Question

C语言中怎样用链表实现增删改查

要求写出程序代码（最好有注释！）

Answer 1

#include <stdio.h>
#include <stdlib.h>

typedef struct node
{
int nDate;
struct node *pstnext;
}Node;

//链表输出
void output(Node *head)
{
Node *p = head->pstnext;
while(NULL != p)
{
printf("%d ", p->nDate);
p = p->pstnext;
}
printf("\r\n");
}

//链表建立
Node* creat()
{
Node *head = NULL, *p = NULL, *s = NULL;
int Date = 0, cycle = 1;
head = (Node*)malloc(sizeof(Node));
if(NULL == head)
{
printf("分配内存失败\r\n");
return NULL;
}
head->pstnext = NULL;

p = head;
while(cycle)
{
printf("请输入数据且当输入数据为0时结束输入\r\n");
scanf("%d", &Date);
if(0 != Date)
{
s = (Node*)malloc(sizeof(Node));
if(NULL == s)
{
printf("分配内存失败\r\n");
return NULL;
}
s->nDate = Date;
p->pstnext = s;
p = s;
}
else
{
cycle = 0;
}
}
p->pstnext = NULL;
return(head);
}

//链表按值查找
void research_Date(Node *head, int date)
{
Node *p;
int n=1;
p = head->pstnext;
while(NULL != p && date != p->nDate)
{
p = p->pstnext;
++n;
}
if(NULL == p)
{
printf("链表中没有找到该值");
}else if(date == p->nDate)
{
printf("要查找的值%d在链表中第%d个位置\r\n", date, n);
}
return;
}

//按序号查找
void research_Number(Node *head, int Num)
{
Node *p=head;
int i = 0;
while(NULL != p && i < Num)
{
p = p->pstnext;
i++;
}
if(p == NULL)
{
printf("查找位置不合法\r\n");
}else if(i == 0)
{
printf("查找位置为头结点\r\n");
}else if(i == Num)
{
printf("第%d个位置数据为%d\r\n", i, p->nDate);
}
}

//在指定元素之前插入新结点
void insert_1(Node *head, int i, int Newdate)
{
Node *pre = head, *New = NULL;
int j = 0;
while(NULL != pre && j < i-1)
{
pre = pre->pstnext;
j++;
}
if(NULL == pre || j > i-1)
{
printf("插入位置不存在\r\n");
}else
{
New = (Node*)malloc(sizeof(Node));
if(NULL == New)
{
printf("分配内存失败\r\n");
return;
}
New->nDate = Newdate;
New->pstnext = pre->pstnext;
pre->pstnext = New;
}

}

//在指定元素之后插入新结点
void insert_2(Node *head, int i, int Newdate)
{
Node *pre = head, *New = NULL;
int j = 0;
while(NULL != pre->pstnext && j < i)
{
pre = pre->pstnext;
j++;
}
if(j == i)
{
New = (Node*)malloc(sizeof(Node));
if(NULL == New)
{
printf("分配内存失败\r\n");
return;
}
New->nDate = Newdate;
New->pstnext = pre->pstnext;
pre->pstnext = New;
}else
{
printf("插入位置不存在\r\n");
}
}

//删除指定结点
void Delete_1(Node *head, int i3)
{
Node *p = head, *pre = NULL;
int j = 0;
while(NULL != p && j < i3)
{
pre = p;
p = p->pstnext;
j++;
}
if(NULL == p)
{
printf("删除位置不存在\r\n");
}else
{
pre->pstnext = p->pstnext;
free(p);
}
}

void main()
{
int date, num; //待查找数据
int i3; //指定删除元素的位置
int i1, i2, Newdate_1, Newdate_2; //待插入的新数据
Node *Head = NULL; //定义头结点
Node *Head_New = NULL;

//链表建立
Head = creat();
printf("输出建立的单链表\r\n");
output(Head);

//链表按值查找
printf("请输入待查找的数据\r\n");
scanf("%d", &date);
research_Date(Head, date);

//链表按序号查找
printf("请输入待查找序号\r\n");
scanf("%d", &num);
research_Number(Head, num);

//在指定第i1个元素之前插入新元素Newdate
printf("在指定第i个元素之前插入新元素Newdate");
printf("请输入i与元素且以逗号间隔\r\n");
scanf("%d,%d", &i1, &Newdate_1);
insert_1(Head, i1, Newdate_1);
printf("插入后新链表\r\n");
output(Head);

//在指定第i2个元素之后插入新元素Newdate
printf("在指定第i个元素之后插入新元素Newdate");
printf("请输入i与元素且以逗号间隔\r\n");
scanf("%d,%d", &i2, &Newdate_2);
insert_2(Head, i2, Newdate_2);
printf("插入后新链表\r\n");
output(Head);

//指定删除i3元素
printf("删除元素的位置\r\n");
scanf("%d", &i3);
Delete_1(Head, i3);
printf("删除后新链表\r\n");
output(Head);

return;
}