C fread不读取结构

我有以下代码将结构写入这样的文件：

void write_assignments_to_file(list* assignments, FILE* file)
{
    while (assignments != NULL) {
       fwrite(assignments->a, sizeof(assignments->a), 1, file);
       assignments = assignments->next;
    }
    fclose(file);
}

这是在写入文件，但当我再次尝试读取该文件时，它会挂起我的代码以便读取，如下所示：

list* read_assignments_from_file(FILE* file)
{
    Assignment* assignment;

    list* item; 
    item = NULL;

    while ( fread(assignment, sizeof(assignment), 1, file) ) {
        printf("Reading an assignment in");
        insert(item, assignment);
    }

    fclose(file);

    return item;
}

typedef struct Assignment {
    char* moduleTitle;
    char* moduleId;
    char* title;
    char* author;
    time_t date_set;
    time_t date_due;
    int weighting;
} Assignment;

我的insert方法如下所示：

list* insert(list* assignment_pointer, Assignment* new_assignment)
{
    list* ap = assignment_pointer;
    if(assignment_pointer != NULL){
        while (assignment_pointer->next != NULL) {
           assignment_pointer = assignment_pointer -> next;
        }
        assignment_pointer -> next = (struct list*)malloc(sizeof(list));
        assignment_pointer = assignment_pointer -> next;
        assignment_pointer -> next = NULL;
        assignment_pointer -> a = new_assignment;
        return ap;
    } else {
        assignment_pointer = (list*) malloc (sizeof(list));
        assignment_pointer -> next = NULL;
        assignment_pointer -> a = new_assignment;
        return assignment_pointer;
    }
}

我的赋值结构定义如下所示：

list* read_assignments_from_file(FILE* file)
{
    Assignment* assignment;

    list* item; 
    item = NULL;

    while ( fread(assignment, sizeof(assignment), 1, file) ) {
        printf("Reading an assignment in");
        insert(item, assignment);
    }

    fclose(file);

    return item;
}

typedef struct Assignment {
    char* moduleTitle;
    char* moduleId;
    char* title;
    char* author;
    time_t date_set;
    time_t date_due;
    int weighting;
} Assignment;

---

那么是什么原因导致我的程序挂起了？

您需要对结构和指针进行更新

Assignment *assignment;
fread(assignment /*which is not set*/, sizeof(assignment) /*probably 4*/, 1, file);

/* Should look more like */
Assignment ass;
fread(&ass, sizeof(ass), 1, file);

可能还有其他问题，但这应该让你开始

您可能应该包括赋值的stuct定义，但我认为您在write（）中也有同样的问题

---

我猜问题是读入未初始化的指针。您没有为

分配分配的内存。你可能想要更像这样的东西：

list* read_assignments_from_file(FILE* file)
{
    Assignment assignment;

    list* item; 
    item = NULL;

    while ( fread(&assignment, sizeof(assignment), 1, file) ) {
        printf("Reading an assignment in");
        insert(item, &assignment);
    }

还请注意，您的原始代码采用
sizeof（assignment）
，当它声明为
assignment*assignment时，它不会达到您所期望的效果。它将为您提供
赋值*
的大小，这是任何其他指针的大小-32位系统上为4字节，64位系统上为8字节