[置顶] 常见的链表操作

#include <stdio.h>  
#include<malloc.h>  
#define LEN sizeof(struct student )  
#define NULL 0  
struct student   
{  
    int num;  
    float score;  
    struct student *next;  
};  
int n;  
//建立链表  
struct student *create(void)  
{  
    struct student *head, *p1,*p2;  
    n=0;  
    p1=p2=(struct student *)malloc(LEN);  
    scanf("%d %f",&p1->next,&p1->score);  
    head=NULL;  
    while(p1->num!=0)  
    {  
        n=n+1;  
        if(n==1) head=p1;    //p1是指向新开辟的结点  
        else p2->next=p1;  
        p2=p1;    //p2指向链表中的最后一个基点  
        p1=(struct student *)malloc(LEN); //开辟新的结点，并且使p1指向他  
        scanf("%d %f",&p1->num,&p1->score);  
    }  
    p2->next=NULL;  
    return (head);  
}  
//删除结点  
struct student *del(struct student  *head,long num)  
{  
    struct student *p1,*p2;  
      
    if(head==NULL)   {printf("\nlist null!\n");goto end;}  
    p1=head;  
    while(num!=p1->num && p1->next!=NULL)   //p1指向不是所要找的结点，并且后面还有结点  
    {  
        p2=p1;  
        p1=p1->next;      //p1后移一个及诶单  
    }       //p1后移一个结点  
    if(num==p1->num)     //找到了  
    {  
        if(p1==head)  head=p1->next;    //若p1指向的是首结点，把第二个结点的地址head  
  
        else p2->next=p1->next;      //or 将下一个结点的地址赋给前一个结点地址  
        printf("delete:%d\n",num);  
        n=n-1;  
        free(p1);  
    }  
    else  printf("%dnot been found !\n",num);  
    end:  
    return(head);  
  
  
}  
//插入学生信息  
 struct student *insert(struct student *head ,struct student *stud)  
{  
    struct student *p0,*p1,*p2;  
    p1=head;         //使p1指向第一个结点  
    p0=stud;        //p0指向要插入的结点  
    if(head==NULL)     //原来的链表是空表  
    {  
        head=p0,p0->next=NULL; //使p0指向的结点作为头结点  
    }  
    else  
    {  
        while ((p1->num>p1->num)&&(p1->next!=NULL))  
        {  
            p2=p1;     //使p2指向刚才p1指向的及诶按  
            p1=p1->next;    //p1后移一个结点  
        }  
        if(p0->num<=p1->num)  
        {  
            if(head==p1)  head=p0;   //插到原来第一个结点之前  
            else p2->next=p0;        //插到p2指向的结点之后  
            p0->next=p1;  
        }  
        else  
        {  
            p1->next=p0;p0->next=NULL;    //插到最后的结点之后  
        }  
    }  
    n=n+1;                            //结点数加1  
    return (head);  
}  
//输出链表  
 void print(struct student *head)  
{  
    struct student *p;  
    p=head;  
    if(head!=NULL)  
        do  
    {  
        printf("%d %f\n",p->num,p->score);  
        p=p->next;  
  
    }  
    while(p!=NULL);  
}  
//main函数  
 void main()  
{  
    struct student *head,stu;  
    long del_num;  
    printf("Input records:\n");  
    head=create();        //建立链表，返回头指针  
    print(head);          //输出全部结点  
  
    printf("\nInput the deleted number:\n");  
    scanf("%ld",&del_num);       //输入要删除的学号  
    while(del_num!=0)  
    {  
    head=del(head,del_num);      //删除后链表的头指针  
    print(head);                       //输出全部结点  
    printf("Input the deleted number:\n");  
    scanf("%ld",&del_num);   
    }  
  
    printf("\nInput the inserted record:\n");  
    stu=(struct student *)malloc(LEN);  
    scanf("%d %f",&stu->num,&stu->score);     //输入要插入的结点  
    {  
    head=insert(head,&stu);                 //插入一个结点，返回头指针的  
    print(head);                                     //输出全部结点  
    printf("\nInput the inserted record:\n");  
    stu=(struct student *)malloc(LEN);  
    scanf("%d %f",&stu->num,&stu->score);  
    }  
}