Defining methods

Here I have another C# program. The first three lines of the Main method display a message that we're waiting, pause for 3 seconds, and print another message that we're done waiting. The next three lines count from 1 to 3.

These are two separate tasks in the same program, but it's hard to tell at a glance which lines belong to which task, or what task they're supposed to be doing.

using System;
using System.Threading;

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Waiting...");
        Thread.Sleep(3000);
        Console.WriteLine("Done");
        Console.WriteLine(1);
        Console.WriteLine(2);
        Console.WriteLine(3);
    }
}

• static keyword means you can call the method all by itself; it doesn't belong to an object.
  • GetType() is an example of a method you can only call on an object.
  • Have to place a dot operator after an object, then call the method: 42.GetType();
  • On the other hand, Console.WriteLine() is an example of a static method; a method you can call all by itself:
  • WriteLine takes arguments in parentheses, but you don't have to refer to an object, add a dot operator, and then call the method.
• void means no return value; we'll talk about return values shortly

static void Wait()
{
}

static void CountToThree()
{
}

• Method body in curly braces: one or more lines of code that will be run when method is called
  • Lines of method body are usually indented to make it clear they're a part of the method, although this isn't required

static void Wait()
{
    Console.WriteLine("Waiting...");
    Thread.Sleep(3000);
    Console.WriteLine("Done");
}

• Calling methods
  • Method name followed by parentheses
  • End statement with semicolon, as always

using System;
using System.Threading;

class Program
{

    static void Wait()
    {
        Console.WriteLine("Waiting...");
        Thread.Sleep(3000);
        Console.WriteLine("Done");
    }

    static void CountToThree()
    {
        Console.WriteLine(1);
        Console.WriteLine(2);
        Console.WriteLine(3);
    }

    static void Main(string[] args)
    {
        Wait();
        CountToThree();
    }

}

The rules regarding the names you can use with a C# method are similar to the rules for naming variables.

• Unlike variables, though, the first letter of the name should be capitalized.
• As with variables, you should use camel case if there are multiple words. So every word after the first should be capitalized as well.
• And of course, you can't use C# keywords, and there should be no spaces in the method name.

OK:

• Average
• CalculateTax

Not OK:

• average
• Calculatetax