Question

try
{
     object result = processClass.InvokeMethod("Create", methodArgs);
}
catch (Exception e)
{  
    // Here I was hoping to get an error code.
}

When I invoke the above WMI method I am expected to get Access Denied. In my catch block I want to make sure that the exception raised was indeed for Access Denied. Is there a way I can get the error code for it ? Win32 error code for Acceess Denied is 5.
I dont want to search the error message for denied string or anything like that.

Thanks

Answer 1

You can use this to check the exception and the inner exception for a Win32Exception derived exception.

catch (Exception e) {  
    var w32ex = e as Win32Exception;
    if(w32ex == null) {
        w32ex = e.InnerException as Win32Exception;
    }    
    if(w32ex != null) {
        int code =  w32ex.ErrorCode;
        // do stuff
    }    
    // do other stuff   
}

Starting with C# 6, when can be used in a catch statement to specify a condition that must be true for the handler for a specific exception to execute.

catch (Win32Exception ex) when (ex.InnerException is Win32Exception) {
    var w32ex = (Win32Exception)ex.InnerException;
    var code =  w32ex.ErrorCode;
}

As in the comments, you really need to see what exception is actually being thrown to understand what you can do, and in which case a specific catch is preferred over just catching Exception. Something like:

  catch (BlahBlahException ex) {  
      // do stuff   
  }

Also System.Exception has a HRESULT

 catch (Exception ex) {  
     var code = ex.HResult;
 }

However, it’s only available from .NET 4.5 upwards.