Having an iterator object, is there something faster, better or more correct than a list comprehension to get a list of the objects returned by the iterator? user_list = [user for user in user_iterator] 3 Answers 3
Given Iterator<Element>, how can we conveniently convert that Iterator to a List<Element>, so that we can use List‘s operations on it such as get(index), add(element), etc. 12 Answers 12
Take the following two lines of code: for (int i = 0; i < some_vector.size(); i++) { //do stuff } And this: for (some_iterator = some_vector.begin(); some_iterator != some_vector.end(); some_iterator++) { //do stuff } I’m told that the second way is preferred. Why exactly is this? 27 Answers 27
I have a custom container class for which I’d like to write the iterator and const_iterator classes. I never did this before and I failed to find an appropriate how-to. What are the guidelines regarding iterator creation, and what should I be aware of ? I’d also like to avoid code duplication (I feel that … Read more
I have a generator function like the following: def myfunct(): … yield result The usual way to call this function would be: for r in myfunct(): dostuff(r) My question, is there a way to get just one element from the generator whenever I like? For example, I’d like to do something like: while True: … … Read more
I made a collection for which I want to provide an STL-style, random-access iterator. I was searching around for an example implementation of an iterator but I didn’t find any. I know about the need for const overloads of [] and * operators. What are the requirements for an iterator to be “STL-style” and what … Read more
Should I use std::sort(numbers.begin(), numbers.end(), std::greater<int>()); or std::sort(numbers.rbegin(), numbers.rend()); // note: reverse iterators to sort a vector in descending order? Are there any benefits or drawbacks with one approach or the other? 11 Answers 11
This question already has answers here: Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop (30 answers) Closed 7 years ago. I’m trying to remove some elements from an ArrayList while iterating it like this: for (String str : myArrayList) { if (someCondition) { myArrayList.remove(str); } } Of course, I get a … Read more
I would like to get the first item from a list matching a condition. It’s important that the resulting method not process the entire list, which could be quite large. For example, the following function is adequate: def first(the_iterable, condition = lambda x: True): for i in the_iterable: if condition(i): return i This function could … Read more
I’m iterating over a vector and need the index the iterator is currently pointing at. AFAIK this can be done in two ways: it – vec.begin() std::distance(vec.begin(), it) What are the pros and cons of these methods? 10 s 10 I would prefer it – vec.begin() precisely for the opposite reason given by Naveen: so … Read more
