readonly modifier prevents a field from being modified after construction.
A read-only field can be assigned only in declaration or in the type's constructor.
using System; class MainClass/*from w w w .ja v a 2 s . c o m*/ { static readonly int v = 5; public static void Main(string[] args) { Console.WriteLine(v); new MyClass(); } } class MyClass { readonly int v; public MyClass() { //constructor v = 6; } }