C++实现单链表的增删改查

#include<iostream>
#include<string>
#include<iomanip>
#include<algorithm>
using namespace std;

int n=0;
struct node {
	int num;
	struct node*next;
};
//创建链表
node *creat()
{
	cout << "输入数据个数：" << endl;
	cin >> n;
	node *head;
	node *p, *r;  //p2指向尾部
	head = new node;
	head->next = NULL;
	cout << "num:" << endl;
	int num;
	cin >> num;
	head->num = num;
	p=r = head;
	for (int i = 0; i < n - 1; i++)
	{
		p = new node;
		p->next = NULL;
		cout << "num:" << endl;
		cin >> num;
		p->num = num;
		r->next = p;
		r = p;
	}
	r->next = NULL;
	return head;

}
//删除链表
node *del(node*head, int key)
{
	node *p, *r;//r是要删除的结点
	if (head == NULL)
	{
		cout << "list null!" << endl;
		return head;
	}
	p = head;
	while (p->next != NULL)
	{
		if (p->next->num == key)
		{
			r = p->next;
			p->next = r->next;
			delete(r);
			cout << "删除结点成功！" << endl;
			return head;
		}
	}
	cout << "不存在该结点！" << endl;
	return head;
}
//插入链表
node *insert(node *head, int key)
{
	node *p = new node;
	node *r = head;
	p->next = NULL;
	p->num = key;
	while (r) {
		if (r->next->num > key)
			break;
		r = r->next;
	}
	p->next = r->next;
	r->next = p;
	cout << "插入成功！" << endl;
	return head;
}
//输出链表
void print(node *head)
{
	node *p = head;
	while (p) {
		cout << p->num << ' ';
		p = p->next;
	}
	cout << endl;
}
int main()
{
	node *head;
	head=creat();
	print(head);
	cout << "输入要删除的数：" << endl;
	int key;
	cin >> key;
	del(head, key);
	print(head);
	cout << "输入要插入的数：" << endl;
	cin >> key;
	insert(head, key);
	cout << "输出最后的链表：" << endl;
	print(head);
	return 0;
}