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尾插法

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
void getinput(struct Book *book);
void addBook(struct Book **library);
void printLibrary(struct Book *library);
void releaseLibrary(struct Book **library);

struct Book
{
char title[128];
char author[40];
struct Book *next;
};

void getinput(struct Book *book)
{
printf("\n请输入书名:");
scanf("%s",book->title);		//scanf中不要有换行符
printf("\n请输入作者:");
scanf("%s",book->author);
}
void addBook(struct Book **library) //采用头插法，往链表中插入元素，library作为头指针，两层解引用，因为它是指向结构体指针的指针
{
struct Book *book,*temp;
book = (struct Book *)malloc(sizeof(struct Book));		//为要插入的元素动态申请一块内存空间
if(book == NULL)
{
printf("内存分配失败!\n");
exit(1);
}
getinput(book);				//获取插入元素的内容
if(*library != NULL)		//如果插入的不是NULL链表
{
temp = *library;
//定位单链表尾部的位置
while(temp!=NULL)
{
temp = temp->next;
}
//插入数据
temp->next = book;
book->next = NULL;
}
else
{
*library = book;
book->next = NULL;
}
}
void printLibrary(struct Book *library)
{
struct Book *book;
int count = 1;
book = library;
while(book!=NULL)
{
printf("\nBook%d:\n",count);
printf("\n书名:%s\n",book->title);
printf("\n作者:%s\n",book->author);
book = book ->next;
count++;
}
}

void releaseLibrary(struct Book **library)
{
struct Book *temp;
while(*library != NULL)
{
temp = *library;
*library = (*library)->next;	//考虑运算符的优先级，->的高于解引用*，故需要加括号。
free(temp);
}
}
int main(void)
{
struct Book *library = NULL;
int ch;
while(1)
{
printf("\n请问是否需要输入书籍或者作者(Y/N): ");
do
{
ch = getchar();
}while(ch!='Y'&&ch!='N');
if(ch=='Y')
{
addBook(&library);
}
else
{
break;
}
}
printf("\n请问是否需要打印书籍信息(Y/N): ");
do
{
ch = getchar();
}while(ch!='Y'&&ch!='N');
if(ch=='Y')
{
printLibrary(library);
}
else
{
releaseLibrary(&library);
}

return 0;
}

执行结果：

上面的方式，每次插入新元素时，都会遍历整个链表，看是否到达链表尾部，才执行插入操作，效率低，改进的方式是在addBook()中引入一个静态的结构体指针，始终指向链表的尾部。

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
void getinput(struct Book *book);
void addBook(struct Book **library);
void printLibrary(struct Book *library);
void releaseLibrary(struct Book **library);

struct Book
{
char title[128];
char author[40];
struct Book *next;
};

void getinput(struct Book *book)
{
printf("\n请输入书名:");
scanf("%s",book->title);		//scanf中不要有换行符
printf("\n请输入作者:");
scanf("%s",book->author);
}
void addBook(struct Book **library) //采用头插法，往链表中插入元素，library作为头指针，两层解引用，因为它是指向结构体指针的指针
{
struct Book *book;
static struct Book *tail;		//定义静态结构体指针，始终指向链表尾部
book = (struct Book *)malloc(sizeof(struct Book));		//为要插入的元素动态申请一块内存空间
if(book == NULL)
{
printf("内存分配失败!\n");
exit(1);
}
getinput(book);				//获取插入元素的内容
if(*library != NULL)		//如果插入的不是NULL链表
{
//插入数据
tail->next = book;
book->next = NULL;
}
else
{
*library = book;
book->next = NULL;
}
tail = book;		//保证tail指向链表尾部
}
void printLibrary(struct Book *library)
{
struct Book *book;
int count = 1;
book = library;
while(book!=NULL)
{
printf("\nBook%d:\n",count);
printf("\n书名:%s\n",book->title);
printf("\n作者:%s\n",book->author);
book = book ->next;
count++;
}
}

void releaseLibrary(struct Book **library)
{
struct Book *temp;
while(*library != NULL)
{
temp = *library;
*library = (*library)->next;	//考虑运算符的优先级，->的高于解引用*，故需要加括号。
free(temp);
}
}
int main(void)
{
struct Book *library = NULL;
int ch;
while(1)
{
printf("\n请问是否需要输入书籍或者作者(Y/N): ");
do
{
ch = getchar();
}while(ch!='Y'&&ch!='N');
if(ch=='Y')
{
addBook(&library);
}
else
{
break;
}
}
printf("\n请问是否需要打印书籍信息(Y/N): ");
do
{
ch = getchar();
}while(ch!='Y'&&ch!='N');
if(ch=='Y')
{
printLibrary(library);
}
else
{
releaseLibrary(&library);
}

return 0;
}