从注册表 C++ 读取值

Question

I want to get the path of where an application is installed. In the registry, there is an entry which gives the path of my application, see this screenshot: http://i56.tinypic.com/2ly1l6s.jpg

I want to read the path where my application is located. In other words, I want the C:\Projects\MyApplication\MyApplication.exe part. Here is what I am trying to do:

HKEY hKey;
wchar_t mydata[2048];
DWORD dataLength = sizeof(mydata);
DWORD dwType = REG_SZ;
LPVOID messagecaliss;
LONG regOpenCriss = RegOpenKeyEx(HKEY_CURRENT_USER, "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run\\", 0, KEY_QUERY_VALUE, &hKey);
GetLastError();
FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL, GetLastError(), NULL,(LPTSTR) &messagecaliss, 0, NULL );
if (regOpenCriss == ERROR_SUCCESS) {
RegQueryValueEx(HKEY_CURRENT_USER, "TestApplication", 0, &dwType, (BYTE*)mydata, &dataLength);
wprintf(L"%s\n", mydata);
system("PAUSE");
}
else
    MessageBox(NULL,(LPCTSTR)messagecaliss,"ERROR",MB_OK|MB_ICONINFORMATION);

This doesn't work, junk characters are printed. Thank you very much.

Answer 1

you're using non-UNICODE version o RegQueryValueEx and you're diplaying it with wide-char version of printf. Use either printf or change to wprintf( L"%S",mydata )

Note: RegQueryValueEx(HKEY_CURRENT_USER,... ) must be RegQueryValueEx( hKey,... )

Answer 2

I got results after:

1. I surround the strings with _T()
2. I call RegQueryValueEx with hKey as the first parameter

You should store the result of RegQueryValueEx in a variable and check it. Handle the failure case...

Answer 3

This doesn't work

How do you know that without checking the return value of RegQueryValueEx ?

junk characters are printed

No. It's not junk. You didn't ask for a wide character string, so you cannot expect to get one. Compile with Unicode enabled and call RegQueryValueEx with L"TestApplication" or _T("TestApplication") or TEXT("TestApplication") . RegQueryValueEx is just a typedef for RegQueryValueExA or RegQueryValueExW , depending on whether Unicode is defined during compile time or not.

Thank you very much

You're welcome.

Answer 4

A main problem with the code you present is that you have C style casts. Each cast is a bug attractor. And in fact, some of your casts are bugs (hiding that you're using incompatible character types).

I want to read the path where my application is located.

Use GetModuleFileName .

MSDN docs :
Retrieves the fully-qualified path

Cheers & hth.,