hi everyone im new to programming so excuse the noob question...
i tried every method to get through with the undefined refernce error but it keeps throwing that error at me
i tried using pointer "->" and the "::" sign and also the dot "."
what am i supposed to do? why cant it compile?
this is my cpp file:
#include <cstdlib>
#include "account.hpp"
using namespace std;
int Account::getAccountNumber()
{
return accountNumber;
}
double Account::getBalance()
{
return balance;
}
void Account::createAccount(LinkedList<Account>& accountsList, string name, int idNumber)
{
...
case 1:
accountsList.addFront(newAcc); //Where the error occurs.
break;
case 2:
do
{
cout << "\n\tWhich position would you like to insert the\n"
<< "\tnew account into?\n"
<< "\tPosition number: #";
cin >> target;
if (cin.fail())
{
cin.clear();
cin.ignore(20,'\n');
cout << "\n\n\tSorry, wrong input. Please enter a correct position.\n\n";
system("pause");
}
}
while(cin.fail());
accountsList.addMiddle(newAcc, target); //and here
break;
case 3:
accountsList.addEnd(newAcc); //and here
break;
}
cout << "\n\n\tAccount Created Successfully\n\n"
<< accountsList;
system("pause");
}
and here is my .hpp
#ifndef ACCOUNT_HPP_INCLUDED
#define ACCOUNT_HPP_INCLUDED
#include "linkedlist.hpp"
#include "generic.hpp"
class Account : public GenericAccount
{
int accountNumber;
double balance;
public:
Account(string name = "empty", int idNumber = 0, int accountNumber = 0, double balance = 0)
: GenericAccount(name, idNumber), accountNumber(accountNumber), balance(balance) {}
int getAccountNumber();
double getBalance();
void createAccount(LinkedList<Account>&, string, int);
void deposit(LinkedList<Account>&, Account&);
void withdraw(LinkedList<Account>&, Account&);
void displayAccount(LinkedList<Account>&, Account&);
void deleteAccount(LinkedList<Account>&);
friend istream& operator>> (istream& is, Account& x)
{
is >> x.accountNumber;
return is;
}
friend ostream& operator << (ostream& os, Account& c)
{
os << "Account Number= " << c.getAccountNumber() << "\t"
<< "Balance= "<< c.getBalance() << endl;
return os;
}
friend bool operator == (Account& a, Account& target)
{
return (a.getAccountNumber() == target.getAccountNumber());
}
};
#endif // ACCOUNT_HPP_INCLUDED
the full project can be downloaded HERE for refernce
THANK YOU ALL IN ADVANCE!
I think the issue is that there is that the addFront method is not being defined for the account type (in fact any type). See Why can templates only be implemented in the header file? for a much better explanation.
Moving the contents of cpp inline in the .h file should do the trick. Another option is to rename the the .cpp file to a .inl and include it at the bottom of linkedList.hpp
Related
I have an object of type piggyBank and I need to write data of this object into a file and then read it. I am aware of how to write/read to a text file but how can I overload the << operator so I can write data about the object into a file?
My code for the class here:
piggyBank.h
#include <string>
#ifndef PIGGYBANK_H
#define PIGGYBANK_H
class PiggyBank
{
private:
std::string owner;
int balance;
bool broken;
int id;
static int nrOfObjects;
public:
PiggyBank(void);
PiggyBank(std::string name);
std::string getOwnerName() const;
void setOwnerName(std::string name);
bool isBroken() ;
int getBalance(int & amount) ;
};
#endif /* PIGGYBANK_H */
piggyBank.cpp
#include "PiggyBank.h"
#include "readWrite.h"
#include <string>
#include <iostream>
using namespace std;
int PiggyBank::nrOfObjects = 0; // outside constructor
PiggyBank::getNrOfObjects(){
return nrOfObjects;
}
PiggyBank::PiggyBank(void){
{this->owner="";this->balance=0;this->broken=false;}
id = ++nrOfObjects;
}
PiggyBank::PiggyBank(std::string name, int startBalance){
{this->owner=name;this->balance=startBalance;this->broken=false;}
id = ++nrOfObjects;
}
string PiggyBank::getOwnerName() const{
return this->owner;
}
void PiggyBank::setOwnerName(string name){
this->owner = name;
}
bool PiggyBank::isBroken() {
return this->broken;
}
int PiggyBank::getBalance(int & amount) {
if(!broken){
amount = balance;
return 0;
}else{
return -1;
}
}
You want the << operator to be a friend to the class and to return ostream&.
Here is a simple example to get an idea about how it works.
friend ostream& operator << (ostream& os, const PiggyBank& obj)
{
// For example something like this
os << "Information that you want to output to the file:\n";
os << "Owner: " << obj.owner << "\n";
return os;
}
And then you can use it like this:
PiggyBack obj;
ofstream fout("file.txt");
// also check to see if the file opened correctly
if(fout.fail())
{
cout << "File failed to open\n";
return 0;
}
fout << obj;
// now you have written the owner information onto the file as well as the message before it
// inside the operator<< overload
// close the resource at the end
fout.close();
The cool part is that you can use it to print to the console too by changing fout to be cout.
For example:
cout << obj; // will print to the console
Very simple. Overload the inserter operator. Write this into your class:
friend std::ostream& operator << (std::ostream& os, const PiggyBank& pb) {
return os << pb.owner << . . . // Whatever you want
Then you can use the inserter operator as for any other data type:
int main() {
PiggyBank pb;
if (std::ofstream os("FileName"); os) {
os << pb << "\n";
}
return 0;
}
I'm trying to ovrerload the cout operator in an assignment and I was forced and asked to split my class into (.h and .cpp). Here is my full code:
instructor.h
#include "person.h"
#ifndef instructor_h
#define instructor_h
class instructor: public person {
private:
int children;
int salary;
string maritalStatus;
public:
instructor();
instructor(string, string, string, int , int ,string);
instructor operator++();
void print();
int calcSalary();
int getSalary();
int getNumOfChildren();
string getMarialStatus();
friend ostream &operator <<(ostream, instructor );
void setSalary(int);
void getNumOfChildren(int);
void setMarialStatus(string);
};
#endif
instructor.cpp
#include <iostream>
#include <string>
#include "instructor.h"
using namespace std;
instructor::instructor() {
}
instructor::instructor(string a , string b, string c , int chil , int sal ,string mar):person(a,b,c)
{
children = chil;
salary = sal;
maritalStatus = mar;
}
instructor instructor::operator ++()
{
children=children+1;
return *this;
}
int instructor::calcSalary() {
int new_sal;
new_sal = salary + children*0.1;
return new_sal;
}
int instructor::getSalary() {
cout <<"Here is the result of your query:"<<endl;
cout <<"================================="<<endl;
cout<< "Salary: "<<salary<<""<<endl;
cout <<"================================="<<endl;
cout <<endl;
return salary;
}
int instructor::getNumOfChildren() {
cout <<"Here is the result of your query:"<<endl;
cout <<"================================="<<endl;
cout<< "Number of children: "<<children<<""<<endl;
cout <<"================================="<<endl;
cout <<endl;
return children;
}
string instructor::getMarialStatus() {
cout <<"Here is the result of your query:"<<endl;
cout <<"================================="<<endl;
cout<< "Marital Status: "<<maritalStatus<<""<<endl;
cout <<"================================="<<endl;
cout <<endl;
return maritalStatus;
}
friend ostream& operator<<(ostream& os, instructor& v){
os << v.children;
return os;
}
void instructor::setSalary(int sal) {
salary = sal;
}
void instructor::getNumOfChildren(int nmc) {
children = nmc;
}
void instructor::setMarialStatus(string sms) {
maritalStatus = sms;
}
void instructor::print() {
person::print();
cout <<"Here is the result of your query:"<<endl;
cout <<"================================="<<endl;
cout<< "Marital Status: "<<maritalStatus<<""<<endl;
cout<< "Number of children: "<<children<<""<<endl;
cout<< "Salary: "<<salary<<""<<endl;
cout <<"================================="<<endl;
cout <<endl;
}
I am getting the following errors:
instructor.cpp(75) : error C2255: 'friend' : not allowed outside of a class definition
instructor.cpp(76) : error C2248: 'instructor::children' : cannot
access private member declared in class 'instructor' 1>
c:\documents and settings\george\my documents\visual studio
2005\projects\hana\hana\instructor.h(7) : see declaration of
'instructor::children' 1>
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
I am using visual studio 2005. Why am I getting those errors?
All of this is cause by my attempt in overloading the operator cout:
friend ostream& operator<<(ostream& os, instructor& v){
os << v.children;
return os;
}
Why is not working?
There are two problems. The first is that you can't use friend outside a class, as the error says. But you don't need to; having declared the function as a friend within the class you just define it outside without having to mention the friend-ness again.
But the other problem is that your declaration and definition don't match. You declared this as a friend:
ostream &operator <<(ostream, instructor );
And then you defined this:
ostream& operator<<(ostream&, instructor&)
Those aren't the same, but they need to be.
Not sure where I am at the moment, trying to figure it out. I need to initialize the members in print() const as it is giving me random gibberish. No matter what I try to do, it does not seem to work. Not sure what to even do. Can anyone give me a hand?
*edit: Added in the rest of the code. Forgot it when I submitted the first time.
Student.cpp
#include "student.h"
//implement the required 3 functions here
Student::Student(const char initId[], double gpa)
{
// initialize a newly created student object with the passed in value
}
bool Student::isLessThanByID(const Student& aStudent) const
{
// compare the current student object with the passed in one by id.
if (strcmp(id, aStudent.id) > 0)
{
return true;
}
else
{
return false;
}
}
bool Student::isLessThanByGpa(const Student& aStudent) const
{
// compare the current student object with the passed in one by gpa
if (gpa < aStudent.gpa)
{
return true;
}
else
{
return false;
}
}
void Student::print() const
{
cout << id << '\t' << gpa << endl;
}
student.h
#ifndef STUDENT_H
#define STUDENT_H
#include <iostream>
using namespace std;
class Student
{
public:
Student(const char initId[], double gpa);
bool isLessThanByID(const Student& aStudent) const;
bool isLessThanByGpa(const Student& aStudent) const;
void print()const;
private:
const static int MAX_CHAR = 100;
char id[MAX_CHAR];
double gpa;
};
#endif
app.cpp
#include "student.h"
int main()
{
Student s1("G10", 3.9);
Student s2("G20", 3.5);
s1.print();
s2.print();
if(s1.isLessThanByID(s2))
{
cout << "about right!" << endl;
}
else
{
cout << "uhmm ..." << endl;
}
if(!s1.isLessThanByGpa(s2))
{
cout << "about right!" << endl;
}
else
{
cout << "uhmm ..." << endl;
}
system("pause");
return 0;
}
There is nothing in that code that sets the values of Student::id and Student::gpa. Your constructor has parameters initId and gpa; you should copy those into your object. Based on the declaration of Student that you provided, something this should be appropriate:
Student::Student(const char initId[], double gpa) : gpa(gpa)
{
strncpy(id, initId, Student::MAX_CHAR-1);
id[Student::MAX_CHAR-1] = '\0';
}
I'm reading a book on C++ and was writing out some code to practice using the interface and implementation of a class. I've searched for solutions to my issue for a while to no avail.
I have a class with an enumeration inside of it. While trying to instantiate an object of that class, I am having trouble accessing the enum types outside of the class. I have tried using Book::Horror, Biblo::Horror, Biblo::Book::Horror, Horror, and even things like Biblo::Book::Genre::Horror. Can't seem to get it to let me access the types of the enum for the instantiation of my object in the main.cpp file.
Any help is appreciated! The more complex uses of C++ are still new to me. Here is my source:
book.h
#include <iostream>
#include <string>
using namespace std;
namespace Biblo{
class Book{
public:
enum Genre{
No_Genre, Horror, Comedy, Romance, Mystery
};
// The rest of this header is working fine I think, just this enum
class Invalid{}; // Used for throwing errors
Book(int n_ISBN, int n_copyrightYear, string n_title, string n_author, Genre n_genre);
Book();
// Accessors (non-modifying)
int getISBN() const { return ISBN; }
int getCopyrightYear() const { return copyrightYear; }
string getTitle() const { return title; }
string getAuthor() const { return author; }
string getGenre() const;
// Mutators
void changeAuthor(string newAuthor);
private:
int ISBN;
int copyrightYear;
string title;
string author;
Genre genre;
}; // End Book
// Helper Functions go here
bool operator==(const Book& a, const Book& b);
bool operator!=(const Book& a, const Book& b);
} // End Biblo
and main.cpp
#include <iostream>
#include "book.h"
using namespace std;
int main()
{
Biblo::Book book(100, 2012, "The Walrus", "The Eggman", Book::Horror); // THIS LINE GIVES ERROR
cout << "ISBN: " << book.getISBN() << endl;
cout << "Copyright: " << book.getCopyrightYear() << endl;
cout << "Title: " << book.getTitle() << endl;
cout << "Author: " << book.getAuthor() << endl;
cout << "Genre: " << book.getGenre() << endl;
return 0;
}
Edit: here is the book.cpp file
#include <iostream>
#include "book.h"
#include <string>
namespace Biblo{
Book::Book(int n_ISBN, int n_copyrightYear, string n_title, string n_author, Genre n_genre)
:ISBN(n_ISBN), copyrightYear(n_copyrightYear), title(n_title), author(n_author), genre(n_genre)
{
// constructor
}
Book::Book()
:ISBN(0), copyrightYear(0), title(""), author(""), genre(Genre::No_Genre)
{
// Default constructor
}
// Accessors
string Book::getGenre() const
{
if (Book.genre == Genre::No_Genre)
return "No Genre!";
if (Book.genre == Genre::Horror)
return "Horror";
if (Book.genre == Genre::Comedy)
return "Comedy";
if (Book.genre == Genre::Romance)
return "Romance";
if (Book.genre == Genre::Mystery)
return "Mystery";
}
// Mutators
void Book::changeAuthor(string newAuthor)
{
author = newAuthor;
}
// Helper Functions
bool operator==(const Book& a, const Book& b)
{
if (a.getISBN() != b.getISBN())
return false;
if (a.getCopyrightYear() != b.getCopyrightYear())
return false;
if (a.getTitle() != b.getTitle())
return false;
if (a.getAuthor() != b.getAuthor())
return false;
if (a.getGenre() != b.getGenre())
return false;
return true;
}
bool operator!=(const Book& a, const Book& b)
{
return !(a==b);
}
} // End Biblo
It seems you tried everything but the thing you needed! The enum is nested inside the Book class which is within the Biblo namespace. The code you are looking for is:
int main()
{
Biblo::Book book(100, 2012, "The Walrus", "The Eggman", Biblo::Book::Horror);
return 0;
}
You need to include the enum class. eg.:
Biblio::Book::Genre::Horror
Bunch of things that are going wrong really.
As others mentioned your enum is stashed one level deeper than you think it is, and your complaint about fixing it then producing an undefined reference is probably because at that point you bump into the fact there's nothing much initialized, and if you got past that you are returning items somewhat poorly when it comes to the enumerator.
If you use the right name space, quickly put in an actual implementation for the constructor, and get the most immediate return for your enum (an int might work) it should work, and probably look like this:
#include <iostream>
#include <string>
using namespace std;
namespace Biblo{
class Book{
public:
enum Genre{
No_Genre, Horror, Comedy, Romance, Mystery
};
// The rest of this header is working fine I think, just this enum
class Invalid{}; // Used for throwing errors
Book(int n_ISBN, int n_copyrightYear, string n_title, string n_author, Genre n_genre);
Book();
// Accessors (non-modifying)
int getISBN() const { return ISBN; }
int getCopyrightYear() const { return copyrightYear; }
string getTitle() const { return title; }
string getAuthor() const { return author; }
int getGenre() const { return genre; }
// Mutators
void changeAuthor(string newAuthor);
private:
int ISBN;
int copyrightYear;
string title;
string author;
Genre genre;
}; // End Book
Book::Book(int n_ISBN, int n_copyrightYear, string n_title, string n_author, Genre n_genre){
ISBN = n_ISBN; copyrightYear = n_copyrightYear; title = n_title; author = n_author;
};
}
using namespace std;
int main()
{
Biblo::Book book(100, 2012, "The Walrus", "The Eggman", Biblo::Book::Horror); // THIS LINE GIVES ERROR
cout << "ISBN: " << book.getISBN() << endl;
cout << "Copyright: " << book.getCopyrightYear() << endl;
cout << "Title: " << book.getTitle() << endl;
cout << "Author: " << book.getAuthor() << endl;
cout << "Genre: " << book.getGenre() << endl;
return 0;
}
Are you sue the book you're following isn't discussing details such as initializer lists or something else for constructors concurrent to, or previous to, the subjects you're looking at?
The code looked somewhat incomplete.
Edited in line here on SO, so bear with the poor formatting and the merged h/cpp look :)
I'm taking a class in C++ and I've run into a problem. We have to create a list of bankaccounts that each have their own savings and checking account. I've come quite far, but now I have to use "ofstream& fout" to print the checking and savings of an imaginairy account.
My header file of "Account.h" looks like this (I think it's correct):
#include <iostream>
#include <cmath>
#include <fstream>
#ifndef ACCOUNT_H
#define ACCOUNT_H
using namespace std;
class Account{
protected:
string number;
double balance;
public:
Account(){}
Account(string nr, double bl);
void deposit(double am);
string get_number();
double get_balance();
double withdraw(double am);
bool equals(Account other);
virtual void print();
void println();
void println(string s);
virtual void println(ofstream& fout);
virtual void read(ifstream& fin);
};
#endif
My definition file is where it all goes horribly wrong with the fstream part:
#include "Account.h"
Account::Account(string nr, double bl){
if (bl >= 0){
number = nr;
balance = bl;
}
else{
number = "incorrect";
}
}
void Account::deposit(double am){
if (am >= 0){
balance = balance + am;
}
}
string Account::get_number(){
return number;
}
double Account::get_balance(){
return balance;
}
double Account::withdraw(double am){
if (0 <= am && am <= get_balance()){
balance = balance - am;
return am;
}
else{
return 0;
}
}
bool Account::equals(Account other){
if (number == other.get_number()){
return true;
}
return false;
}
void Account::print(){
cout << "<Account(" << number << ",";
cout << balance << ")>" ;
}
void Account::println(){
print();
cout << endl;
}
void Account::println(string s){
cout << s;
println();
}
void Account::println(ofstream& fout){
fout << number << ",";
fout << balance;
fout << endl;
}
void Account::read(ifstream& fin){
fin >> number;
}
There is something wrong with the declaration of void Account::println(ofstream& fout). It gives me the output
<Account(number,balance,0)>
instead of
<Account(number,balance)>
Why does this happen? I have many more problems with the printing of the savings and checking numbers, but i feel if I understand why this is happening I can solve those. Thank you to anyone who wants to help me.
Account::println(ofstream&) will print "", but since the balance is a double, it prints with a decimal place:
if balance == 0.0, it will be printed as eiter 0.0 or 0,0, depending on your locale.
Either way, you have way too many print methods, and I think the solution should be implemented through an output operator:
Header:
class Account {
// ....
// no print methods defined
};
std::ostream& operator <<(std::ostream& out, const Account& a);
Source:
std::ostream& operator <<(std::ostream& out, const Account& a)
{
return out << "";
}
Client code:
#include <iostream> // console
#include <fstream> // file
Account a;
// print to console
std::cout << a << std::endl;
// print to file
std::ofstream fout("./account.txt");
fout << a << std::endl;