; count++)
{
    // prompt for input, snipped
    cin >> cName;
    if (cName == "Done") 
    {
        break;
    }
}

Answer 2

您可以使用 break;:

if (cName == "Done") {
    break;
}

此外，您的程序中还有一个错字。有

if (count = 1)

你实际上每次都将 count 重置为 1。这应该是：

if (count == 1)

Answer 3

您可以将条件直接添加到循环中，

for (int count = 1; cName != "Done"; count++)

或在循环中使用 if 和 break。

if( cName == "Done" )
     break;

您还可以在循环内容中使用三元：

cout << "Please enter the name of Contestant #" << count << ". If there are no" << (count > 1) ? "more" : "" << "Contestants enter ""Done"";
cin >> cName;

Answer 4

除了处理 "Done"，您还应该检查输入和输出操作是否成功，两者都可以通过 if/else 语句完成：

if (std::ofstream outFile("NamesAndAverage.txt"))
    for (int count = 1;; count++)
    {
        cout << "Please enter the name of Contestant #" << count << "."
                "If there are no ";
        if (count > 1) std::cout << "more ";
        std::cout << "contestants enter \"Done\"\n";
        if (cin >> cName && cName != "Done")
            // use cName...
        else
            break;
     }
else
     std::cerr << "unable to open output file\n";

如何让用户输入的单词退出循环？

How to get a word entered by the user to exit a loop?

c++

loops

for-loop

exit

break