Why I can't construct a wstring from char*

Question

According I build fill a char* from this code :

char* pathAppData = nullptr;
size_t sz = 0;
_dupenv_s(&pathAppData, &sz, "APPDATA");

I can easily construct a string with this code and append this string in the future :

std::string sPathAppData(pathAppData);
sPathAppData.append("\\MyApplication");

But I can't create a wstring from this code. Why is so complicated to work with wstring ? I am going crazy with all theses types.

std::wstring wPathAppData(pathAppData); // Impossible

Answer 1

You could use wchar_t directly and use corresponding wchar_t supported API to retrieve data directly to wchar_t and then construct wstring. _dupenv_s function has a wide counterpart - _wdupenv_s.

Your code then would look like this:

wchar_t* pathAppData = nullptr;
size_t sz = 0;
_wdupenv_s(&pathAppData, &sz, L"APPDATA");
std::wstring wPathAppData(pathAppData);
wPathAppData.append(L"\\MyApplication")

Also this could be an interesting read: std::wstring VS std::string