destructor dilemma

[Petr_Kropotkin]

Here is class for rational numbers

#ifndef RATIONAL_H
#define RATIONAL_H
 
class  rational{
public:
 rational(short =0,short=0,short=0, short=0);
 ~rational();
 void setRational(short =0,short=0,short=0, short=0);
 void Add();
 void Subtract();
 void Multiply();
 void Divide();
 void  PrettyPrint(char ch);
 void floatPrint();
private:
short r1;
short r2;
short r3;
short r4;
};
#endif // RATIONAL_H

#ifndef RATIONAL_H
#define RATIONAL_H

class  rational{
public:
 rational(short =0,short=0,short=0, short=0);
 ~rational();
 void setRational(short =0,short=0,short=0, short=0);
 void Add();
 void Subtract();
 void Multiply();
 void Divide();
 void  PrettyPrint(char ch);
 void floatPrint();
private:
short r1;
short r2;
short r3;
short r4;
};
#endif // RATIONAL_H

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Upon compiling I get an error for my destructor:
H:\C++_How_To_Program\chap06\rational_numbers/main.cpp:101: undefined reference to `rational::~rational()'

This occurs in any class I create. I can't figure out why.