调用提取重载程序会产生错误 undefined reference to `operator>>

Question

我正在尝试使用名为“美元”的 class 将浮点数更改为货币格式。 但是当我尝试使用美元 class 时出现错误。 Dollars class 具有并重载提取运算符：

istream & operator >> (istream & in, Dollars & rhs)
{
   // initially zero                                                                        
   rhs.cents = 0;
   if (in.fail())
      return in;

   // skip leading spaces and dollar signs;                                                 
   while (isspace(in.peek()) || in.peek() == '$')
      in.get();

   // is the next character a negative?                                                     
   bool negative = false;
   while ('-' == in.peek() || '(' == in.peek())
   {
      negative = true;
      in.get();
   }

   // consume digits, assuming they are dollars                                             
   while (isdigit(in.peek()))
      rhs.cents = rhs.cents * 10 + (in.get() - '0');

   // everything up to here was dollars so multiply by 100                                  
   rhs.cents *= 100;

   // did we get a decimal                                                                  
   if ('.' == in.peek())
   {
      // consume the decimal                                                                
      in.get();

      // next digit is in the 10cent place if it exists                                     
      if (isdigit(in.peek()))
         rhs.cents += (in.get() - '0') * 10;
      // the final digit is the 1cent place if it exists                                    
      if (isdigit(in.peek()))
         rhs.cents += (in.get() - '0');
   }

   // take care of the negative stuff                                                       
   rhs.cents *= (negative ? -1 : 1);

   // see if there is a trailing )                                                          
   if (')' == in.peek())
      in.get();

   return in;
}

这是我尝试使用它的地方：

Dollars dollar;

cout << "Float to convert to Dollars: ";
cin >> dollars;

然后我在编译时得到这个错误：

未定义对 `operator>>(std::istream&, Dollars&)' 的引用 collect2：错误：ld 返回 1 个退出状态

Answer 1

你写了operator <<但你试图打电话给operator >>