无法将参数从“ SIZE_T *”转换为“ size_t *”-如何进行投射？

Question

On some Windows API call, I get: cannot convert argument 6 from 'size_t *' to 'SIZE_T *' .

This answer tells me that SIZE_T and std::size_t are different types. I know that both describe the same thing, just by different SDKs (C compiler vs. Windows SDK), so I want to cast

reinterpret_cast<SIZE_T *>(&my_size_t_var)`

Is there a less-ugly way to do it?

Edit: SIZE_T is (when compiling for 64-bit targets, at least):

typedef ULONG_PTR SIZE_T, *PSIZE_T; 
typedef unsigned __int64 ULONG_PTR, *PULONG_PTR; 

Edit2: I'm using Win32 compressions API, specifically Compress , which has a parameter _In_ SIZE_T UncompressedDataSize , which I want to call with some std::vector<byte>.size() .

Answer 1

I would do this:

static_assert(sizeof(size_t) == sizeof(SIZE_T), "Expect size_t to be same size as SIZE_T");

somewhere near your reinterpret_cast<SIZE_T*>(&my_size_t_var) .

This will ensure that they are compatible in size, which is the key point.

Answer 2

They are the same types on x86-64, but on x86(32 bits) they are not. SIZE_T is unsigned long and size_t is unsigned int on x86 so you have to use either reinterpret_cast or C-style cast: (SIZE_T*)&my_size_t_var . Alternatively you can switch to x86-64. I'm afraid these are the only options you have in this case.