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();
}