C++ 項目中的指針/引用

Question

我只學習了幾個月的 C++。 我們有一個關於指針/引用的項目。 這是我提交的下面的代碼。 但是，我的老師說我的代碼中沒有包含指針/引用。 我確信我在第 31-42 行做了。 我在理解指針時遇到問題。 請就我應該做的不同之處提供反饋。

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
using namespace std;

int main()

{
  //Opening File
  ifstream cafefile;
  cafefile.open("cafeteria.txt");

  //Check for errors
  if (!cafefile)
  {
      cout << "cafeteria.txt did not open properly" << endl;
      exit(9999);
  }

//String & char 
  string choice;
  string array[4][3];
  char out;

  //Pointers to the food 
  string food[] { "Cheese Pizza", "Hamburger", "Fish Sticks", "Mystery Meat" };
  string *foodptr {food};

  //Set yes & no to 4 array 
  int yes[4]{ 0 };
  int no[4]{ 0 };

  //pointer for integer Yes / NO 
  int* yesptr{ yes };
  int* noptr{ no };


  //Counters of Likes & Dislikes set = 0 
  int like = {0};
  int dislike = {0};


  for (int i = 0; i < 4; i++)

  {
      //Reopen the file
      ifstream file("cafeteria.txt");

      while (getline(file, choice))

      {

          istringstream pick(choice); //istringstream is input stream class, which operates on string

          getline(pick, choice, '\t');
          if (foodptr[i] == choice)

          {

              pick >> choice;
              if (choice == "Y")

                  like++;     //increment

              else if (choice == "N")

                  dislike++;  //increment

          }
      }

      //Setting the yes = like 

      yesptr[i] = like;
      noptr[i] = dislike;

      //Set to 0
      like = 0;
      dislike = 0;
  }

  for (int m = 0; m < 4; m++)

  {
      array[m][0] = foodptr[m];
  }

  for (int j = 0; j < 4; j++)

  {
      array[j][1] = to_string(yesptr[j]);
  }

  for (int i = 0; i < 4; i++)

  {
      array[i][2] = to_string(noptr[i]);
  }

  //Display of the Program
  cout << "School Cafeteria Survey!" << endl; 
  cout << endl; 
  cout << "Food Item" << "\t" << "Like" << "\t" << "Dislike" << endl; //Gives the tab space Horizontally in your output 

  for (int i = 0; i < 4; i++)
  {
      for (int j = 0; j < 3; j++)
      {
          cout << array[i][j] << "\t";
      }
      cout << endl;
  }

  //Background color, making it unique
  system("color 6");

  //Exit the Prgram
  cout << endl; 
  cout << "Please enter 'E' to exit!";
  cin >> out; 
  if (out == 'e' || out == 'E')
  {
      exit(0);
  }

  system("pause");    //pause the program

  return 0;

}

請提供有關我應該解決的問題的解決方案。

Answer 1

如果您動態創建數組會更好，即使用指針動態創建二維數組

string **array;
array = new int *[4];
for(int i=0; i<4; i++){
    array[i] = new int[3];
}

除此之外，您的老師一定希望您不使用索引訪問這些數組，而是使用指針和引用。 這意味着您不應該使用yesptr[i]訪問數組，而應該使用*(ysptr + i) 。 因此，例如，如果您處於循環中，請執行以下操作

for (int m = 0; m < 4; m++)
{
    *(*(array+m)+0) = *(foodptr+m);
}