RegQueryInfoKey
The RegQueryInfoKey
function retrieves information about a specified registry key.
LONG RegQueryInfoKey (
|
HKEY hKey, |
// handle of key to
query |
|
LPTSTR lpClass, |
// address of
buffer for class string |
|
LPDWORD lpcbClass, |
// address of size
of class string buffer |
|
LPDWORD lpReserved, |
// reserved |
|
LPDWORD lpcSubKeys, |
// address of
buffer for number of subkeys |
|
LPDWORD lpcbMaxSubKeyLen, |
// address of
buffer for longest subkey name length |
|
LPDWORD lpcbMaxClassLen, |
// address of
buffer for longest class string length |
|
LPDWORD lpcValues, |
// address of
buffer for number of value entries |
|
LPDWORD lpcbMaxValueNameLen, |
// address of
buffer for longest value name length |
|
LPDWORD lpcbMaxValueLen, |
// address of
buffer for longest value data length |
|
LPDWORD lpcbSecurityDescriptor, |
// address of
buffer for security descriptor length |
|
PFILETIME lpftLastWriteTime |
// address of
buffer for last write time |
|
); |
|
Parameters
hKey
Identifies a
currently open key or any of the following predefined reserved handle values:
HKEY_CLASSES_ROOT
HKEY_CURRENT_USER
HKEY_LOCAL_MACHINE
HKEY_USERS
lpClass
Points to a
buffer that receives the key s class name. This parameter can be NULL.
lpcbClass
Points to a
variable that specifies the size, in characters, of the buffer pointed to by
the lpClass parameter. This size should include the terminating null
character. When the function returns, this variable contains the length of the
class string stored in the buffer. The count returned does not include the
terminating null character. If the buffer is not big enough, the function
returns ERROR_MORE_DATA, and the variable contains the size of the string, in
characters, without counting the null character.
If lpClass is NULL, lpcbClass can be NULL.
Windows NT:
If the lpClass parameter is a valid address, but the lpcbClass
parameter is not (for example, it is NULL), the function returns ERROR_INVALID_PARAMETER.
Windows 95:
If the lpClass parameter is a valid address, but the lpcbClass
parameter is not (for example, it is NULL), the function returns ERROR_SUCCESS
instead of ERROR_INVALID_PARAMETER. To ensure compatibility with other platforms,
verify that lpcbClass is valid before calling the function.
lpReserved
Reserved;
must be NULL.
lpcSubKeys
Points to a
variable that receives the number of subkeys contained by the specified key.
This parameter can be NULL.
lpcbMaxSubKeyLen
Points to a
variable that receives the length, in characters, of the key s subkey with the
longest name. The count returned does not include the terminating null
character. This parameter can be NULL.
lpcbMaxClassLen
Points to a
variable that receives the length, in characters, of the longest string
specifying a subkey class. The count returned does not include the terminating
null character. This parameter can be NULL.
lpcValues
Points to a
variable that receives the number of values associated with the key. This
parameter can be NULL.
lpcbMaxValueNameLen
Points to a
variable that receives the length, in characters, of the key s longest value
name. The count returned does not include the terminating null character. This
parameter can be NULL.
lpcbMaxValueLen
Points to a
variable that receives the length, in bytes, of the longest data component
among the key s values. This parameter can be NULL.
lpcbSecurityDescriptor
Points to a
variable that receives the length, in bytes, of the key s security descriptor.
This parameter can be NULL.
lpftLastWriteTime
Pointer to a FILETIME structure. This parameter
can be NULL.
If you are querying the registry on a computer running Windows NT, the
function sets the members of the FILETIME structure to indicate the last
time that the key or any of its value entries was modified.
If you are querying the registry on a computer running Windows 95, the
function sets the members of the FILETIME structure to zero. This is
because the Windows 95 operating system does not keep track of registry key
last write time information.
Return Values
If the
function succeeds, the return value is ERROR_SUCCESS.
If the
function fails, the return value is a nonzero error code defined in WINERROR.H.
You can use the FormatMessage
function with the FORMAT_MESSAGE_FROM_SYSTEM flag to get a generic description
of the error.
Remarks
The key
identified by the hKey parameter must have been opened with KEY_QUERY_VALUE
access (KEY_READ access includes KEY_QUERY_VALUE access).
See Also