How to export registry and snap registry

How to export the Windows registry to a file with a C++ API? How to snap the Windows registry and how to find differences between two registries? For example, I want to know the registey changes after installing a new software.
Hope the reply. Thank you!
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You must use RegEnumValue/RegEnumValueEx Api. See more info in Windows doc
or in MSDN.
You can use 'RegSaveKey()' to achieve this:

RegSaveKey (Win32)  

LONG RegSaveKey(hkey, lpszFile, lpsa)

HKEY hkey;      /* handle of key where save begins      */
LPCTSTR lpszFile;      /* address of filename to save to      */
LPSECURITY_ATTRIBUTES lpsa;      /* address of security structure      */

The RegSaveKey function saves the given key and all of its subkeys and values to a new file.

However, finding the differences is quite a nuisance, but the GNU 'diff' ( should be a great help

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