How Can I Handle Native Exceptions and Access Specific Error Information in C#?

Handling Native Exceptions in C# Code

In C#, it is possible to catch exceptions originating from unmanaged libraries. A standard try-catch block is sufficient to handle such exceptions. However, to access specific error information from the native exception, you can use the Win32Exception class.

The Win32Exception class provides a NativeErrorCode property that returns the native error code associated with the exception. You can use this property to perform specific handling or display custom error messages.

For instance, consider a scenario where you are attempting to open a file using a native application. The code below demonstrates how to handle potential exceptions, including native exceptions:

const int ERROR_FILE_NOT_FOUND = 2;
const int ERROR_ACCESS_DENIED = 5;
const int ERROR_NO_APP_ASSOCIATED = 1155;

void OpenFile(string filePath)
{
    Process process = new Process();

    try
    {
        process.StartInfo.FileName = filePath;
        process.StartInfo.Verb = "Open";
        process.StartInfo.CreateNoWindow = true;
        process.Start();
    }
    catch (Win32Exception e)
    {
        if (e.NativeErrorCode == ERROR_FILE_NOT_FOUND || 
            e.NativeErrorCode == ERROR_ACCESS_DENIED ||
            e.NativeErrorCode == ERROR_NO_APP_ASSOCIATED)
        {
            MessageBox.Show(this, e.Message, "Error", 
                    MessageBoxButtons.OK, 
                    MessageBoxIcon.Exclamation);
        }
    }
}

In this example, we catch the Win32Exception and check the NativeErrorCode property. If the error code matches one of the specified values (e.g., file not found, access denied, etc.), we display a custom error message.

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