0

所以我一直在努力解决这个问题。我的所有代码目前都可以工作，除了我的最后一个模块，我试图比较两个数组的差异并将问题编号记录到一个新数组中。我不确定如何设置它。任何帮助将不胜感激。

主要问题是我正在创建的数组不正确。我不知道如何设置一个随着输入值而变大的空白数组。除非我真的把这个概念搞砸了。当我尝试不同的事情时，我有当前注释掉的问题。

#include <iostream>
using namespace std;

const int COLS = 20;
void input_data(char [], int);
void compare_data(char [], int, char [], int);

int main()
{
    char letters[COLS];
    char answers[] = { 'A', 'D', 'B', 'B',
                       'C', 'B', 'A', 'B',
                       'C', 'D', 'A', 'C',
                       'D', 'B', 'D', 'C',
                       'C', 'A', 'D', 'B'};

    input_data(letters, COLS);
    compare_data(letters, COLS, answers, COLS);
}

void input_data(char letter[], int size)
{
    cout << "Please enter the student's answers for each of the questions. \n";
    cout << "Press Enter after typing each answer. \n";
    cout << "Please enter only an A, B, C, or D for each question. \n";
    for (int i = 1; i <= size; i++)
    {
        cout << "Question " << i << ": ";
        cin >> letter[i - 1];
        while (letter[i - 1] != 'A' && 
                letter[i - 1] != 'B' &&
                letter[i - 1] != 'C' &&
                letter[i - 1] != 'D')
        {
            cout << "Please enter only A, B, C, or D \n";
            cout << "Question " << i << ":";
            cin >> letter[i - 1];
        }
    }
}

void compare_data(char letter[], int size, char answer[], int cols)
{
    int ans_correct = 0;
    int ans_wrong = 0;
    //int incorrect[20];
    for (int i = 1; i <= size; i++)
    {
        if (letter[i] == answer[i])
            ans_correct += 1;
        else
        {
            ans_wrong += 1;
            //incorrect[i-1] = i;
        }
    }

    if (ans_correct >= 15)
        cout << "The student passed the exam. \n";
    else
        cout << "The student did not pass the exam. \n";

    cout << "Correct Answers: " << ans_correct << endl;
    cout << "Incorrect Answers: " << ans_wrong << endl << endl;

    cout << "Questions that were answered incorrectly: \n";
    for (int i = 1; i < size; i++)
    {
        //cout << incorrect[i-1] << endl;
    }
}
4

1 回答 1

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好的，这是一个工作版本。它不会增长不正确的数组，因为对于这样一个小操作来说这将是多余的，并且无论如何您都在使用常量“COLS”。

既然这是一个 c++ 标记的问题，如果你真的想要一个动态数组，为什么不使用 std::vector 呢？你可以用 C 风格的数组做类似的事情，但它非常混乱。

void compare_data(char letter[], int size, char answer[], int cols)
{
   int ans_correct = 0;
   int ans_wrong = 0;
   //setup array big enough to hold all answers
   //and initialize to 0
   int incorrect[COLS] = {0};
   // Your original code had wrong loop limits!
   for (int i = 0; i < size; i++)
   {
     if (letter[i] == answer[i])
        ans_correct += 1;
     else
     {
        //Fill in incorrect only on wrong answers!
        //But the number you want to record is the
        //the number of the question, which is i + 1
        incorrect[ans_wrong] = i + 1;
        ans_wrong += 1;
    }
}

if (ans_correct >= COLS/2)
    cout << "The student passed the exam. \n";
else
    cout << "The student did not pass the exam. \n";

cout << "Correct Answers: " << ans_correct << endl;
cout << "Incorrect Answers: " << ans_wrong << endl << endl;

cout << "Questions that were answered incorrectly: \n";
//Even if the array is bigger, you don't wnat to output the
//unused parts
for (int i = 0; i < ans_wrong; i++)
{
    cout << incorrect[i] << endl;
}
}
于 2018-11-01T07:53:14.763 回答