C语言中将CSV数据解析至结构体时出现类型转换错误的解决方案咨询

Let's break down your code's key issues and fix them step by step:

1. Correct Your Struct Definitions #

Your structs have two critical flaws that break data storage:

• In struct Course, char *course_name[50]; declares an array of 50 char pointers, but you only need a single pointer to reference the course names from dataArr. Simplify it to:

  struct Course {
      char *course_name;
      int grade;
  };
  

• In struct Student, struct Course; is an incomplete declaration—it doesn't create a member to hold the student's courses. Since each student has 6 courses, declare an array of struct Course:

  struct Student {
      char *name;
      struct Course courses[6];
      int index;
  };
  

  (If you want to avoid dynamic memory later, you can swap char *name; with char name[50]; instead.)

2. Fix the Uninitialized sName Pointer #

You’re using char *sName; without allocating memory for it. Calling strcpy(sName, token); writes to random memory, causing undefined behavior. Fix this either by:

• Using a fixed-size array: char sName[50];
• Or dynamically allocating memory: sName = malloc(strlen(token) + 1); (remember to free this later!)

3. Fix Struct Initialization Syntax #

Your original struct initialization line had invalid syntax—you can’t nest course data that way, and you were accidentally assigning an int to a pointer member (from your original flawed course_name array). Instead:

• Create a struct Student instance (or array of instances) before parsing
• Assign the student’s name first
• Fill each Course in the courses array as you parse grades

Revised Working Code #

Here’s the full fixed code that correctly parses your CSV into structs:

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

// Fixed Struct Definitions
struct Course {
    char *course_name;
    int grade;
};

struct Student {
    char *name;
    struct Course courses[6];
    int index;
};

char *dataArr[6] = {"Intro to Programming","Databases","Computer Architecture","Ethics in Computer Science","Advanced Programming","Puzzles and Problem Solving"};

void Import_and_Print() {
    printf("\nImporting files and storing data in structs...\n\n");
    FILE * fp;
    char * line = NULL;
    size_t len = 0;
    ssize_t read;
    int student_index = 0;
    const char s[2] = ",";
    char *token;

    fp = fopen("Sample2.csv", "r");
    if (fp == NULL)
        exit(EXIT_FAILURE);

    // Skip the header line
    read = getline(&line, &len, fp);

    // Array to store students (adjust size based on your CSV)
    struct Student students[3];

    while ((read = getline(&line, &len, fp)) != -1 && student_index < 3) {
        // Make a copy of the line so strtok doesn't modify the original
        char *csvData = strdup(line);
        token = strtok(csvData, s);

        // Allocate memory for student name and copy it
        students[student_index].name = malloc(strlen(token) + 1);
        strcpy(students[student_index].name, token);
        printf("Student name: %s\n", students[student_index].name);

        token = strtok(NULL, s);
        int course_idx = 0;
        while (token != NULL && course_idx < 6) {
            int in_grade = atoi(token);
            // Assign course name and grade to the struct
            students[student_index].courses[course_idx].course_name = dataArr[course_idx];
            students[student_index].courses[course_idx].grade = in_grade;
            printf("Course: %s\tGrade: %i\n", dataArr[course_idx], in_grade);

            token = strtok(NULL, s);
            course_idx++;
        }

        students[student_index].index = student_index;
        student_index++;
        free(csvData); // Clean up the copied line
        printf("\n\n");
    }

    // Verify stored data works correctly
    printf("Verifying stored struct data:\n");
    for (int i = 0; i < student_index; i++) {
        printf("Student %d: %s\n", i, students[i].name);
        for (int j = 0; j < 6; j++) {
            printf("  %s: %d\n", students[i].courses[j].course_name, students[i].courses[j].grade);
        }
    }

    // Clean up dynamic memory
    for (int i = 0; i < student_index; i++) {
        free(students[i].name);
    }
    free(line);
    fclose(fp);
}

int main() {
    Import_and_Print();
    return 0;
}

Key Changes Explained #

• Struct Fixes: Properly defined the course array in Student and simplified Course to hold a single pointer for course names.
• Memory Safety: Used malloc for student names (and freed them later to avoid leaks) and strdup to protect the original input line from strtok modifications.
• Parsing Logic: Separated student name parsing from grade parsing, then filled each course in the student's array one by one.
• Verification: Added a section to print stored struct data so you can confirm the data is being saved correctly.

内容的提问来源于stack exchange，提问作者Clauric