C# process class output

Question

In a C# 2010 desktop application, I have the following question about have my application executing another application by using the process class and checking the output from executing the other process:
1. When an error occurs, is there a way to rate how severe the error is? If so, can you tell me who to tell what the severity level of the error is?
2. Is there a way to tell when the return code value is an error, warning, and/or an informational level message? If this is possible, can you tell me how to rate the values levels that are returned by the process?

Vulpes · Accepted Answer

If the programmer does nothing and a program terminates normally, then an error code of 0 will be returned to Windows.
If the programmer does nothing and a program terminates abnormally, then one of a large number of error codes may  be returned to windows depending on the reason for the termination. See here for a list of the system error codes:
http://msdn.microsoft.com/en-us/library/ms681381(VS.85).aspx
The error code returned will be written to the environment variable %ERRORLEVEL%, so if you're running a console application from the command line, you can tell what error code has been returned by typing in the following immediately after termination:
echo %errorlevel%
This error code also shows up in the ExitCode property when you run a process programatically from a .NET application.
I suppose you could build a dictionary of these errors and display the appropriate message for the error code. However, if you have control of the application that you're launching and can change its source code, a better idea would be to catch any errors that occur and return a custom error code. You could then work out your system (using saying errors above 16000) depending on reason ansd severity, and also allow for warnings and information as well as errors.
You could either return the error code to Windows by returning a value from the Main Method or, where appropriate, force an exit using Environment.Exit(errorCode).