Code Golf: C#: Convert ulong to Hex String

The solution is actually really simple, instead of using all kinds of quirks to format a number into hex you can dig down into the NumberFormatInfo class.

The solution to your problem is as follows...

return string.Format("0x{0:X}", temp);

Though I wouldn't make an extension method for this use.

You can use string.format:

string.Format("0x{0:X4}",200);

Check String Formatting in C# for a more comprehensive "how-to" on formatting output.