链表的基本操作

链表的基本操作包括建立链表、链表的插入、删除、输出和查找等。

#include<stdlib.h>
#include<stdio.h>
#include<conio.h>
#include<ctype.h>
#define NULL 0
#define LEN sizeof(struct student)

extern unsigned _floatconvert; /*防止floating point formats not linked 错误发生*/
#pragma extref _floatconvert

typedef struct student
{
long num;
float score;
struct student *next;
}STU;

int n;

STU *CreateEnd()
{
STU *p1,*p2,*head;
n=0;head=NULL;
p1=(STU *)malloc(LEN); /*创建第一个结点*/
scanf("%ld,%f",&p1->num,&p1->score);
p1->next=NULL;
while(p1->num!=0) /*将结点加入链表*/
{
++n;
if(n==1) /*是第一个结点，作表头*/
head=p1;
else /*不是第一个结点，作表尾*/
p2->next=p1;
p2=p1;
p1=(STU *)malloc(LEN); /*开辟下一个结点*/
scanf("%ld,%f",&p1->num,&p1->score);
p1->next=NULL;
}
free(p1); /*释放最后一个结点所占的内存*/
return (head); /*返回链表的头指针*/
}
STU *CreateStart()
{
STU *head,*p;
n=0;
head=NULL;
p=(STU *)malloc(LEN);
scanf("%ld,%f",&p->num,&p->score);
p->next=head;
while(p->num!=0)
{
++n;
head=p;
p=(STU *)malloc(LEN);
scanf("%ld,%f",&p->num,&p->score);
p->next=head;
}
free(p);
return (head);
}
void print(STU *head)
{
STU *p;
printf("\nNow,These %d nodes are :\n",n);
p=head;
do
{
printf("%ld\t%5.1f\n",p->num,p->score);
p=p->next;
}while(p!=NULL);
}

STU *insert(STU *head,STU *stud)
{
STU *p0,*p1,*p2;
p1=head; /*p1指向第一个结点*/
p0=stud; /*p0指向要插入的结点*/
if(head==NULL) /*原来是空表*/
{head=p0;p0->next=NULL;} /*使p0指向的结点作为链表第一个结点*/
else
{
while((p0->num>p1->num)&&(p1!=NULL))
{p2=p1;p1=p1->next;} /*找插入点*/
if(head==p1) /*作为表头*/
{p0->next=head;head=p0;}
else /*插到p2指向的结点之后*/
{p2->next=p0;p0->next=p1;}
}
++n;
return head;
}

STU *del(STU *head,long num)
{
STU *p1,*p2;
if(head==NULL)
{printf("\nList null!\n");goto end;} /*链表为空*/
p1=head; /*从头结点开始查找*/
while(num!=p1->num && p1!=NULL) /*p1指向的不是所要找的结点，并且没有到表尾*/
{p2=p1;p1=p1->next;} /*后移一个结点*/
if(num==p1->num) /*找到需要删除的结点*/
{
if(p1==head) /*p1指向的是头结点*/
head=p1->next; /*第二个结点成为新的头结点*/
else
p2->next=p1->next; /*后继结点的地址赋给前一结点*/
printf("delete:%ld\n",num);
free(p1);
n--;
}
else
printf("%ld not been found!\n",num);
end:
return head;
}
STU *find(STU *head,long num)
{
STU *p1,*p2;
if(head==NULL)
{printf("\nlist null!\n");goto end;}
p1=head;
while(num!=p1->num && p1!=NULL)
{p2=p1;p1=p1->next;}
if(p1!=NULL)
printf("find:%ld %5.1f\n",num,p1->score);
else
printf("%ld not been found!\n",num);
end:
return head;
}
void main()
{
STU *head,*stu;
long find_num,del_num;
char letter;
head=CreateEnd();
//head=CreateStart();
print(head);

do
{
printf("A Insert student information\n");
printf("B Find student information\n");
printf("C Delete student information\n");
printf("Q Quit\n");
printf("Please select: \n");

letter = getch();
letter = toupper(letter);

switch (letter)
{
case 'A':
printf("Please input the information of student:\n");
stu=(STU *)malloc(LEN);
scanf("%d,%f",&stu->num,&stu->score);
head=insert(head,stu);
print(head);
break;
case 'B':
printf("Please input the find number:\n");
scanf("%ld",&find_num);
head=find(head,find_num);
print(head);
break;
case 'C':
printf("Please input the delete number:\n");
scanf("%ld",&del_num);
head=del(head,del_num);
print(head);
break;
}
}while (letter != 'Q');
getch();
}