How can I get the description of a file extension in .NET

Question

HI,

Windows provides descriptions for file extension such as \"Control Panel Item\" for .cpl files and \"PowerISO File\" for .daa files. Is there any way I can obtai

Answer 1

You can search the registry like this:

• Search default value of the extension in HKEY_CLASSES_ROOT. For example The default value of HKEY_CLASSES_ROOT\.txt is txtfile.
• Then search default value of the previous result: For example The default value of HKEY_CLASSES_ROOT\txtfile is Text Document.

After two searches the answer is Text Document.

You can test any other extension by RegEdit.

Visit this link: http://www.codeproject.com/KB/cs/GetFileTypeAndIcon.aspx?display=Print

This is implementation of these two searches:

public static class Helper
{
    public static string GetFileDescription(string fileName)
    {
        if (fileName == null)
        {
            throw new ArgumentNullException("fileName");
        }

        RegistryKey registryKey1 = null;
        RegistryKey registryKey2 = null;
        try
        {
            FileInfo fileInfo = new FileInfo(fileName);

            if (string.IsNullOrEmpty(fileInfo.Extension))
            {
                return string.Empty;
            }

            string extension = fileInfo.Extension.ToLowerInvariant();

            registryKey1 = Registry.ClassesRoot.OpenSubKey(extension);
            if (registryKey1 == null)
            {
                return string.Empty;
            }

            object extensionDefaultObject = registryKey1.GetValue(null);
            if (!(extensionDefaultObject is string))
            {
                return string.Empty;
            }

            string extensionDefaultValue = (string)extensionDefaultObject;

            registryKey2 = Registry.ClassesRoot.OpenSubKey(extensionDefaultValue);
            if (registryKey2 == null)
            {
                return string.Empty;
            }

            object fileDescriptionObject = registryKey2.GetValue(null);
            if (!(fileDescriptionObject is string))
            {
                return string.Empty;
            }

            string fileDescription = (string)fileDescriptionObject;
            return fileDescription;
        }
        catch (Exception)
        {
            return null;
        }
        finally
        {
            if (registryKey2 != null)
            {
                registryKey2.Close();
            }

            if (registryKey1 != null)
            {
                registryKey1.Close();
            }
        }
    }
}