Check if the key already exists (RegOpenKey) - c++

Question

I did this:
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
HKEY CH;
if(RegCreateKey(HKEY_LOCAL_MACHINE, L"Software\\Microsoft\\Windows\\CurrentVersion\\Run",&CH) != 0)
{
printf("Erro - RegCreateKey\n");
system("PAUSE");
return -1;
}
if(RegOpenKey(HKEY_LOCAL_MACHINE, L"Software\\Microsoft\\Windows\\CurrentVersion\\Run",&CH) != 0) // Abre a CH "Minha CH"
{
printf("Erro - RegOpenKey\n");
system("PAUSE");
return -1;
}
if(RegSetValueEx(CH,L"PROC",0,REG_SZ,(LPBYTE) L"C:\\pasta1\\pasta2\\txt.txt",200) != 0)
printf("Erro - RegSetValue\n");
RegCloseKey(CH);
printf("\nsucesso !\n");
system("PAUSE");
return 0;
system("PAUSE");
}
Now I want do it:
if(key already exist) {
//don't make nothing
} else
Create key
...
What the function that I need to do it ? Because if not, I ever gonna create a key that already exist. And if I can avoid it would be great.

Answer 1

Use RegCreateKeyEx. It opens the key if it already exists, and creates it if it doesn't. lpdwDisposition parameter tells you which of these two effects actually happened. For example:
DWORD disposition = 0;
RegCreateKeyEx(..., &disposition);
if (disposition == REG_CREATED_NEW_KEY) {
/* new key was created */
} else {
/* existing key was opened */
}