Safe C++ std::string to TCHAR * conversion?

I am trying to convert a std::string to a TCHAR* for use in CreateFile(). The code i have compiles, and works, but Visual Studio 2013 comes up with a compiler warning:

warning C4996: 'std::_Copy_impl': Function call with parameters that may be unsafe - this call relies on the caller to check that the passed values are correct. To disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to use Visual C++ 'Checked Iterators'

I understand why i get the warning, as in my code i use std::copy, but I don't want to define D_SCL_SECURE_NO_WARNINGS if at all possible, as they have a point: std::copy is unsafe/unsecure. As a result, I'd like to find a way that doesn't throw this warning.

The code that produces the warning:

std::string filename = fileList->getFullPath(index);
TCHAR *t_filename = new TCHAR[filename.size() + 1];
t_filename[filename.size()] = 0;
std::copy(filename.begin(), filename.end(), t_filename);
audioreader.setFile(t_filename);

audioreader.setfile() calls CreateFile() internally, which is why i need to convert the string.

"fileList" and "audioreader" are instances of classes i wrote myself, but I'd rather not change the core implementation of either if at all possible, as it would mean I'd need to change a lot of implementation in other areas of my program, where this conversion only happens in that piece of code. The method I used to convert there was found in a solution i found at http://ift.tt/1B3ne95

I've seen something similar in another question (Converting string to tchar in VC++) but i can't quite fathom how to adapt the answer to work with mine as the size of the string isn't constant. All other ways I've seen involve a straight (TCHAR *) cast (or something equally unsafe), which as far as i know about the way TCHAR and other windows string types are defined, is relatively risky as TCHAR could be single byte or multibyte characters depending on UNICODE definition.

Does anyone know a safe, reliable way to convert a std::string to a TCHAR* for use in functions like CreateFile()?