How to Safely Read Values from the Windows Registry

Detecting Registry Key Existence

To determine if a registry key exists:

LONG lRes = RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"SOFTWARE\\Perl", 0, KEY_READ, &hKey);
if (lRes == ERROR_SUCCESS) {
  // Key exists
} else if (lRes == ERROR_FILE_NOT_FOUND) {
  // Key does not exist
}

Reading Registry Values

To retrieve the default value of a key:

std::wstring strKeyDefaultValue;
GetStringRegKey(hKey, L"", strKeyDefaultValue, L"bad");

To retrieve a string value:

std::wstring strValueOfBinDir;
GetStringRegKey(hKey, L"BinDir", strValueOfBinDir, L"bad");

To retrieve a DWORD value:

DWORD nValue;
LONG nError = GetDWORDRegKey(hKey, L"DWORD_Value_Name", nValue, 0);

To retrieve a Boolean value:

bool bValue;
LONG nError = GetBoolRegKey(hKey, L"BOOL_Value_Name", bValue, false);

Additional Notes

The following library dependencies are required for these functions:

• Advapi32.lib

Remember, these functions are for reading values only. Avoid writing to the registry if possible.