You can use Vec‘s extend method. extend takes a value of any type that implements IntoIterator (which includes all iterator types) and extends the Vec by all elements returned from the iterator: vector.extend(it) Since extend belongs to the Extend trait, it also works for many other collection types.
push_back() and push_front() are defined in terms of insert(). Similarly, pop_back() and pop_front() are defined in terms of erase(). Here’s what the C++03 standard says about iterator invalidation for insert() (23.2.1.3/1): An insert in the middle of the deque invalidates all the iterators and references to elements of the deque. An insert at either end … Read more
If you want to remove elements, you can use retain(), which removes elements from the vector if the closure returns false: let mut vec = vec![1, 2, 3, 4]; vec.retain(|&x| x % 2 == 0); assert_eq!(vec, [2, 4]); If you want to modify the elements in place, you have to do that in a for … Read more
There is no such helper method on the Iterator trait directly. However, there are two main ways to do it: Use the [T]::chunks() method (which can be called on a Vec<T> directly). However, it has a minor difference: it won’t produce None, but the last iteration yields a smaller slice. For always-exact slices that omit … Read more
They are somewhat redundant with each other. However, as you say, Drain just borrows the vector, in particular, it has a lifetime connected with the vector. If one is wishing to return an iterator, or otherwise munge iterators in the most flexible way possible, using into_iter is better, since it’s not chained to the owner … Read more
Use the itertools.tee() function to produce copies; these use a buffer to share results between different iterators: from itertools import tee my_list = [5, 4, 3,2] first_it = iter(my_list) first_it, second_it = tee(first_it) print next(first_it) # prints 5 print next(second_it) # prints 5 print next(first_it) # prints 4 Note that you should no longer use … Read more
The erase() method returns a new (valid) iterator that points to the next element after the deleted one. You can use this iterator to continue with the loop: std::vector<std::string>::iterator iter; for (iter = m_vPaths.begin(); iter != m_vPaths.end(); ) { if (::DeleteFile(iter->c_str())) iter = m_vPaths.erase(iter); else ++iter; }
You can achieve this like following : map<string, int>::iterator it; for (it = symbolTable.begin(); it != symbolTable.end(); it++) { std::cout << it->first // string (key) << ‘:’ << it->second // string’s value << std::endl; } With C++11 ( and onwards ), for (auto const& x : symbolTable) { std::cout << x.first // string (key) << … Read more
I would prefer it – vec.begin() precisely for the opposite reason given by Naveen: so it wouldn’t compile if you change the vector into a list. If you do this during every iteration, you could easily end up turning an O(n) algorithm into an O(n^2) algorithm. Another option, if you don’t jump around in the … Read more
Yes, there is a way to do it! You can’t print the iterator because it is not defined to have a value. But you can perform arithematic operations on them and that helps you to print the value (of the iterator). Do the following. cout << it – v.begin(); Example: #include <iostream> #include <algorithm> #include … Read more