简单的单向链表

简单的单向链表

  ElemType READ();
 int LENGTH(LinkList list);
 int ISEMPTY(LinkList list);
 LinkList FIND(LinkList list,ElemType item);
 int INSERTLINK(LinkList list,int i,ElemType item);
 void DELETELIST(LinkList list);

  1 #include<stdio.h>
  2 #include<stdlib.h>
  3 #include <string.h>
  4 typedef int ElemType;
  5 //链结点类型
  6 typedef struct node{
  7     ElemType  data;
  8     struct node *link;
  9 }LNode,*LinkList;
 10 ElemType READ();
 11 int LENGTH(LinkList list);
 12 int ISEMPTY(LinkList list);
 13 LinkList FIND(LinkList list,ElemType item);
 14 //在非空线性链表的第i个链结点后插入一个数据信息为item的链节点
 15 int INSERTLINK(LinkList list,int i,ElemType item);
 16 void DELETELIST(LinkList list);
 17 ElemType READ()
 18 {
 19     ElemType a;
 20     printf("Please input a number
");
 21     scanf("%d",&a);
 22     return a;
 23 }
 24 //建立一个线性链表
 25 LinkList CREATE(int n)
 26 {
 27     //p:新结点指针 r:尾部指针 list:头指针
 28     LinkList p,r,list = NULL;
 29     ElemType a;
 30     int i = 0;
 31     for(i = 0 ;i<n;i++)
 32     {
 33         a = READ();
 34         p = (LinkList)malloc(sizeof(LNode));
 35         p->data = a;
 36         p->link = NULL;
 37         if(list == NULL)
 38             list  = p;
 39         else
 40             r->link = p;
 41         r = p;
 42     }
 43     return (list);
 44 }
 45 void OUTPUT(LinkList list)
 46 {
 47     LinkList p;
 48     p = list;
 49     if(p == NULL){printf("linklist is empty
");return;}
 50     while(p!=NULL)
 51     {
 52         printf("%d ",(p->data));
 53         p = p->link;
 54     }
 55     printf("
");
 56 }
 57 int main()
 58 {
 59     int n,op;
 60      printf("Please input the size of LinkList
");
 61     scanf("%d",&n);
 62     LinkList list = CREATE(n);
 63     OUTPUT(list);
 64     while(1)
 65     {
 66         printf("option:
1:insert 2:delete 3:build
");
 67         scanf("%d",&op);
 68         switch(op)
 69         {
 70             case 1:
 71                 printf("input position and value
");
 72                 int pos,val;
 73                 scanf("%d%d",&pos,&val);
 74                 INSERTLINK(list,pos,val);
 75                 OUTPUT(list);
 76                 break;
 77             case 2:DELETELIST(list);
 78                 //list = NULL;
 79                 OUTPUT(list);
 80                 break;
 81             case 3:
 82                 if(ISEMPTY(list))
 83                 {
 84                     printf("input the size of linklist
");
 85                     scanf("%d",&n);
 86                     list = CREATE(n);
 87                     OUTPUT(list);
 88                 }
 89                 else {printf("delete list at first
");}
 90                 break;
 91                 
 92             }
 93         }
 94 }
 95 int LENGTH(LinkList list)
 96 {
 97     int num=0;
 98     LinkList p = list;
 99     while(p!=NULL)
100     {
101         num++;
102         p = p->link;
103     }
104     return num;
105 }
106 int ISEMPTY(LinkList list)
107 {
108     return list == NULL;
109 }
110 //返回被查找节点的地址，否则返回NULL
111 LinkList FIND(LinkList list ,ElemType item)
112 {
113     LinkList p = list;
114     while(p!=NULL&&p->data!=item)
115     {
116         p = p->link;
117     }
118     return p;
119 }
120 int INSERTLINK(LinkList list ,int i,ElemType item)
121 {
122     //查找第i个结点
123     LinkList p = list,newNode;
124     int j = 1;
125     while(j<i&& p != NULL)
126     {
127         j++;
128         p = p->link;
129     }
130     if(j!=i||p==NULL)
131     {
132         printf("链表中不存在第i个链结点
");
133         return -1;
134     }
135     newNode = (LinkList)malloc(sizeof(LNode));//申请一个新的链结点
136     newNode -> data = item;
137     newNode -> link = p->link;
138     p->link = newNode;
139     return 1;
140     
141 }
142 void DELETELIST(LinkList list)
143 {
144     LinkList p = list;
145     while(p!= NULL)
146     {
147         list = p->link;
148         free(p);
149         p = list;
150     }
151     list = NULL;//把整个链表删除后 让头指针为NULL list是指针 为什么 最后list!=NULL
152 }