C++ 输入/输出运算符重载

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  输入/输出运算符重载

  C ++能够使用流提取运算符>>和流插入运算符<<输入和输出内置数据类型。流插入和流提取运算符也可以重载，以执行用户定义类型（如对象）的输入和输出。在此，使运算符重载函数成为该类的friend类非常重要，因为它将在不创建对象的情况下被调用。下面的示例说明提取运算符>>和插入运算符<<的方式。

  
  #include <iostream>
  using namespace std;
   
  class Distance {
     private:
        int feet;             // 0 to infinite
        int inches;           // 0 to 12
        
     public:
        // required constructors
        Distance() {
           feet = 0;
           inches = 0;
        }
        Distance(int f, int i) {
           feet = f;
           inches = i;
        }
        friend ostream &operator<<( ostream &output, const Distance &D ) { 
           output << "F : " << D.feet << " I : " << D.inches;
           return output;            
        }
  
        friend istream &operator>>( istream  &input, Distance &D ) { 
           input >> D.feet >> D.inches;
           return input;            
        }
  };
  
  int main() {
     Distance D1(11, 10), D2(5, 11), D3;
  
     cout << "Enter the value of object : " << endl;
     cin >> D3;
     cout << "First Distance : " << D1 << endl;
     cout << "Second Distance :" << D2 << endl;
     cout << "Third Distance :" << D3 << endl;
  
     return 0;
  }
  

  编译并执行上述代码后，将产生以下结果-

  
  $./a.out
  Enter the value of object :
  70
  10
  First Distance : F : 11 I : 10
  Second Distance :F : 5 I : 11
  Third Distance :F : 70 I : 10