LNK2019 with a sample from MSDN - c++

Question

Tried to copy the code from the .cpp file in Common File Dialog Sample got some LNK2019. It seems like a problem with the linking of 3 functions.
Here are the errors:
Severity Code Description Project File Line Suppression State
Error LNK2019 unresolved external symbol __imp_TaskDialog referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl CDialogEventHandler::ChooseFromFolder(void)" (?ChooseFromFolder#CDialogEventHandler##QEAA?AV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std##XZ) Build-A-Font C:\Users\nadav\Desktop\SFML\Build-A-Font\Build-A-Font\FileDialog.obj 1
Error LNK2019 unresolved external symbol __imp_PSGetPropertyDescriptionListFromString referenced in function "public: virtual long __cdecl CDialogEventHandler::OnTypeChange(struct IFileDialog *)" (?OnTypeChange#CDialogEventHandler##UEAAJPEAUIFileDialog###Z) Build-A-Font C:\Users\nadav\Desktop\SFML\Build-A-Font\Build-A-Font\FileDialog.obj 1
Error LNK2019 unresolved external symbol QISearch referenced in function "public: virtual long __cdecl CDialogEventHandler::QueryInterface(struct _GUID const &,void * *)" (?QueryInterface#CDialogEventHandler##UEAAJAEBU_GUID##PEAPEAX#Z) Build-A-Font C:\Users\nadav\Desktop\SFML\Build-A-Font\Build-A-Font\FileDialog.obj 1
That is their code after some modifications for my needs:
#pragma once
#define STRICT_TYPED_ITEMIDS
#include <shlobj.h>
#include <shlwapi.h>
#include <string>
#include <sstream>
#pragma comment(linker, "\"/manifestdependency:type='Win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"")
// Added for changing the entry point
#pragma comment(linker, "/subsystem:windows /ENTRY:mainCRTStartup")
const COMDLG_FILTERSPEC c_rgSaveTypes[] =
{
{L"Word Document (*.doc; *.docx)", L"*.doc;*.docx"},
{L"Powerpoint Presentation (*.ppt; *.pptx)", L"*.ppt;*.pptx"},
{L"Web Page (*.htm; *.html)", L"*.htm;*.html"},
{L"Text Document (*.txt)", L"*.txt"},
{L"All Documents (*.*)", L"*.*"}
};
// Indices of file types
#define INDEX_WORDDOC 1
#define INDEX_PRPNTPR 2
#define INDEX_WEBPAGE 3
#define INDEX_TEXTDOC 4
// Controls
#define CONTROL_GROUP 2000
#define CONTROL_RADIOBUTTONLIST 2
#define CONTROL_RADIOBUTTON1 1
#define CONTROL_RADIOBUTTON2 2 // It is OK for this to have the same ID as CONTROL_RADIOBUTTONLIST,
// because it is a child control under CONTROL_RADIOBUTTONLIST
// IDs for the Task Dialog Buttons
#define IDC_BASICFILEOPEN 100
/* File Dialog Event Handler *****************************************************************************************************/
class CDialogEventHandler : public IFileDialogEvents,
public IFileDialogControlEvents
{
public:
// IUnknown methods
IFACEMETHODIMP QueryInterface(REFIID riid, void** ppv)
{
static const QITAB qit[] = {
QITABENT(CDialogEventHandler, IFileDialogEvents),
QITABENT(CDialogEventHandler, IFileDialogControlEvents),
{ 0 },
#pragma warning(suppress:4838)
};
return QISearch(this, qit, riid, ppv);
}
IFACEMETHODIMP_(ULONG) AddRef()
{
return InterlockedIncrement(&_cRef);
}
IFACEMETHODIMP_(ULONG) Release()
{
long cRef = InterlockedDecrement(&_cRef);
if (!cRef)
delete this;
return cRef;
}
// IFileDialogEvents methods
IFACEMETHODIMP OnFileOk(IFileDialog*) { return S_OK; };
IFACEMETHODIMP OnFolderChange(IFileDialog*) { return S_OK; };
IFACEMETHODIMP OnFolderChanging(IFileDialog*, IShellItem*) { return S_OK; };
IFACEMETHODIMP OnHelp(IFileDialog*) { return S_OK; };
IFACEMETHODIMP OnSelectionChange(IFileDialog*) { return S_OK; };
IFACEMETHODIMP OnShareViolation(IFileDialog*, IShellItem*, FDE_SHAREVIOLATION_RESPONSE*) { return S_OK; };
IFACEMETHODIMP OnOverwrite(IFileDialog*, IShellItem*, FDE_OVERWRITE_RESPONSE*) { return S_OK; };
// This method gets called when the file-type is changed (combo-box selection changes).
// For sample sake, let's react to this event by changing the properties show.
IFACEMETHODIMP OnTypeChange(IFileDialog* pfd)
{
IFileSaveDialog* pfsd;
HRESULT hr = pfd->QueryInterface(&pfsd);
if (SUCCEEDED(hr))
{
UINT uIndex;
hr = pfsd->GetFileTypeIndex(&uIndex); // index of current file-type
if (SUCCEEDED(hr))
{
IPropertyDescriptionList* pdl = NULL;
switch (uIndex)
{
case INDEX_WORDDOC:
// When .doc is selected, let's ask for some arbitrary property, say Title.
hr = PSGetPropertyDescriptionListFromString(L"prop:System.Title", IID_PPV_ARGS(&pdl));
if (SUCCEEDED(hr))
{
// FALSE as second param == do not show default properties.
hr = pfsd->SetCollectedProperties(pdl, FALSE);
pdl->Release();
}
break;
case INDEX_WEBPAGE:
// When .html is selected, let's ask for some other arbitrary property, say Keywords.
hr = PSGetPropertyDescriptionListFromString(L"prop:System.Keywords", IID_PPV_ARGS(&pdl));
if (SUCCEEDED(hr))
{
// FALSE as second param == do not show default properties.
hr = pfsd->SetCollectedProperties(pdl, FALSE);
pdl->Release();
}
break;
case INDEX_TEXTDOC:
// When .txt is selected, let's ask for some other arbitrary property, say Author.
hr = PSGetPropertyDescriptionListFromString(L"prop:System.Author", IID_PPV_ARGS(&pdl));
if (SUCCEEDED(hr))
{
// TRUE as second param == show default properties as well, but show Author property first in list.
hr = pfsd->SetCollectedProperties(pdl, TRUE);
pdl->Release();
}
break;
}
}
pfsd->Release();
}
return hr;
};
// IFileDialogControlEvents methods
// This method gets called when an dialog control item selection happens (radio-button selection. etc).
// For sample sake, let's react to this event by changing the dialog title.
IFACEMETHODIMP OnItemSelected(IFileDialogCustomize* pfdc, DWORD dwIDCtl, DWORD dwIDItem)
{
IFileDialog* pfd = NULL;
HRESULT hr = pfdc->QueryInterface(&pfd);
if (SUCCEEDED(hr))
{
if (dwIDCtl == CONTROL_RADIOBUTTONLIST)
{
switch (dwIDItem)
{
case CONTROL_RADIOBUTTON1:
hr = pfd->SetTitle(L"Longhorn Dialog");
break;
case CONTROL_RADIOBUTTON2:
hr = pfd->SetTitle(L"Vista Dialog");
break;
}
}
pfd->Release();
}
return hr;
};
IFACEMETHODIMP OnButtonClicked(IFileDialogCustomize*, DWORD) { return S_OK; };
IFACEMETHODIMP OnCheckButtonToggled(IFileDialogCustomize*, DWORD, BOOL) { return S_OK; };
IFACEMETHODIMP OnControlActivating(IFileDialogCustomize*, DWORD) { return S_OK; };
CDialogEventHandler() : _cRef(1) { };
private:
~CDialogEventHandler() { };
long _cRef;
};
// Instance creation helper
HRESULT CDialogEventHandler_CreateInstance(REFIID riid, void** ppv)
{
*ppv = NULL;
CDialogEventHandler* pDialogEventHandler = new (std::nothrow) CDialogEventHandler();
HRESULT hr = pDialogEventHandler ? S_OK : E_OUTOFMEMORY;
if (SUCCEEDED(hr))
{
hr = pDialogEventHandler->QueryInterface(riid, ppv);
pDialogEventHandler->Release();
}
return hr;
}
// This code snippet demonstrates how to work with the common file dialog interface
std::string BasicFileOpen()
{
// CoCreate the File Open Dialog object.
IFileDialog* pfd = NULL;
HRESULT hr = CoCreateInstance(CLSID_FileOpenDialog, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pfd));
if (SUCCEEDED(hr))
{
// Create an event handling object, and hook it up to the dialog.
IFileDialogEvents* pfde = NULL;
hr = CDialogEventHandler_CreateInstance(IID_PPV_ARGS(&pfde));
if (SUCCEEDED(hr))
{
// Hook up the event handler.
DWORD dwCookie;
hr = pfd->Advise(pfde, &dwCookie);
if (SUCCEEDED(hr))
{
// Set the options on the dialog.
DWORD dwFlags;
// Before setting, always get the options first in order not to override existing options.
hr = pfd->GetOptions(&dwFlags);
if (SUCCEEDED(hr))
{
// In this case, get shell items only for file system items.
hr = pfd->SetOptions(dwFlags | FOS_FORCEFILESYSTEM);
if (SUCCEEDED(hr))
{
// Set the file types to display only. Notice that, this is a 1-based array.
hr = pfd->SetFileTypes(ARRAYSIZE(c_rgSaveTypes), c_rgSaveTypes);
if (SUCCEEDED(hr))
{
// Set the selected file type index to Word Docs for this example.
hr = pfd->SetFileTypeIndex(INDEX_WORDDOC);
if (SUCCEEDED(hr))
{
// Set the default extension to be ".doc" file.
hr = pfd->SetDefaultExtension(L"doc");
if (SUCCEEDED(hr))
{
// Show the dialog
hr = pfd->Show(NULL);
if (SUCCEEDED(hr))
{
// Obtain the result, once the user clicks the 'Open' button.
// The result is an IShellItem object.
IShellItem* psiResult;
hr = pfd->GetResult(&psiResult);
if (SUCCEEDED(hr))
{
// We are just going to print out the name of the file for sample sake.
PWSTR pszFilePath = NULL;
hr = psiResult->GetDisplayName(SIGDN_FILESYSPATH, &pszFilePath);
if (SUCCEEDED(hr))
{
TaskDialog(NULL,
NULL,
L"CommonFileDialogApp",
pszFilePath,
NULL,
TDCBF_OK_BUTTON,
TD_INFORMATION_ICON,
NULL);
CoTaskMemFree(pszFilePath);
}
psiResult->Release();
}
}
}
}
}
}
}
// Unhook the event handler.
pfd->Unadvise(dwCookie);
}
pfde->Release();
}
pfd->Release();
}
TCHAR filepath[1024];
if (hr == S_OK)
{
std::stringstream pff;
pff << filepath;
return pff.str();
}
return "";
}
I changed their code in the original files I downloaded from the github and it worked just fine. I tried to copy it to another project and it just won't work (the LNK2019 errors)

Answer 1

I thought I'd provide a sort of meta-answer to this: how did Jerry know what libraries you need to link with? And, as ever, the answer lies in the documentation.
First of all, let's take a look at those linker errors (I've cut them down a bit for clarity, using templates usually tends to lead to verbose / hard to read error messages):
Unresolved symbol __imp_TaskDialog referenced in function <irrelevant>
Unresolved symbol __imp_PSGetPropertyDescriptionListFromString referenced in function <irrelevant>
Unresolved symbol QISearch referenced in function <irrelevant>
First up, you can ignore the __imp_ bit. This just tells you that the function is imported from a DLL. So that leaves us with the following unresolved references:
TaskDialog
PSGetPropertyDescriptionListFromString
QISearch
So, time to go Googling.
The documentation for TaskDialog is here, and if you scroll down to the 'requirements' section at the bottom of the page you will see:
Library Comctl32.lib
So that's nailed that one (note that capitalisation doesn't matter here, I don't know why Microsoft document this stuff in such a weird way).
In a similar vein, we can easily discover that PSGetPropertyDescriptionListFromString is in Propsys.lib, and QISearch is in Shlwapi.lib. End of story.
I hope that shows you how it's done. Every Windows developer needs to understand how to do this and how to find and read the (extensive) documentation that Microsoft provide in general.