GetComputerNameExA function (sysinfoapi.h)
Retrieves a NetBIOS or DNS name associated with the local computer. The names are established at system startup, when the system reads them from the registry.
Syntax
BOOL GetComputerNameExA(
[in] COMPUTER_NAME_FORMAT NameType,
[out] LPSTR lpBuffer,
[in, out] LPDWORD nSize
);
Parameters
[in] NameType
The type of name to be retrieved. This parameter is a value from the COMPUTER_NAME_FORMAT enumeration type. The following table provides additional information.
[out] lpBuffer
A pointer to a buffer that receives the computer name or the cluster virtual server name.
The length of the name may be greater than MAX_COMPUTERNAME_LENGTH characters because DNS allows longer names. To ensure that this buffer is large enough, set this parameter to NULL and use the required buffer size returned in the lpnSize parameter.
[in, out] nSize
On input, specifies the size of the buffer, in TCHARs. On output, receives the number of TCHARs copied to the destination buffer, not including the terminating null character.
If the buffer is too small, the function fails and GetLastError returns ERROR_MORE_DATA. This parameter receives the size of the buffer required, including the terminating null character.
If lpBuffer is NULL, this parameter must be zero.
Return value
If the function succeeds, the return value is a nonzero value.
If the function fails, the return value is zero. To get extended error information, call GetLastError. Possible values include the following.
| Return code | Description |
|---|---|
|
The lpBuffer buffer is too small. The lpnSize parameter contains the number of bytes required to receive the name. |
Remarks
If group policy is not set for the local machine, the GetComputerNameEx function retrieves the NetBIOS or DNS names established at system startup. If group policy is set, the function returns the primary domain name set by group policy. Name changes made by the SetComputerName or SetComputerNameEx functions do not take effect until the user restarts the computer.
If the local computer is not configured to use DNS names, GetComputerNameEx will not return DNS information. To configure the computer to do this, follow the steps outlined in the operating system help and change the primary DNS suffix of the computer, then restart the computer.
The behavior of this function can be affected if the local computer is a node in a cluster. For more information, see ResUtilGetEnvironmentWithNetName and UseNetworkName.
If you are working with environments that use different DNS layouts, where the computer's FQDN does not match the FQDN of its domain, use LsaQueryInformationPolicy instead.
To compile an application that uses this function, define the _WIN32_WINNT macro as 0x0500 or later. For more information, see Using the Windows Headers.
Examples
#define _WIN32_WINNT 0x0500
#include <windows.h>
#include <stdio.h>
#include <tchar.h>
void _tmain(void)
{
TCHAR buffer[256] = TEXT("");
TCHAR szDescription[8][32] = {TEXT("NetBIOS"),
TEXT("DNS hostname"),
TEXT("DNS domain"),
TEXT("DNS fully-qualified"),
TEXT("Physical NetBIOS"),
TEXT("Physical DNS hostname"),
TEXT("Physical DNS domain"),
TEXT("Physical DNS fully-qualified")};
int cnf = 0;
DWORD dwSize = _countof(buffer);
for (cnf = 0; cnf < ComputerNameMax; cnf++)
{
if (!GetComputerNameEx((COMPUTER_NAME_FORMAT)cnf, buffer, &dwSize))
{
_tprintf(TEXT("GetComputerNameEx failed (%d)\n"), GetLastError());
return;
}
else _tprintf(TEXT("%s: %s\n"), szDescription[cnf], buffer);
dwSize = _countof(buffer);
ZeroMemory(buffer, dwSize);
}
}
Note
The sysinfoapi.h header defines GetComputerNameEx as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | sysinfoapi.h (include Windows.h) |
| Library | Kernel32.lib |
| DLL | Kernel32.dll |
See also
ResUtilGetEnvironmentWithNetName
ResUtilSetResourceServiceEnvironment