C++快速入门 课件源码讨论之重载<<操作符

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1. #include <iostream>
   
2. #include <string>
   
3. #include <stdlib.h>
   
4. class Rational
   
5. {
   
6. public:
   
7.         Rational(int num,int denom);
   
8.         Rational operator+(Rational rhs);
   
9.         Rational operator-(Rational rhs);
   
10.         Rational operator*(Rational rhs);
    
11.         Rational operator/(Rational rhs);
    
12. private:
    
13.         void normalize();
    
14.         int numerator;
    
15.         int denominator;
    
16.         friend std::ostream& operator<<(std::ostream& os, Rational f);
    
17. };
    
18. 
    
19. Rational::Rational(int num, int denom)
    
20. {
    
21.         numerator = num;
    
22.         denominator = denom;
    
23.         normalize();
    
24. }
    
25. 
    
26. void Rational::normalize()
    
27. {
    
28.         if (denominator<0)
    
29.         {
    
30.                 numerator = -numerator;
    
31.                 denominator = -denominator;
    
32.         }
    
33.         int a = abs(numerator);
    
34.         int b = abs(denominator);
    
35.         while (b>0)
    
36.         {
    
37.                 int t = a%b;
    
38.                 a = b;
    
39.                 b = t;
    
40.         }
    
41.         numerator /= a;
    
42.         denominator /= a;
    
43. }
    
44. Rational Rational::operator+(Rational rhs)
    
45. {
    
46.         int a = numerator;
    
47.         int b = denominator;
    
48.         int c = rhs.numerator;
    
49.         int d = rhs.denominator;
    
50.         int e = a*b + c*d;
    
51.         int f = b*d;
    
52.         return Rational(e, f);
    
53. }
    
54. Rational Rational::operator-(Rational rhs)
    
55. {
    
56.         rhs.numerator =- rhs.numerator;
    
57.         return operator+(rhs);
    
58. }
    
59. Rational Rational::operator*(Rational rhs)
    
60. {
    
61.         int a = numerator;
    
62.         int b = denominator;
    
63.         int c = rhs.numerator;
    
64.         int d = rhs.denominator;
    
65.         int e = a*c;
    
66.         int f = b*d;
    
67.         return Rational(e, f);
    
68. }
    
69. Rational Rational::operator/(Rational rhs)
    
70. {
    
71.         int t = rhs.numerator;
    
72.         rhs.numerator = rhs.denominator;
    
73.         rhs.denominator = t;
    
74.         return operator*(rhs);
    
75. }
    
76. std::ostream& operator<<(std::ostream& os, Rational f);
    
77. int main()
    
78. {
    
79.         Rational f1(2, 16);
    
80.         Rational f2(7, 8);
    
81.         std::cout << f1 << "+"<< f2 << "=" << (f1 + f2) << "\n";
    
82.         std::cout << f1 << "-" << f2 << "=" << (f1  - f2) << "\n";
    
83.         std::cout << f1 << "*" << f2 << "=" << (f1 *  f2) << "\n";
    
84.         std::cout << f1 << "/" << f2 << "=" << (f1 /  f2)  << "\n";
    
85.         return 0;
    
86. }
    
87. std::ostream& operator<<(std::ostream& os, Rational f)
    
88. {
    
89.         os << f.numerator << "/" << f.denominator;
    
90.         return os;
    
91. }

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