[C语言 - 7] 结构体struct

A. 基本知识

 

与数组的对比

数组：

构造类型

只能有多个相同类型的数据构成

 

结构体：

结构体类型

可以由多个不同类型的数据构成

 

1. 定义类型

     struct Student
     {
         int age;
         char *name;
         float height;
     };

 

2. 定义结构体变量

定义变量的多种方式

a.

     //define a struct variable
     struct Student stu = {, "simon", 1.65f};

 

b.

     struct Student {
         int age;
         char *name;
         float height;
     } stu = {, "simon", 1.65f};

 

     /*错误写法
     struct Student p;
     p = {17, "Tom"};
      */

c.

     struct Student p;
     p.age = ;
     p.name = "Tom”;

d.

     struct Student p2 = {, "Sam”};

e.

     struct Student p3 = {.name="Judy", .age= };

f.匿名

     struct
     {
         int age;
         char *name;
     } stu3;

 

3. 不允许结构体进行递归定义

在结构体构造代码内定义本结构体的变量

 

4. 可以包含其他的结构体

 void test1()
 {
     struct Date
     {
         int year;
         int month;
         int day;
     };

     struct Student
     {
         int age;
         struct Date birthday;
     };

     struct Student stu = {, {, , }};

     printf("my birthday ==> %d-%d-%d\n", stu.birthday.year, stu.birthday.month, stu.birthday.day);
 }

 

5. 结构体数组

     struct Student
     {
         int age;
         char *name;
         float height;
     } stus[];

 

匿名

     struct
     {
         int age;
         char *name;
         float height;
     } stus[];

 

6. 结构体作为函数参数， 传递的仅仅是成员的值

 

7. 指向结构体的指针

 void test4()
 {
     struct Person p = {, "ss"};
     struct Person *pointer;

     pointer = &p;

     printf("test4: person's age = %d\n", p.age);//It's p!!!, not pointer!!
     printf("test4: person's age = %d\n", (*pointer).age);
     printf("test4: person's age = %d\n", pointer->age);
 }

 

==> 3种方式访问结构体成员变量

a. struct.v

b. (*pointer).v

c. pointer->v

 

8.结构体内存分配

a.定义的时候不会分配存储空间

b.定义结构体变量的时候分配空间，分配的空间大小是最大成员变量的倍数

 

 

9.结构体复制

     struct Student p2 = {, "Sam"};
     struct Student p3 = {.name="Judy", .age= };
     p3 = p2;
     printf("p3: age->%d, name-.%s\n", p3.age, p3.name);

 

out:

p3: age->17, name->.Sam