Initialize a wchar_t[] using a string - c++

Question

Currently, I'm dealing with WMI for collecting the log files from a remote machine.
I have the username of the remote machine initialized as given below.
wchar_t pszName[]=L"My username";
pszName[] is a wchar_t array. The trouble I face is that when I pass my username as a parameter of string datatype, I need to initialize wchar_t array using a string.
I cannot use a wchar_t* pointer because it gives me an error on the later part of the program. I need to initialize something like
string username = "My username";
wchar_t pszName[] = .....?.....;

Answer 1

#include <string>
#include <vector>
#include <windows.h>
std::wstring str_to_wstr(std::string const & str)
{
int length = MultiByteToWideChar(CP_UTF8, 0, str.c_str(), str.length(), 0, 0);
if (!length)
return L"utf-8 to utf-16 conversion error!";
std::vector<wchar_t> buffer(length + 1);
if (!MultiByteToWideChar(CP_UTF8, 0, str.c_str(), str.length(), buffer.data(), length))
return L"utf-8 to utf-16 conversion error!";
return std::wstring(buffer.data(), length);
}
// ...
std::string username{ "My username" };
std::wstring utf_16_username{ str_to_wstr(username) };
// ... use:
utf_16_username.data(); // wherever you would have used pszName

Answer 2

You can use the std::mbstowcs function to convert your string into wchar_t*:
std::string username = "My username"; //set your username
wchar_t pszName[] = L"My username"; //initialize pszName with a certain length wide string
std::mbstowcs(pszName, name.c_str(), std::wcslen(pszName)); //copy and convert name from username to pszName
And you need to include:
#include <string>
#include <cstdlib>
Be aware, that you have to give a maximum length for pszName, and that this value actually has to have allocated at least this length in memory! Otherwise you get runtime crashes!
With the current implementation, you can just insert a dummy name of the right length into pszName and get the right length with the std::wcslen function.