removing illlegal char from filename code example

Example 1: removing illlegal char from filename

public string ReplaceInvalidChars(string filename)
{
    return string.Join("_", filename.Split(Path.GetInvalidFileNameChars()));    
}

Example 2: removing illlegal char from filename

public string RemoveInvalidChars(string filename)
{
    return string.Concat(filename.Split(Path.GetInvalidFileNameChars()));
}