C 结构体 typedef (取别名) 共用体union 枚举enum

=========结构体定义 ========

//一系列不同类型的数据类型
//类型！=变量，结构体不分配内存
struct Student{
char name[20];
int age;

}Lucy;
//全局变量
int aaa;
int bbb;
//锁定结构体数量
struct {
   char name[20];
   int age;
   char gender[10];
   int classId;

}stu33,stu44;

//结构体定义和初始化
int main(){
   struct Student stu1 = { "你知不知道", 25};
   struct Student stu2;
   strcpy(stu2.name,"何以笙箫默");
   stu1.age = 20;
   printf("%s,%d\n", stu1.name, stu1.age);

system("pause");
return 0;
}

=======//结构体的数组======

struct Student{
char name[20];
int age;

}Lucy;

//结构体的数组
int main(){
   int i;
   //大括号可以加，也可以不加，最好加上
   struct Student stu1[3] = { { "曾经仗剑走天涯", 20 }, { "程序员", 25 }, { "bug太多", 23 } };
   for (i = 0; i < 3; i++)
   {
       printf("%s,%d\n", stu1[i].name, stu1[i].age);
   }
   struct Student stu2[5];

   for ( i = 0; i < 5; i++)
   {
       stu2[i].age = 20 + i;
       strcpy(stu2[i].name, "日光浴");
       printf("%s,%d\n", stu2[i].name, stu2[i].age);
   }

   struct Student *stu=stu1;
   for (i = 0; i < 3; i++)
   {
       printf("%s , %d\n", stu1[i].name, stu1[i].age);
   }

   struct Student *stud;
   stud = (Student *)malloc(sizeof(struct Student) * 4);
   //你需要赋值的指针，赋值成什么，空间多大
   memset(stud, 0, sizeof(struct Student) * 4);
   for (i = 0; i < 4; i++)
   {
       (stud+i)->age = 20 + i;
       strcpy((stud + i)->name, "水手平");
       //stud[i].age = 20+i ;
       //strcpy(stud[i].name, "nihao");
       printf("%s, %d\n", stud[i].name, stud[i].age);
   }

system("pause");
return 0;
}

======结构体中添加结构体指针成员变量单链表=======

int enqueNode(Node *head, int data){
   Node *node = (Node *)malloc(sizeof(Node));
   if (node == NULL){
       return 0;
   }
   node->data = data;
   node->next = NULL;
   Node *p = head;
   while (p->next != NULL){
       p = p->next;
   }
   p->next= node;
   return 1;
}
int main(){
   int num = 10;
   int i = 0;
   Node *list;
   list = (Node *)malloc(sizeof(struct Node));
   list->data = 0;
   list->next = NULL;
   for ( i = 0; i < num; i++)
   {
       enqueNode(list,i+1);
   }
   while (list->next != NULL){
       printf("%d\n", list->data);
       list = list->next;
   }
   system("pause");
   return 0;
}

========typedef 指令取别名===========

typedef int _in;
typedef char *string;
typedef int(*PFI) (char *, char *);
int fun(char *, char *){
   return 0;
}
//二叉树
typedef Tnode * Treeptr;
typedef struct Tnode{
   char * word;
   int count;
   //Tnode *left;
   //Tnode *right;
   Treeptr left;
   Treeptr right;
} BinaryTreeNode;

int main(){
   _in a = 20;
   printf("%d \n", a);
   string str;
   str = "hello world";
   char *ch;
   ch = "hello world";
   printf("%s ,%s \n ", ch, str);

   char *p;
   PFI pf;
   pf = fun;
   pf(p, p);

BinaryTreeNode * node;
node = (BinaryTreeNode *)malloc(sizeof(BinaryTreeNode));

system("pause");
return 0;
}

=======共用体======

//将不同类型的数据类型放到同一段内存中
//共用一段内存，当然节省内存
union MyUnion{
   int a;
   char b;
   float c;
};
int main(){
   MyUnion un;
   printf("%#x,%#x,%#x\n",&un.a,&un.b,&un.c);
   un.a = 10;
   un.b= 's';
   un.c = 10.2;
   printf("%d,%c,%f\n", un.a,un.b, un.c);
   system("pause");
   return 0;
}

=====//枚举 c语言中直接使用=======

enum{
sunday,monday,
tudesday,wendendsday

};

int main(){
   printf("%d\n",sunday);
   int a=10;
   int *p;
   p=&a ;
   int a[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
   int *p1;
   *p1 = a;

system("pause");

return 0;
}

C 结构体 typedef (取别名) 共用体union 枚举enum

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