The code now works and adds a new user, I just need to save it$,$ and when the user asks me$,$ the new one I create will let me enter the main menu normally.

int main$()\{$

vector elements $=\{$

Article$("$Paper$",50),$

Article$("$Feather$",20),$

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

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

Article$("$Draft$",5)$

$\}$;

vector cart;

string inputUser, inputPass;

while $($true$)\{$

cout $<<$ "User: $"$;

cin $>>$ inputUser;

cout $<<$ "Password: $"$;

cin $>>$ inputPass;

if $($User::validateUser$($inputUser$,$ inputPass$))\{$

cout $<<"---$ Welcome to my online store $---"<>$ response;

if $($response $=="*")\{$

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

cin $>>$ inputUser;

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

cin $>>$ inputPass;

cout $<<$ "User successfully registered.

$"$;

continue;

$\}$

$\}$

$\}$

internal choice;

do $\{$

cout $<<"1.$ View articles" $<<$ endl;

cout $<<"2.$ View cart" $<<$ endl;

cout $<<"3.$ Exit" $<<$ endl;

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

cin $>>$ election;

change $($choice$)\{$

Case $1$: $\{$

int subselection;

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 $($suboption $==1||$ suboption $==2)\{$

double price limit;

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

cin $>>$ price limit;

cout $<<$ "Available items:

$"$;

for $($int i $=0$; i $<$ elements.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 element name;

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

cin $>>$ element name;

for $($const self and item: items$)\{$

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

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

$\}$

$\}$

$\}$

char addToCart;

cout $<<"$Do you want to add an item to your cart? $($Y$/$N$)$: $"$;

cin $>>$ addToCart;

if $($addToCart $==\text{'}$Y$\text{'}||$ addToCart $==\text{'}$y$\text{'})\{$

int itemNumber;

int itemQuantity;

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

cin $>>$ itemNumber;

cout $<<$ "Enter the amount: $"$;

cin $>>$ itemQuantity;

if $($itemNumber $>0$ && itemNumber $<=$ items.size$())\{$

items$[$itemNumber $-1].$setQuantity$($itemQuantity$)$;

cart.push$\_$back$($items$[$itemNumber $-1])$;

cout $<<$ "Item added to cart." $<<$ endl;

$\}$

else $\{$

cerr $<<$ "Invalid item number." $<<$ endl;

$\}$

string cont;

cout $<<"$Do you want to exit to the main menu or continue adding items?$($Menu$/$Add$)$: $"$;

cin $>>$ cont;

while $($cont $==$ "Add"$)\{$

int itemNum, qty;

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

cin $>>$ itemNum;

cout $<<$ "How many pieces?";

cin $>>$ qty;

items$[$itemNum $-1].$setQuantity$($qty$)$;

cart.push$\_$back$($items$[$itemNum $-1])$;

cout $<<$ "Item added to cart.

$"$;

cout $<<"$Do you want to exit to the main menu or continue adding items?$($Menu$/$Add$)$: $"$;

cin $>>$ cont;

$\}$

$\}$

break;

$\}$

case $2$: $\{$

cout $<<$ "Your cart:" $<<$ endl;

double total $=0$;

for $($size$\_$t i $=0$; i $<$ cart.size$()$; i$++)\{$

cout $<<($i $+1)<<"."<<$ cart$[$i$].$getName$()<<",$ Price: $$"<<$ cart$[$i$].$getPrice$()<<",$ Quantity: $"<<$ cart$[$i$].$getQuantity$()<<$ endl;

total $+=$ cart$[$i$].$getPrice$()*$ cart$[$i$].$getQuantity$()$;

$\}$

cout $<<$ "Total cost: $$"<<$ total $<<$ endl;

string checkout;

cout $<<"$Do you want to pay or continue shopping?? $($Pay$/$Continue$)$: $"$;

cin $>>$ checkout;

if $($checkout $==$ "Checkout"$)\{$

cout $<<$ "Press Ok to close the sale..

$"$;

string Ok;

cin $>>$ Ok;

if $($Ok $=="$Ok$")\{$

cout $<<$ "Sale successfully closed. Thank you for shopping with us$!"<<$ endl;

cart.clear$()$;

$\}$

$\}$

break;

$\}$

case $3$:

cout $<<$ "Goodbye!" $<<$ endl;

break;

default:

cerr $<<$ "Invalid choice." $<<$ endl;

break;

$\}$

$\}$ while $($choice $!=3)$;

return $0$;

$\}$