#include 
    
     #include 
     
      #include 
      
       struct AGE{    int year;    int month;    int day;};struct Student{    char *name;    int num;    struct AGE birthday;    float score;};int main(){    // 注意写法1与写法2 不能混用    // 写法1    struct Student* stu = NULL;    stu = (struct Student *)malloc(sizeof(struct Student));    (*stu).num = 12;    printf("%d\n", (*stu).num);    // 写法2    struct Student *stu1 = (struct Student *)malloc(sizeof(struct Student));    stu1->name = "jack";    printf("%s\n", stu1->name);    return 0;}