linker error undefined reference

[ephekt]

The output count function is giving me a killer headache can someone please tell whats wrong with this function. The problem calls for a function called outputCount that has one formal parameter ostream. When I run my code I just get a error that says "[Linker error] undefined reference to `CounterType::outputCount(std::ostream&)' " So what did i do wrong? please help

  #include <iostream>
using namespace std;

class CounterType
{
       int count;
public:
     CounterType();
     CounterType(int);
     int getCount();
     void outputCount(ostream&);
     int plusOne();
     int minusOne();
};
CounterType::CounterType () : count(0)
{}

CounterType::CounterType(int)
{}

int CounterType::getCount()
{
     return count;
}

int CounterType::plusOne()
{
    count++;
    return count;
}

int CounterType::minusOne()
{
    count--;
    return count;
}

void outputCount(ostream&)
{
     cout << count;
}
 

int main( )
{
        cout << "Testing the CounterType class";

        CounterType testOne, testTwo(50);

        cout << "\n\nInitial Values:\n"  << testOne.getCount() << " ";
        testTwo.outputCount(cout);

        while (testOne.getCount() < 30)
            testOne.plusOne();

        while (testTwo.getCount() > 30)
            testTwo.minusOne();

        cout << "\n\nFinal Values:\n" << testOne.getCount() << " ";
        testTwo.outputCount(cout);

system("pause");
return 0;
}
 

[Chervil]

Line 38 CounterType:: is missing.