[C语言

 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

1     struct Student
2     {
3         int age;
4         char *name;
5         float height;
6     };

 

2. 定义结构体变量

定义变量的多种方式

a.

1     //define a struct variable
2     struct Student stu = {27, "simon", 1.65f};

 

b.

1     struct Student {
2         int age;
3         char *name;
4         float height;
5     } stu = {25, "simon", 1.65f};

 

1     /*错误写法
2     struct Student p;
3     p = {17, "Tom"};
4      */

c.

1     struct Student p;
2     p.age = 17;
3     p.name = "Tom”;

d.   

1     struct Student p2 = {17, "Sam”};

e. 

1     struct Student p3 = {.name="Judy", .age= 44};

f.匿名

1     struct
2     {
3         int age;
4         char *name;
5     } 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

 1 void test1()
 2 {
 3     struct Date
 4     {
 5         int year;
 6         int month;
 7         int day;
 8     };
 9    
10     struct Student
11     {
12         int age;
13         struct Date birthday;
14     };
15    
16     struct Student stu = {25, {1989, 8, 10}};
17    
18     printf("my birthday ==> %d-%d-%d
", stu.birthday.year, stu.birthday.month, stu.birthday.day);
19 }

 

5. 结构体数组

1     struct Student
2     {
3         int age;
4         char *name;
5         float height;
6     } stus[5];

 

匿名

1     struct
2     {
3         int age;
4         char *name;
5         float height;
6     } stus[5];

 

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

 1 void test4()
 2 {
 3     struct Person p = {33, "ss"};
 4     struct Person *pointer;
 5    
 6     pointer = &p;
 7    
 8     printf("test4: person's age = %d
", p.age);//It's p!!!, not pointer!!
 9     printf("test4: person's age = %d
", (*pointer).age);
10     printf("test4: person's age = %d
", pointer->age);
11 }

 

==> 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

1     struct Student p2 = {17, "Sam"};
2     struct Student p3 = {.name="Judy", .age= 44};
3     p3 = p2;
4     printf("p3: age->%d, name-.%s
", p3.age, p3.name);

 

out:

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