Delete last char of string

strgroupids = strgroupids.Remove(strgroupids.Length - 1);

MSDN:

String.Remove(Int32):

Deletes all the characters from this string beginning at a specified position and continuing through the last position

What about doing it this way

strgroupids = string.Join( ",", groupIds );

A lot cleaner.

It will append all elements inside groupIds with a ',' between each, but it will not put a ',' at the end.