Signed vs. unsigned integers for lengths/counts

Question

For representing a length or count variable, is it better to use signed or unsigned integers?

It seems to me that C++ STL tends to p

Answer 1

It's natural to use unsigned types for counts and sizes unless we're in some context where they can be negative and yet be meaningful. My guess is that C++ follows this same logic of its elder brother C, in which strlen() returns size_t and malloc() takes size_t.

The problem in C++ (and C) with signed and unsigned integers is that you must know how they are converted to one another when you're using a mixture of the two kinds. Some advocate using signed ints for everything integer to avoid this issue of programmers' ignorance and inattention. But I think programmers must know how to use their tools of trade (programming languages, compilers, etc). Sooner or later they'll be bit by the conversion, if not in what they have written, then in what someone else has. It's unavoidable.

So, know your tools, choose what makes sense in your situation.