Mitch Wheat - Treat the cause, not the symptoms!

/// <summary>

/// See main overload.

/// </summary>

/// <param name="fullFilePathname">a fully pathed filename</param>

/// <returns>a unique fully pathed filename</returns>

public static string EnsureUniqueFilename(string fullFilePathname)

{

    string destFolder = Path.GetDirectoryName(fullFilePathname);

    if (String.IsNullOrEmpty(destFolder))

        throw new ArgumentException("You must pass a fully pathed filename");

    return EnsureUniqueFilename(fullFilePathname, destFolder);

}

/// <summary>

/// Return a unique filename of the form, 'Copy of (?) OriginalFilename.ext'

/// NOTE: Does not adhere to the full semantics of the file explorer copy logic.

///       which creates first copy named as 'Copy of OriginalFilename.ext'

///       Nor does it rename any files. It simply returns a filename which is unique

///       It does not take into account multiple threads attempting to make use 

///       of the same filename.

/// </summary>

/// <param name="fullFilePathname">a fully pathed filename</param>

/// <param name="destFolder">a destination folder</param>

/// <returns>a unique fully pathed filename</returns>

public static string EnsureUniqueFilename(string fullFilePathname, string destFolder)

{

    string filename = Path.GetFileName(fullFilePathname);

    string renamedFile = Path.Combine(destFolder, Path.GetFileName(fullFilePathname));

    // Check if a file with same name exists in folder and try a modified name if neccessary...

    int intCopy = 0;

    while (File.Exists(renamedFile))

    {

        intCopy++;

        renamedFile = Path.Combine(destFolder, "Copy (" + intCopy.ToString() + ") of " + filename);

    }

    return renamedFile;

}