undefined reference to template function

Hi guys,
I am coding a RTS game but I cant compile my dataLoader function. It gives that errors when want to call it:

 
obj\Debug\FileSystem\getBackground.o||In function `Z13getBackgroundv':|
undefined reference to `bool dataLoader<int>(int&, std::string, std::string)'
undefined reference to `bool dataLoader<std::string>(std::string&, std::string, std::string)'

obj\Debug\main.o||In function `main':|
undefined reference to `bool dataLoader<int>(int&, std::string, std::string)'
undefined reference to `bool dataLoader<int>(int&, std::string, std::string)'


and here is my code:

a part of main.cpp:
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    //Window size
    int width;
    int height;

    if( !dataLoader<int>( width, "settings/resolution.txt", "width" ) || !dataLoader<int>( height, "settings/resolution.txt", "height" ) )
    {
        return -1;
    }


getBackground.cpp:
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#include <SFML/Graphics.hpp>
#include <cstdlib>
#include <ctime>
#include "../func_declerations.h"
#include <string>

sf::Texture getBackground()
{
    int number_of_backgrounds;
    int chosen;
    sf::Texture chosenTexture;
    dataLoader<int>( number_of_backgrounds, "settings/backgrounds", "number" );

    std::string backgrounds[ number_of_backgrounds ];

    for( int i = 0; i < number_of_backgrounds; ++i )
    {
        dataLoader<std::string>( backgrounds[ i ], "settings/backgrounds" ,  "background" + i  );
    }

    std::srand( time(NULL) );

    chosen = ( (std::rand()) % number_of_backgrounds );

    chosenTexture.loadFromFile( backgrounds[ chosen ] );

    return chosenTexture;
}


Settings.cpp (File name should be changed)
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#include <fstream>
#include <cstdlib>
#include <ctime>
#include <string>
#include "../func_declerations.h"

template< typename T >
bool dataLoader( T &value, std::string directory, std::string search )
{
    std::ifstream load( directory );

    std::string part_of_content;

    if( !load.is_open() )
    {
        return false;
    }

    while( load >> part_of_content )
    {
        if( part_of_content == search )
        {
            load >> value;
            return true;
        }
    }

    return false;
}


func_declerations.h
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#ifndef FUNC_DECLERATIONS_H_INCLUDED
#define FUNC_DECLERATIONS_H_INCLUDED

#include <SFML/Graphics.hpp>
#include <string>

template< typename T >
bool dataLoader( T &value, std::string directory, std::string search );

sf::Texture getBackground( );

#endif // FUNC_DECLERATIONS_H_INCLUDED 
Just call it like dataLoader(int, string1, string2)
Thanks for help but that doesnt work.
http://www.cplusplus.com/forum/general/113904/

@ResidentBiscuit: No, that is not how you call a function.
The compiler needs to have access to the entire template definition at the point where it compiles the function call. You therefore need to include the entire template function definition in the header, not just the prototype.
@ne555, uh how?
I would have to say you problem is as mikey said. You must define the templated functions in the header not in the implementation file.
Thanks for helps. It worked with Mikey's way.
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