12

Rational

  1. #include <iostream>
  2. #include <cstdlib>
  3.  
  4. using namespace std;
  5.  
  6. #ifdef DEBUG
  7. int debug = 0;  // 0 - off, 1 - on
  8. #endif
  9.  
  10. #ifdef DEBUG
  11. #define ONDEBUG( expr ) do { if ( debug ) { expr; } } while ( 0 )
  12. #else
  13. #define ONDEBUG( expr )
  14. #endif
  15.  
  16. class Rational {
  17.     friend Rational operator*( const Rational &, const Rational & );
  18.     friend bool operator==( const Rational &, const Rational & );
  19.     friend ostream &operator<<( ostream &ostr, const Rational &r );
  20.     friend istream &operator>>( istream &istr, Rational &r );
  21. public:
  22.     ~Rational( )
  23.     {
  24.         cout << "DESTRUCTOR\n";
  25.     }
  26.     Rational( int n=0, int d=1 ) : num( n ), den( d )
  27.     {
  28.         cout << "CONSTRUCTOR\n";
  29.         reduce();
  30.     };
  31.     Rational( const Rational &r ) : num( r.num ), den( r.den )
  32.     {
  33.         cout << "COPY\n";
  34.     };
  35.     Rational &operator=( const Rational &r )
  36.     {
  37.         cout << "OPERATOR =\n";
  38.         num = r.num;
  39.         den = r.den;
  40.  
  41.         return *this;
  42.     };
  43.     Rational &operator*=( const Rational &r )
  44.     {
  45.         cout << "OPERATOR *=\n";
  46.         num *= r.num;
  47.         den *= r.den;
  48.  
  49.         reduce();
  50.  
  51.         return *this;
  52.     };
  53.     operator double() const;
  54.     Rational operator++();
  55.     Rational operator++( int );
  56.     int &operator[]( int );
  57.  
  58.     void print( ) const { cout << num << '/' << den; }
  59.     void printf( ) const { cout << double(num) / double(den); }
  60.     int numerator( ) const { return num; }
  61.     int denominator( ) const { return den; }
  62.  
  63. private:
  64.     int num, den;
  65.     int gdc( int x, int y )
  66.     {
  67.         ONDEBUG( cout << "gdc( " << x << ", " << y << " )" << endl; );
  68.         return y == 0 ? x : gdc( y, x%y );
  69.     }
  70.     void reduce( )
  71.     {
  72.         int g = gdc( num, den );
  73.         ONDEBUG( cout << "gdc=" << g << endl; );
  74.         num /= g, den /= g;
  75.     }
  76. };
  77.  
  78. Rational::operator double() const
  79. {
  80.     return double(num) / double(den);
  81. }
  82.  
  83. Rational Rational::operator++()
  84. {
  85.     num += den;
  86.  
  87.     return *this;
  88. }
  89.  
  90. Rational Rational::operator++( int fake )
  91. {
  92.     Rational t = *this;
  93.     num += den;
  94.  
  95.     return t;
  96. }
  97.  
  98. int &Rational::operator[]( int i )
  99. {
  100.     if ( i == 1 )
  101.         return num;
  102.     if ( i == 2 )
  103.         return den;
  104.     cerr << "ERROR: Rational::operator[] - Bad argument";
  105.     exit( 1 );
  106. }
  107.  
  108. Rational operator*( const Rational &x, const Rational &y )
  109. {
  110.     cout << "OPERATOR *\n";
  111.     Rational z( x.num * y.num, x.den * y.den );
  112.     return z;
  113. }
  114.  
  115. bool operator==( const Rational &x, const Rational &y )
  116. {
  117.     cout << "OPERATOR ==\n";
  118.  
  119.     return x.num * y.den == x.den * y.num;
  120. }
  121.  
  122. ostream &operator<<( ostream &ostr, const Rational &r )
  123. {
  124.     ostr << r.num << "/" << r.den;
  125.  
  126.     return ostr;
  127. }
  128.  
  129. istream &operator>>( istream &istr, Rational &r )
  130. {
  131.     cout << "Num? ";
  132.     cin >> r.num;
  133.     cout << "Den? ";
  134.     cin >> r.den;
  135.  
  136.     r.reduce();
  137.  
  138.     return istr;
  139. }
  140.  
  141. Rational f( Rational r )
  142. {
  143.     Rational s = r;
  144.  
  145.     return s;
  146. }
  147.  
  148. int main()
  149. {
  150.     Rational x( 21, 66 );   // will be reduced
  151.     Rational y = x;
  152.     {
  153.         Rational x = 4;
  154.         cout << "x=", x.print(), cout << "=", x.printf(), cout << endl;
  155.     }
  156.     cout << "x=", x.print(), cout << "=", x.printf(), cout << endl;
  157.     cout << "y=", y.print(), cout << "=", y.printf(), cout << endl;
  158.     cout << endl;
  159.  
  160.     cout << "num=" << x.numerator() << endl;
  161.     cout << "den=" << x.denominator() << endl;
  162.     cout << endl;
  163.     {
  164.         const Rational PI( 22, 7 );
  165.         cout << "PI=", PI.print(), cout << "=", PI.printf(), cout << endl;
  166.         x = PI;
  167.     }
  168.     cout << "x=", x.print(), cout << "=", x.printf(), cout << endl;
  169.     cout << endl;
  170.  
  171.     x = f( y );
  172.     cout << endl;
  173.     {
  174.         Rational x(22, 7);
  175.         Rational y(-3, 8);
  176.         Rational z = x * y; // calls operator =
  177.  
  178.         cout << "x=", x.print(), cout << endl;
  179.         cout << "y=", y.print(), cout << endl;
  180.         cout << "z=", z.print(), cout << endl;
  181.         cout << endl;
  182.  
  183.         x *= y;
  184.         cout << "x=" << x << endl;                          // calls operator <<
  185.         cout << (x == z ? "x=y\n" : "x!=y\n");  // calls operator ==
  186.     }
  187.     cout << endl;
  188.     cin >> x;                                                               // calls operator >>
  189.     cout << "x=" << x << endl;
  190.     cout << "x=" << (double)x << endl;          // calls operator double()
  191.     cout << "x=" << (double)++x << endl;        // calls operator ++
  192.     cout << "x=" << (double)x++ << endl;        // calls operator ++
  193.     cout << "x=" << x << endl;
  194.     cout << endl;
  195.     x[ 1 ] = 22;                                                        // calls operator []
  196.     x[ 2 ] = 7;                                                         // calls operator []
  197.     cout << "x=" << (double)x << endl;
  198. }

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