将指针转换为LPVOID *

Question

I have following code:

IShellLink* psl;
HRESULT hres = CoCreateInstance(
    CLSID_ShellLink, 
    NULL, 
    CLSCTX_INPROC_SERVER, 
    IID_IShellLink, 
    (LPVOID*)&psl);

It is correctly compiled. But I need to replace (LPVOID*)&psl by *_cast . What cast I must use?

static_cast<LPVOID*>(&psl) generates an error (in MSVC 2013).

Will it be correct to use reinterpret_cast<LPVOID*>(&psl) ?

Answer 1

Yes, reinterpret_cast is the correct choice. Usually, the conversion from a type* to a void* should be done implicit, while the conversion from a void* to a type* should be done with a static_cast. But in your case you're converting from a type** to a void**, which leaves you no choice but to use a reinterpret_cast. It is still somewhat "safer" than a c-style cast though, because you cannot cast away constness.

Answer 2

I think you may have to use the reinterpret_cast, as the CoCreateInstance function's last parameter is used for output purposes. See this link: https://msdn.microsoft.com/en-us/library/windows/desktop/ms686615(v=vs.85).aspx

So whether you do a C-Style cast or use the reinterpret_cast, the function just wants to put a pointer value into your variable "psl" after making an object in heap.