RegQueryValueEx Giving error 234

RegQueryValueEx(key,REG_DAYCNT,NULL,&type,(LPBYTE) &dayqry,&size)
the first time i run this statement in my program i get a 234 (ERROR_MORE_DATA ) error . I looked it up but its about not having enough buffer memory. My concern is that when i run the same statement again it works perfectly. Also about the buffer not being big enough is kinda strange because im quering a dword -which should always be the same size i think-

If someone can help , or know about this kind of problems please answer , thx.

Show us how you're declaring all the variables you're passing to the function.

Code:

#define REG_LIB     HKEY_CURRENT_USER

const char* REG_MAP     = "SOFTWARE\\Mirrosoft\\Autoshutdown";
const char* REG_CNTDWN  = "CNTDWN";
const char* REG_DAYCNT  = "DAYCNT";
const char* REG_LIMIT   = "LIMIT";
....

int getVartime(void)
{
  HKEY key;
  DWORD result;
  int toReturn=0;

  if(testInitRun(DEFAULTTIME,DEFAULTTIME,curTime()));

  if(ERROR_SUCCESS != RegCreateKeyEx(REG_LIB,REG_MAP,0,NULL,REG_OPTION_NON_VOLATILE,KEY_ALL_ACCESS,NULL,&key,&result))
  {
    printf("Problem opening registry\n");
  }
  else
  {
    DWORD limitqry;
    DWORD cntqry;
    DWORD dayqry=0;
    DWORD type;
    DWORD size;
    int test;
    
    //Is it a new day??
    if(ERROR_SUCCESS != (test = RegQueryValueEx(key,REG_DAYCNT,NULL,&type,(LPBYTE)&dayqry,&size)))
    {
     printf("Problem opening registry\n %d\n",test);
     //RegQueryValueEx(key,REG_DAYCNT,NULL,&type,(LPBYTE)&dayqry,&size);
    }
  ...

in the last if part it goes wrong , if i uncomment the second query , the second one works then correctly

The size argument is an in/out argument. So you need to initialise it:

Code:

    DWORD size = sizeof(dayqry);
    int test;
    
    //Is it a new day??
    if(ERROR_SUCCESS != (test = RegQueryValueEx(key,REG_DAYCNT,NULL,&type,(LPBYTE)&dayqry,&size)))

that seems to be it ; thx