Why does the constructor of my static class never seem to get called?

Question

I'm writing a Console application in C#. When the application is run I need it to check a few things before doing any work such as whether certain settings and directories exist. I have a static class for this stored in Logging.cs and I have put the checks in the constructor for this class but it never seems to get called.

Here's a very basic example:

Program.cs

internal class Program
{
    private static void Main(string[] args)
    {
        Console.WriteLine("Started application");
        Console.ReadKey(); // Stops the application exiting so I can read the output
    }
}

Logging.cs

internal static class Logging
{
    static Logging()
    {
        // The checks are all here, for the demo we'll just use WriteLine
        Console.WriteLine("Logging constructor");
    }
}

Expected console output:

Started application
Logging constructor <-- This line never appears

I know I could create a static method inside the Logging class called DoStartupChecks and call it from Main in Program.cs, but I want to understand what I've done wrong here. Maybe the answer is to create the method and call it but I want to understand why the above example is wrong first.

Static constructor gets called the first time the class is used, not when your program is loaded. So your example would indeed not cause the constructor to be called. — Mark, Feb 04 '16 at 14:13
OK that makes sense. I thought that making it static would create an instance and therefore call the constructor. This makes more sense. Thanks. — Equalsk, Feb 04 '16 at 14:17

MakePeaceGreatAgain · Accepted Answer · 2016-02-04T14:19:05.657

5

The static constructor is called when a class is referenced the very first time, e.g. by calling any of its members, by creating an instance of it or by calling a method on it.

Thus you have to write something like this:

private static void Main(string[] args)
{
    Logging.DoSomething();
    Console.WriteLine("Started application");
    Console.ReadKey(); // Stops the application exiting so I can read the output
}

From MSDN:

It [the static constructor] is called automatically before the first instance is created or any static members are referenced.

edited Feb 04 '16 at 14:19

answered Feb 04 '16 at 14:12

MakePeaceGreatAgain

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So I guess I do need a method after all and by calling the method it would also cause the constructor to be called? – Equalsk Feb 04 '16 at 14:14
Method, constant, property, field... it could be anything. – MakePeaceGreatAgain Feb 04 '16 at 14:16
Cool, that makes sense to me. I mistakenly thought that making it static would be enough. Thanks. (I have to wait to accept). – Equalsk Feb 04 '16 at 14:16

Why does the constructor of my static class never seem to get called?

1 Answers1