单链表的实现---数据结构学习（一）

线性表的链式存储结构即为单链表，单链表可方便的进行插入、删除，但不具备随机存储的特点。

具体的实现如下：（包括初始化，插入，删除，输出和求链表长度）

#include<iostream>

using namespace std;

int getlen();

struct node

{
int data;
node *next;

};

node *head;

void init()

{
node *p;
p = (node*)new node;
int x, n;
cout << "输入链表长度：";
cin >> n;
for (int i = 1; i <= n; i++)
{
node *news;
news = (node*)new node;
cout << "输入第" << i << "个数:";
cin >> x;
news->data = x;
news->next = NULL;
if (i==1)
{
p = news;
head = p;
}
else
{
p->next = news;

p = news;
}
}
cout << "初始化完成！" << endl;

}

void output()

{
node *p;
p = head;
cout << "当前链表是：";
while (p != NULL)
{
cout << p->data<<" ";
p = p->next;
}
cout << endl;

}

void insert()

{
node *p;
p = head;
node *news;
news = (node*)new node;
int x, n,m;
m = getlen();
cout << "输入插入位置：";
cin >> n;
if (n<1 || n>m + 1)
{
cout << "该位置不存在！";
exit(0);
}
cout << endl;
cout << "插入的值是：";
cin >> x;
news->data = x;
news->next = NULL;
if (n==1)
{
news->next = head;
head = news;
}
else
{
for (int i = 1; i < n-1; ++i)
{
p = p->next;
}
news->next = p->next;
p->next = news;
}

}

void dele()

{
node *p;
p = head;
node *news = (node*)new node;
int  n,m;
m = getlen();
cout << "输入删除位置：";
cin >> n;
if (n<1 || n>m)
{
cout << "位置不存在！";
exit(0);
}
if (n == 1)
{
head = p->next;
free(p);
}
else
{
for (int i = 1; i < n - 1; ++i)
p = p->next;
news = p->next;
p->next = news->next;
free(news);
}

}

int getlen()

{
node *p;
p = head;
int n = 0;
while (p != NULL)
{
n++;
p = p->next;
}
cout << "链表长度是：" << n << endl;
return n;

}

int main()

{
init();
output();
insert();
getlen();
output();
dele();
getlen();
output();

}