The ‘object’ Base Class in .NET

What is the Object Base Class?

In .NET, the **object** class is the ultimate **base class for all types**. Whether it's a **value type** (like int, bool) or a **reference type** (like classes and arrays), every type in .NET **inherits from** the object class.

The **object** class provides essential methods that enable **type checking, equality comparison, hashing, and string conversion**.

Key Methods of the object Class

The object class defines several **important methods** that can be overridden in derived classes:

• ToString(): Converts an object into a string representation.
• Equals(object obj): Compares two objects for equality.
• GetHashCode(): Returns a unique identifier (hash code) for an object.
• GetType(): Retrieves the runtime type of the current object.

Example: Using Methods from the object Class

Here’s an example demonstrating how the **key methods of the object class** work in C#:

class Person
{
    public string Name { get; set; }

    public override string ToString()
    {
        return $"Person: {Name}";
    }
}

Person person = new Person() { Name = "Alice" };
Console.WriteLine(person.ToString());  // Output: Person: Alice
Console.WriteLine(person.GetType());   // Output: Person
Console.WriteLine(person.GetHashCode());  // Output: HashCode of the object
        

In this example:

• ToString() is overridden to return a custom string representation.
• GetType() returns the **runtime type** of the object.
• GetHashCode() returns a **unique hash code** for the object.

Polymorphism and the Object Class

Since **all types inherit from object**, C# allows **polymorphism**, where objects of different types can be assigned to an **object** reference.

Example: Using Object for Multiple Data Types

object obj = new Person() { Name = "Bob" };
Console.WriteLine(obj.ToString());  // Output: Person: Bob

obj = 123;  // Now obj holds an integer
Console.WriteLine(obj.ToString());  // Output: 123
        

In this example, the **same object reference** stores:

• An instance of Person (custom class)
• An int value (value type)

This demonstrates **polymorphism**, where different data types can be treated as object.

Best Practices When Using object

While object provides flexibility, it **should be used with caution** to avoid unnecessary performance issues.

• Avoid Boxing and Unboxing: When storing value types in object, it leads to **boxing**, which affects performance.
• Prefer Generics: Instead of using object, use **generics** (List<T>, Dictionary<TKey, TValue>) for better type safety.
• Override Equals() and GetHashCode() Properly: When using objects as keys in collections like **hash tables**.

Performance Considerations

Using object can sometimes lead to **performance drawbacks**, especially when working with value types.