Question

I am trying to retrieve some values from the registry.
Here is the full path:
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes]
“ThemeChangesMousePointers”=0x00000001 (1)

And here is my code:

HKEY hKey;
DWORD dwDisp = REG_DWORD;
DWORD dwType;
DWORD dwSize = sizeof(DWORD);
DWORD dwValue = 0;
DWORD dwReturn;
char buffer[255] = {0};
//char* buffer;
//DWORD buffer = 0;
DWORD dwBufSize = sizeof(buffer);

if( RegOpenKey(HKEY_LOCAL_MACHINE,
    _T("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Themes")
    ,&hKey) == ERROR_SUCCESS)
{
    dwType = REG_DWORD;
    if( RegQueryValueEx(hKey,_T("ThemeChangesMousePointers"),0, &dwType, (LPBYTE) buffer, &dwBufSize) == ERROR_SUCCESS)
    {
        printf("Key value is: %d \n", buffer);
        printf("GetLastError reports %d \n", GetLastError());
    }
    else
    {
        printf("Cannot query for key value \n");
    }
}

I have tried debugging and it seems like my buffer output variable is giving me a weird output:

Key value is: 2554292
Error is 0

Every time I run the code again, I get different values. How can I get the real value and not a different one?

EDIT: Post above has been edited to ask a different question.

Also, if this isn’t enough code, I can add more.

Answer 1

RegQueryValueEx does not call SetLastError, it returns it’s error code directly.

Return Value

If the function succeeds, the return value is ERROR_SUCCESS.
If the function fails, the return value is a system error code.
If the lpData buffer is too small to receive the data, the function returns ERROR_MORE_DATA.
If the lpValueName registry value does not exist, the function returns ERROR_FILE_NOT_FOUND.

EDIT IN RESPPONSE TO COMMENT:

I initially answered your specific question, bit with regards to the code you posted, there are still several remaining problems:

• You’re calling the deprecated method RegOpenKey rather than RegOpenKeyEx.
• You’re trying to read an integer but you’re reading it as a char * string. This is the most likely cause of the problems you’re getting… the function’s returning an integer but you’re printing it as a string.
• Your IF conditional is backwards

HKEY hKey;
DWORD dwDisp = REG_DWORD;
DWORD dwSize = sizeof(DWORD);
DWORD dwValue = 0;
DWORD dwReturn;
DWORD dwBufSize = sizeof(DWORD);

if( RegOpenKeyExW(HKEY_LOCAL_MACHINE,
    L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Themes"
    ,0, KEY_QUERY_VALUE, &hKey) == ERROR_SUCCESS)
{
    DWORD error = RegQueryValueExW(hKey,L"ThemeChangesMousePointers",0,0, reinterpret_cast<LPBYTE>(&dwReturn), &dwBufSize);
    if(error == ERROR_SUCCESS)
    {
        printf("Key value is: %d \n", dwReturn);
    }
    else
    {
        printf("Cannot query for key value; Error is: %d\n", error);
    }
}
RegCloseKey(hKey);