How to Retrieve Values from the Windows Registry using C ?

Reading Values from the Windows Registry

When working with Windows systems, it often becomes necessary to access and retrieve data from the registry. The registry stores crucial configuration settings, user preferences, and software-related information. This article will guide you on how to safely check if a registry key exists and programmatically retrieve its value using C .

Determining Registry Key Existence

To determine if a registry key exists, call the RegOpenKeyExW function with the key path and preferred permissions. If the function returns ERROR_SUCCESS, the key exists. If it returns ERROR_FILE_NOT_FOUND, the key specifically does not exist. Otherwise, the key's existence cannot be determined.

Retrieving Registry Key Value

Once you have confirmed the existence of a registry key, you can programmatically retrieve its value. The specific function to use depends on the value's data type. Common types include strings, DWORDs, and booleans. Here's how to retrieve each type:

String Value:

<code class="c++">std::wstring strValueOfBinDir;
GetStringRegKey(hKey, L"BinDir", strValueOfBinDir, L"bad");</code>

DWORD Value:

<code class="c++">DWORD nValue;
LONG nError = GetDWORDRegKey(hKey, L"MyDWORD", nValue, 0);</code>

Boolean Value:

<code class="c++">bool bValue;
LONG nError = GetBoolRegKey(hKey, L"MyBool", bValue, false);</code>

Remember to include the Advapi32.lib library dependency in your code.

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