#10 – The Return Value from Main() Sets ERRORLEVEL Variable in Windows

June 27, 2010 4 Comments

If your Main() function returns an integer value, you can check that value in the calling program or script using the ERRORLEVEL environment variable.  By convention, a return value of 0 indicates success and any other value indicates an error.  Below is a sample .bat file that calls a program called MyProgram and then checks the return value.

@echo off

MyProgram

IF "%ERRORLEVEL%" == "0" goto OK

:NotGood
    echo Bad news.  Program returned %ERRORLEVEL%
    goto End

:OK
    echo Everything A-OK

:End

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#9 – Main() Should Not Be Public

June 26, 2010 Leave a comment

The following code will compile, but is not recommended, according to the MSDN documentation. If Main() is public, other classes could call it.  But this violates the intent for Main(), which is meant to only be called once, when the program is invoked.

class Program
{
    static public void Main()
    {
        Console.WriteLine("This would compile..");
    }
}

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#8 – The Main() Function Can Return an int

June 25, 2010 4 Comments

Instead of returning void, Main() can return an integer value, which can then be read by the calling program or script.  Notice that the return type of the function is an int

class Program
{
    static int Main()
    {
        Console.WriteLine("Doing something..");

        if (DateTime.Today.DayOfWeek == DayOfWeek.Monday)
            return -1;     // Monday is bad
        else
            return 0;
    }
}

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#6 – An Even Smaller C# Program

June 23, 2010 2 Comments

In The Smallest Possible C# Program, I mentioned a couple things as optional.  For the record, here’s the absolute smallest C#.NET program that you can write.  (Assuming that you don’t need it to actually do anything).

class Program
{
    static void Main()
    {
    }
}

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#2 – The Smallest Possible C# Program

June 19, 2010 2 Comments

The smallest possible C# program would consist of a static Main() function inside of a class. The namespace is actually optional, as is the args parameter.

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("2,000 Things Was Here..");
        }
    }
}



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#1 – What the Main() Signature Looks Like

June 18, 2010 Leave a comment

The standard entry point for a C# program is a static function named Main().  It typically looks like this:

static void Main(string[] args)

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