WinReg v2.2.3

High-level C++ Wrapper Around the Low-level Windows Registry C-interface API

by Giovanni Dicanio

The Windows Registry C-interface API is very low-level and hard to use.

I developed some C++ wrappers around this low-level Win32 API, to raise the semantic level, using C++ classes like std::wstring, std::vector, etc. instead of raw C-style buffers and low-level mechanisms.

For example, the REG_MULTI_SZ registry type associated to double-NUL-terminated C-style strings is handled using a much easier higher-level vector<wstring>. My C++ code does the translation between high-level C++ STL-based stuff and the low-level Win32 C-interface API.

Moreover, Win32 error codes are translated to C++ exceptions.

The Win32 registry value types are mapped to C++ higher-level types according the following table:

Win32 Registry Type	C++ Type
REG_DWORD	DWORD
REG_QWORD	ULONGLONG
REG_SZ	std::wstring
REG_EXPAND_SZ	std::wstring
REG_MULTI_SZ	std::vector<std::wstring>
REG_BINARY	std::vector<BYTE>

I initially developed this code using Visual Studio 2015 with Update 3; then I used Visual Studio 2017, and currently Visual Studio 2019. I have no longer tested the code with previous compilers. The code compiles cleanly at /W4 in both 32-bit and 64-bit builds.

This is a header-only library, implemented in the WinReg.hpp header file.

WinRegTest.cpp contains some demo/test code for the library: check it out for some sample usage.

The library exposes three main classes:

• RegKey: a tiny efficient wrapper around raw Win32 HKEY handles
• RegException: an exception class to signal error conditions
• RegResult: a tiny wrapper around the raw return codes of the Windows Registry C API functions

There are many member functions inside the RegKey class, that wrap many parts of the native C-interface Windows Registry API, in a convenient C++ way.

For example, you can simply open a registry key and get registry values with C++ code like this:

RegKey  key(HKEY_CURRENT_USER, L"SOFTWARE\\SomeKey");

DWORD   dw = key.GetDwordValue (L"SomeDwordValue");
wstring s  = key.GetStringValue(L"SomeStringValue");

Or you can enumerate all the values under a given key with simple C++ code like this:

auto values = key.EnumValues();

for (const auto & v : values)
{
    //
    // Process current value:
    //
    //   - v.first  (wstring) is the value name
    //   - v.second (DWORD)   is the value type
    //
    ...
}

The library also offers methods that return error codes wrapped in RegResult, instead of throwing RegException on failure. These methods are named in the form of TryAction, e.g. RegKey::TryOpen(), RegKey::TryGetDwordValue(), etc. You can take a look at the test code in WinRegTest.cpp for some sample usage.

The library stuff lives under the winreg namespace.

See the WinReg.hpp header for more details and documentation.

Thanks to everyone who contributed to this project with some additional features and constructive comments and suggestions.