An iterator is stateful. The idea is that if you call Iterable.iterator() twice you’ll get independent iterators – for most iterables, anyway. That clearly wouldn’t be the case in your scenario. For example, I can usually write: public void iterateOver(Iterable<String> strings) { for (String x : strings) { System.out.println(x); } for (String x : strings) … Read more
This code should work: >>> iter = (i for i in range(50)) >>> sum(1 for _ in iter) 50 Although it does iterate through each item and count them, it is the fastest way to do so. It also works for when the iterator has no item: >>> sum(1 for _ in range(0)) 0 Of … Read more
The best argument easily is the one made by Dijkstra himself: You want the size of the range to be a simple difference end − begin; including the lower bound is more “natural” when sequences degenerate to empty ones, and also because the alternative (excluding the lower bound) would require the existence of a “one-before-the-beginning” sentinel value. … Read more
It’s quite simple. Say I have a vector: std::vector<int> vec; I fill it with some data. Then I want to get some iterators to it. Maybe pass them around. Maybe to std::for_each: std::for_each(vec.begin(), vec.end(), SomeFunctor()); In C++03, SomeFunctor was free to be able to modify the parameter it gets. Sure, SomeFunctor could take its parameter … Read more
How do you call .begin() and .end() on a C-array ? Free-functions allow for more generic programming because they can be added afterwards, on a data-structure you cannot alter.
There’s an alternative to the StopIteration by using next(iterator, default_value). For exapmle: >>> a = iter(‘hi’) >>> print next(a, None) h >>> print next(a, None) i >>> print next(a, None) None So you can detect for None or other pre-specified value for end of the iterator if you don’t want the exception way.
You could use Map.prototype.forEach((value, key, map) => void, thisArg?) : void instead Use it like this: myMap.forEach((value: boolean, key: string) => { console.log(key, value); });
Try this: vector<Type>::iterator nth = v.begin() + index;
Use the .clone() method on your List. It will return a shallow copy, meaning that it will contain pointers to the same objects, so you won’t have to copy the list. Then just use Collections. Ergo, Collections.reverse(list.clone()); If you are using a List and don’t have access to clone() you can use subList(): List<?> shallowCopy … Read more
An Iterable is a simple representation of a series of elements that can be iterated over. It does not have any iteration state such as a “current element”. Instead, it has one method that produces an Iterator. An Iterator is the object with iteration state. It lets you check if it has more elements using … Read more