Windows读写注册表的例子

在MSDN中，有个读写注册表的例子，很有参考价值。拷贝在这里：

说明部分：

Platform SDK: Debugging and Error Handling

Adding a Source to the Registry

You can use the default Application log without adding an event source to the registry. However, Event Viewer will not be able to map your event identifier codes to message strings unless you register your event source and provide a message file. For more information, see Message Files.

You can add a new source name to the registry by opening a new registry subkey under the Application key or a custom log using the RegCreateKeyEx function, and adding registry values to the new subkey using the RegSetValueEx function. The following example opens a new source and adds a message-file name and a bitmask of supported types.

下面是MSDN给的代码：

BOOL AddEventSource(
LPTSTR pszLogName, // Application log or a custom log
LPTSTR pszSrcName, // event source name
LPTSTR pszMsgDLL,  // path for message DLL
DWORD  dwNum)      // number of categories
{
HKEY hk;
DWORD dwData, dwDisp;
TCHAR szBuf[MAX_PATH];

// Create the event source as a subkey of the log.

wsprintf(szBuf,
"SYSTEM\\CurrentControlSet\\Services\\EventLog\\%s\\%s",
pszLogName, pszSrcName);

if (RegCreateKeyEx(HKEY_LOCAL_MACHINE, szBuf,
0, NULL, REG_OPTION_NON_VOLATILE,
KEY_WRITE, NULL, &hk, &dwDisp))
{
printf("Could not create the registry key.");
return FALSE;
}

// Set the name of the message file.

if (RegSetValueEx(hk,              // subkey handle
"EventMessageFile",        // value name
0,                         // must be zero
REG_EXPAND_SZ,             // value type
(LPBYTE) pszMsgDLL,        // pointer to value data
(DWORD) lstrlen(pszMsgDLL)+1)) // length of value data
{
printf("Could not set the event message file.");
RegCloseKey(hk);
return FALSE;
}

// Set the supported event types.

dwData = EVENTLOG_ERROR_TYPE | EVENTLOG_WARNING_TYPE |
EVENTLOG_INFORMATION_TYPE;

if (RegSetValueEx(hk,      // subkey handle
"TypesSupported",  // value name
0,                 // must be zero
REG_DWORD,         // value type
(LPBYTE) &dwData,  // pointer to value data
sizeof(DWORD)))    // length of value data
{
printf("Could not set the supported types.");
RegCloseKey(hk);
return FALSE;
}

// Set the category message file and number of categories.

if (RegSetValueEx(hk,              // subkey handle
"CategoryMessageFile",     // value name
0,                         // must be zero
REG_EXPAND_SZ,             // value type
(LPBYTE) pszMsgDLL,        // pointer to value data
(DWORD) lstrlen(pszMsgDLL)+1)) // length of value data
{
printf("Could not set the category message file.");
RegCloseKey(hk);
return FALSE;
}

if (RegSetValueEx(hk,      // subkey handle
"CategoryCount",   // value name
0,                 // must be zero
REG_DWORD,         // value type
(LPBYTE) &dwNum,   // pointer to value data
sizeof(DWORD)))    // length of value data
{
printf("Could not set the category count.");
RegCloseKey(hk);
return FALSE;
}

RegCloseKey(hk);
return TRUE;
}

在MSDN的这个例子上，自己又写了下面的例子进行演练，用的是Windows Application类型。为了简化，class的声明&定义都放在cpp文件中了。

#include <windows.h>

class RegHelper {
public:
RegHelper();
~RegHelper();

BOOL Open();
BOOL Query(DWORD &value);
BOOL Update(DWORD value);

private:
CHAR* GetLastErrorText(DWORD errorCode);

private:
enum {DEFAULT_VALUE = 100};
HKEY m_hRootKey;
HKEY m_hTargetKey;
LPCTSTR m_szTargetKey;
LPCTSTR m_szItemName;
};

RegHelper::RegHelper()
{
m_hRootKey = HKEY_LOCAL_MACHINE;
m_hTargetKey = NULL;
m_szTargetKey = "Software\\Microsoft\\Windows\\CurrentVersion\\here_is_my_keys";
m_szItemName = "Number";
}

RegHelper::~RegHelper()
{
if (m_hTargetKey) RegCloseKey(m_hTargetKey);
}

BOOL RegHelper::Open()
{
DWORD dwDisposition;

DWORD dwErrorCode = RegCreateKeyEx(HKEY_LOCAL_MACHINE, m_szTargetKey,
0, NULL, REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, NULL, &m_hTargetKey, &dwDisposition);

if (ERROR_SUCCESS != dwErrorCode) {
printf("%s\n", GetLastErrorText(dwErrorCode));
m_hTargetKey = NULL;
return FALSE;
}

if (dwDisposition == REG_CREATED_NEW_KEY) Update(DEFAULT_VALUE);

return TRUE;
}

BOOL RegHelper::Query(DWORD &value)
{
if (NULL == m_hTargetKey) return FALSE;

DWORD dwType;
DWORD len;
DWORD dwErrorCode = RegQueryValueEx(m_hTargetKey, m_szItemName, NULL, &dwType,
(LPBYTE)&value, &len);
if (dwErrorCode != ERROR_SUCCESS) {
printf("%s\n", GetLastErrorText(dwErrorCode));
return FALSE;
}

return dwType != REG_DWORD;
}

BOOL RegHelper::Update(DWORD value)
{
if (NULL == m_hTargetKey) return FALSE;

DWORD dwErrorCode = RegSetValueEx(m_hTargetKey,
m_szItemName,
0,
REG_DWORD,
(LPBYTE) &value,
sizeof(DWORD));

if (dwErrorCode != ERROR_SUCCESS) {
printf("%s\n", GetLastErrorText(dwErrorCode));
return FALSE;
}

return TRUE;
}

CHAR* RegHelper::GetLastErrorText(DWORD errorCode) {
static CHAR pBuf[1024] = { 0 };
const ULONG bufSize = 1024;
DWORD retSize;
LPTSTR pTemp = NULL;

pBuf[0] = '0';

retSize = FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_ARGUMENT_ARRAY,
NULL,
errorCode,
LANG_NEUTRAL,
(LPTSTR)&pTemp,
0,
NULL);
if (retSize > 0) {
pTemp[strlen(pTemp) - 2] = '\0'; //remove cr and newline character
sprintf(pBuf, "%0.*s", bufSize, pTemp);
LocalFree((HLOCAL)pTemp);
}

return(pBuf);
}

int main(int argc, char* argv[])
{
RegHelper helper;
if (!helper.Open()) return 1;

DWORD value;
helper.Query(value); // TODO exception ...
printf("value: %d\n", value);

value++;
if (!helper.Update(value)) {
printf("Update failed.\n");
return 1;
}

helper.Query(value);
printf("value: %d\n", value);

return 0;
}

其中获取错误码对应上一篇文档：

Windows开发常用的获取错误码对应文本的例子