C++建立动态链表

#include<iostream>
#include<string>
using namespace std;
class book
{
public:
int num;
double price;
book* next;
};
bool check（string str）
{
for（int i=0;i<str.length（）;i++）
{
   if（（str[i]>"9"||str[i]<"0"）&&（str[i]！="."））
    return false;
}
return true;
}book* create（）
{
book *p1,*p2=NULL,*head=NULL;
p1=new book;
head=p1;
p2=p1;
cout<<"please enter number of book,then 0 to end: ";
string str_num,str_price;
cin>>str_num;
while（！check（str_num））
{cout<<"the enter of your is error,please enter true number: ";cin>>str_num;}
p1->num=atoi（str_num.c_str（））;
if（p1->num==0）
{
   delete p1;p2->next=NULL;p2=NULL;head=NULL;cout<<"p1->num=0 ";return head;
}
while（p1->num！=0）
{
   cout<<"please enter price of the book: ";
   cin>>str_price;
   while（！check（str_price））
   {cout<<"the enter of your is error;please enter true number: ";cin>>str_price;}
   p1->price=atof（str_price.c_str（））;
   p2=p1;
   p1=new book;
   p2->next=p1;
   cout<<"please enter number of book,then 0 to end: ";
   cin>>str_num;
   while（！check（str_num））
   {cout<<"the enter of your is error;please enter true number: ";cin>>str_num;}
   p1->num=atoi（str_num.c_str（））;
   cout<<p1->num;
}
delete p1;
p2->next=NULL;
return head;
}void print（book* head）
{
book* p;
p=head;
cout<<"num"<<" "<<"price"<<" ";
while（p）
{
   cout<<p->num<<" "<<p->price<<" ";
   p=p->next;
}
delete p;
}
int main（）
{
book* head=NULL;
head=create（）;
print（head）;
delete head;
return 0;
}