关于重载运算符的疑问
本帖最后由 huanhuan30 于 2013-02-17 14:19:54 编辑 《professional c# 4.0 and .net 4》上说
“In addition, the comparison operators must return a bool”

但是我在
http://msdn.microsoft.com/en-us/library/aa288467(v=VS.71).aspx
example2 上看到他返回的是自己的 类



我到底该怎么理解？
[解决办法]

   public static implicit operator DBBool(bool x) 
   {
      return x? dbTrue: dbFalse;
   }

   // Explicit conversion from DBBool to bool. Throws an 
   // exception if the given DBBool is dbNull, otherwise returns
   // true or false:
   public static explicit operator bool(DBBool x) 
   {
      if (x.value == 0) throw new InvalidOperationException();
      return x.value > 0;
   }

   // Equality operator. Returns dbNull if either operand is dbNull, 
   // otherwise returns dbTrue or dbFalse:
   public static DBBool operator ==(DBBool x, DBBool y) 
   {
      if (x.value == 0 
[解决办法]
 y.value == 0) return dbNull;
      return x.value == y.value? dbTrue: dbFalse;
   }