I think the 2009 paper “Pairs do not make good ranges” by Alisdair Meredith is at least part of the answer. Basically, many algorithms return pairs of iterators that are actually not guaranteed to be valid ranges. It seems they removed the support for pair<iterator,iterator> from the for-range loop for this reason. However, the proposed … Read more
It’s mainly so you can make start and end statements clearer when creating HTML in loops: <table> <? while ($record = mysql_fetch_assoc($rs)): ?> <? if (!$record[‘deleted’]): ?> <tr> <? foreach ($display_fields as $field): ?> <td><?= $record[$field] ?></td> <? endforeach; ?> <td> <select name=”action” onChange=”submit”> <? foreach ($actions as $action): ?> <option value=”<?= $action ?>”><?= $action … Read more
If you are using foreach inside a function and you are expecting an array or a Traversable object you can type hint that function with: function myFunction(array $a) function myFunction(Traversable) If you are not using foreach inside a function or you are expecting both you can simply use this construct to check if you can … Read more
This is the way to iterate on this array: foreach($hotels as $row) { foreach($row[‘rooms’] as $k) { echo $k[‘boards’][‘board_id’]; echo $k[‘boards’][‘price’]; } } You want to iterate on the hotels and the rooms (the ones with numeric indexes), because those seem to be the “collections” in this case. The other arrays only hold and group … Read more
It’s a bit of an oversimplification to say that the enhanced for loop is more efficient. It can be, but in many cases it’s almost exactly the same as an old-school loop. The first thing to note is that for collections the enhanced for loop uses an Iterator, so if you manually iterate over a … Read more
There are many ways, one is to use a counter: $i = 0; foreach ($arr as $k => $v) { /* Do stuff */ if (++$i == 2) break; } Other way would be to slice the first 2 elements, this isn’t as efficient though: foreach (array_slice($arr, 0, 2) as $k => $v) { /* … Read more
What Jason said is totally correct in his answer but I thought I would give it a shot, to better clarify. This is actually a classic closure problem. Typically it would look something like: for(var i = 0; i < 10; i++){ setTimeout(function(){ console.log(i); },i * 1000) } The novice would expect the console to … Read more
What you want to achieve is totally possible with Array#forEach — although in a different way you might think of it. You can not do a thing like this: var array = [‘some’, ‘array’, ‘containing’, ‘words’]; array.forEach(function (el) { console.log(el); wait(1000); // wait 1000 milliseconds }); console.log(‘Loop finished.’); … and get the output: some array … Read more
to achieve just that result you could do foreach (array_combine($courses, $sections) as $course => $section) but that only works for two arrays
if is not a loop structure, so you cannot “break out of it”. You can, however, break out of the foreach by simply calling break. In your example it has the desired effect: $device = “wanted”; foreach($equipxml as $equip) { $current_device = $equip->xpath(“name”); if ( $current_device[0] == $device ) { // found a match in … Read more