C# stringのreferenceEquals

string a = "aaa";
string b = "aaa";

Console.WriteLine(a == b);  // true
Console.WriteLine(object.ReferenceEquals(a, b));  // true

string a = "aaa";

string b = "aaa";

Console.WriteLine(a == b); // true

Console.WriteLine(object.ReferenceEquals(a, b)); // true

string a = "aaa";
string b = "aa";
b += "a";

Console.WriteLine(a == b);  // true
Console.WriteLine(object.ReferenceEquals(a, b));  // false

string a = "aaa";

string b = "aa";

b += "a";

Console.WriteLine(a == b); // true

Console.WriteLine(object.ReferenceEquals(a, b)); // false