How to convert wstring into byte vector

How to convert wstring into byte vector

Hi I have a few typedefs:
typedef unsigned char Byte;
typedef std::vector<Byte> ByteVector;
typedef std::wstring String;
I need to convert String into ByteVector, I have tried this:
String str = L"123";
ByteVector vect(str.begin(), str.end());
As a result vectror contains 3 elements: 1, 2, 3. However it is wstring so
every charcter in this string is wide so my expected result would be: 0,
1, 0, 2, 0, 3.
Is there any standart way to do that or I need to write some custom function.