Overridden Equals() : Object Reference : Class C# Examples

    
using  System;
using  System.Text;



class  Person
{
        public  Person(string  fname,  string  lname,  string  ssn,  byte  a)
        {
        FirstName  =  fname;
        LastName  =  lname;
        SSN  =  ssn;
        age  =  a;
        }

    public  string  FirstName;
    public  string  LastName;
    public  string  SSN;
    public  byte  age;

    public  override  bool  Equals(object  o)
    {
        Person  temp  =  (Person)o;
        if(temp.FirstName  ==  this.FirstName  &&
              temp.LastName  ==  this.LastName  &&
              temp.SSN  ==  this.SSN  &&
              temp.age  ==  this.age)
        {
            return  true;
        }
        else
            return  false;
    }

    public  override  string  ToString()
    {
        StringBuilder  sb  =  new  StringBuilder();
                    sb.AppendFormat("[FirstName=  {0}",  this.FirstName);
                    sb.AppendFormat("  LastName=  {0}",  this.LastName);
                    sb.AppendFormat("  SSN=  {0}",  this.SSN);
                    sb.AppendFormat("  Age=  {0}]",  this.age);

        return  sb.ToString();
    }

    public  override  int  GetHashCode()
    {
        return  SSN.GetHashCode();
    }
}


class  MainClass
{
        public  static  void  Main(string[]  args)
        {
        Person  p1  =  new  Person("Fred",  "Jones",  "222-22-2222",  98);
        Person  p2  =  new  Person("Fred",  "Jones",  "222-22-2222",  98);

        
        if(p1.Equals(p2)  &&  p1.GetHashCode()  ==  p2.GetHashCode())
            Console.WriteLine("P1  and  P2  have  same  state\n");
        else
            Console.WriteLine("P1  and  P2  are  DIFFERENT\n");

        }
}