Basic types to expose on a C++ API

Question

I'm targeting Windows but I don't see any reason why some API code I'm writing cannot use basic C++ types. What I want to do is expose methods that return strings and ints. In the C# world I'd just use string, and have a unicode string, but in VC++ I've got the option of using std::string, std::wstring, or MFC/ATL CStrings.

Should I just use std::wstring exclusively to support unicode, or can I use std::string which would be compiled to unicode based on my build settings? I'm leaning toward the latter. I'd prefer to provide Get[Item]AsCString() methods on my objects for other string types.

Also should I be using size_t instead of integer?

The API is going to be used by me, and perhaps a future developer working on the C++ GUI. It is a way to separate concerns. My preferences:

• Intuitiveness for other developers.
• Forward compatibility with VC++
• Compatibility with other C++ compilers
• Performance (this is a lesser concern for me, but need the startup time for rest of my app)

Any guides would be appreciated.

Answer 1

You should probably stick to the STL string type. The MFC CString class is built on top of that nowadays anyway.

As has been noted before, using wstring is not a magic bullet to address Unicode issues since there are many Unicode characters that still require multiple wchars to encode.

Using Utf-8 instead has potential benefits (you don't have to worry about endianness for example).

On Windows, all modern kernels are wchar based, so there is a (minimal) performance overhead involved if you use the 8bit char versions of APIs.