How to get SPUser name from User Id

Sometimes we get uniques user id from sharepoint but the requirement is for name.

This can be done in one simple line:

using (SPSite site=new SPSite(siteurl))
{
using (SPWeb web=site.OpenWeb())
{
string userName= web.AllUsers.GetByID(Convert.ToInt32(userid)).Name;
}
}

Line number 5 actually gets the user name by searching all users in the 'web' scope by searching userId.