Skip to main content
주 콘텐츠로 건너뛰기
GetUserName function

Retrieves the name of the user associated with the current thread.

Use the GetUserNameEx function to retrieve the user name in a specified format. Additional information is provided by the IADsADSystemInfo interface.


  _Out_   LPTSTR  lpBuffer,
  _Inout_ LPDWORD lpnSize


lpBuffer [out]

A pointer to the buffer to receive the user's logon name. If this buffer is not large enough to contain the entire user name, the function fails. A buffer size of (UNLEN + 1) characters will hold the maximum length user name including the terminating null character. UNLEN is defined in Lmcons.h.

lpnSize [in, out]

On input, this variable specifies the size of the lpBuffer buffer, in TCHARs. On output, the variable receives the number of TCHARs copied to the buffer, including the terminating null character.

If lpBuffer is too small, the function fails and GetLastError returns ERROR_INSUFFICIENT_BUFFER. This parameter receives the required buffer size, including the terminating null character.

Return value

If the function succeeds, the return value is a nonzero value, and the variable pointed to by lpnSize contains the number of TCHARs copied to the buffer specified by lpBuffer, including the terminating null character.

If the function fails, the return value is zero. To get extended error information, call GetLastError.


If the current thread is impersonating another client, the GetUserName function returns the user name of the client that the thread is impersonating.

If GetUserName is called from a process that is running under the "NETWORK SERVICE" account, the string returned in lpBuffer may be different depending on the version of Windows. On Windows XP, the "NETWORK SERVICE" string is returned. On Windows Vista, the “<HOSTNAME>$” string is returned.


For an example, see Getting System Information.


Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]


Winbase.h (include Windows.h)





Unicode and ANSI names

GetUserNameW (Unicode) and GetUserNameA (ANSI)

See also

System Information Functions