correct idiom for container

[keith]

Is the following code well-formed and portable?

Value value;
Container<Value> c;

c.push_back(value);
c.erase(--c.end());

Container can be std::string, std::vector...

 

[Jonathan Lee]

It's not quite that simple. If the iterator is a class type you can
decrement it. So if the iterator isn't a class type, the code is
ill-formed; if the iterator is a class type, the code works fine. But
it's not portable.

Using rbegin() instead of --end() should fix that.

--Jonathan

 

[James Kanze]

It's not quite that simple. If the iterator is a class type you can
decrement it.

Maybe. If the iterator is a class type and the increment
operator is a member, you can decrement it. If the increment
operator is a free function, taking the iterator as a non-const
reference, you can't. (I don't know of any implementations
which do it that way, but I don't know why. It's the way I'd do
it.)