C# program that leaves untouched errorlevel

Question

Is there a way to read ERRORLEVEL from an C# so you can return it and keeps unchanged when finishes?

It seems that Environment.ExitCode begins with 0 when the program starts. This program always writes 0.

To too lazy; didn't read people: the following code is not the program I want to write, but a test to prove that Environment.ExitCode is not inherited from errorlevel, %errorlevel% or any previous exit code just in case of doubt.

using System;

namespace test {
    class Program {
        static void Main() {
            Console.WriteLine("{0}",Environment.ExitCode);
        }
    }
}

My goal is to write a program that, when used in a batch, doesn't interfere with the current errorlevel so it can be used afterwards. I know you can save it and restore it inside the batch...

...
command1 with options "or not"
set elsaved=%errorlevel%
my_cs_program run without telling it which errorlevel is
REM Damn, I cleared errorlevel, thank science I saved it before
call :setel %elsaved%
...
goto :eof

:setel
exit /b %1

... but it's a nuisance. It would be better if the invocation left errorlevel alone.

...
        static void Main() {
...
            var parent_cmd_errorlevel=exotic_funtion();
...
            Environment.ExitCode = parent_cmd_errorlevel;
...

This way I don't have to mind about it in the batch.

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tl;dr: Is it possible to write a C# program transparent to errorlevel? If not in C#, is there any other language? What one? More generally: can a cmd.exe child process obtain the errorlevel of its parent? Maybe wmic would help?

---

To downvoters/duplicate-voters: I know how to specify the exit code of a console application in .NET:

...
        static void Main() {
...
            Environment.ExitCode = whatever;
...

Or

...
        static int Main() {
...
            return(whatever);
...

Am I wrong? If you are not interested in this problem, please leave the question alone but AFAIK this has not been asked in SO or another SE KB.

Answer 1

You cannot read the ERRORLEVEL from the last program, but you could pass it as argument and then set it again:

class Program
{
    static void Main(string[] args)
    {
        Environment.ExitCode = int.Parse(args[0]);
    }
}

And then call it in your batch like this:

cd "some path that returns an error"
.\Console1App.exe %errorlevel%

REM Print the error code of the cd command
echo %errorlevel%

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Note that this only works if the %errorlevel% environment variable is not set. The way CMD works is that it will pass the actual errorlevel as fallback when %errorlevel% is not set