System.Linq Distinct method

• First seen directly .Distinct Distinct certainly be taken for granted () called with.
• Distinct need to know where the object is to come and go as a unit of weight. When you Select new map of the same time even if property values ​​will not be de-emphasis.
• Use a single column on a little here by using the 
• Use multiple columns (for example, I need to re-KeyValuePairModel the object):

   public  class KeyValuePairModel 
      { 
          public  String the Name { GET ; the SET ;}
           public  String Code { GET ; the SET ;} 
      } 
  // here bottom will first determine whether the object is relatively the same object will first call GetHashCode if not the same object will be called Equals method. 
      public  class KeyValuePairRowComparer: the IEqualityComparer <KeyValuePairModel> 
      { 
          public  BOOL Equals (KeyValuePairModel T1, T2 KeyValuePairModel) 
          { 
              return (t1.name == == t2.Name && t1.Code t2.Code); 
          } 
          public  int GetHashCode(KeyValuePairModel t)
          {
              return t.ToString().GetHashCode();
          }
      }

   

• use:

  arealist.Select(c => new KeyValuePairModel() { Code = c.CityCode, Name = c.CityName }).Distinct(new KeyValuePairRowComparer())