That isn't even close - either you don't understand VB or you don't understand C#...
Try using a code converter - there are several online, but this one's quite good:
Code Converter C# to VB and VB to C# – Telerik[
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It gave me this:
private void StockETDStdCalc()
{
DateTime DateSOP;
string DateSOPFormat, DateDaySOP;
DateSOP = default(DateTime);
DateSOPFormat = null;
DateDaySOP = null;
DateSOP = DateTime.Now;
DateSOP = DateSOP.AddDays(+5);
if (Strings.Format(DateSOP, "ddd") == "6")
DateSOP = DateSOP.AddDays(+2);
else if (Strings.Format(DateSOP, "ddd") == "7")
DateSOP = DateSOP.AddDays(+1);
DateSOPFormat = Strings.Format(DateSOP, "MM") + "-" + Strings.Format(DateSOP, "dd") + "-" + Strings.Format(DateSOP, "yyyy");
TxtBx_ETD.Text = DateSOPFormat;
}
Which is poor quality C#, but it at least going to do the same job as the input code...