Readonly ,Const Keyword with static Modifier

Question

can we use a static modifier with a Readonly and Const variable

my question is that i want to know what is diff. b/w

public static const int ab = 13;
public static readonly int ab = 10;

and

public const int ab = 13;
public readonly int ab = 10;

because const and readonly variable are all ready static for a class

Manish Kumar Choudhary · Answer

Public static readonly fields are a little unusual; public static properties (with only a get ) would be more common (perhaps backed by a private static readonly field). Const values are burned directly into the call-site; this is double edged: it is useless if the value is fetched at runtime, perhaps from config if you change the value of a const, you need to rebuild all the clients but it can be faster, as it avoids a method call... ...which might sometimes have been inlined by the JIT anyway If the value will never change, then const is fine - Zero etc make reasonable consts ;-p Other than that, static properties are more common. Go through following link for more details http://www.stum.de/2009/01/14/const-strings-a-very-convenient-way-to-shoot-yourself-in-the-foot/

Nanhe Siddique · Answer

const fields has to be initialized while declaration only, while readonly fields can be initialized at declaration or in the constructor. const variables can declared in methods ,while readonly fields cannot be declared in methods. const fields cannot be used with static modifier, while readonly fields can be used with static modifier. A const field is a compile-time constant, the readonly field can be used for run time constants.