C++ Magic 8 Ball with Vectors

问题

I'm trying to take a Magic 8 Ball program that was originally using arrays and change it to a program that uses vectors instead. The task that I was given was to take the code below and do a couple of things to it.

use the push_back() function to initialize the vector
modify the signature and prototype of the getAnswer() function
modify the code in the body of the getAnswer() function
remove any unneeded code, such as your constant for the number of answers

    #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];
    }

回答1:

This example might help:

#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;
}

Specifically:

Use C++ features to your advantage, to eliminate unnecessary code like "push_back() or initializing with "(8)".
Never use a hard-coded constant like "SIZEOF_ANSWER" if there's a dynamic alternative like "vector.size()".
Note the use of pass by reference: in string getAnswer(vector<string> & magicEightBallAnswers).
You should call "srand()" with a seed before using "rand()".
Etc.

来源：https://stackoverflow.com/questions/62480746/c-magic-8-ball-with-vectors

标签

c++

vector