Help need to convert this code to C#

I 'm not familiar with VB.NET at all. I need to convert this function to C#. Can anyone please give me a hand?

Public Function GetAppGUID(ByVal sectionId As String) As String

    Dim hexString As String = Nothing
    Dim i As Integer
    Dim guidlen As Integer

    guidlen = 16

    If sectionId.Length < guidlen Then
        sectionId = sectionId & N开发者_高级运维ew String(" ".Chars(0), guidlen - sectionId.Length)
    End If

    For i = 1 To guidlen
        hexString = hexString & Hex(Asc(Mid(sectionId, i, 1)))
    Next

    GetAppGUID = hexString

End Function

C# solution is below

    private string GetAppGUID(string sectionId)
    {
        string hexString = null;
        int i = 0;
        int guidLength = 0;

        guidLength = 16;

        if (sectionId.Length < guidLength)
        {
            sectionId = sectionId + new string(" "[0], guidLength - sectionId.Length);
        }

        foreach (char c in sectionId)
        {
            int tmp = c;
            hexString += String.Format("{0:x2}", (uint)System.Convert.ToUInt32(tmp.ToString()))
        }

        return hexString;
    } 

The method uses some VB specific functions that do not have C# equivalents. The functionality could easily be approximated but to use as is, simply add a reference to Microsoft.VisualBasic.

    public string GetAppGUID(string sectionId)
    {

        string hexString = null;
        int i = 0;
        int guidlen = 0;

        guidlen = 16;

        if (sectionId.Length < guidlen)
        {
            sectionId = sectionId + new string(' ', guidlen - sectionId.Length);
        }

        for (i = 1; i <= guidlen; i++)
        {
            hexString = hexString 
                + Microsoft.VisualBasic.Conversion.Hex(Microsoft.VisualBasic.Strings.Asc(Microsoft.VisualBasic.Strings.Mid(sectionId, i, 1)));
        }

        return hexString;

    }

These tools don't know some VB functions. There is no Conversion.Hex or Strings.Asc, String.Mid in C#. Any help?

Thanks everyone. I kind of talking rubbish before. The tools are good and yes they convert for you. But is confusing right. The tools use Microsoft.VisualBasic to do the

hexString = hexString + Conversion.Hex(Strings.Asc(Strings.Mid(sectionId, i, 1)));

Which is kind of OK. Does anyone see anything wrong with this?

Thanks