undefined reference to Vector<String> g++ link error

dany2704's Avatar, Join Date: Feb 2013
Newbie Member
have compiled the dependent files of my source file mycpp.c and linked the files in the order which they have used .All the dependant files are available in the same folder.
**//Compilation**
$ g++ -c -w -Wno-deprecated String.c Vector.c DPStream.c CJ_Base.c mycpp.c
**//Linking**
$ g++ -g -o myexe String.o Vector.o DPStream.o CJ_Base.o mycpp.o
Vector.h
Code:
#include <iostream.h>
#include <fstream.h>
#include <iomanip.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

#include "String.h"
#include "Storage.h"


template <class Object>
class Vector : public Storage{

public:
// ctors & dtor
Vector ();
Vector (int);
~Vector();

// overloaded operators
Object& operator[] (int nSubscript);
void operator<<(Object &);
void operator<<(char *);

// access methods
int Count(){return _iCurrElem;};
int Print(ofstream &);
void Flush();
Resize(int);

int IsType() {return VectorType;};

private:
long _iCurrElem;
Object *moj;
long _iUpperBound;

void _reserve(int);
};
#endif
Vector.c

Code:
#include"Vector.h"

template <class Object>
Vector<Object>::Vector ()
{
moj = new Object[3];
}

template <class Object>
Vector<Object>::Vector (int e)
{
moj = new Object[e];
}

template <class Object>
Vector<Object>::~Vector ()
{
delete[] moj;
}

template <class Object>
Vector<Object>::operator<<(Object &)
{
//stmt
}

template <class Object>
Vector<Object>::operator<<(char* ch)
{
//stmt
}

template <class Object>
Vector<Object>::Print(ofstream &foutput)
{
//stmt
}
Included the header files in the below order in mycpp.h
Code:
#include <iostream.h>
#include <fstream.h>
#include <iomanip.h>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include "String.h"
#include "Vector.h"
#include "DPStream.h"
#include "CJ_Base.h"
g++ compiler throws an error

DPStream.o: In function `DPStream::operator<<(Vector<String>&)':
DPStream.c:(.text+0x396): undefined reference to `Vector<String>::Print(std::basic_ofstream<char, std::char_traits<char> >&)'
mycpp.o: In function `mycpp::ProcessFile()':
mycpp.o:(.text+0x24e): undefined reference to `Vector<String>::operator<<(String&)'
mycpp.o:(.text+0x2e5): undefined reference to `Vector<String>::operator<<(char*)'
mycpp.o:(.text+0x310): undefined reference to `Vector<String>::Flush()'
mycpp.o:(.text+0x32b): undefined reference to `Vector<String>::operator<<(String&)'
mycpp.o:(.text+0x346): undefined reference to `Vector<String>::operator<<(String&
mycpp.o: In function `mycpp::~mycpp()':
mycpp.o:(.text+0x24e): undefined reference to `Vector<String>::operator<<(String&)'


Could you please help me to resolve the issue
Thanks for looking into this
0
DRK's Avatar, Join Date: Apr 2012
DRK
Light Poster
1. C++ source files should have .cpp extension, not .c .
2. Include files for C++ standard library don't require .h extension:
Code:
#include <iostream>
#include <fstream>
#include <iomanip>
3. Include files inherited from C standard library have c prefix in their names:
Code:
#include <cstdio>
#include <cstring>
#include <cstdlib>
4. You missed return type in operators and methods definitions:
Code:
template <class Object>
void Vector<Object>::operator<<(Object &)
Code:
template <class Object>
void Vector<Object>::operator<<(char* ch)
Code:
template <class Object>
int Vector<Object>::Print(ofstream &foutput)
5. Semicolon after method definition is dispensable:
Code:
int Count(){return _iCurrElem;}
int IsType() {return VectorType;}