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Registry namespace

C++ class for manipulating Windows Registry. Wraps & simplifies native Windows API and combines it with power of modern C++11.

Table of contents

• Table of contents
• Root registry keys
• Opening registry keys
• Creating registry keys
• Deleting registry key
• Flush registry
• Save registry key to file
• Check if registry key exists
• Check if registry value exists
• Save boolean value to registry
• Read boolean value from registry
• Save integer value to registry
• Read integer value from registry
• Save string value to registry
• Read string value from registry
• Enumerating registry subkeys

NOTE:
All methods can throw exceptions, if system error occurs!

All exceptions thrown are derived from std::exception class, so don't forget to wrap your code with try / catch block.

Root registry keys

Following windows registry root keys are predefined within Registry namespace, and can be accessed directly in your code

Registry::ClassesRoot
Registry::CurrentUser
Registry::LocalMachine
Registry::Users
Registry::CurrentConfig

Opening registry keys

Existing windows registry key can be opened simply by call to RegistryKey::Open() method specifying path to registry key.

NOTE:
Registry key is closed automatically when RegistryKey object goes out of scope.

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication");

        // do work needed
    }
    catch (const std::exception&)
    {
    	// handle thrown exception
    }

    return 0;
}

Registry key is by default opened with read access, same as if you open registry key as follows

auto access = Registry::DesiredAccess::Read;

auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication", access);

Desired access for opening registry keys can be combined

auto access = Registry::DesiredAccess::Read | Registry::DesiredAccess::Write;
		
auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication", access);

Creating registry keys

Registry keys can be created in a same way as if they are opened.

Simply by using RegistryKey::Create() method. Usage is same as when opening keys.

NOTE:
You must have sufficient privileges to create registry keys under specific root key. In other case std::system_error exception will be thrown

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto access = Registry::DesiredAccess::Read | Registry::DesiredAccess::Write;

        auto key = Registry::LocalMachine->Create(L"SOFTWARE\\MyCompany\\MyApplication", access);

        // do work needed
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

RegistryKey can be created also from native windows registry key handle HKEY.

NOTE:
In case hKey is nullptr, std::invalid_argument is thrown

Registry::RegistryKey_ptr key = std::make_shared<Registry::RegistryKey>(hKey);

Using with native API

RegistryKey has HKEY() operator overloaded, thus can be used with conjunction with native Windows registry API.

Usage is as follows

auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication");

DWORD dwValue = 0;
DWORD cbData = sizeof(dwValue);
DWORD dwType;

LSTATUS lStatus = RegQueryValueEx(*key, L"SomeDWORDValue", nullptr, &dwType, reinterpret_cast<LPBYTE>(&dwValue), &cbData);
if (lStatus == ERROR_SUCCESS)
{
    // DO SOMETHING
}

Deleting registry key

Flush registry

Save registry key to file

Check if registry key exists

HasKey() or Exists() methods can be used to check, whether registry key contains specified subkey.

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto key = Registry::LocalMachine->Create(L"SOFTWARE\\MyCompany\\MyApplication");
        if (key->HasKey(L"SomeSubKey"))
        {
            // TRUE
        }
        else
        {
            // FALSE
        }
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Check if registry value exists

To check if windows registry key contains specific value use HasValue() method as follows

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto key = Registry::LocalMachine->Create(L"SOFTWARE\\MyCompany\\MyApplication");
        if (key->HasValue(L"Version"))
        {
            // TRUE
        }
        else
        {
            // FALSE
        }
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Save boolean value to registry

To save boolean value to registry, use SetBoolean() method as follows

NOTE:
Boolean value is stored in registry as REG_DWORD. 0 for false and 1 for true.

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto key = Registry::LocalMachine->Create(L"SOFTWARE\\MyCompany\\MyApplication");
		
        key->SetBoolean(L"EnableLogger", true);
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Read boolean value from registry

To read boolean value from registry use GetBoolean() method as follows

NOTE:
RegistryKey class use REG_DWORD registry value data type to work with boolean value. If registry value is 0, false is returned. If registry value is above 0, value of true is returned.

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto key = Registry::LocalMachine->Create(L"SOFTWARE\\MyCompany\\MyApplication");
        auto enabled = key->GetBoolean(L"EnableLogger");
        if (enabled)
        {
            // do work
        }
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Save integer value to registry

To save signed / unsigned integer values to registry, use one of methods

• SetInt32()
• SetUInt32()
• SetInt64()
• SetUInt64()

as follows

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto access = Registry::DesiredAccess::Write;

        auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication\\Logger", access);
		
        key->SetInt32(L"Severity", -3);
        key->SetUInt32(L"Timeout", 10000);

        key->SetInt64(L"SomeBigNumber", -9223372036854775808);
        key->SetUInt64(L"Id", 0xf0f0f0f0f0f0f0f0);
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Read integer value from registry

To read signed / unsigned integer values from registry, use one of methods

• GetInt32()
• GetUInt32()
• GetInt64()
• GetUInt64()

as follows

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication\\Logger");
		
        std::cout << key->GetInt32(L"Severity")         << std::endl;
        std::cout << key->GetUInt32(L"Timeout")         << std::endl;
        std::cout << key->GetInt64(L"SomeBigNumber")    << std::endl;
        std::cout << key->GetUInt64(L"Id")              << std::endl;
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Save string value to registry

To save string value to registry use SetString() method as follows

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto access = Registry::DesiredAccess::Write;

        auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication\\Logger", access);
		
        key->SetString(L"FileName", L"c:\\Program Files\\MyCompany\\MyApplication\\log.txt");
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Read string value from registry

To read string value from windows registry use GetString() method as follows

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication\\Logger");
		
        auto logFileName = key->GetString(L"FileName");

        // work with read value
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Save expandable string value to registry

To save string value to registry use SetExpandString() method in same manner as SetString().

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto access = Registry::DesiredAccess::Write;

        auto key = Registry::LocalMachine->Open(L"SOFTWARE\\MyCompany\\MyApplication\\Logger", access);
		
        key->SetExpandString(L"InstallDir", L"%ProgramFiles%\\My Company\\My Product\\");
    }
    catch (const std::exception&)
    {
        // handle thrown exception
    }

    return 0;
}

Enumerating registry subkeys

Eumerating registry key subkeys is done as follows, using lambda expression

#include <Registry.hpp>

using namespace m4x1m1l14n;

int main()
{
    try
    {
        auto key = Registry::LocalMachine->Open(L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall");

        key->EnumerateSubKeys([](const std::wstring& name) -> bool
        {
            // Process subkey
            std::wcout << name << std::endl;

            // Return true to continue processing, false otherwise
            return true;
        });
    }
    catch (const std::exception& ex)
    {
        // handle thrown exception
    }

    return 0;
}