c++ - 满足中断条件后继续循环

Question

我目前的作业要求我允许用户传递字符串，并将罗马数字转换为十进制值。我遇到了一个问题，当随机单词通过程序时，它必须返回最长的有效前缀，而忽略其余字符。我的代码通过while循环运行，一旦达到中断条件，它将再次为其余字符重复代码。我不确定下一步应该采取什么步骤来修复此代码以正确输出。下图显示了通过代码传递的字符。
Image of test failure

#include <iostream>
#include <ctype.h>

using namespace std;
int
main (){
   while (!cin.eof ()){
    char inputChar;
    int result = 0;
    while (cin.get (inputChar))
    {
        inputChar = toupper (inputChar);
        if (inputChar == 'M')
            result = result + 1000;
        else if (inputChar == 'D')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M')
            {
                result = result - 500;
                continue;
            }
            else if (inputChar == 'D'){
                result = result;
                continue;
            }
            else
            {
                result = result + 500;
                continue;
            }
        }
        else if (inputChar == 'C')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D')
            {
                result = result - 100;
                continue;
            }
            else
            {
                result = result + 100;
                continue;
            }
        }
        else if (inputChar == 'L')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D' || inputChar == 'C')
            {
                result = result - 50;
                continue;
            }
            else
            {
                result = result + 50;
                continue;
            }
        }
        else if (inputChar == 'X')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D' || inputChar == 'C'
                || inputChar == 'L')
            {
                result = result - 10;
                continue;
            }
            else
            {
                result = result + 10;
                continue;
            }
        }
        else if (inputChar == 'V')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D' || inputChar == 'C'
                || inputChar == 'L' || inputChar == 'X')
            {
                result = result - 5;
                continue;
            }
            else
            {
                result = result + 5;
                continue;
            }
        }
        else if (inputChar == 'I')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D' || inputChar == 'C'
                || inputChar == 'L' || inputChar == 'X' || inputChar == 'V')
            {
                result = result - 1;
                continue;
            }
            else
            {
                result = result + 1;
                continue;
            }
        }
        else{
            break;
        }
    }
    if (result != 0)
    {
        cout << result << endl;
    }
}
return 0;
}

Answer 1

您的break语句不会同时出现在两个while循环中。它只打破内部循环，而不打破外部循环。您可以使用标志告诉外循环不要继续:

int main() 
{
   bool exit_loop = false; // define a flag here
   while (!cin.eof()) {
      char inputChar;
      int result = 0;
      if (exit_loop) // check the flag here
         break;
      while (cin.get(inputChar))
      {

并在将单位设置为true时:

 }
 else 
 {
    exit_loop = true; // set the flag here
    break;
 }