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-   -   undefined reference to Vector<String> g++ link error (http://www.go4expert.com/forums/undefined-reference-vectorstring-g-link-t29474/)

dany2704 7Feb2013 23:11

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

DRK 11Feb2013 14:40

Re: undefined reference to Vector<String> g++ link error
 
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;}



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