Enumerate all file type associations - c++

Question

I want to list all the file type associations app names. My code:
#include <windows.h>
#include <shlwapi.h>
#include <ShlObj.h>
#include <iostream>
#pragma comment(lib, "shlwapi.lib")
int main()
{
IQueryAssociations *iQueryAssoc = nullptr;
HRESULT assocHRes = AssocCreate(CLSID_QueryAssociations, IID_IQueryAssociations, reinterpret_cast<void**>(&iQueryAssoc));
if (assocHRes == S_OK) {
HWND hWnd = GetConsoleWindow();
LPCWSTR pszAssoc = L".xls";
HRESULT initAssocHRes = iQueryAssoc->Init(NULL, pszAssoc, NULL, hWnd);
if (initAssocHRes == S_OK) {
TCHAR buffer[1024];
DWORD bufferSize = 1024;
HRESULT getStrAssocHRes = iQueryAssoc->GetString(ASSOCF_NONE, ASSOCSTR_FRIENDLYAPPNAME, NULL, buffer, &bufferSize);
if (getStrAssocHRes == S_OK) {
std::wcout << "App name: " << std::wstring(buffer).c_str() << std::endl;
} else {
std::wcout << "iQueryAssoc GetString failed!" << std::endl;
}
} else {
std::wcout << "iQueryAssoc Init failed!" << std::endl;
}
} else {
std::wcout << "AssocCreate failed!" << std::endl;
}
iQueryAssoc->Release();
system("PAUSE");
return 0;
}
My code works but it displays app name only for the ".xls" extension. I think, I need to use the while (iQueryAssoc->QueryInterface()) to get all of them. Is there any example how to use it? Should I call init method first and then QueryInterface method or just call QueryInterface method without init method?
Additionally, I have found the SHAssocEnumHandlers method:
IEnumAssocHandlers *pEnumHandlers = nullptr;
IAssocHandler *assocHandler = nullptr;
HRESULT initAssocHRes = SHAssocEnumHandlers(NULL, ASSOC_FILTER_NONE, &pEnumHandlers);
if (initAssocHRes == S_OK) {
while (pEnumHandlers->Next(1, &assocHandler, nullptr) == S_OK) {
std::cout << "Test..." << std::endl;
}
} else {
std::cout << "Failed: " << initAssocHRes << std::endl;
}
But for me, it fails with the following error: Failed: -2147024882 E_OUTOFMEMORY - Failed to allocate necessary memory. I think, the issue with: IEnumAssocHandlers are null and not initialized. What method should I use to initialize the IEnumAssocHandlers? Thank you.
I have found, these lines of code leads to E_OUTOFMEMORY issue:
IEnumAssocHandlers *pEnumHandlers = NULL;
HRESULT initAssocHRes = SHAssocEnumHandlers(NULL, ASSOC_FILTER_RECOMMENDED, &pEnumHandlers);
Also, I got this warning:
Any ideas? Thank you.
Updated code:
#include <windows.h>
#include <shlwapi.h>
#include <ShlObj.h>
#include <iostream>
#include "hresinfo.h"
#pragma comment(lib, "shlwapi.lib")
#pragma comment(lib, "shell32.lib")
int main()
{
IEnumAssocHandlers *pEnumHandlers = nullptr;
HRESULT initAssocHRes = SHAssocEnumHandlers(NULL, ASSOC_FILTER_NONE, reinterpret_cast<IEnumAssocHandlers**>(&pEnumHandlers));
if (initAssocHRes == S_OK) {
IAssocHandler *pAssocHandler = nullptr;
LPWSTR pszName = nullptr;
while (pEnumHandlers->Next(1, &pAssocHandler, NULL) == S_OK) {
if (pAssocHandler) {
pAssocHandler->GetUIName(&pszName);
printf_s("%S \n", pszName);
}
}
if (pAssocHandler) {
pAssocHandler->Release();
}
} else {
HRESInfo::getErrorMsg(initAssocHRes);
}
if (pEnumHandlers) {
pEnumHandlers->Release();
}
system("PAUSE");
return 0;
}
Screenshot:

Answer 1

You don't say which call is actually failing (so please do so), but if you look at the documentation for IEnumAssocHandlers::Next, it doesn't say anywhere that the third parameter (pceltFetched) can be nullptr, so I would change your code to:
if (initAssocHRes == S_OK) {
ULONG handlers_retrieved = 0;
while (pEnumHandlers->Next(1, &assocHandler, &handlers_retrieved) == S_OK) {
...

Answer 2

Also first parameter to SHAssocEnumHandlers must not be null:
wchar_t *extension = L".jpg";
HRESULT initAssocHRes = SHAssocEnumHandlers(extension, ...