string s1 = "xyz";
string s2 = "xyz";
Console.WriteLine(" s1 reference equals s2 : {0}", object.ReferenceEquals(s1, s2));

string x = "a" + "b";
string y = "ab";

string s1 = "xyz";

string s2 = "xy";
s2 += "z";

Console.WriteLine("s1 ref = s2 : {0}", object.ReferenceEquals(s1, s2));

s1 ref = s2 : False