[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
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\n", 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\n", p.age);//It's p!!!, not pointer!! 9 printf("test4: person's age = %d\n", (*pointer).age); 10 printf("test4: person's age = %d\n", 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\n", p3.age, p3.name);
out:
p3: age->17, name->.Sam
