c - 如何循环遍历数据文件以填充结构？

Question

程序规范:

从以下格式的数据文件中读取问题:

Question

Number of choices

N-amount of choices

Correct answer

例子:

What is the capital of France?

3

Madrid

Sydney

Paris

Paris

一次向用户提出一个问题并跟踪他们的分数等。

我目前拥有的:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define MAX_LINE_SIZE 60
#define MAX_LIST_SIZE 15
#define MAX_QUIZ_SIZE 10

typedef struct question {
    char *question;
    char **choices;
    int n_choices;
    char *correct_answer;
} QUESTION;

typedef struct quiz {
    struct question *questions;
    int n_questions;
} QUIZ;

char *dupString(const char *s) {
// copies a string

    char *dup = malloc(strlen(s) + 1);
    strcpy(dup, s);
    return dup;
}

void free_choices(QUESTION *q) {
// free memory

    for(int i = 0; i < q->n_choices; i++) {
        free(q->choices[i]);
    }

    free(q->choices);
}


int ask(QUESTION *q) {
    // Return 1 for correct guess, 0 for incorrect guess.

    int choice;

    // Print the question
    printf("\n%s\n", q->question);

    // Print the choices
    for (int i = 0; i <= q->n_choices-1; i++) {
        printf("%d : %s", i+1, q->choices[i]);
    }

    // Get user guess
    do {
        printf("Select an answer [1-%d]: ", q->n_choices);
        scanf("%d", &choice);
     
        /* Not sure how to structure here*/
        if (strcmp(q->choices[choice-1], q->correct_answer) == 0) {
            // if correct return 1
            return 1;
        }
    } while (choice < 1 || choice > q->n_choices);
    // Incorrect
    return 0;
    }


struct question parseQuestion(FILE *pData) {

    int qIndex, numChoices; 
    char question[MAX_LINE_SIZE], temp[MAX_LINE_SIZE], choices[MAX_LINE_SIZE], correctAns[MAX_LINE_SIZE];

    QUESTION q = {NULL, NULL, 0, NULL};

    // Eat first line = QUESTION
    fgets(question, MAX_LINE_SIZE, pData);
    q.question = question;

    // Eat second line = NUMBER OF CHOICES
    fgets(temp, MAX_LINE_SIZE, pData);
    numChoices = atoi(temp);
    q.n_choices = numChoices;

    // Allocate memory
    q.choices = calloc(q.n_choices, sizeof(char*));

    // Eat nth lines = CHOICES
    for (qIndex=0; qIndex<=numChoices-1; qIndex++) {
        fgets(choices, MAX_LINE_SIZE, pData);
        q.choices[qIndex] = dupString(choices);
    }

    // Eat nth + 1 line = CORRECT ANSWER
    fgets(correctAns, MAX_LINE_SIZE, pData);
    q.correct_answer = correctAns;

    return q;   
    }

int main() {

    int num = 0;        // question being asked
    int strikes = 0;    // incorrect guesses

    FILE* pData;

    char *filename = "tickle.txt";
    char c;

    if ((pData = fopen(filename, "r"))) {

        printf("Welcome to the 2014 Quiz-festival!\n\n");
        printf("Are you ready to begin? [Y/y]\n");
        c = getchar();

        if (c == 'Y' || c == 'y') {
            QUESTION question = parseQuestion(pData);
            ask(&question);
            free_choices(&question);
        } else {
            printf("Come back again.\n");
            return 0;
        }

    } else {
        printf("File failed to open.");
    }

    fclose(pData);
    return 0;
}

感谢@alk 如何发现我的错误，已解决。

我仍然无法理解的是如何遍历数据文件并用问题结构填充测验结构。

所以这就是我目前正在努力的地方。据我所知，只要我能让它正常工作，我就非常接近完成这个小程序。

Answer 1

parseQuestion() 复制选项但没有复制问题和答案。

相反，它只是将两个数组的地址复制到本地定义的变量 QUESTION q，该变量在返回时被复制。

问题和答案字符串的内存在函数返回时被释放，之后访问它会调用未定义的行为。