基于输入文件内容的数组比较的大小

Question

因此，我一直在做一个实验室作业，其中涉及使用数组和从输入文件读取。 输入验证之一需要数组比较的大小。 在此特定作业中，我尝试使用if语句打印出无效/错误消息，并且条件是，如果文件中的学生答案数量与其他文件中的正确答案数量不同，它将打印出错误信息。 我尝试使用sizeof数组函数，但是没有用。 这是我的作业代码：

#include <iostream>
#include <iomanip>
#include <string>
#include <fstream>

using namespace std;

int readAnswers(string answerFile, char ansArray[]);
void displayAnswers(int maxSpace, char testAnswers[], char studentAnswers[]);

int main()
{
   const int maxSpace = 20;
   char testAnswers[maxSpace];
   char studentAnswers[maxSpace];
   string stuansFile, correctansFile;
   ifstream inputFile;

   cout << "Enter student answers file name" << endl;
   cin >> stuansFile;
   cout << "Enter correct answers file name" << endl;
   cin >> correctansFile;
   if(readAnswers(stuansFile, studentAnswers) != -1)
   {
      if(readAnswers(correctansFile, testAnswers) != -1)
      {
         if (sizeof(studentAnswers) != sizeof(testAnswers))
         {
            cout << "The student answers file has " << sizeof(studentAnswers) << " entries and the correct answers file has " << sizeof(testAnswers) << endl;
            cout << "Grading cannot be done if they are not the same" << endl;
         }
         else if(sizeof(studentAnswers) == 0 && sizeof(testAnswers) == 0)
         {
            cout << "The number of student answers and correct answers are both 0" << endl;
            cout << "No grade can be calculated" << endl;
         }
         else
         {
            displayAnswers(maxSpace, testAnswers, studentAnswers);
         }
      }
      else
      {

      }
   }
   else
   {
      cout << "Error. File and arrays cannot be read." << endl;
   }
   return 0;
}

int readAnswers(string answerFile, char ansArray[])
{
   ifstream inputFile;
   inputFile.open(answerFile);
   char inAnswer;
   int i = 0;

   if(inputFile.fail())
   {
      cout << "File \"" << answerFile << "\" could not be opened" << endl;
      return -1;
   }

   while (inputFile >> inAnswer)
   {
      ansArray[i] = inAnswer;
      i++;

      if(i == 30)
      {
         return 30;
      }
   }
   inputFile.close();
   return i;
}

void displayAnswers(int maxSpace, char testAnswers[], char studentAnswers[])
{
   int j = 0;
   double gradePercent;
   for(int i = 0; i < maxSpace; i++)
   {
      if(studentAnswers[i] != testAnswers[i])
      {
         cout << "Question " << i+1 << " has incorrect answer '" << studentAnswers[i] << "', the correct answer is '" << testAnswers[i] << "'" << endl;
      }
      else
      {
         j++;
      }
   }

   cout << maxSpace - j << " questions were missed out of " << maxSpace << endl;
   gradePercent = ((double)j/maxSpace)*100;
   cout << "The student grade is " << gradePercent << "%." << endl;
   if (gradePercent >= 70)
   {
      cout << "The student passed" << endl;
   }
   else
   {
      cout << "The student failed" << endl;
   }

}