I'm getting a linker error?

Error 1 error LNK2019: unresolved external symbol "public: __thiscall Fraction::Fraction(int,int)" (??0Fraction@@QAE@HH@Z) referenced in function "public: class Fraction __thiscall Fraction::Add(class Fraction,class Fraction)" (?Add@Fraction@@QAE?AV1@V1@0@Z) C:\Users\Jesse\Desktop\C++ II\Chapter_15_Exercise_1\Chapter_15_Exercise_1\Cha pter_15_Exercise_1.obj Chapter_15_Exercise_1

Any idea how to fix this? I can't figure out for the life of me how to fix it?

Code:

#include <iostream>
using std::cout;
using std::endl;

#pragma once

class Fraction
{
public:
	Fraction (int numer = 1, int denom = 1);
	~Fraction()
	{ }

	Fraction Add ( Fraction left_frac, Fraction right_frac);
	Fraction Subtract ( Fraction left_frac, Fraction right_frac);
	Fraction Multiply ( Fraction left_frac, Fraction right_frac);
	Fraction Divide ( Fraction left_frack, Fraction right_frac);
	void Display ();
	void SetNumer (int numer);
	void SetDenom( int numer);
	int GetNumer();
	int GetDenom();


private:
	int m_numer;
	int m_denom;
	void Reduce();
};

Fraction Fraction::Add(Fraction left_frac, Fraction right_frac)
{
	Fraction New_Frac;

	New_Frac.SetDenom( left_frac.m_denom * right_frac.m_denom );
	New_Frac.SetNumer( ( left_frac.m_denom * right_frac.m_numer ) + ( right_frac.m_denom * left_frac.m_numer ) );

	return New_Frac;
}

Fraction Fraction::Subtract(Fraction left_frac, Fraction right_frac)
{
	Fraction New_Frac;

	New_Frac.SetDenom( left_frac.m_denom * right_frac.m_denom );
	New_Frac.SetNumer( (right_frac.m_denom * left_frac.m_numer) - (left_frac.m_denom * right_frac.m_numer) );

	return New_Frac;
}

Fraction Fraction::Multiply(Fraction left_frac, Fraction right_frac)
{
	Fraction New_Frac;

	New_Frac.SetNumer( left_frac.m_numer * right_frac.m_numer );
	New_Frac.SetDenom( left_frac.m_denom * right_frac.m_denom );

	return New_Frac;
}

Fraction Fraction::Divide(Fraction left_frac, Fraction right_frac)
{
	Fraction New_Frac;

	New_Frac.SetNumer( left_frac.m_numer * right_frac.m_denom );
	New_Frac.SetDenom( left_frac.m_denom * right_frac.m_numer );

	return New_Frac;
}

void Fraction::Display()
{
	cout << m_numer << " / " << m_denom << endl;
}

void Fraction::SetNumer( int number)
{
	m_numer = number;
}

void Fraction::SetDenom( int number)
{
	m_denom = number;
}

int Fraction::GetNumer()
{
	return m_numer;
}

int Fraction::GetDenom()
{
	return m_denom;
}


int main()
{
	//Fraction f1( 1, 2),
	//		 f2( 3, 4),
	//		 f3;

	//f3.Multiply(f1, f2);

	//f1.Display();
	//cout << " * ";
	//f2.Display();
	//cout << " = ";
	//f3.Display();

	return 0;
}

You need to write your constructor:

Code:

Fraction (int numer = 1, int denom = 1);

it's because you never actually define Fraction::Fraction(int, int). you only declare it.