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Field

Description

Access modifiers:

Access Modifier In the same class In the child classes at the same assembly In the other classes at the same assembly Child classes at other assembly Other classes at other assembly
private Yes No No No No
protected Yes Yes No Yes No
private protected Yes Yes No No No
internal Yes Yes Yes No No
protected internal Yes Yes Yes Yes No
public Yes Yes Yes Yes Yes

Info

Default access modifier is private

Modifiers

Static fields are stored outside the object. Static fields are common to all objects of a class.

class BankAccount {
    long accountNumber;
    string accountHolderName;
    double currentBalance;
    static string bankName;
}
Category Instance Fields Static Fields
Storage Stored in Objects Stored in Class's memory
Related to Represents data related to objects. Represents common data that belongs to all objects.
Declaration Declared without "static" keyword.
Syntax: type fieldName;		 Declared with "static" keyword.
Syntax: static type fieldName;
Accessible with Accessible with object (through reference variable). Accessible with class name only (not with object).

Constant Fields are like static fields, that are common to all objects of the class.

  • We can't change the value of constant field.
  • Constant Fields are accessible with class name (not with object).
  • Constant Fields are not stored in the object; will not be stored anywhere.
  • Constant Fields will be replaced with its value, while compilation; so it will not be stored anywhere in memory.
  • Constant Fields must be initialized, in line with declaration (with a literal value only).
  • Constants can also be declared as 'local constants' (in a method).

Readonly Fields are like instance fields, that is stored in every object, individually.

  • We can't change the value of a readonly field.
  • Readonly Fields are accessible with a reference variable (with object).
  • Readonly Fields must be initialized, either "in-line with declaration" or "in the constructor".

Fields are variables that are declared in the class; but stored in objects.

  • private, protected, private protected, internal, protected internal, public
  • static, const, readonly
  • Instance fields are individual for each object; Static fields are common (one-time) for all objects.
  • Constants must be initialized along with declaration; Readonly fields must be initialized either along with declaration or in instance constructor.