range() and xrange() take a third parameter that specifies a step. So you can do the following. range(10, 0, -1) Which gives [10, 9, 8, 7, 6, 5, 4, 3, 2, 1] But for iteration, you should really be using xrange instead. So, xrange(10, 0, -1) Note for Python 3 users: There are no separate … Read more
(Update: My other answer here lays out the non-jQuery options much more thoroughly. The third option below, jQuery.each, isn’t in it though.) Four options: Generic loop: var i; for (i = 0; i < substr.length; ++i) { // do something with `substr[i]` } or in ES2015+: for (let i = 0; i < substr.length; ++i) … Read more
[*] g.next() has been renamed to g.__next__(). The reason for this is consistency: special methods like __init__() and __del__() all have double underscores (or “dunder” in the current vernacular), and .next() was one of the few exceptions to that rule. This was fixed in Python 3.0. [*] But instead of calling g.__next__(), use next(g). [*] … Read more
You can use a range with a step size of 2: Python 2 for i in xrange(0,10,2): print(i) Python 3 for i in range(0,10,2): print(i) Note: Use xrange in Python 2 instead of range because it is more efficient as it generates an iterable object, and not the whole list.
Old question but the remaining answers are outdated as of C++11 – you can use a ranged based for loop and simply do: std::map<std::string, std::map<std::string, std::string>> mymap; for(auto const &ent1 : mymap) { // ent1.first is the first key for(auto const &ent2 : ent1.second) { // ent2.first is the second key // ent2.second is the … Read more
Let me give a few examples with some alternatives to avoid a ConcurrentModificationException. Suppose we have the following collection of books List<Book> books = new ArrayList<Book>(); books.add(new Book(new ISBN(“0-201-63361-2”))); books.add(new Book(new ISBN(“0-201-63361-3”))); books.add(new Book(new ISBN(“0-201-63361-4”))); Collect and Remove The first technique consists in collecting all the objects that we want to delete (e.g. using an … Read more
Use children() and each(), you can optionally pass a selector to children $(‘#mydiv’).children(‘input’).each(function () { alert(this.value); // “this” is the current element in the loop }); You could also just use the immediate child selector: $(‘#mydiv > input’).each(function () { /* … */ });
Use forEach its a built-in array function. Array.forEach(): yourArray.forEach(function (arrayItem) { var x = arrayItem.prop1 + 2; console.log(x); });
This depends on the language being used. You wrote ‘language-agnostic’, so I’ll give some examples. In Java, C, and Python, recursion is fairly expensive compared to iteration (in general) because it requires the allocation of a new stack frame. In some C compilers, one can use a compiler flag to eliminate this overhead, which transforms … Read more
Use next: (1..10).each do |a| next if a.even? puts a end prints: 1 3 5 7 9 For additional coolness check out also redo and retry. Works also for friends like times, upto, downto, each_with_index, select, map and other iterators (and more generally blocks). For more info see http://ruby-doc.org/docs/ProgrammingRuby/html/tut_expressions.html#UL.