I've done a major rewrite on this. See http://www.animats.com/source boost_fixed_string.hpp - fixed strings boost_fixed_string_cstring.hpp - sprintf, etc. boost_fixed_string_test.cpp - a test program This does much the same thing as Dunn's fixed_string, but with a somewhat simpler structure. The main template class is "fixed_string<TYPE,LEN>", which is generic and does all the work. This is derived from the abstract class "fixed_string_base<TYPE>", which is used when you need a reference or pointer to a fixed string of unknown length. It doesn't do anything but redirect virtual functions. Then we define, very simply, "char_string<LEN>" "char_string_base" "wchar_string<LEN>" "wchar_string_base" These are just instantiations of fixed_string, but they also define functions that need type-based handling. So far, this is only "vsnprintf". There are no conditionals, other than the usual workaround for an MSVC problem. fixed_string has a length. Length is lazy-evaluated; some operations make the length -1, which forces a recount of the string when next the length is needed. The C-type operations and subscripting are all checked for length. Iterators are supported, but, consistent with std::string semantics, they are unsafe. Comments? John Nagle Animats