Determining the current username

GetUserName API function is very familiar with developers that use API frequently. Why does Builder.com let it bother us?
By the way, the tip itself is insufficience. The second argument of GetUserName API function is the maximum length of username that developer want to get back, if the username is longer than that it (returned string) will be truncated - this is the main different from other APIs, those often return the length of other parameter (returned string) - so we must provide a value for it before calling GetUserName.
Consenquently, the value assigned to second argument depend on developer's purpose. If he want to get the whole name of current user, he must set it to maximum length of username that Windows accept (those of you find it interesting can search MS document). If the developer just want to get first x character of username, he assign x to the second argument.
Peter Aitken's explaination is not clear (and in fact, it does not explain anything).

The sample code is not good, either. It takes time to calculate Len(UserName) and uses a hard code value of 40. I'd rather write it as follow:

'Max length of username we want to get back
Const MaxUsernameLen=40

UserName = Space(MaxUsernameLen)
GetUserName UserName, MaxUsernameLen

Maybe I am too new to this, however I like to use
Function NameOfUser() As String
NameOfUser = Environ("UserName")
End Function