a program about fractions
 

Hey guys,
I was wondering if you could help me fix my program. I'm witing a program in C++ that adds, subtracts, multiplies and divides fractions. I'm suppose to put in the cosntructor that the denominator cannot be 0 or a negative number and i also I have to reduce the fraction. I have no problem adding, subtracting , etc. When i run it saids that there's no appropriate default constructor available for x, a, and b. Well take a look at my code so, you can see what i mean.

 #include <iostream.h>

#include <math.h>

class RationalNumbers

{

public:

 RationalNumbers(double, double);

 RationalNumbers operator+(const RationalNumbers &) const;

 RationalNumbers operator-(const RationalNumbers &) const;

 RationalNumbers operator*(const RationalNumbers &) const;

 RationalNumbers operator/(const RationalNumbers &) const;



 friend ostream &operator<<(ostream&, const RationalNumbers &);

 friend istream &operator>>(istream&, RationalNumbers & );

private:

 double numerator;

 double denominator;

};

 

// Constructor

RationalNumbers::RationalNumbers( double num, double den ) 

{ 

num=numerator;

if (den>0)

{den=denominator;}

 

 



}

//void RationalNumbers::reduce()

//{}

// addition 

RationalNumbers RationalNumbers::operator+( const RationalNumbers &part2 ) const

{

   return RationalNumbers( numerator*part2.denominator+part2.numerator*denominator, 

          denominator*part2.denominator );

} 

// subtraction 

RationalNumbers RationalNumbers::operator-( const RationalNumbers &part2 ) const

{

   return RationalNumbers( numerator*part2.denominator-part2.numerator*denominator, 

          denominator*part2.denominator  );

}

//multiplication

RationalNumbers RationalNumbers::operator *( const RationalNumbers &part2 ) const

{

 return RationalNumbers(numerator*part2.numerator, denominator*part2.denominator);

}

//Division

RationalNumbers RationalNumbers::operator /(const RationalNumbers &part2) const

{

 return RationalNumbers(numerator*part2.denominator, denominator*part2.numerator);

}

 

 

istream &operator>>(istream &in, RationalNumbers &part2)

{

 in>>part2.numerator;

 in.ignore();

 in>>part2.denominator ;

 

 return in;

}

// show form: (a, b)

ostream &operator <<(ostream &out, const RationalNumbers &part2)

{out<<part2.numerator<<"/"<<part2.denominator <<endl;

return out;

}



int main()

{

 RationalNumbers x;

 RationalNumbers a;

 RationalNumbers b;

 

 cout<<"Enter 2 integers for a:\n";

 cin>>a;

 

 cout<<"\nEnter 2 integers for b:\n";

 cin>>b;



 

 cout<<"x = a + b: ";

 x=a+b;

 cout<<x;

 

 cout<<"x = a - b: ";

 x=a-b;

 cout<<x;

 cout<<"x = a*b: ";

 x=a*b;

 cout<<x;

 

 cout<<"x=a/b:  ";

 x=a/b;

 cout<<x;

 



 

 return 0;

}

Re: a program about fractions
 

Your only constructor takes two parameters.

// Constructor

RationalNumbers::RationalNumbers( double num, double den )

{

num=numerator;

if (den>0)

{den=denominator;}

}

But you instantiate some objects without supplying parameters.

 RationalNumbers x;

 RationalNumbers a;

 RationalNumbers b;

1. You need to define a constructor that takes no parameters.

// Constructor

RationalNumbers::RationalNumbers( ) 

: numerator(0.0), denominator(1.0) {}

2. Or supply defaults for your constructor that takes two parameters.

// Constructor

RationalNumbers::RationalNumbers( double num = 0.0, double den = 1.0 ) 

: numerator(num), denominator(den) {}

3. Or instantiate your objects using your existing constructor.

 RationalNumbers x(0.0,1.0);

 RationalNumbers a(0.0,1.0);

 RationalNumbers b(0.0,1.0);

Re: a program about fractions
 

Thank you, The Other Dave.

I fixed my problem. Now is running perfectly. Now my program has a constructor that prevents a 0 denominator in a fraction and reduces fractions that are not in reduce form and avoids negative numbers. I overloaded the addition, multiplication, subtraction and division operators and the relational and equality operators too. Here is how it looks now.
Feel free to give any comments.

 #include <iostream.h>

#include <math.h>

class RationalNumbers

{

public:

 RationalNumbers(double=0.0, double=1.0);

 RationalNumbers operator+(const RationalNumbers &) const;

 RationalNumbers operator-(const RationalNumbers &) const;

 RationalNumbers operator*(const RationalNumbers &) const;

 RationalNumbers operator/(const RationalNumbers &) const;

 bool operator<(const RationalNumbers &) const;

 bool operator>(const RationalNumbers &) const;

 bool operator<=(const RationalNumbers &) const;

 bool operator>=(const RationalNumbers &) const;

 bool operator==(const RationalNumbers &) const;

 bool operator!=(const RationalNumbers &) const;

 friend ostream &operator<<(ostream&, const RationalNumbers &);

 friend istream &operator>>(istream&, RationalNumbers & );



private:

 double numerator;

 double denominator;

};

 

// Constructor

RationalNumbers::RationalNumbers( double num, double den ) 

   : numerator( num ), denominator(den) 

        

{ num=numerator;

if (denominator>0)

den=denominator;

else cout<<"Error Try again"<<endl;

int i;

 for(i=2; i<=numerator; ++i) {

  if( ((numerator/i) == ((int)(numerator/i))) && ((denominator/i) == ((int)(denominator/i))) ) {

   numerator /= i;

   denominator /= i;

   --i;           

  }

 }

} 

 

 

// addition 

RationalNumbers RationalNumbers::operator+( const RationalNumbers &part2 ) const

{

   return RationalNumbers( numerator*part2.denominator+part2.numerator*denominator, 

          denominator*part2.denominator );

} 

// subtraction 

RationalNumbers RationalNumbers::operator-( const RationalNumbers &part2 ) const

{

   return RationalNumbers( numerator*part2.denominator-part2.numerator*denominator, 

          denominator*part2.denominator  );

}

//multiplication

RationalNumbers RationalNumbers::operator *( const RationalNumbers &part2 ) const

{

 return RationalNumbers(numerator*part2.numerator, denominator*part2.denominator);

}

//Division

RationalNumbers RationalNumbers::operator /(const RationalNumbers &part2) const

{

 return RationalNumbers(numerator*part2.denominator, denominator*part2.numerator);

}

//a is less than b

bool RationalNumbers::operator <(const RationalNumbers &part2) const

{double temp, temp2;

temp=numerator*part2.denominator;

temp2=part2.numerator*denominator;

 if (temp < temp2)

 return true;

 else

 return false;

}

//a is greater than b

bool RationalNumbers::operator >(const RationalNumbers &part2) const

{double temp, temp2;

temp=numerator*part2.denominator;

temp2=part2.numerator*denominator;

if(temp > temp2)

return true;

else

return false;

}

//a is less or equal to b

bool RationalNumbers::operator <=(const RationalNumbers &part2) const

{double temp, temp2;

temp=numerator*part2.denominator;

temp2=part2.numerator*denominator;

if(temp <= temp2)

return true;

else

return false;

}

bool RationalNumbers::operator >=(const RationalNumbers &part2) const

{double temp, temp2;

temp=numerator*part2.denominator;

temp2=part2.numerator*denominator;

if(temp >= temp2)

return true;

else

return false;

}

// a is equal to b

bool RationalNumbers::operator ==(const RationalNumbers &part2) const

{

if(numerator == part2.numerator && denominator==part2.denominator)

return true;

else

return false;

}

//a not equal to b

bool RationalNumbers::operator !=(const RationalNumbers &part2) const

{

if(numerator == part2.numerator && denominator==part2.denominator)

return false;

else

return true;

}

istream &operator>>(istream &in, RationalNumbers &part2)

{

 in>>part2.numerator;

 in.ignore();

 in>>part2.denominator ;

 

 return in;

}

// show form: (a, b)

ostream &operator <<(ostream &out, const RationalNumbers &part2)

{out<<part2.numerator<<"/"<<part2.denominator <<endl;

return out;

}



int main()

{

 

 RationalNumbers x;

 RationalNumbers a;

 RationalNumbers b;



 cout<<"Enter a fraction for a:\n";

 cin>>a;

 

 cout<<"\nEnter a fraction for b:\n";

 cin>>b;



 cout<<"x = a + b: ";

 x=a+b;

 cout<<x;

 

 cout<<"x = a - b: ";

 x=a-b;

 cout<<x;

 cout<<"x = a*b: ";

 x=a*b;

 cout<<x;

 

 cout<<"x=a/b:  ";

 x=a/b;

 cout<<x;

 

 a<b;

 if (a<b)

 cout<<"a<b"<<endl;

 a>b;

 if(a>b)

 cout<<"a>b"<<endl;

 

 a<=b;

 if(a<=b)

 cout<<"a<=b"<<endl;

 a>=b;

 if(a>=b)

 cout<<"a>=b"<<endl;

 a==b;

 if(a==b)

 cout<<"a equals b"<<endl;

 a!=b;

 if (a!=b)

 cout<<"a not equal to b"<<endl<<endl;

 return 0;

}

I wanted to put a while loop so the program keeps asking the user to enter another fraction but i didn't know how to stop the loop. I wanted to do something like this:

  int main()

{

 

 RationalNumbers x;

 RationalNumbers a;

 RationalNumbers b;

                 while(1){          // loop  I don't know how to stop it

 cout<<"Enter a fraction for a:\n";

 cin>>a;

 

 cout<<"\nEnter a fraction for b:\n";

 cin>>b;

                 if(?) exit(0);  // I don't know what to put between the parentesis

 cout<<"x = a + b: ";

 x=a+b;

 cout<<x;

  blah, blah, blah...

........

  a==b;

 if(a==b)

 cout<<"a equals b"<<endl;

 a!=b;

 if (a!=b)

 cout<<"a not equal to b"<<endl<<endl;

 }

 return 0;

}

Re: a program about fractions
 

>I wanted to put a while loop so the program keeps asking the user to enter another fraction but i didn't know how to stop the loop.

Here is one way.

int main()

{

   char c;

   do

   {

          /* ... */

          cout << "Continue? (y/n) ";

          cin  >> c;

   } while ( c == 'y' );

   return 0;

}

Something you should know about checking for floating point equality:
http://www.eskimo.com/~scs/C-faq/q14.5.html

You're not using anything from <math.h>

The linter also tells me this.

[Info 1739] Binary operator 'RationalNumbers::operator+(const RationalNumbers &) const' should be non-member function

[Info 1754] Expected symbol 'operator+=' to be declared for class 'RationalNumbers'

[Info 1739] Binary operator 'RationalNumbers::operator-(const RationalNumbers &) const' should be non-member function

[Info 1754] Expected symbol 'operator-=' to be declared for class 'RationalNumbers'

[Info 1739] Binary operator 'RationalNumbers::operator*(const RationalNumbers &) const' should be non-member function

[Info 1754] Expected symbol 'operator*=' to be declared for class 'RationalNumbers'

[Info 1739] Binary operator 'RationalNumbers::operator/(const RationalNumbers &) const' should be non-member function

[Info 1754] Expected symbol 'operator/=' to be declared for class 'RationalNumbers'

[Info 1739] Binary operator 'RationalNumbers::operator<(const RationalNumbers &) const' should be non-member function

[Info 1739] Binary operator 'RationalNumbers::operator>(const RationalNumbers &) const' should be non-member function

[Info 1739] Binary operator 'RationalNumbers::operator<=(const RationalNumbers &) const' should be non-member function

[Info 1739] Binary operator 'RationalNumbers::operator>=(const RationalNumbers &) const' should be non-member function

[Info 1739] Binary operator 'RationalNumbers::operator==(const RationalNumbers &) const' should be non-member function

[Info 1739] Binary operator 'RationalNumbers::operator!=(const RationalNumbers &) const' should be non-member function

I'm not exactly sure what it is trying to tell me, though. Here are the explanations of the diagnostic messages.Perhaps this may mean more to you.

Re: a program about fractions
 

I've gotten to like a particular style, and I'm not pushing it here. Style can make code easier to read and thus easier to debug. Just for the sake of comparison, here is much the same code done with shorter names and more whitespace between operators.

#include <iostream>

using std::cin;

using std::cout;

using std::endl;

using std::istream;

using std::ostream;



class rational

{

   double num;

   double den;

public:

   // Constructor

   rational::rational( double n = 0.0, double d = 1.0 ) : num( n ), den( d )

   {

          if ( den > 0 )

          {

                 d = den;

          }

          else

          {

                 cout << "Error Try again" << endl;

          }

          for ( int i = 2; i <= num; ++i )

          {

                 if ( ((num/i) == ((int)(num/i))) && ((den/i) == ((int)(den/i))) )

                 {

                        num /= i;

                        den /= i;

                        --i;

                 }

          }

   }

   // addition

   rational rational::operator+ ( const rational &rhs )

   {

          return rational( num * rhs.den + rhs.num * den, den * rhs.den );

   }

   // subtraction

   rational rational::operator- ( const rational &rhs ) const

   {

          return rational( num * rhs.den - rhs.num * den, den * rhs.den );

   }

   // multiplication

   rational rational::operator* ( const rational &rhs ) const

   {

          return rational(num * rhs.num, den * rhs.den);

   }

   // division

   rational rational::operator/ ( const rational &rhs ) const

   {

          return rational(num * rhs.den, den * rhs.num);

   }

   // less than

   bool rational::operator<  ( const rational &rhs ) const

   {

          return( num * rhs.den < rhs.num * den );

   }

   // greater than

   bool rational::operator>  ( const rational &rhs ) const

   {

          return( num * rhs.den > rhs.num * den );

   }

   // less or equal to

   bool rational::operator<= ( const rational &rhs ) const

   {

          return( num * rhs.den <= rhs.num * den );

   }

   // greater than or equal to

   bool rational::operator>= ( const rational &rhs ) const

   {

          return( num * rhs.den >= rhs.num * den );

   }

   // equality

   bool rational::operator== ( const rational &rhs ) const

   {

          return num == rhs.num && den==rhs.den;

   }

   // inequality

   bool rational::operator!= ( const rational &rhs ) const

   {

          return !( num == rhs.num && den==rhs.den );

   }

   // extraction

   friend ostream &operator<< ( ostream&, const rational& );

   // insertion

   friend istream &operator>> ( istream&, rational& );

};



istream &operator>> ( istream &in, rational &rhs )

{

   return in >> rhs.num >> rhs.den;

}



// show form: (a, b)

ostream &operator<< ( ostream &out, const rational &rhs )

{

   return out << rhs.num << "/" << rhs.den;

}



int main()

{

   rational x, a, b;

   char c;

   do

   {

          cout << "Enter a fraction for a: ";

          cin  >> a;



          cout << "Enter a fraction for b: ";

          cin  >> b;



          x = a + b; cout << "x = a + b: " << x << endl;

          x = a - b; cout << "x = a - b: " << x << endl;

          x = a * b; cout << "x = a * b: " << x << endl;

          x = a / b; cout << "x = a / b: " << x << endl;



          cout << "Continue? (y/n) ";

          cin  >> c;

   } while ( c == 'y' );

   return 0;

}



/* my output

Enter a fraction for a: 1 2

Enter a fraction for b: 1 3

x = a + b: 5/6

x = a - b: 1/6

x = a * b: 1/6

x = a / b: 3/2

Continue? (y/n) y

Enter a fraction for a: 1 4

Enter a fraction for b: 1 5

x = a + b: 9/20

x = a - b: 1/20

x = a * b: 1/20

x = a / b: 5/4

Continue? (y/n) n

*/

I also shortened a few of the functions. And I moved the endl out of the extraction operator.

But notice in your constructor how you are using initializer syntax to assign to the denominator, then in the body you check for greater than zero to see whether to assign it -- it may have already been assigned. Also, how do you "Try again" on a constructor?

Re: a program about fractions
 

oops, I forgot to erase num( n ), den( d ) when i made the restrictions for the denominator. I didn't notice since it didn't give me a error message. Thanks for pointing that out.


The Other Dave, your program doesn't read a fraction, it only reads two intergers.

Re: a program about fractions
 

>The Other Dave, your program doesn't read a fraction, it only reads two intergers.

Sure it does. I just chose to use whitespace as the delimiter instead of a '/'. Add in more code to ignore the '/' if you wish.