What is the Difference Between Field and Property in C#?
💡 Concept: Field vs Property
In C#, fields are variables declared directly in a class, while properties provide controlled access to private fields using getters and setters. Properties support encapsulation and can include logic.
📘 Quick Intro
A field is like a basic variable in a class. A property wraps a field with logic, offering read/write control and integration with .NET features like data binding and serialization.
🧠 Analogy
A field is like an open shelf anyone can access directly. A property is like a locked drawer with a key that lets you control what goes in and out. Properties add protection, validation, and control.
🔧 Technical Explanation
- 🔹 Fields are simple class-level variables (e.g.,
private int age;). - 🔹 Properties expose data via
getandsetaccessors. - 🔹 Properties support logic, validation, or computed values.
- 🔹 Auto-implemented properties simplify property creation.
- 🔹 Fields cannot participate in data binding or serialization directly.
🎯 Use Cases
- ✅ Use fields for internal logic or constants.
- ✅ Use properties to expose data safely to other classes or frameworks.
- ✅ Use properties with backing fields when validation is required.
- ✅ Properties are ideal for public interfaces or APIs.
💻 Code Example
public class Student
{
// Field
private int age;
// Property
public int Age
{
get { return age; }
set
{
if (value > 0)
age = value;
}
}
// Auto-implemented Property
public string Name { get; set; }
}
❓ Interview Q&A
Q1: What is a field in C#?
A: A field is a class-level variable used to store data directly.
Q2: What is a property?
A: A property provides controlled access to a field using getters and setters.
Q3: Can properties have logic?
A: Yes, you can include validation or computed logic in property accessors.
Q4: When should I use a property over a field?
A: Use a property when you want to expose data with control or validation.
Q5: Can you serialize a field directly?
A: Not easily—serialization works better with properties.
Q6: What is an auto-implemented property?
A: A property that automatically provides a backing field for basic get/set operations.
Q7: Are fields accessible outside the class?
A: Only if declared public, which is discouraged for encapsulation.
Q8: Can properties have only getters?
A: Yes, for read-only properties.
Q9: Do properties support expression-bodied members?
A: Yes, using C# syntax like =>.
Q10: Can fields have default values?
A: Yes, you can initialize them at declaration.
📝 MCQs
Q1. What is a field in C#?
- A method
- A variable declared at class level
- A property
- An interface
Q2. Which provides encapsulation?
- Field
- Constant
- Property
- Static variable
Q3. Can you add logic in a property?
- No
- Yes
- Only for get
- Only in fields
Q4. What does an auto-implemented property use internally?
- A constant
- A method
- A hidden backing field
- Nothing
Q5. Which is used for public APIs?
- Fields
- Constructors
- Properties
- Events
Q6. Are fields good for validation?
- Yes
- Only static
- No
- Sometimes
Q7. What can have expression-bodied members?
- Fields
- Delegates
- Properties
- Structs
Q8. What does the get accessor do?
- Assigns the value
- Returns the value
- Deletes the value
- Initializes the object
Q9. Which supports binding in XAML?
- Field
- Constant
- Property
- Enum
Q10. Can you override a field?
- Yes
- No
- Only static
- With attributes
💡 Bonus Insight
Fields are ideal for internal, hidden data, while properties give flexibility and maintainability. Following the rule "fields private, properties public" helps achieve solid OOP design and safe exposure of data.
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