Create a shortcut to my application in startup - c++

Question

I want Create a shortcut to my application in startup . I used visual c++ 2010 and windows 7.
HRESULT CreateLink(LPCWSTR lpszPathObj, LPCSTR lpszPathLink, LPCWSTR lpszDesc){
HRESULT hres;
IShellLink* psl;
hres = CoCreateInstance(CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, IID_IShellLink, (LPVOID*)&psl);
if (SUCCEEDED(hres))
{
IPersistFile* ppf;
psl->SetPath(lpszPathObj);
psl->SetDescription(lpszDesc);
hres = psl->QueryInterface(IID_IPersistFile, (LPVOID*)&ppf);
if (SUCCEEDED(hres))
{
WCHAR wsz[MAX_PATH];
MultiByteToWideChar(CP_ACP, 0, lpszPathLink, -1, wsz, MAX_PATH);
hres = ppf->Save(wsz, TRUE);
ppf->Release();
}
psl->Release();
}
return hres;
}
But, when I was performing not creating. in line :
hres = CoCreateInstance(CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, IID_IShellLink, (LPVOID*)&psl);
get error. and not performing Remains my program.

Answer 1

The returned HRESULT does not just indicate success and failure. In the case of failure, the HRESULT tells you why the call failed. When you encounter a failure, you need to decode the HRESULT to find out why the call failed.
In this case the call is so simple that there is just one obvious failure mode. You did not initialize COM. With probability very close to 1, the value returned by the call to CoCreateInstance is CO_E_FIRST, with value 0x800401f0, which indicates that COM has not been initialized.
You'll want to add a call to CoInitializeEx(NULL, COINIT_APARTMENTTHREADED) at startup, and match it with a call to CoUninitialize() when you are done with COM.
For what it is worth, I think that your function would be better if all of its parameters were wide strings. A function like this should not be worrying itself with such conversions. If you need to make such conversions, then include some helper methods in your code to perform them. You can add a function to convert from std::string to std::wstring and that should be all you ever need.

Answer 2

You need to initialize COM before performing your tasks:
HRESULT CreateLink(LPCSTR lpszPathObj, LPCSTR lpszPathLink, LPCSTR lpszDesc){
HRESULT hres;
IShellLink* psl;
hres = CoCreateInstance(CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, IID_IShellLink, (LPVOID*)&psl);
if (SUCCEEDED(hres))
{
IPersistFile* ppf;
psl->SetPath(lpszPathObj);
psl->SetDescription(lpszDesc);
hres = psl->QueryInterface(IID_IPersistFile, (LPVOID*)&ppf);
if (SUCCEEDED(hres))
{
WCHAR wsz[MAX_PATH];
MultiByteToWideChar(CP_ACP, 0, lpszPathLink, -1, wsz, MAX_PATH);
hres = ppf->Save(wsz, TRUE);
ppf->Release();
}
psl->Release();
}
return hres;
}
int main()
{
CoInitialize(0); // Initialize COM
CreateLink("C:\\hello.lnk", "C:\\hello.obj", "hello");
CoUninitialize();
return 0;
}
Also: watch out for LPCSTR/LPCWSTR (wide) conversions. The hres parameter contains additional information in case you were wondering what's wrong with your code.