Question

I want to process elements from a vector for some time. To optimize this I don’t want to remove an item when it is processed and I remove all processed items at the end.

vector<Item*>::iterator it;
for(it = items.begin(); it != items.end(); ++it)
{
    DoSomething(*it);

    if(TimeIsUp())
    {
        break;
    }
}

items.erase(items.begin(), it);

Is it safe to use erase when it == items.end()? In documentaion it is said that erase() will erase [first,last) and this should be safe but I want to be sure.

EDIT:

Is it safe to use std::vector.erase(begin(), begin())?

Answer 1

What that [first,last) means is everything between first and last, including first but not including last. It denotes a half-open set. Had they used [first,last], last would also be included; had they they used (first,last), first and last would be excluded.

There is a problem with your code. You want the element at it to be deleted if it isn’t equal to end(). Instead of items.erase (items.begin(),it), you should be using

if (it != items.end()) {
   items.erase (items.begin(), it+1);
}
else {
   items.clear(); // same as items.erase (items.begin(), items.end())
}