Read and Write Windows Registry to Store Data Using C#

The Windows Registry is a hierarchical database for storing many kinds of system and application settings. Prior to the Registry, .ini files in the form of text files were commonly used for storing these settings. However, these files were unable to meet all the requirements of a modern application. Especially in multi-user scenarios the .ini files were nearly useless.

On the other hand, the Windows Registry uses one logical repository that is able to store user-specific settings. According to Microsoft, there are several advantages over the obsolete .ini files like faster parsing, backup or restoration.

Structure of the Registry

The Registry is based on the two basic elements, keys and values and the entire structure is a tree with several root elements that slightly differ depending on the version of Windows you are currently using. The keys are container objects very similar to folders that can contain other keys or values. The values can be a string, binary, or DWORD depending on the scenario.

The most common root element structure is as follows:

HKEY_CLASSES_ROOT

This root element holds the information about registered (installed) applications and associated file extensions. For example, Windows is able to open the .pdf extension with Acrobat Reader because of the settings in this key. It is not advised to alter these keys manually and the Folder Options in the Windows Explorer should be used instead.

HKEY_CURRENT_USER

This root element represents the currently logged-in user and their specific settings. It is a link to a subkey of HKEY_USERS that corresponds to the current user. It cannot be edited.

HKEY_LOCAL_MACHINE

This root element contains five subkeys (hardware, security accounts manager, security, software, system) that are used for storing many kinds of settings used by the operating system. Hardware, security and security accounts manager subkeys can't be edited. It is not advised to manully alter the rest as it might result in a system crash.

HKEY_USERS

This root element holds all the user profiles used on the machine. Even though it can be edited, you should be very cautious when doing so.

HKEY_CURRENT_CONFIG

This root element contains read-only settings about the available hardware settings. These settings are not permanently stored on disk, but generated at the boot time and updated at runtime.

Windows Registry and C#