Add the article class as a$.$txt file or text file, just like the user class.

User class

#include

#include

#include

using namespace std;

class User $\{$

private:

string username;

string password;

public:

User$($const string & user, const string & pass$)$ : username$($user$),$ password$($pass$)\{\}$

bool authenticate$($const string & inputUser, const string & inputPass$)$ const $\{$

return $($username $==$ inputUser$)$ && $($password $==$ inputPass$)$;

$\}$

static bool validateUser$($const string & inputUser, const string & inputPass$)\{$

ifstream file$("$user$.$txt$")$;

if $(!$file.is$\_$open$())\{$

cerr $<<$ "Error opening file" $<<$ endl;

return false;

$\}$

string storedUser, storedPass;

while $($file $>>$ storedUser $>>$ storedPass$)\{$

if $($storedUser $==$ inputUser && storedPass $==$ inputPass$)\{$

return true;

$\}$

$\}$

return false;

$\}$

$\}$;

Main

int main$()\{$

vector items $=\{$

Item$("$Paper$",50),$

Item$("$Feather$",20),$

Item$("$Laptop$",100),$

Item$("$Pencil$",10),$

Item$("$Draft$",5)$

$\}$;

vector cart;

switch $($choice$)\{$

case $1$: $\{$

int subChoice;

cout $<<"1.$ View items below a certain price" $<<$ endl;

cout $<<"2.$ View items above a certain price" $<<$ endl;

cout $<<"3.$ Search by name" $<<$ endl;

cout $<<$ "Enter your choice: $"$;

cin $>>$ subChoice;

if $($subChoice $==1||$ subChoice $==2)\{$

double priceLimit;

cout $<<$ "Enter price limit: $"$;

cin $>>$ priceLimit;

cout $<<$ "Available items:

$"$;

for $($int i $=0$; i $<$ items.size$()$; i$++)\{$

if $(($subChoice $==1$ && items$[$i$].$getPrice$()<$ priceLimit$)||($subChoice $==2$ && items$[$i$].$getPrice$()>$ priceLimit$))\{$

cout $<<$ i $+1<<"."<<$ items$[$i$].$getName$()<<"-$ Price: $$"<<$ items$[$i$].$getPrice$()<<$ endl;

$\}$

$\}$

$\}$

else if $($subChoice $==3)\{$

string itemName;

cout $<<$ "Enter item name: $"$;

cin $>>$ itemName;

for $($const auto & item : items$)\{$

if $($item$.$getName$()==$ itemName$)\{$

cout $<<$ "Item: $"<<$ item.getName$()<<",$ Price: $$"<<$ item.getPrice$()<<$ endl;

$\}$

$\}$

$\}$