C编程调用指针的指针

Question

我定义了这些结构:

typedef struct {
  char *first_name;
  char *last_name;
  char SSN[9];
  float gpa;
  struct student *next;
} student;

typedef struct {
    student *head;
    student *current;
    student *tail;
} students;

在我的主函数中，我想在学生结构中添加一个学生。然后，调用类主任的名字。我该怎么做？

void add(students *list, student *a) {
    if(list->head) {
        a->next = NULL;
        list->head = &a;
        list->current = list->head;
        list->tail = NULL;
    } else {
        printf("Will implement");
    }
}

int main()
{
    students grade1;

   student a;
   a.first_name = &"Misc";
   a.last_name = &"Help";

   add(&grade1, &a);

   printf("%s %s", a.first_name, a.last_name);
   printf("%s", grade1.head->first_name);
}

printf("%s",grade1.head->first_name);

似乎不起作用。有什么建议吗？

谢谢

Answer 1

首先，您必须初始化对象 grade1 的所有数据成员。例如

students grade1 = { 0 };

其次代替

student a;
a.first_name = &"Misc";
a.last_name = &"Help";

至少应该有这样的

student *a = malloc( sizeof( student ) );
a->first_name = "Misc";
a->last_name = "Help";
a->next = NULL;

函数add可能看起来像

void add( students *list, student *a ) 
{
    if ( list->tail == NULL )
    {
        list->head = list->tail = a;
    }
    else
    {
        list->tail->next = a;
    }
}

它可以被称为

add( &grade1, a );