如何计算此 C++ 代码中的正确答案

Question

我正在尝试运行此代码，它将计算用户做出了多少正确答案。

但我不知道怎么做。我想我应该使用if 或嵌套的if 来做到这一点。我该怎么做？

这将要求用户输入他们的正确答案，A、B、C 或 D。然后我想增加 n：

#include <stdio.h>
#include <conio.h>

#define p printf
#define s scanf

main () {
    int Ttl;
    char Ln, Mi, Fn,
         A1,   A2,  A3,  A4,  A5,  A6,  A7,  A8,  A9, A10,
         A11, A12, A13, A14, A15, A16, A17, A18, A19, A20;

    clrscr();

    p("\n)
    p("\n\nEnter your last name: ");
    s("%s", &Ln);
    p("\nEnter your middle initial: ");
    s("%s", &Mi);
    p("\nEnter your first name: ");
    s("%s", &Fn);
    p("\nType the corresponding letter to each question.");
    p("\n1.) Shortcut for'New Line'");
    p("\n  A. Ctrl + R          C. Ctrl + M ");
    p("\n  B. Ctrl + QC          D. Ctrl + KC ");
    p("\nAnswer: ");
    s("%s", A1);
    p("\n2.) Shortcut for'Up Arrow Key'");
    p("\n  A. Ctrl + Z          C. Ctrl + X ");
    p("\n  B. Ctrl + QC          D. Ctrl + E ");
    p("\nAnswer: ");
    s("%s", A2);
    p("\n3.) Shortcut for'Down Arrow Key'");
    p("\n  A. Ctrl + X          C. Ctrl + E ");
    p("\n  B. Ctrl + C          D. Ctrl + R ");
    p("\nAnswer: ");
    s("%s", A3);
    p("\n4.) Shortcut for'Scroll Down'");
    p("\n  A. Ctrl + X          C. Ctrl + R ");
    p("\n  B. Ctrl + E          D. Ctrl + Z ");
    p("\nAnswer: ");
    s("%s", A4);
    p("\n5.) Shortcut for'Page Up'");
    p("\n  A. Ctrl + K          C. Ctrl + R ");
    p("\n  B. Ctrl + Q          D. Ctrl + C ");
    p("\nAnswer: ");
    s("%s", A5);
    p("\n6.) Shortcut for'Page Down'");
    p("\n  A. Ctrl + Q          C. Ctrl + K ");
    p("\n  B. Ctrl + C          D. Ctrl + Z ");
    p("\nAnswer: ");
    s("%s", A6);
    p("\n7.) Shortcut for'Top of a File'");
    p("\n  A. Ctrl + KY          C. Ctrl + KC  ");
    p("\n  B. Ctrl + QC          D. Ctrl + QR ");
    p("\nAnswer: ");
    s("%s", A7);
    p("\n8.) Shortcut for'Bottom of a File'");
    p("\n  A. Ctrl + QC          C. Ctrl + KY ");
    p("\n  B. Ctrl + QS          D. Ctrl + KC ");
    p("\nAnswer: ");
    s("%s", A8);
    p("\n9.) Shortcut for'Copy Block'");
    p("\n  A. Ctrl + QY          C. Ctrl + KC ");
    p("\n  B. Ctrl + KY          D. Ctrl + QC ");
    p("\nAnswer: ");
    s("%s", A9);
    p("\n10.) Shortcut for'Delete Block'");
    p("\n  A. Ctrl + QR          C. Ctrl + QC ");
    p("\n  B. Ctrl + KC          D. Ctrl + KY ");
    p("\nAnswer: ");
    s("%s", A10);
    p("\n11.) Hot Keys Command 'Saves the file currently being edited'");
    p("\n  A. F6          C. F2 ");
    p("\n  B. F4          D. F9 ");
    p("\nAnswer: ");
    s("%s", A11);
    p("\n12.) Hot Keys Command'Loads a File'");
    p("\n  A. F7          C. F1");
    p("\n  B. F3          D. F8");
    p("\nAnswer: ");
    s("%s", A12);
    p("\n13.) Hot Keys Command'Compiles and link the program'");
    p("\n  A. F4          C. F3 ");
    p("\n  B. F2          D. F9 ");
    p("\nAnswer: ");
    s("%s", A13);
    p("\n14.) Hot Keys Command'Compiles file to .obj file'");
    p("\n  A. Alt + F9          C. Alt + F5 ");
    p("\n  B. Alt + F2          D. Alt + F7 ");
    p("\nAnswer: ");
    s("%s", A14);
    p("\n15.) Hot Keys Command'Next error'");
    p("\n  A. Alt + F4          C. Alt + F9 ");
    p("\n  B. Alt + F7          D. Alt + F8 ");
    p("\nAnswer: ");
    s("%s", A15);
    p("\n16.) Hot Keys Command'Previous error'");
    p("\n  A. Alt + F7          C. Alt + F9 ");
    p("\n  B. Alt + F3          D. Alt + F1 ");
    p("\nAnswer: ");
    s("%s", A16);
    p("\n17.) Hot Keys Command'Activates the file menu'");
    p("\n  A. Alt + E           C. Alt + C ");
    p("\n  B. Alt + F          D. Alt + O ");
    p("\nAnswer: ");
    s("%s", A17);
    p("\n18.) Hot Keys Command'Quit the Turbo C program'");
    p("\n  A. Alt + D          C. Alt + P ");
    p("\n  B. Alt + C          D. Alt + X ");
    p("\nAnswer: ");
    s("%s", A18);
    p("\n19.) Hot Keys Command'Runs the program'");
    p("\n  A. Ctrl + F3          C. Ctrl + F2 ");
    p("\n  B. Ctrl + F5          D. Ctrl + F9 ");
    p("\nAnswer: ");
    s("%s", A19);
    p("\n20.) Hot Keys Command'Switches between windows'");
    p("\n  A. F2          C. F6 ");
    p("\n  B. F4          D. F8 ");
    p("\nAnswer: ");
    s("%s", A20);
    p("Thank you for answering the following question");
    p("\nCalculating correct answers. Please wait...");
    delay(5000);
    p("\nYour total correct answer is: ");
    p("\n\t\tEnd of the Program");

    getche();
}

Answer 1

我建议使用 有序映射 数据结构。这由 key 和 value 对组成。如果您使用的是标准库，它有一个有序的地图数据结构，该结构与底层red-black tree 一起运行以进行数据存储。

对于您的示例，您可以简单地使用问题编号（或任何组合）作为键，并将结果答案作为值。

因此，要检查学生是否正确回答了问题，您可以输入问题键进行查找，然后返回正确的答案值。然后，您可以将此值与选择的答案进行比较。

Here is the documentation for the standard library ordered map data structure

地图可以很容易地预先填充您布置的数据。只需创建一个函数来解析您的文本文件并创建一组插入到映射中的键/值对。这是程序员非常常见的使用模式。许多软件工程公司添加了诸如 PopulateValuesFromFile(...) 之类的函数来填充数据结构的数据。它还使代码看起来更干净，因为它没有填充很多硬编码的字符串。

Answer 2

这是一种使用结构数组的方法。这样您就可以在同一个地方保留尽可能多的参数（与问题相关）：

#include <stdio.h>


typedef struct {
    const char *question;
    int correct_answer;
    int given_answer;
} question_t;


int main() {

    question_t questions[] = {
        {"how many wings does bird have?\n1) 55\t3) 3\n2) 5\t4) 2", 4},
        {"how many heads does frog have?\n1) 55\t3) 3\n2) 1\t4) 2", 2},
        {NULL},
    };
    
    int number_of_corrent_unswers = 0;
    for(int i=0; questions[i].question != NULL; i++) {
        puts(questions[i].question);
        scanf("%d", &questions[i].given_answer);
        if(questions[i].given_answer == questions[i].correct_answer) {
            number_of_corrent_unswers++;
        }
    }
    printf("number of correct answers: %d\n", number_of_corrent_unswers);
    return 0;
}