Browsing Questions About iterator (1)

How would one create an iterative function (or iterator object) in python?

How do I make a tree data structure in C++ that uses iterators instead of pointers? I couldn't find anything in the STL that can do this. What I would like to do is to be able to create and manipulate trees like this: #include <iostream> #include <tree> using namespace std; int main() { tree…

I'm looking for the basic loop like: for(int i = 0; i < MAX; i++) { doSomething(i); } but for bash.

I'm having some trouble getting Boost Xpressive to work as I expect. I'm trying to split a line of text into fields delimited by tab characters: wstring ws = L"Field1\tField2\tField3"; wsregex_token_iterator fieldIt(ws.begin(), ws.end(), as_xpr(L'\t'), -1); wsregex_token_iterator endIt; So…

I'm returning to c++ after being away for a bit and trying to dust off the old melon. In Java Iterator is an interface to a container having methods: hasNext(), next() and remove(). The presence of hasNext() means it has the concept of a limit for the container being traversed. //with an Ite…

I often see code like: Iterator i = list.iterator(); while(i.hasNext()) { ... } but I write that (when Java 1.5 isn't available or for each can't be used) as: for(Iterator i = list.iterator(); i.hasNext(); ) { ... } because It is shorter It keeps i in a smaller scope It …

Suppose we have an iterator (an infinite one) that returns lists (or finite iterators), for example one returned by infinite = itertools.cycle([[1,2,3]]) What is a good Python idiom to get an iterator (obviously infinite) that will return each of the elements from the first iterator, then e…

Suppose I want to implement in C++ a data-structure to store oriented graphs. Arcs will be stored in Nodes thanks to STL containers. I'd like users to be able to iterate over the arcs of a node, in an STL-like way. The issue I have is that I don't want to expose in the Node class (that will act…

As far as variable naming conventions go, should iterators be named i or something more semantic like count ? If you don't use i , why not? If you feel that i is acceptable, are there cases of iteration where it shouldn't be used?

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 th…

I'd love to figure it out myself but I was wondering roughly what's the algorithm for converting a function with yield statements into a state machine for an enumerator? For example how does C# turn this: IEnumerator<string> strings(IEnumerable<string> args) { IEnumerator<string> enumerator2 =…

When iterating over elements of a vector it is preferred to use iterators instead of an index (see Why use iterators instead of array indices? ). std::vector<T> vec; std::vector<T>::iterator it; for ( it = vec.begin(); it != vec.end(); ++it ) { // do work } However, it can be necessary to…

The 3-argument form of list::splice() moves a single element from one list to the other. SGI's documentation explicitly states that all iterators, including the one pointing to the element being moved remain valid. Roguewave's documentation does not say anything about iterator invalidation prope…

I'm trying to learn C++ so forgive me if this question demonstrates a lack of basic knowledge, you see, the fact is, I have a lack of basic knowledge. I want some help working out how to create an iterator for a class I have created. I have a class 'Shape' which has a container of Points. I…

I'm trying to figure out the best way to determine if I'm in the last iteration of a loop over a map in order to do something like the following: for (iter = someMap.begin(); iter != someMap.end(); ++iter) { bool last_iteration; // do something for all iterations if (!last_iteration) { …