How to programmatically figure out if a user account is a member of a particular group in Windows?

Question

Given a group name and a user account, I would like to know if the supplied user belongs to a particular group. The user can be a local user or a domain user and the group c

Answer 1

UserPrincipal.IsMemberOf(GroupPrincipal) "returns a Boolean value that specifies whether the principal is a member of the specified group".