Type to learn 3 program series#

I agree it would be much better if the documentation for resize just covered all it's bases with regards to which exceptions get thrown in all cases. Only because you were curious what steps might have led you to the exception that was thrown.

Type to learn 3 program series#

I give this series of steps not because I think anyone would/should be expected to dig this much through docs every time they write code. It throws length_error when new_cap > max_size(). Here you would read that vector::reserve takes a parameter new_cap which determines the new capacity of a vector. Since your case with max_size() + 1 is certainly going to involve increasing vector capacity, you might suspect this function is involved. From the capacity page, you would read that vector::reserve is used for explicitly increasing the capacity of the vector. Linked in this chunk of text is the doc page for capacity. Since your case is absolutely going to be greater than the current container capacity, this might be worth looking into. If n is also greater than the current container capacity, an automatic reallocation of the allocated storage space takes place. Starting with, if you've got a case like yours pushing max_size(), you might pay special attention to the case listed on this doc page which states: the resize()s inheriting certain parts of their behavior from reserve() - and then drawing the inescapable inferences. You get where you want to go by studying everything about the class, template, or algorithm in question, understanding how it must work - i.e. The C++ standard itself has some gaps not to mention 2nd-hand sources of documentation like the one you're looking at. My question is, from looking at this documentation, how do you get to that? > Maybe I missed something obvious. The total overall difference, related to exceptions, between the two overloads is due to any exception differences between the value's default constructor and/or its copy/move constructors.

But in terms of exception behavior during reallocation they must be identical.

The only difference between them is that one default-constructs new values when the vector grows and the other one copy-constructs. It goes without saying that resize() uses reserve() to grow the vector's capacity, when needed, and inherits its exception guarantees/behavior.īut the same thing must be true with the 2nd resize() overload. The first overload's description is lifted straight from reserve() that just precedes it. It's fairly obvious that when it comes to exceptions that might be generated as a result of reallocations, both overloads should have the same exception behavior. I found nothing on a more general in vector itself, nor in 'Container Requirements', there was some discussion of exception guarantees but none pertaining to the specific details of vector's resize() or reserve(). That's the only mention of exceptions in resize(). Remarks: If an exception is thrown there are no effects. Of a non-Cpp17CopyInsertable T there are no effects.Ĭonstexpr void resize(size_type sz, const T& c) Remarks: If an exception is thrown other than by the move constructor I happen to have a copy of N4860 handy which is, basically, the C++20 version, and while looking up what the C++ standard itself says about resize()'s exceptions, I found that the two resize() overloads define their exception behavior as follows: Let's just see what the C++ standard itself says about two versions of the overloaded resize() vector method. The complexity of the language has increased so much over the years, accumulating multiple revisions to the C++ standard, that even the C++ standard itself can be at odds with itself, sometimes.