Re: iostream >> string, but fixed length string - how?

Indeed. This is what I have gone with, using a const cast for simplicity but
which could break if compiled with an implementation of std::string that does
things differently: (which, if it ever happens, will at least be picked up by
the unit tests)

  struct fixedLength {
    std::string& data;
    int len;
    fixedLength(std::string& data, int len) :
      data(data),
      len(len)
    {
    }
  };

  std::istream& operator >> (std::istream& s, const fixedLength& n)
  {
    n.data.resize(n.len);
    s.read(const_cast<char *>(n.data.c_str()), n.len);
    return s;
  }

Then it can be used as:

  std::string foo;
  stream >> fixedLength(foo, 123);

I'll probably have to create another class for the times when I want to read
in the same amount of data but have the string stop at the first null.

Thanks again both for your suggestions.

Cheers,
Adam.