一，结构体变量定义及初始化
#include<stdio.h>
#include<string.h>
//定义结构体，可以在主函数内定义
struct student
{
char name[32];
char gender;
int age;
//其boy是先定义到后边初始化，people是定义的同时初始化，但是这两种用法不建议使用
}boy,people = {"yyy", 'y', '0'};
int main()
{
printf("%s\n%c\n%c\n", people.name, people.age, people.gender);
struct student person = {"xxx", 'x', 'x'};
printf("%s\n%c\n%c\n", person.name, person.age, person.gender);
//对boy进行初始化
strcpy(boy.name, "Jack");
boy.age = 24;
boy.gender = 'm';
printf("%s\n%d\n%c\n", boy.name, boy.age, boy.gender);
//对girl和girl1进行定义及初始化
struct student girl,girl1;
strcpy(girl.name, "Alisa");
girl.age = 24;
girl.gender = 'w';
printf("%s\n%c\n%c\n", girl.name, girl.age, girl.gender);
//结构体变量可以直接赋值给相同类型结构体
girl1 = girl;
printf("%s\n%c\n%c\n", girl1.name, girl1.age, girl1.gender);
return 0;
}
二，无名结构体
#include<stdio.h>
#include<string.h>
struct
{
char gender;
int age;
//无名结构变量必须在定义后定义,
}stu;
int main()
{
stu.age = 28;
printf("%d\n", stu.age);
return 0;
}
备注：无名结构体很少使用
三，宏定义结构体
#include<stdio.h>
#include<string.h>
struct student
{
char gender;
int age;
}; //结构体的“;”不能少
#define STU struct student //宏定义结构体
int main()
{
STU stu, stu1; //宏定义STU使用
stu.gender = 'm';
stu1.age = 25;
printf("%d\n%c\n", stu1.age, stu.gender);
}
四，结构体嵌套
#include<stdio.h>
#include<string.h>
struct date
{
int year;
int month;
int day;
};
struct student
{
char name[32];
int age;
struct date birth; //结构体嵌套
};
int main()
{
struct student stu;
strcpy(stu.name, jack);
stu.age = 25;
stu.birth.year = 1991;
stu.birth.month = 3;
stu.birth.day = 21;
printf("His name is %s\nHe births in %d.%d.%d\n", stu.name,
stu.age, stu.birth.year, stu.birth.month, stu.birth.day);
return 0;
}
五，结构体数组
#include<stdio.h>
#include<string.h>
struct student
{
int age;
char name[32];
}
int main()
{
struct student arr[3] =
{
{24, "Jack"},
{23, "Alisa"},
{25, "Jays"}
} //结构体数组
printf("arr[0].age:%d\narr[1].name:%s\n",arr[0].age, arr[1].name);
reurn 0;
}
六，结构体指针
#include<stdio.h>
#include<string.h>
struct date
{
int year;
int month;
int day;
};
struct student
{
char name[32];
int age;
struct date birth;
};
int main()
{
struct student stu;
struct student *p = &stu; //结构体指针
strcpy(p->name, jack);
p->age = 25;
p->birth.year = 1991;
p->birth.month = 3;
p->birth.day = 21;
printf("His name is %s\nHe births in %d.%d.%d\n", p->name,
p->age, p->birth.year, p->birth.month, p->birth.day);
return 0;
}
七，typedef 重命名
#include<stdio.h>
#include<string.h>
typedef struct student
{
int age;
char name[32];
//相当将struct student重命名为STU，而非宏定义
}STU;
typedef int M;
M a = 4; //M和int的作用是一样的，只是重命名
int b = 5;
M c = a + b;
printf("%d + %d = %d\n", a, b, c);
return 0;
}
八，结构体大小
#include<stdio.h>
struct A //8
{
char a;
char b;
int c;
};
struct B //32
{
char a;
int b;
char c[23];
};
struct C //16
{
char a;
int c[3];
};
struct D //6
{
char a;
short b;
char c
};
struct E //4
{
char a;
char b;
short c;
};
int main()
{
printf("sizeof(struct A) = %ld\n",sizeof(struct A));
printf("sizeof(struct B) = %ld\n",sizeof(struct B));
printf("sizeof(struct C) = %ld\n",sizeof(struct C));
printf("sizeof(struct D) = %ld\n",sizeof(struct D));
printf("sizeof(struct E) = %ld\n",sizeof(struct E));
return 0;
}
内存对齐：
Linux:4字节
Windows:8字节
默认从偏移量为0的位置开始存储
每个字母所占字节数是其自生大小的整数倍
九，联合体
#include<stdio.h>
union untype
{
int a;
float b;
char c;
};
int main()
{
union untype un;
un.a = 123;
un.b = 3.14;
un.c = 'f';
printf("%d\n", un.a); //一次只能访问一个值
//printf("%d\n", un.b);
//printf("%d\n", un.c);
return 0;
}
十，枚举类型
#include<stdio.h>
enum type
{
A, //若不赋值，默认为0，B为1，C为2
B,
C,
D = 12,
E = 3,
F //最后一个没有“,”，F递增为4
};
int main()
{
enum type num;
num.A //ERROR
num = A;
printf("input num:");
scanf("%d", &num);
swich(num)
{
case A:
printf("0\n");
break;
case B:
printf("1\n");
break;
default:
break;
}
return 0;
}
十一，链表
- 链式存储结构，线性存储结构，其大小可动态改变，链表由一个个结点串起来的数据链，节点由数据域和指针域。
- 分配空间
//申请一块堆空间，大小为sizeof(struct student) pa = (struct date *)malloc (sizeof(struct student)); free(pa); //释放空间
- 创建一个头结点：
struct student *head;
head = (struct student *)malloc(sizeof(struct student));
头结点标识一个链表，即链表名称
头结点的数据域不存放数据，指针域存放下一个结点的地址，头结点只是为了标识这个链表
#include<stdio.h>
#include<stdlib.h>
struct student
{
int ID;
char name[32];
struct student *next;
};
#define LEN sizeof(struct student)
struct student *add_link(struct student *head)
{
struct student *temp = (struct student*)malloc(LEN);
printf("input ID:\n");
scanf("%d", &temp->ID);
printf(" input name:\n");
scanf("%s", temp->name);
temp->next = NULL; //可以省略
temp->next = head->next;
head->next = temp;
temp = NULL; //要置空，防止成为野指针
return head;
}
struct student *delete_head(struct student *head)
{
struct student *temp = head->next;
head->next = temp->next;
free(temp);
temp = NULL;
return head;
}
void show_link(struct student *head)
{
struct student *p = head->next;
printf("ID\tname\n");
while(p != NULL)
{
printf("%d\t%s\n", p->ID, p->name);
p = p->next;
}
}
int main()
{
//创建链表
struct student *head;
head = (struct student *)malloc(LEN);
head->next = NULL;
int i = 0;
for(i = 0; i < 5; i++)
head = add_link(head); //头插插入链表调用
show_link(head);
head = delete_head(head); //头删删除链表调用
show_link(head);
return 0;
}
结论
1，链表是一个难点，链表的插入和删除是重点。
2，弄清链表的实现方式，并自己写出代码实现。
