7.2.    ________________________________193

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    my_string.

7.2.    

     C++.  
         
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,    .

      .

   

1.    ( ).

2.     (.  2.5  . 46).

3.    .

4.    .

5. ,  ,   ( -
).

   (promotion) ,    -
.     float  double, .!, char,
short  enum  int.  ,     -
 .

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rational ().

  rational, 

// 

class rational{

public:

rational(int n = 0) : a(n),q(l){}

rational(int i, int j) : a(i), q(j){}

rational(double r) : q(BIG), a(r * BIG){}

void print() const { cout  a  " / "  q ; }

operator double(){return static_cast<double>(a)/q;}