Use Path class instead of string manipulations

Today i've found such a code in my project. This code was added by other developer. The interesting thing about this code is bold line:

  private static string GetFullPath(string directoryPath, string fileName)
  {
      if (string.IsNullOrEmpty(directoryPath))
          throw new ArgumentOutOfRangeException("directoryPath");
      if (string.IsNullOrEmpty(fileName))
          throw new ArgumentOutOfRangeException("fileName");

      return string.Format("{0}\\{1}", directoryPath.Trim('\\'), fileName);
  }

What is wrong? If you want to be sure that path will be constructed properly use Path class and it static methods. Here is how this code should look like:

      private static string GetFullPath(string directoryPath, string fileName)
    {
        if (string.IsNullOrEmpty(directoryPath))
            throw new ArgumentOutOfRangeException("directoryPath");
        if (string.IsNullOrEmpty(fileName))
            throw new ArgumentOutOfRangeException("fileName");

        return Path.Combine(directoryPath, fileName);
    }

Conclusion: Use Path class for file path manipulations instead of string manipulations