g++ error: undefined reference while netbeans compiles in linux [duplicate] - c++

Question

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"undefined reference to" using 'g++' to compile a C++ program
(3 answers)
Closed 9 years ago.
Im using NetBeans IDE in linux mint for C++ programming. NetBeans compiles the code just fine but when i try to compile the main.cpp using g++ as in g++ main.cpp i get undefined reference errors:
I know there are many questions like this one and they the problem can be fixed by using the right -l library but I couldn't find any related to NetBeans/g++ and I couldn't figure how to overcome this problem.
Any help is appreciated.
Errors:
tmp/ccXSo5xI.o: In function `main':
main.cpp:(.text+0x82): undefined reference to `Hospital::Hospital(int, int, int)'
main.cpp:(.text+0xf3): undefined reference to `Resident::Resident(int, int)'
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.
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main.cpp
#include <iostream>
#include <cstdio>
#include "Resident.h"
#include "Hospital.h"
#include <stack>
using namespace std;
void readFromFiles(int [][10], int [][10]);
void readFromFiles(Hospital*[10], Resident*[10]);
void print10(int [][10], int [][10]);
void print10(Hospital*[10], Resident*[10]);
int main(void) {
int hospital[10][10] = {0};
int resident[10][10] = {0};
Hospital **hospitals = new Hospital*[10];
for(int i = 0 ; i < 10 ; i++)
hospitals[i] = new Hospital(3, i, 10); //3: quota, i: hospital number, 10:prefereneceLength
Resident **residents = new Resident*[10];
for(int i = 0 ; i < 10 ; i++)
residents[i] = new Resident(i,10); //i: hospital number, 10:prefereneceLength
.
.
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Hospital.h
#ifndef HOSPITAL_H
#define HOSPITAL_H
#include "Resident.h"
using namespace std;
class Hospital {
public:
//constructors & destructors
Hospital();
Hospital(const int, const int, const int);
Hospital(const Hospital& orig);
virtual ~Hospital();
//getters & setters
int getNumber();
int getQuota();
int** getPreferenceList();
//member functions
void addPreference(const int, const int);
private:
int number;
int* preferenceList[2]; //1st row: preference order ; 2nd row: admission status
int quota;
Resident *admittedResidents;
};
#endif /* HOSPITAL_H */
Resident.h
#ifndef RESIDENT_H
#define RESIDENT_H
class Resident {
public:
//constructors & destructors
Resident();
Resident(const int, const int);
Resident(const Resident& orig);
virtual ~Resident();
//getters, setters
int getNumber();
int* getPreferenceList();
bool getAdmissionStatus();
//member functions
void addPreference(const int, const int);
private:
int number; //resident number
int proposalCount;
int* preferenceList; //not inverse, unlike Hospitals pref list
bool admissionStatus;
};
#endif /* RESIDENT_H */
I know that's a lot of code even though I shortened them, but I think they are the necessary parts. Thanks.

Answer 1

You need to include all source files:
g++ main.cpp hospital.cpp resident.cpp

Answer 2

g++ main.cpp will try to compile and link main.cpp into an executable (a.out). In the link stage, ld is not finding the symbols for the Hospital and Resident constructors while are called in main.cpp because they have not yet been compiled.
If you just want to compile main.cpp, use:
g++ -c main.cpp
You can link the object files later using:
g++ main.o hospital.o resident.o
If you want to compile and link the whole lot:
g++ main.cpp hospital.cpp resident.cpp