带向量的C++魔术8球

Question

我正在尝试将最初使用数组的Magic8Ball程序转换为一个使用向量的程序。给我的任务是把下面的代码带到下面，并对它做一些事情。

• 使用push_back()函数初始化向量
• 修改getAnswer()函数的签名和原型
• 修改getAnswer()函数正文中的代码
• 删除任何不需要的代码，如答案数量的常量。

    #include <iostream>
    #include <string>
    #include <iomanip>
    #include <string>
    #include <stdio.h>
    #include <fstream>
    #include <stdio.h>


    using namespace std;

    string getAnswer();


    const string exitString = "x";
    const int SIZEOF_ANSWERS = 8;
    string magicEightBallAnswers[SIZEOF_ANSWERS] = { "Yes", "No", "Maybe", "It's not certain", "The outlook is good",
                                                     "The outlook is poor", "Time will tell", "Most likely" };



    int main(int argc, char *argv[])
    {
        bool keepGoing = true;

        while (keepGoing)
        {
            string question;

            //prompt for and get the question
            cout << "What is your question?  (Enter 'x' to exit)" << endl;
            getline(cin, question);

            //this assumes that the user enters a lower case x
            if (question.compare(exitString) == 0)
                keepGoing = false;
            else
            {
                cout << getAnswer() << endl;
            }   
        }

        return 0;
    }


    string getAnswer()
    {
        int index = rand() % SIZEOF_ANSWERS;
        return magicEightBallAnswers[index];
    }

Answer 1

这个例子可能会有所帮助：

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>

using namespace std;

string getAnswer(vector<string> &  magicEightBallAnswers)
{
  int i = rand() % magicEightBallAnswers.size();
  return magicEightBallAnswers[i];
}

int main()
{
  vector<string> magicEightBallAnswers {
    "Yes",
    "No",
    "Maybe",
    "It's not certain",
    "The outlook is good",
    "The outlook is poor",
    "Time will tell",
    "Most likely"
  };

  // Initialize rand()
  srand(time(NULL));

  string question;
  while (true) {
    // Prompt for and get the question
    cout << "What is your question?  (Enter 'x' to exit)" << endl;
    getline(cin, question);
    if (question == "x")
      break;

    // Ask question
    cout << getAnswer(magicEightBallAnswers) << endl;
  }

  // Done
  cout << "Bye!  Let's play again soon!" << endl;
  return 0;
}

具体地说：

• 利用C++特性来消除不必要的代码，如"push_back()“或"(8)”初始化。
• 如果有像“SIZEOF_ANSWER()”这样的动态选项，千万不要使用像“vector.size”这样的硬编码常量。
• 注意参照通过：in string getAnswer(vector<string> & magicEightBallAnswers)的用法。
• 在使用"rand()“之前，应该用种子调用"srand()”。
• 等。