I've started to "port" my Java implementation of dynamic array to C++ and somehow i'm facing a strange linker error (LNK2019 and LNK2011) in my code, although i don't see any place which can produce such error.
I think it has something to do with constructor, but i can't find what exactly.
Thank you for your help!
DynStackArrayQueue.cpp (test class) :
#include <iostream>
#include "DynArray.h"
using namespace std;
int main()
{
DynArray dynA (3, 6);
}
DynArray.h
#pragma once
class DynArray {
private:
int growthFactor, maxOverhead;
int elements[];
public:
DynArray(int growthFactor, int maxOverhead);
}
DynArray.cpp
#include <iostream>
#include "DynArray.h"
using namespace std;
DynArray::DynArray(int growthFactor, int maxOverhead) {
this->growthFactor = growthFactor;
this->maxOverhead = maxOverhead;
}
The error itself:
You have missed a semicolon at the end of the class declaration. This leads to a compilation error, which you actually should be able to see before the linker error. Solution: add a semicolon after the closing brace of your DynArray class definition.
Related
So I have two classes - Dvd and DvdGroup. DvdGroup basically manages an array of dvds and provide manipulative member functions for that class. The problem is whenever I try to compile DvdGroup.cc using the command 'g++ -c Dvd.Group.cc', I get a bunch of errors all related to not having 'Dvd' declared and I'm not sure why.
Here are some errors below:
DvdGroup.h:14:12: error: ‘Dvd’ has not been declared void add(Dvd*);
DvdGroup.h:18:3: error: ‘Dvd’ does not name a type Dvd* dvdCollection[MAX_DVDS];
DvdGroup.cc: In copy constructor ‘DvdGroup::DvdGroup(DvdGroup&)’:
DvdGroup.cc:15:6: error: ‘Dvd’ was not declared in this scope for(Dvd d: dvds){
I feel like I'm missing something and they could all be fixed by one solution because they all involve having the Dvd class undeclared but I can't seem to figure out what. I was wondering if anyone could tell me what I'm doing wrong? I would really appreciate any help with fixing this.
DvdGroup.cc:
#include <iostream>
using namespace std;
#include "DvdGroup.h"
DvdGroup::DvdGroup(int n){
numDvds = n;
}
DvdGroup::DvdGroup(DvdGroup& dvds){
numDvds = dvds.numDvds;
for(Dvd d: dvds){
Dvd newDvd = Dvd;
}
}
DvdGroup::~DvdGroup(){
//code
}
void DvdGroup::add(Dvd* d){
//code
}
DvdGroup.h:
#ifndef DVDGROUP_H
#define DVDGROUP_H
#define MAX_DVDS 15
#include <string>
using namespace std;
class DvdGroup
{
public:
DvdGroup(int);
DvdGroup(DvdGroup&);
~DvdGroup();
void add(Dvd*);
private:
Dvd* dvdCollection[MAX_DVDS];
int numDvds;
};
#endif
Don't know if the Dvd header file is needed, but here:
Dvd.h:
#ifndef DVD_H
#define DVD_H
#define MAX_DVDS 15
#include <string>
class Dvd{
public:
Dvd(string, int);
void set(string, int);
Dvd(Dvd&);
int getYear();
~Dvd();
void print();
private:
string title;
int year;
};
#endif
What you need to do is to provide Dvd class definition for DvdGroup class. It is needed to know what type of symbol is this. Solution for your problem should be addition of:
#include "Dvd.h"
line to DvdGroup.h file.
I've created 2 header files. ListA.h and ListN.h
They both make their own use their own unique class List. When I compile my program (even though they have no way of knowing the other exists, it says the following error)
Im pretty sure it shouldnt be a redefinition, but it obviously is. Any help is appreciated.
ListA.h
#ifndef __LISTA_H_
#define __LISTA_H_
#include <iostream>
using namespace std;
class List{
public:
List(int = 0);
List(const List&);
~List();
};
#endif
ListN.h
#ifndef __LISTN_H_
#define __LISTN_H_
#include <iostream>
using namespace std;
class List{
public:
List(int = 10);
List(const List&);
~List();
};
#endif
ListA.cpp
#include "ListA.h"
using namespace std;
List::List(int mySize)
{
//...
}
ListN.cpp
#include "ListN.h"
#include <iostream>
using namespace std;
List::List(int size)
{
//...
}
Main
#include <iostream>
#include "ListN.h"
using namespace std;
int main()
{
List myList;
return 0;
}
Both cpp files are being compiled by the compiler. Thus, when the linker goes to link the files together, it gets confused, since there are multiple List classes.
To fix this, you could use namespaces, or you cold not expose at least one of the List classes.
Alternatively, if the idea was to be able to include ListN.h vs ListA.h for configuration purposes, this is the wrong way to do so. Either you should have a #define parameter for the header, or you should find some other way, such as through #ifdef. For example (I'm not 100% sure this would compile, but you get the idea):
List.h
#ifndef __LIST_H_
#define __LIST_H_
#ifndef LIST_PARAM
#define LIST_PARAM 0
#endif
#include <iostream>
using namespace std;
class List{
public:
List(int = LIST_PARAM);
List(const List&);
~List();
};
#endif
main.cpp
#include <iostream>
#define LIST_PARAM 10
#include "List.h"
using namespace std;
int main()
{
List myList;
return 0;
}
I personally don't like this method; it is much better to just pass the value in to the constructor:
int main()
{
List myList{ 10 };
return 0;
}
When linker trying to link find the definition / symbol for List, it does found in two different obj file and hence linker givers error. In visual studio error number : LNK2005
To solve this error, either:
To fix, add /FORCE:MULTIPLE to the linker command line options
Add the classes in two different namespaces which will avoid this error.
ListN.h
#ifndef __LIST_H_
#define __LIST_H_
#include <iostream>
using namespace std;
namespace ListN
{
class List{
public:
List(int = 10);
List(const List&);
};
}
#endif
ListN.cpp
#include "ListN.h"
#include <iostream>
using namespace std;
namespace ListN
{
List::List(int size)
{
//...
}
}
Main.cpp
#include <iostream>
#include "ListN.h"
int main()
{
ListN::List myList;
return 0;
}
I'm trying to create a vector which will store objects. I have added to the header file of the class as a private data member.
I am trying to initialize this vector as being empty (so that I can add objects to it later on in the program) but when I compile this program to test, this error is returned:
...error: '_bookingVector' was not declared in this scope|
I think the problem is with my initialization list on my default constructor(_bookingVector is obviously the vector):
Schedule::Schedule() : _bookingVector()
{ }
Is my syntax wrong? Or are vectors initialized differently?
Here is my code:
Schedule.h
#ifndef SCHEDULE_H
#define SCHEDULE_H
#include "Booking.h"
#include <vector>
using namespace std;
class Schedule
{
public:
Schedule();
void AddBooking(int bday, int btime, int btrainer, int bid);
void RemoveBooking(int bday, int btime);
void DisplaySchedule();
void DisplayAvailableTimeSlots();
//For Testing
void DisplayDebug();
private:
vector<Booking> _bookingVector;
};
#endif // SCHEDULE_H
Schedule.cpp
#include "Schedule.h"
#include "Booking.h"
#include <vector>
#include <iostream>
Schedule::Schedule() : _bookingVector()
{ }
void AddBooking(int bday, int btime, int btrainer, int bid){
Booking bookingObject(bday, btime, btrainer, bid);
_bookingVector.push_back(bookingObject);
}
void DisplayDebug(){
for(int i = 0; i < _bookingVector.size(); ++i){
cout << _bookingVecotr[i] << endl;
}
}
I'm very eager to learn what I'm doing wrong and fix it.
The issue is not with the constructor, which looks fine if unnecessary1. The issue is that you have defined AddBooking and DisplayDebug as non-member functions, but these should be members in order to access other members of the class.
Modify the definitions to be in the scope of the Schedule class thus:
void Schedule::AddBooking(int bday, int btime, int btrainer, int bid) { ...
^^^^^^^^^^
void Schedule::DisplayDebug(){ ...
^^^^^^^^^^
Also, don't say using namespace std in a header file (I'd go further and say don't say it anywhere but there isn't universal agreement on that.)
1 Your default constructor does not do anything that the compiler-generated one wouldn't do. You can safely remove it.
As a beginner programer, I can't seem to catch what is going astray here. I removed some code to show that the error results from this simple syntax:
main:
#include <iostream>
#include <vector>
using namespace std;
class Grader
{
public:
Grader( );
void addScore( int score )
{
vectorofints.push_back(score);
}
vector<int> vectorofints;
};
int main()
{
Grader g;
return 0;
}
You've declared a constructor for Grader so must provide an implementation. The easiest way to do this is to change
Grader( );
to
Grader( ) {}
Alternatively, if you just removed the declaration of the constructor, the compiler will generate it for you.
When I do this, my compiler complains. There are 3 errors that emerge, though no error messages visible:
#include <stdlib.h>
#include <vector>
#include <string>
#include "ParseException.h"
#include "CycleFoundException.h"
#include "UnknownTargetException.h"
using namespace std;
class Maker
{
private:
vector<Node> storage;
public:
Maker(string file) throw (ParseException, CycleFoundException, UnknownTargetException);
vector<string> makeTarget(string targetName);
};
struct Node
{
string target;
vector<string> dependencies;
string command;
int discoverytime;
int finishtime;
int visited;
Node* next;
};
The compiler does not like my vector<Node> storage declaration. When I do vector<int> storage instead, it compiles without complaint. Is it wrong to declare an object of one class in another class? I thought this was alright.
Looks like you need to put the definition of Node before the definition of Maker.
You use the type name Node in the definition of Maker (in the line vector<Node> storage), but because you haven't defined Node yet the compiler doesn't know what it is.