create_and_del_key.c

#include <windows.h>

#if define UNICODE
	#define RegOpenKeyEx RegOpenKeyExW
	#define RegCreateKeyEx RegCreateKeyExW
	#define RegDeleteKey RegDeleteKeyW
#else
	#define RegOpenKeyEx RegOpenKeyExA
	#define RegCreateKeyEx RegCreateKeyExA
	#define RegDeleteKey RegDeleteKeyA
#endif

#define MAX_KEY_LENGTH 255

HKEY Open(HKEY root,LPTSTR path, REGSAM permission)
{
	HKEY hKey;
	LONG lResult = RegOpenKeyEx(
		root, //HKEY_LOCAL_MACHINE,  HKEY_USERS,  HKEY_CURRENT_CONFIG,  HKEY_CLASSES_ROOT,  HKEY_CURRENT_USER
		path, // the path of the key
		0,    // must be 0
		permission, //KEY_WRITE, KEY_READ, KEY_ALL_ACCESS, KEY_QUERY_VALUE, KEY_ENUMERATE_SUB_KEYS
		&hKey // OUT : The result [pass by refrence]
		);

	if (lResult == ERROR_SUCCESS)
		return hKey;
	return INVALID_HANDLE_VALUE;
}

void Close(HKEY hKey)
{
	RegCloseKey(hKey);
}

HKEY CreateKey(HKEY hKey, LPTSTR path, REGSAM permission)
{
	DWORD result;
	HKEY hKeyResult;
	RegCreateKeyEx(hKey, // the opened key
		path, // the path of the key
		NULL, //Reserved
		NULL, // Class Name
		0,    // 0 || REG_OPTION_NON_VOLATILE || REG_OPTION_VOLATILE
		permission, // KEY_WRITE, KEY_READ, KEY_ALL_ACCESS, KEY_QUERY_VALUE, KEY_ENUMERATE_SUB_KEYS
		NULL,     // Security Attribute
		&hKeyResult, // OUT : return the created key
		&result      // OUT : return REG_CREATED_NEW_KEY || REG_OPENED_EXISTING_KEY
		);
	if (result == REG_CREATED_NEW_KEY)
		return hKeyResult;
	return INVALID_HANDLE_VALUE;
}

void DeleteKey(HKEY hKey, LPTSTR path)
{
	RegDeleteKey(hKey, path);
}

int main()
{
	HKEY hKey = Open(HKEY_CURRENT_USER, "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer", KEY_ALL_ACCESS);
	if (hKey != INVALID_HANDLE_VALUE)
	{
		//do your job
		if (CreateKey(hKey, "xyz",KEY_ALL_ACCESS) == INVALID_HANDLE_VALUE)
			DeleteKey(hKey, "xyz");
	}
	Close(hKey);
	return 0;
}