Returns the length of the string, in terms of number of characters (utf code units).
size_t length() const pure nothrow @nogc @property scope @trusted;
This is the number of actual characters that conform the contents of the
BasicString, which is not necessarily equal to its storage capacity.
BasicString!char str = "123"; assert(str
.length == 3); BasicString!wchar wstr = "123"; assert(wstr .length == 3); BasicString!dchar dstr = "123"; assert(dstr .length == 3);