using class instance on two classes..c++

Question

I basically do not know how to ask this question, I am fairly new to c++...anyway my problem is, I am trying to create this vendingmachine class and this user class, the user needs to have access to the insertCoins method and makePurchase methods from vendingMachine.cpp I tried creating an instance of the class vending machine inside the method calls in user.cpp as it is here, but when I try to list the items in vending machine obviously the list is untouched because theinstance I create inside the method calls in user.cpp are just temporary...how would I get a global instance so that I use it within user.cpp while using it within vending machine inside main.cpp...

#include "user.h"
#include "VendingMachine.h"

user::user(){
}

user::~user(){

}

void user::makePurchase(int choice){
    VendingMachine vm;
    vm.purchaseProduct(choice);
}

void user::insertCoins(double coin){
    VendingMachine vm;
    vm.insertCoins(coin);
}

~~~~~~~~~~~~~

#include "VendingMachine.h"
#include "machineOperator.h"
#include "user.h"
using namespace std;

int main(){

VendingMachine vm = VendingMachine();
user u = user();
vm.listProducts();
cout << endl;
u.insertCoins(1.0);
u.insertCoins(1.0);
u.makePurchase(2);
vm.listProducts();
cout << endl;

return 0;

 }

~~~~~~~~~~~~~~~~~~~

    /*
 * user.h
 *
 *  Created on: Jan 12, 2014
 *      Author: Andrey
 */

#ifndef USER_H_
#define USER_H_

class user {

public:
    user();
    ~user();
    void makePurchase(int);
    void insertCoins(double);
};

#endif /* USER_H_ */

Blacktempel · Accepted Answer · 2014-01-13 08:04:46Z

4

It is natural to assume that a user can purchase from and insert coin to many different vending machines.

void user::makePurchase (VendingMachine &vm, int choice)
{
    vm.purchaseProduct(choice);
}

void user::insertCoins (VendingMachine &vm, double coin)
{
    vm.insertCoins(coin);
}

edited Jan 13, 2014 at 8:04

Blacktempel

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answered Jan 13, 2014 at 7:30

user534498

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13 Comments

Andrey Arias Over a year ago

I tried this but it gives me this..."prototype for 'void user::makePurchase(VendingMachine&, int)' does not match any in class 'user' "

pingul Over a year ago

@AndreyArias You have to add it your user declaration (user.h), as you must have done with all your other functions.

Blacktempel Over a year ago

@AndreyArias: I am assuming the first code snippet in your question is the header #include "machineOperator.h". You included the header files: #include "VendingMachine.h" and #include "user.h" in the main.cpp too. Remove those from there and it will work.

Blacktempel Over a year ago

@AndreyArias: As I think this is not really an answer (as long as it is not the solution) and I don't want to mess it up as comment... here is it: pastebin.com/yjEZwTnq

Blacktempel Over a year ago

Use the forward declaration class VendingMachine; before your class user {...};.

|

Raniz · Accepted Answer · 2014-01-13 13:04:28Z

0

Use a pointer to the VendingMachine in your user and pass it in to the constructor.

user.h

class VendingMachine;

class User {
    private:
        VendingMachine* vm;
}

user.cc

#include "user.h"
#include "vendingmachine.h"

User::User(VendingMachine* vm): vm(vm) {}

void User::makePurchase(int choice){
    vm->purchaseProduct(choice);
}

void User::insertCoins(double coin){
    vm->insertCoins(coin);
}

main.cc

#include "VendingMachine.h"
#include "machineOperator.h"
#include "user.h"
using namespace std;

int main(){

    VendingMachine vm = VendingMachine();
    User u = User(&vm);
    vm.listProducts();
    cout << endl;
    u.insertCoins(1.0);
    u.insertCoins(1.0);
    u.makePurchase(2);
    vm.listProducts();
    cout << endl;

    return 0;

}

edited Jan 13, 2014 at 13:04

answered Jan 13, 2014 at 7:31

Raniz

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1 Comment

Raniz Over a year ago

user534498's reply probably makes more sense with passing the vending machine to the methods.

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