When to use property and field in C# class

In C#, "property" and "field" are two fundamental constructs used to define data members within a class. Understanding when to use each is important for creating well-designed and maintainable code. Let's explore when to use a property and when to use a field in C#:

1. Fields:

• Fields are used to store data within a class or struct.
• Fields are typically private or protected and are accessed directly within the class where they are declared.
• Fields are often used for internal implementation details and are not directly exposed to external classes.
• Fields do not have built-in access control or validation mechanisms.

Example:

private int age; // Field

   public void SetAge(int newAge)
   {
       age = newAge; // Accessing and modifying the field directly
   }

   

2. Properties:

• Properties provide a controlled way to access and modify the state (fields) of an object.
• Properties encapsulate the access to fields, allowing for validation, computation, or other logic when getting or setting the value.
• Properties have a syntax similar to fields but often have a get and/or set accessor, which allows controlled access to the underlying field.
• Properties can be public, private, protected, etc., and can have different access levels for the get and set accessors.

Example:

   private int age; // Field

   public int Age // Property
   {
       get { return age; } // Accessing the field through the get accessor
       set
       {
           if (value >= 0) // Validation logic
               age = value; // Setting the field through the set accessor
       }
   }

In summary, use fields to store data directly within a class or struct, especially for internal implementation details. Use properties when you want to control access to the data (fields) by providing additional logic, validation, or encapsulation. It's a good practice to use properties to expose class members to other classes and to maintain better control and flexibility over your class's behavior and state.