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// Note we are now returning an int, rather than void.

static int Main(string[] args)

{

// Display a message and wait for Enter key to be pressed.

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Console.WriteLine("***** My First C# App *****");

Console.WriteLine("Hello World!");

Console.WriteLine();

Console.ReadLine();

// Return an arbitrary error code.

return -1;

}

Let’s now capture Main()’s return value with the help of a batch file. Using the Windows

Explorer, navigate to the folder containing your compiled application (for example,

C:\SimpleCSharpApp\bin\Debug). Add a new text file (named SimpleCSharpApp.bat) to the

Debug folder that contains the following instructions (if you have not authored *.bat files

before, don’t concern yourself with the details; this is a test . . . this is only a test):

@echo off

rem A batch file for SimpleCSharpApp.exe

rem which captures the app's return value.

SimpleCSharpApp

@if "%ERRORLEVEL%" == "0" goto success

:fail

echo This application has failed!

echo return value = %ERRORLEVEL%

goto end

:success

echo This application has succeeded!

echo return value = %ERRORLEVEL%

goto end

:end

echo All Done.

At this point, open a command prompt and navigate to the folder containing your executable

and new *.bat file (again, for example, C:\SimpleCSharpApp\bin\Debug). Execute the batch logic

by typing its name and pressing the Enter key. You should find the following output, given that your

Main() method is returning -1 (see Figure 3-1). Had the Main() method returned 0, you would see

the message “This application has succeeded!” print to the console.

Figure 3-1.

Capturing an application’s return value via a batch file

Again, a vast majority (if not all) of your C# applications will use void as the return value from

Main(), which as you recall implicitly returns the error code of zero. To this end, the Main() methods

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used in this text will indeed return void (and the remaining projects will certainly not need to make

use of batch files to capture return codes!).