Input/Output Operators 重载

C ++能够使用流提取运算符>>和流插入运算符< 流插入和流提取操作符也可以重载以执行用户定义类型（如对象）的输入和输出。

在这里，重要的是使操作符重载函数成为类的朋友，因为它将在不创建对象的情况下被调用。

以下示例解释了如何提取运算符>>和插入运算符<

#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时，会产生以下结果 -

$./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