单链表的创建+ 求表长+ 查找+插入+删除

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

using namespace std;

struct node{
int data ;
struct node * next ;
} ;

//建立单链表，返回头结点
struct node * CreateLinkList(){
char ch ;
int x ;
struct node  * head ;
struct node * r , * P ;
head = (struct node *)malloc(sizeof(struct node)) ;
head->next  = NULL ;
r = head ;
ch =getchar( ) ;
while(ch != '*'){
//  cout<<"ch = " << ch<< endl;
scanf("%d" , & x) ;
// cout<<"x = " << x << endl;
P = (struct node *)  malloc(sizeof(struct node)) ;
P->data = x ;
P->next = NULL ;
r->next = P ;
r = r-> next ;
ch = getchar( ) ;
}
return head ;
}
//输出头结点为head表的单链表
void PutOut(struct node * head){
struct node * p = head ;
while(p->next != NULL){
p = p->next ;
cout<<p->data << endl;
}
}

//求头结点为head表表长
int LengthLinkList( struct node * head){
struct node * P =  head ;
int  j = 0 ;
while(P-> next != NULL){
P = P->next ;
j++ ;
}
return j ;
}

//元素的查找
//1在头结点为head表的单链表中查找值为x的节点，并返回其位置
struct node * LocateLinkList( struct node * head , int x){
struct node * p = head->next ;
while(p!= NULL && (p->data != x)){
p = p-> next ;
}
return p ;
}
//2在单链表head中查找第i个元素并返回其位置，无第i个元素返回NULL
struct node * GetLinkList(struct node* head , int i){
struct node * p = head ;
int j = 0 ;
while( j < i && (p->next != NULL)){
p = p -> next ;
j++ ;
}
if(j == i)
return p ;
else{
return NULL ;
}
}
//插入
//在头结点为head表的单链表中第i个位置上插入值为x的元素
struct node* insertLinkList(struct node * head , int x , int i){
struct node * p , * s ;
p = GetLinkList(head , i- 1 ) ; //找到第i个节点的前驱
if(p == NULL){
printf("第i-1个元素不存在，参数i有错\n") ;
}
else{
s = (struct node *) malloc(sizeof(struct node)) ;
s->data = x ;
s->next = p->next ;
p->next = s ;
}
return head ;
}
//删除单链表head中第i个节点 ， 并返回链表
struct node * deleteLinkList(struct node * head , int i){
struct node * p = GetLinkList(head , i - 1) ;
struct node * s ;
if(p == NULL)
printf("第i-1个元素不存在， 参数i有错 \n") ;
else{
s = p->next ;
p->next = s->next ;
free(s) ;
}
return head ;
}

int main(){
int i , x;
cout<<"建立单链表：（请输入【空格】1 2 3 4 5 6 7*）"<< endl;
struct node * h =  CreateLinkList() ;
cout<<"显示单链表"<< endl;
PutOut(h) ;
int len = LengthLinkList(h) ;
cout<<"该链表的表长 = " << len << endl;
struct node *  r ,  *r1;
r = LocateLinkList(h , 2) ;

cout<<"输出查找x = 2并返回其位置"<< endl;
cout << r->data << endl;
while(r->next != NULL){
r = r->next ;
cout<< r->data << endl;
}

r = GetLinkList(h , 3) ;
cout<<"输出查找第3个元素，并返回其位置"<< endl;
cout << r->data << endl;
while(r->next != NULL){
r = r->next ;
cout<< r->data << endl;
}

cout<<"在head单链表中第i个位置插入值为x,并返回链表"<< endl;
cout<<"请输入x"<< endl;
scanf("%d" , &x) ;
cout<<"请输入i"<<endl;
scanf("%d" , &i) ;

r1 = insertLinkList(h, x , i ) ;
cout<<"输出插入元素后的链表" << endl;
PutOut(r1) ;
cout<<"删除h单链表中第i个元素，并返回链表"<< endl;
cout<<"请输入i"<< endl;
scanf("%d" , &i) ;
r1 = deleteLinkList(h , i) ;
cout<<"输出删除后的链表" << endl;
PutOut(r1) ;
return 0 ;
}