Immutable C#

String is immutable 

• Once created, it cannot be changed. 
• Each method of string is returns a new string instead of altering the original.
• You can re-reference the back to original to get back the new string.
• Thread safe
• Low Perfomance when continuous change of value.

StringBuilder is mutable 

• Efficient way to repeatedly append of string.

int i = 1;

int newI = i;

newI = 2;

Console.WriteLine("Old int :" + i);

Console.WriteLine("New int :" + newI);

Console.WriteLine("====================");

string str = "mystring";

string newString = str;

string newString2 = str.Replace('s', 'o');

newString = "asd";

Console.WriteLine("Old String :" + str);

Console.WriteLine("New String :" + newString);

Console.WriteLine("New String 2:" + newString2);

Console.WriteLine("==================");

MyClass myClass = new MyClass { myString = "TestString", myInt = 1 };

MyClass newMyClass = myClass;

newMyClass.myString = "Test";

newMyClass.myInt = 2;

Console.WriteLine("Old Object String :" + myClass.myString + "|Old Class Int :"+ myClass.myInt);

Console.WriteLine("New Object String :" + newMyClass.myString + "|Old Class Int :" + newMyClass.myInt);

--------------Result ----------------------

Old int : 1 //Value Type, so no change

New int : 2

====================

Old String : mystring   //immutable string , so no change

New String : asd

New String 2: myotring

==================

Old Object String : Test|Old Class Int :2 //object & object inside value type is reference type, so will change

New Object String : Test|Old Class Int :2