Use Nullable Data Types Whenever Required

Use Nullable Data Types Whenever Required

Nullable data types are a special kind of value types that can hold either a valid value or a null value. Nullable data types are useful when you need to represent the absence or undefined state of a value, such as in a database or user input¹.

To declare a nullable data type, you can use the ? operator after the value type name, such as int?, bool?, DateTime?, etc. Alternatively, you can use the generic Nullable<T> struct, where T is the value type, such as Nullable<int>, Nullable<bool>, Nullable<DateTime>, etc.

To assign a null value to a nullable data type, you can use the null keyword or the default value expression, such as int? x = null; or int? x = default;.

To access the value of a nullable data type, you can use the Value property or the null-coalescing operator (??), such as int y = x.Value; or int y = x ?? 0;.

To check if a nullable data type has a valid value or not, you can use the HasValue property or the null-conditional operator (?.), such as if (x.HasValue) { ... } or if (x?.Value > 0) { ... }.

For example, consider this class that represents a product:

public class Product
{
    // A non-nullable property
    public string Name { get; set; }

    // A nullable property
    public decimal? Price { get; set; }

    // A constructor
    public Product(string name, decimal? price)
    {
        Name = name;
        Price = price;
    }

    // A method that prints the product details
    public void PrintDetails()
    {
        Console.WriteLine($"Name: {Name}");
        Console.WriteLine($"Price: {Price?.ToString("C") ?? "N/A"}");
    }
}