当我选择7.如何从管理菜单中插入记录后，我如何返回所有结构，如果我返回管理菜单，我将再次看到该记录。
例如
用户：admin 通：管理
然后我选择2.Insert Product之后我会选择1.display，之后我7.log out。现在我想再次以管理员身份登录，但我希望再次查看所有数据。请帮助这是我们的论文项目。
#include <iostream>
#include <string>
#include <iomanip>
#include <conio.h>
using namespace std;
struct product{
string pname,pid;
int qnty;
double price;
product *ptr;
};
//Function Declaration
void Menu(string username);
void InsertProduct();
void DeleteProduct();
void DisplayProduct();
void SearchProduct();
void PurchaseProduct();
//
product *head;
int main() //Account Login
{
int pw=0,n;
char pwc=' ';
string username,password;
cout<<"\n ==============================================================================="<<endl<<endl;
cout<<"\t\t\t LICA'S GROCERY STORE"<<endl<<endl;
cout<<" ==============================================================================="<<endl<<endl;
cout<<"\t\t\t Username: ";
getline(cin, username);
cout<<"\n\t\t\t Password: ";
do
{
pwc=getch();
if(pwc==13||pwc==' ')
{
break;
}
cout<<"*";
password+=pwc;
pw++;
}
while(pwc!=13||pwc!=' ');
n=username.length();
for(int a=0; a!=n; a++)
{
if(isupper(username.at(a)))
{
username.at(a) = tolower(username.at(a));
}
}
if(username=="admin" && password=="Admin")
{
system("CLS");
cout<<"\n ==============================================================================="<<endl<<endl;
cout<<"\t\t\t\t WELCOME ADMIN!"<<endl<<endl;
cout<<" ==============================================================================="<<endl<<endl;
Menu(username);
return main();
}
else if(username=="cashier" && password=="Cashier")
{
system("CLS");
cout<<"\n ==============================================================================="<<endl<<endl;
cout<<"\t\t\t\t WELCOME CASHIER!"<<endl<<endl;
cout<<" ==============================================================================="<<endl<<endl;
Menu(username);
}
else
{
system("CLS");
cout
<<"\n\t\t Invalid Username or Password. Please Try Again"<<endl;
return main();
}
system("pause");
return 0;
}
//
//
//
//
//
void Menu(string username)
{
head=NULL;
int menu;
if(username=="admin")
{
do
{
cout
<<"\t MENU: "
<<"\n\n\t\t\t A. FILE MAINTENANCE" <<endl
<<"\n\t\t\t\t 1. Display All Products"<<endl
<<"\t\t\t\t 2. Insert New Product"<<endl
<<"\t\t\t\t 3. Delete A Product" <<endl
<<"\t\t\t\t 4. Search A Product"<<endl
<<"\n\t\t\t B. SALES MODULE"<<endl
<<"\n\t\t\t\t 5. Cashier"<<endl
<<"\t\t\t\t 6. Print Receipt."<<endl
<<"\n\t\t\t C. EXIT"<<endl
<<"\n\t\t\t\t 7. Log Out"<<endl;
cout<<"\n\t Choose an option (1 to 7 only): ";
cin>>menu;
cin.ignore();
switch(menu)
{
case 1:
cout<<"\n ============================================================================="<<endl<<endl;
cout<<"\t\t\t DISPLAY ALL PRODUCTS"<<endl<<endl;
cout<<" ============================================================================="<<endl<<endl;
DisplayProduct();
system("pause");
system("CLS");
break;
case 2:
cout<<"\n ============================================================================="<<endl<<endl;
cout<<"\t\t\t INSERT NEW PRODUCT"<<endl;
cout<<" ============================================================================="<<endl<<endl;
InsertProduct();
break;
case 3:
cout<<"\n ============================================================================="<<endl<<endl;
cout<<"\t\t\t DELETE A PRODUCT"<<endl;
cout<<" ============================================================================="<<endl<<endl;
DeleteProduct();
break;
case 4:
cout<<"\n ============================================================================="<<endl<<endl;
cout<<"\t\t\t SEARCH A PRODUCT" <<endl;
cout<<" ============================================================================="<<endl<<endl;
SearchProduct();
break;
case 5:
cout<<"\n ============================================================================="<<endl<<endl;
cout<<"\t\t\t PURCHASE PRODUCTS"<<endl;
cout<<" ============================================================================="<<endl<<endl;
PurchaseProduct();
case 7:
cout<<"\n\n THANK YOU ADMIN!"<<endl<<endl;
break;
default:
cout<<"\n\n INVALID INPUT!"<<endl<<endl;
}
}while(menu!=7);
}
else
{
cout
<<"Choose an Option"
<<"\n1.Sales Module"
<<"\n2.Exit"<<endl;
cin>>menu;
switch(menu)
{
case 1:
cout<<"Sales Module";
break;
case 2:
cout<<"Exit!";
break;
default:
cout<<"Invalid Input!";
}
}
}
void InsertProduct()
{
product *newproduct;
newproduct=new product;
cout<<"\n\n\tEnter Product Name:";getline(cin,newproduct->pname);
cout<<"\n\tEnter Product Quantity:";cin>>newproduct->qnty;
cout<<"\n\tEnter Product ID:";cin>>newproduct->pid;
cout<<"\n\tEnter Product Price:";cin>>newproduct->price;
cin.ignore();
newproduct->ptr=NULL;
if(head==NULL)
head=newproduct;
else
{
product *lastproduct;
lastproduct=head;
while(lastproduct->ptr!=NULL)
lastproduct=lastproduct->ptr;
lastproduct->ptr=newproduct;
}
cout<<"\n\tProduct is inserted"<<endl;
system("pause");
system("CLS");
}
void DeleteProduct()
{
DisplayProduct();
product *current,*previous;
current=head;
int x;
if (current==NULL)
{
cout<<"\n\t\tNo Products Found.";
}
else
{
cout<<"\n\t\tEnter Product No. to delete:";
cin>>x;
int i=1;
if(x==1)
{
head=current->ptr;
delete current;
cout<<"\n\t\tProduct is deleted";
DisplayProduct();
}
else
{
while(i<x&¤t!=NULL)
{
previous=current;
current=current->ptr;
i=i++;
}
if(current==NULL)
{
cout<<"\n\t\tProduct does not Exist";
}
else
{
previous->ptr=current->ptr;
delete current;
cout<<"\n\t\tProduct is deleted";
DisplayProduct();
}
}
}
system("pause");
system("CLS");
}
void DisplayProduct()
{
product *current;
current=head;
int i=1;
cout<<setiosflags(ios::left);
while(current!=NULL)
{
cout<<"\n\t\t"<<setw(4)<<i;
cout<<setw(25)<<current->pname<<setw(3)<<current->qnty <<setw(3)<<current->pid <<setw(3)<<current->price;
current=current->ptr;
i++;
}
}
void SearchProduct()
{
string sid;//Name to search
product *current;
current=head;
if (current==NULL)
cout<<"\n\t\tNo Products Found";
else
{
cout<<"\n\t\tEnter product to search: ";
cin>>sid;
int i=1;
while(sid.compare(current->pid))
{
current=current->ptr;
if (current==NULL)
break;
i++;
}
if(current!=NULL)
cout<<"\n\t\t"<<current->pid<<" is Product No."<<i;
else
cout<<"\n\t\t"<<sid<<" is not in the list.";
DisplayProduct();
cout<<endl;
}
system("pause");
system ("CLS");
}
void PurchaseProduct()
{
}
答案 0 :(得分：0)
您的数据在内存中，直到您将其保存到硬盘，因此您需要实现某种机制来实现这一目标。
您可以选择多种选项，例如使用数据库，普通文件（XML，YAML，JSON等等...）和对象searialization 我认为这是你现在最好的选择。有几个库可以做到这一点，但是一开始我建议你使用这个tutorial。然后转到A practical guide to C++ serialization。
我建议序列化，因为我意识到你刚刚开始使用C ++。而其他选项如数据库和格式化文件（xml，Yaml等等）需要更复杂的代码。
玩得开心!!!在您阅读了所有这些内容并（尝试将其付诸实践）之后，如果您仍然无法解决问题，请回到这里，我们将很乐意为您提供帮助。