Better C Strings, Simply
If you program in C, strings are just in your imagination. What you really have is a character pointer, and we all agree that a string is every character from that point up until one of the characters is zero. While that’s simple and useful, it is also the source of many errors. For example, writing a 32-byte string to a 16-byte array or failing to terminal a string with a zero byte. [Thasso] has been experimenting with a different way to represent strings that is still fairly simple but helps keep things straight.
Like many other languages, this setup uses counted strings and string buffers. You can read and write to a string buffer, but strings are read-only. In either case, there is a length for the contents and, in the case of the buffer, a length for the entire buffer.
We’ve seen schemes like this before and [Thasso] borrowed the idea from [Chris Wellons]. The real issue, of course, is that you now have to rewrite or wrap any “normal” C functions you have that take or return strings. We’ve also seen this done where the length is stored ahead of the string so you don’t have a field for the character pointer:
struct str
{
sz len;
char dat[0];
};
Even though the prototypical structure has a zero length, the actual structure can be larger.
If you are worried about efficiency, [Thasso] and [Wellons] both point out that modern compilers are good at handling small structures, so maybe that’s an advantage to not putting the data directly into the struct. If you need characters larger than one byte, the [Wellons] post has some thoughts on that, too.
This is all old hat on C++, of course. No matter how you encode your strings, you should probably avoid the naughty ones. Passwords, too.