What are partial classes?

Partial classes in C# allow defining a single class across multiple physical source code files. This is useful for separating generated code from handwritten code, as well as when working in a team, enabling multiple developers to work on the same class simultaneously.

Key points:

• All parts must be marked with the partial keyword.
• All parts must have the same access modifier (e.g., public, internal).
• Parts can contain fields, properties, methods, events, nested types.
• During compilation, all parts are combined into one class.

Example usage:

File 1: MyClassPart1.cs

// Definition of the first part of the class
public partial class MyClass
{
    public int MyProperty { get; set; }

    public void Method1()
    {
        // Method 1 logic
    }
}

File 2: MyClassPart2.cs

// Definition of the second part of the class
public partial class MyClass
{
    public string MyField;

    public void Method2()
    {
        // Method 2 logic
    }
}

In this case, the MyClass class will contain both the property MyProperty, the field MyField, and the methods Method1() and Method2().