The reason why you don’t see such practice is quite subjective and cannot have a definite answer, because I have seen many of the code which uses your mentioned way rather than iterator style code. Following can be reasons of people not considering vector.size() way of looping: Being paranoid about calling size() every time in … Read more
list(your_iterator)
The first form is efficient only if vector.size() is a fast operation. This is true for vectors, but not for lists, for example. Also, what are you planning to do within the body of the loop? If you plan on accessing the elements as in T elem = some_vector[i]; then you’re making the assumption that … Read more
Better use a library like Guava: import com.google.common.collect.Lists; Iterator<Element> myIterator = … //some iterator List<Element> myList = Lists.newArrayList(myIterator); Another Guava example: ImmutableList.copyOf(myIterator); or Apache Commons Collections: import org.apache.commons.collections.IteratorUtils; Iterator<Element> myIterator = …//some iterator List<Element> myList = IteratorUtils.toList(myIterator);
Choose type of iterator which fits your container: input, output, forward etc. Use base iterator classes from standard library. For example, std::iterator with random_access_iterator_tag.These base classes define all type definitions required by STL and do other work. To avoid code duplication iterator class should be a template class and be parametrized by “value type”, “pointer … Read more
Create a generator using g = myfunct() Everytime you would like an item, use next(g) (or g.next() in Python 2.5 or below). If the generator exits, it will raise StopIteration. You can either catch this exception if necessary, or use the default argument to next(): next(g, default_value)
http://www.cplusplus.com/reference/std/iterator/ has a handy chart that details the specs of ยง 24.2.2 of the C++11 standard. Basically, the iterators have tags that describe the valid operations, and the tags have a hierarchy. Below is purely symbolic, these classes don’t actually exist as such. iterator { iterator(const iterator&); ~iterator(); iterator& operator=(const iterator&); iterator& operator++(); //prefix increment … Read more
Actually, the first one is a bad idea. Use either the second one, or this: struct greater { template<class T> bool operator()(T const &a, T const &b) const { return a > b; } }; std::sort(numbers.begin(), numbers.end(), greater()); That way your code won’t silently break when someone decides numbers should hold long or long long … Read more
Use an Iterator and call remove(): Iterator<String> iter = myArrayList.iterator(); while (iter.hasNext()) { String str = iter.next(); if (someCondition) iter.remove(); }
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