static class and method in C#

In C#, a static class or method is a member that belongs to the type itself, rather than to an instance of the type. This means that you can access it without creating an instance of the class.

Here is an example of defining a static class in C#:

static class MathHelpers
{
    public static double Multiply(double a, double b)
    {
        return a * b;
    }

    public static double Divide(double a, double b)
    {
        return a / b;
    }
}

In this example, we define a static class called MathHelpers with two static methods, Multiply and Divide. We can call these methods without creating an instance of the MathHelpers class, like this:

double result1 = MathHelpers.Multiply(2.0, 3.0);
double result2 = MathHelpers.Divide(6.0, 2.0);

Rules to keep in mind while using static classes and methods:

• static classes and methods are members of the type itself, not of an instance of the type. They can be accessed using the dot notation, without creating an instance of the class.
• static classes and methods cannot access instance members of a class, as there is no instance to refer to. They can only access other static members or const fields.
• static classes cannot be instantiated, as they have no instance state. They can only contain static members.
• static methods cannot be overridden or used in polymorphism, as they are not associated with any instance of a class.
• static members are loaded into memory when the program starts, and they remain in memory for the duration of the program. This can have performance implications for large or complex static classes and methods.
• It’s generally recommended to use static members when you need to share functionality across multiple instances of a class, or when you have a utility class that doesn’t need instance state.

Overall, static classes and methods are a useful tool in C# for creating utility classes, shared functionality, or other types of functionality that do not depend on instance state. By understanding the rules and best practices for using them, you can create more efficient and maintainable code in C#.