ipairs() and pairs() are slightly different, as you can see on the manual reference. A less-technical description could be that: ipairs() returns index-value pairs and is mostly used for numeric tables. The non-numeric keys are ignored as a whole, similar to numeric indices less than 1. In addition, gaps in between the indexes lead to … Read more
Procedural elements like loops are not part of the SQL language and can only be used inside the body of a procedural language function, procedure (Postgres 11 or later) or a DO statement, where such additional elements are defined by the respective procedural language. The default is PL/pgSQL, but there are others. Example with plpgsql: … Read more
A forward loop is like this: for x in 0..100 { println!(“{}”, x); } And a reverse loop is done by calling Iterator::rev to reverse the order: for x in (0..100).rev() { println!(“{}”, x); }
Off the top of my head, no. I think the best you could do is something like this: def loop(f,n): for i in xrange(n): f() loop(lambda: <insert expression here>, 5) But I think you can just live with the extra i variable. Here is the option to use the _ variable, which in reality, is … Read more
for in loops over enumerable property names of an object. for of (new in ES6) does use an object-specific iterator and loops over the values generated by that. In your example, the array iterator does yield all the values in the array (ignoring non-index properties).
function allDescendants (node) { for (var i = 0; i < node.childNodes.length; i++) { var child = node.childNodes[i]; allDescendants(child); doSomethingToNode(child); } } You loop over all the children, and for each element, you call the same function and have it loop over the children of that element.
Or you could use the subsets method. You’ll have to convert your list to a set first though. scala> List(1,2,3).toSet[Int].subsets.map(_.toList).toList res9: List[List[Int]] = List(List(), List(1), List(2), List(3), List(1, 2), List(1, 3), List(2, 3), List(1, 2, 3))
Iterating over an array using for…in doesn’t guarantee order, however ES6 introduces a new construct for…of. My limited testing of implementations of for…of indicates that it does iterate in order on array, but is this property guaranteed? Yes, the order of for-of on arrays is guaranteed by the array iterator definition: It will visit the … Read more
Ok, so first off, let me say this: Use while(true), as it gives the most semantic meaning. You need to parse for (;;) as it’s not something you see often. With that said, let’s analyze: Opcodes The code while(true) { break; } echo “hi!”; Compiles down to the opcodes: 0: JMPZ(true, 3) 1: BRK(1, 3) … Read more
You can (but generally shouldn’t) use a local struct type. for ( struct { int i; char* ptr; } loopy = { 0, bam }; loopy.i < 10 && * loopy.ptr != 0; ++ loopy.i, ++ loopy.ptr ) { … } Since C++11, you can initialize the individual parts more elegantly, as long as they … Read more