C语言学习 18-10-24

1.链表

链表可以按照链式存储多个结构体类型的数据，在C语言中使用要指向的结构体类型的指针来指向下一个节点（类似于python中单链表使用class Node里的node.next属性）。
使用一个记录个人信息的结构体来进行链表的演示：

#include "stdio.h"

typedef struct NAMENOTE
{
	int id;
	char *name;
	char *tel_num;
	struct NAMENOTE *p_next;
}NameNote;

int main()
{
	NameNote c = {1, "C", "123456789", NULL};
	NameNote python = {2, "python", "654654689", NULL};
	NameNote java = {3, "Java", "165432789", NULL};
	//将上述三个结构体对象链接为一个链表
	c.p_next = &python;
	python.p_next = &java;
	
	printf("id:%-5d, name:%-10s, telephone number:%-11d", c.id, c.name, c.tel_num);
	printf("id:%-5d, name:%-10s, telephone number:%-11d", c.p_next->id, c.p_next->name, c.p_next->tel_num);
	printf("id:%-5d, name:%-10s, telephone number:%-11d", c.p_next->p_next->id, c.p_next->p_next->name, c.p_next->p_next->tel_num);
	
	
	return 0;
}

2. 结构体内部声明本结构体类型的指针

在一个结构体中声明一个本结构体的指针不能用 typedef 起的别名，只能用 struct+结构体名* 来声明。

typedef struct NAMENOTE
{
	int id;
	char *name;
	char *tel_num;
	struct NAMENOTE *p_next;         //在此处使用 NameNote *p_next 声明指针是错误的，因为还没有完成typedef的声明
}NameNote;

3.链表的遍历

遍历链表首先需要找到一个链表的头节点（或头指针）。

#include <stdio.h>

typedef struct NAMENOTE
{
	int id;
	char *name;
	char *tel_num;
	struct NAMENOTE *p_next;
}NameNote;

int main()
{
	//1.声明三个节点
	NameNote c = {1, "C", "111", NULL};
	NameNote python = {2, "python", "222", NULL};
	NameNote java = {3, "java", "333", NULL};
	NameNote *p_flag = &c;
	
	//2.将这三个节点进行链接
	c.p_next = &python;
	python.p_next = &java;
	
	//3.进行遍历
	while(p_flag != NULL)
	{
		printf("id:%-5d, name:%-10s, telephone number:%-11s\n", p_flag->id, p_flag->name, p_flag->tel_num);
		p_flag = p_flag->p_next;
	}
	
	return 0;
}

4.手动添加链表

本次的手动添加链表的思想是先创建一个 struct 对象，再使用该对象进行链接。
注：本次不使用头指针指向头节点的方法

#include <stdio.h>

typedef struct NAMENOTE
{
	int id;
	char *name;
	char *tel_num;
	struct NAMENOTE *p_next;
}NameNote;

void AppendNode(NameNote *head_node, NameNote *append_node);

int main()
{
	//1.声明三个节点
	NameNote c = {1, "C", "111", NULL};
	NameNote python = {2, "python", "222", NULL};
	NameNote java = {3, "java", "333", NULL};
	NameNote *p_flag = &c;
	
	
	
	return 0;
}

void AppendNode(NameNote *head_node, NameNote *append_node)
{
	while(head_node->p_next != NULL)
	{
		head_node = head_node->p_next;
	}
	head->p_next = append_node;
	
	return;
}