Enumerate all file type associations

Question

Hello! 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? Thank you.

Answer 1

In fact, the documentation for SHAssocEnumHandlers is wrong (it does not enumerate all extensions)
Windows (System Settings) does a loop on extensions by reading registry (RegEnumKey, HKEY_CLASSES_ROOT) and get information for each extension mainly with IQueryAssociations, like you used

Answer 2

See nf-shobjidl_core-shassocenumhandlers

The docs say -

pszExtra

Type: PCWSTR

A pointer to a null-terminated buffer that contains a single file type extension, for instance ".jpg". Only handlers associated with the given extension are enumerated. If this value is NULL, all handlers for all extensions are enumerated.