如何在c++中从注册表中读取字符串值

Question

请有人告诉我怎么了？我复制了此代码并给出错误error_FILE_NOT_FOUND注册表中有一个字符串值，名称为"；name"；

string GetRegistry()
{
DWORD dwType = REG_SZ;
HKEY Handler = 0;
string subkey = "Key123\";
string value_name = "name";
DWORD AnswerType;
char data[32];
DWORD buffer_size = 32;
LSTATUS Answer = RegOpenKeyA(HKEY_CURRENT_USER, subkey.c_str(), &Handler);
if (Answer != ERROR_SUCCESS) {
return "Faild To Open Registry Key";
}
Answer=RegGetValueA(Handler, subkey.c_str(), value_name.c_str(), RRF_RT_REG_SZ, &AnswerType, data, &buffer_size);
RegCloseKey(Handler);
string return_data = "";
for (unsigned int a = 0; a < 32; a++) {
return_data += (char)*(data + a);
}
return return_data;
}

Answer 1

您滥用了RegGetValueA()。

其lpValue参数相对于其lpSubKey参数，后者相对于其hkey参数。

您正在使用RegOpenKeyA()(已弃用，应改为使用RegOpenKeyExA())打开HKEY_CURRENT_USERKey123密钥，然后调用RegGetValuA()，其hKey参数设置为该打开密钥，lpSubKey参数设置为"Key123"，lpValue参数设置为"name"。

因此，您要求RegGetValueA()读取HKEY_CURRENT_USERKey123Key123name值，但您的意思是读取HKEY_CURRENT_USERKey123name值。这就是RegGetValueA()与ERROR_FILE_NOT_FOUND一起失败的原因。

所以，你需要：

• 使用RegOpenKeyExA()打开HKEY_CURRENT_USERKey123，然后使用RegQueryValueEx()(或RegGetValueA()与lpSubKey=NULL)读取该打开密钥中的name值，例如：

  string GetRegistry()
  {
  HKEY Handler = NULL;
  string subkey = "Key123";
  string value_name = "name";
  char data[32];
  DWORD buffer_size = 32;
  LSTATUS Answer = RegOpenKeyExA(HKEY_CURRENT_USER, subkey.c_str(), 0, KEY_QUERY_VALUE, &Handler);
  if (Answer != ERROR_SUCCESS) {
  return "Failed To Open Registry Key";
  }
  Answer = RegQueryValueExA(Handler, value_name.c_str(), NULL, NULL, (LPBYTE)data, &buffer_size);
  RegCloseKey(Handler);
  if (Answer != ERROR_SUCCESS) {
  return "Failed To Read Registry Value";
  }
  // the data MAY or MAY NOT be null-terminated,
  // ignore the terminator if it is present...
  if ((buffer_size > 0) && (data[buffer_size-1] == '')) {
  --buffer_size;
  }
  return string(data, buffer_size);
  }
  

  string GetRegistry()
  {
  HKEY Handler = NULL;
  string subkey = "Key123";
  string value_name = "name";
  char data[32];
  DWORD buffer_size = 32;
  LSTATUS Answer = RegOpenKeyExA(HKEY_CURRENT_USER, subkey.c_str(), 0, KEY_QUERY_VALUE, &Handler);
  if (Answer != ERROR_SUCCESS) {
  return "Failed To Open Registry Key";
  }
  Answer = RegGetValueA(Handler, NULL, value_name.c_str(), RRF_RT_REG_SZ, NULL, data, &buffer_size);
  RegCloseKey(Handler);
  if (Answer != ERROR_SUCCESS) {
  return "Failed To Read Registry Value";
  }
  // the data IS null-terminated, ignore the terminator...
  return string(data, buffer_size-1);
  }
  

• 单独使用RegGetValueA()，完全不使用RegOpenKeyExA()，例如：

  string GetRegistry()
  {
  HKEY Handler = NULL;
  string subkey = "Key123";
  string value_name = "name";
  char data[32];
  DWORD buffer_size = 32;
  LSTATUS Answer = RegGetValueA(HKEY_CURRENT_USER, subkey.c_str(), value_name.c_str(), RRF_RT_REG_SZ, NULL, data, &buffer_size);
  if (Answer != ERROR_SUCCESS) {
  return "Failed To Read Registry Key Value";
  }
  // the data is null-terminated, ignore the terminator...
  return string(data, buffer_size-1);
  }