Question

Possible Duplicate:
Why do I get “unresolved external symbol” errors when using templates?
“undefined reference” to a template class function

I got error on line: Console::getInstance()->readObjectData(a); in main.cpp

undefined reference to void Console::readObjectData<std::string>std::string&)

Console.h
http://pastebin.com/WsQR7JNq

#define CONSOLE_H
#include <string>

using namespace std;

class Console
{
public:
    static Console* getInstance();


    template <typename T>
    void readObjectData(T& o);
protected:
private:
    Console();  // Private so that it can  not be called
    Console(Console const&);             // copy constructor is private
    Console& operator=(Console const&);  // assignment operator is private
    static Console* m_pInstance;


};
    #endif // CONSOLE_H

Console.cpp
http://pastebin.com/N02HjgBw

#include "Console.h"
#include "Log.h"
#include <iostream>
#include <sstream>
#include <string>

using namespace std;

// Global static pointer used to ensure a single instance of the class.
Console* Console::m_pInstance = NULL;

Console::Console()
{

}

Console::Console(Console const&)
{

}

Console& Console::operator=(Console const&)
{

}

Console* Console::getInstance()
{
if (!m_pInstance)   // Only allow one instance of class to be generated.
    m_pInstance = new Console;

return m_pInstance;
}


template <typename T>
void Console::readObjectData(T& o) {
     //cin >> o;
}

main.cpp
http://pastebin.com/U6qAJUN1

#include "Console.h"

using namespace std;

int main()
{

    string a;

    Console::getInstance()->readObjectData(a);
    return 0;
}

any ideas?

Answer 1

You cannot define template<>’d function in .cpp file.

Move

template <typename T>
void Console::readObjectData(T& o) {
     //cin >> o;
}

To header file.