Class methods

As previously mentioned, classes can store two different things:

• fields - variables that hold data relevant to the class.
• methods - functions that are attached to the class and can operate on its data.

Defining a method

You’ve already defined a method in a class, since the first hello world program you wrote was actually a method named Main inside a class named Program.

This wasn’t quite a regular class method, though - it was a static method.

Static methods

A static method is not tied to a specific object of the class. Instead, it belongs to the class itself.

That means that it can be called without creating an object of the class:

ClassName.StaticMethodName();

…instead of:

ClassName objectName = new ClassName();
objectName.InstanceMethodName();

When to use a static method

We should use a static method whenever the function doesn’t need to access any data from a specific object of the class - or when it operates on data that is shared across the entire program - static fields.

Method syntax

Just like we covered in the methods article, we define a method inside a class using this syntax:

access_modifier return_type MethodName(parameter_list)
{
    // Method body goes here
}

We can optionally add the static keyword after the access modifier to make the method static.

Example

Take our program from before about the Car class with fields for make, price and year:

class Car
{
    public string make;
    public float price;
    public int year;
}

Let’s say we added a method to print the car’s details:

class Car
{
    public string make;
    public float price;
    public int year;

    public void PrintDetails()
    {
        Console.WriteLine($"Make: {make}, Price: {price}, Year: {year}");
    }
}

We can then call PrintDetails on any object of the Car class to print its details:

Car myCar = new Car();
myCar.make = "Toyota";
myCar.price = 25000;
myCar.year = 2020;
myCar.PrintDetails();

Car anotherCar = new Car();
anotherCar.make = "Honda";
anotherCar.price = 22000;
anotherCar.year = 2019;
anotherCar.PrintDetails();

This would output:

Make: Toyota, Price: 25000, Year: 2020
Make: Honda, Price: 22000, Year: 2019

Static method example

Let’s say we have a class named MathUtilities that contains a static method to calculate the square of a number:

class MathUtilities
{
    public static int Square(int number)
    {
        return number * number;
    }
}

We can call the Square method without creating an object of the MathUtilities class:

int result = MathUtilities.Square(5);
Console.WriteLine(result); // Outputs: 25

This is a good use for a static method, because it doesn’t need to access any instance-specific data - it just performs a calculation based on the input parameter.