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• Recursive solution to finding patterns

  - by user2997162

  I was solving a problem on recursion which is to count the total number of consecutive 8's in a number. For example: input: 8801 output: 2 input: 801 output: 0 input: 888 output: 3 input: 88088018 output:4 I am unable to figure out the logic of passing the information to the next recursive call about whether the previous digit was an 8. I do not want the code but I need help with the logic. For an iterative solution, I could have used a flag variable, but in recursion how do I do the work which flag variable does in an iterative solution. Also, it is not a part of any assignment. This just came to my mind because I am trying to practice coding using recursion.

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• Detecting when Javascript is performing poorly

  - by what-the-crap

  I'm working on a webapp in jquery that, on older machines or machines without much resources, may perform poorly. To get around this I'd like to make a degraded version that disables some of the features, particularly those that rely on large images. How can I tell if my app is running poorly on the user's computer in jquery or javascript in general? I just need a way to call a function that will degrade the app. (especially when the user may run low on system memory) The only way I can think of is for manual user intervention, but the option would add clutter for users that don't need it and users that do need it may not notice it. Thanks!

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• c++: at what point should I start using "new char[N]" vs a static buffer "char[Nmax]"

  - by dan

  My question is with regard to C++ Suppose I write a function to return a list of items to the caller. Each item has 2 logical fields: 1) an int ID, and 2) some data whose size may vary, let's say from 4 bytes up to 16Kbytes. So my question is whether to use a data structure like: struct item { int field1; char field2[MAX_LEN]; OR, rather, to allocate field2 from the heap, and require the caller to destroy when he's done: struct item{ int field1; char *field2; // new char[N] -- destroy[] when done! Since the max size of field #2 is large, is makes sense that this would be allocated from the heap, right? So once I know the size N, I call field2 = new char[N], and populate it. Now, is this horribly inefficient? Is it worse in cases where N is always small, i.e. suppose I have 10000 items that have N=4?

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• why can not see my method if i implamented interface to normal class?

  - by Phsika

  i can not see MyLoad.TreeLoader(.... but why i can not see? i implemented iloader to TreeViewLoad. i should see TreeLoader why? namespace Rekursive { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { //treeView1.Nodes.Add("Test"); iloader MyLoad = new TreeViewLoad(); MyLoad.loader("test", treeView1, 1); // i can not see MyLoad.TreeLoader(.... but why i can not see? // i implemented iloader to TreeViewLoad. i should see TreeLoader why? //TreeViewLoad myloader = new TreeViewLoad(); } } interface iloader { void loader(string nodeName, TreeView myTre, int id); } class TreeViewLoad : iloader { public void TreeLoader(TreeView tre) { // i will call loader... } public void loader(string nodeName, TreeView myTre, int id) { myTre.Nodes.Add(nodeName + id.ToString()); if (id

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• Picking photo from Photochooser or holding hardware back button cause active timers ring

  - by Nznoonee

  This is very strange problem, and all the people I had asked to confirm it said that it takes place. I have a Threading.Timer instance which fires every 15 minutes. And if I call the PhotoChooser view and then select a photo from it, when going back to the calling page my application calls that timer's callback! I tried different timers either it be Timer from Threading namespace or Dispatcher timer. The same happens when being in my app I hold the back button of my device and then choose the app from the list. My application is as plain as it can be - the timer with a callback and method calling PhotoChooser. Could anyone help with solution or workaround please?

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• String formatting [str.format()] with a dictionary having a key which is a str() of a number

  - by decimus phostle

  Python neophyte here. I was wondering if someone could help with the KeyError I am getting when using a dictionary for string interpolation in str.format. dictionary = {'key1': 'val1', '1': 'val2'} string1 = 'Interpolating {0[key1]}'.format(dictionary) print string1 The above works fine and yields: Interpolating val1 However doing the following: dictionary = {'key1': 'val1', '1': 'val2'} string2 = 'Interpolating {0[1]}'.format(dictionary) print string2 results in: Traceback (most recent call last): File "test.py", line 3, in <module> string2 = 'Interpolating {0[1]}'.format(dictionary) KeyError: 1L So the problem seems to be in the interpretation of the numeric key as a list index, IMHO. Is there any way to work around this? (i.e. convey that this is instead a dictionary key) TIA and apologies if this question has been asked before(couldn't find anything relevant with my search-fu).

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• Java inheritance question

  - by user247866

  So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = method-call();` // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void some-method(LIst<A> a) However, when I do: C c = new C(). c. some-method(b) I get an error that some-method is not applicable for the argument List, instead it's expecting to get List. Is there a good way to fix this problem? Many thanks!

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• Dynamic memory allocation with default values

  - by viswanathan

  class A { private: int m_nValue; public: A() { m_nValue = 0; } A(int nValue) { m_nValue = nValue); ~A() {} } Now in main if i call A a(2);// 2 will be assigned for m_nValue of object A. Now how do we do this if i want to define an array of objects. Also how do we do this if i dynamically create objects using operator new like A *pA; pA = new A[5];// while creating the object i want the parameterised constructor to be //called I hope the question is clear. Do let me know if more explanation is needed

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• Are there any Android YouTube Player Flags?

  - by stormin986

  My goal is to launch a video in the YouTube player, and then return to my app. I realize I can't control what's going on in another app, BUT I'm wondering if the YouTube app supports any kind of flags or data set in the calling Intent that might support this functionality. Anyone aware of any? I cannot find any documentation on the YouTube app/activities. I had to watch the logs just to figure out which activity to call in the first place (so the choose app dialog didn't appear).

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• Execute code when Eclipse workbench loads

  - by Krt_Malta

  Hi! I'm writing an Eclipse plug-in and I've bumped into an issue. Amongst others I'm creating a new custom perspective. I need to execute some code when the workbench loads. I'm using a WorkbenchAdvisor and putting the code in the initialize method. However as it is now it's not being called... Apparently I need to call this PlatformUI.createAndRunWorkbench(display, new ApplicationWorkbenchAdvisor(); but I don't know where to put this... I can't put it in the createInitialLayout of the perspective because this is only called when the perspective is created for the first time. Any ideas please? Thanks and regards, Krt_Malta

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• How to step inside NSManagedObject; access individual attributes.

  - by user300972

  NSManagedObject *entryObj = [self.fetchedResultsController objectAtIndexPath:indexPath]; entryObj consists of four String attributes. If I NSLog entryObj, I get the information I want. I cannot figure out how to access each of these properties individually. I read a similar post where the solution was to call "entity." I cannot figure out how to use "entity" to access a specific attribute. Any ideas? References? Tutorials? Thanks in advance.

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• jQuery - Set selected value of all dropdowns on page

  - by Tgibson

  Hello Frieds, I have another jQuery question. For a user control with lots of database activity, I would like to use jQuery to set the selected values of all of the dropdowns to their "current" value. I want to do this to make the page appear to have finished the database call. My jQuery skill is not the best, but I believe I need to use the pageLoad(). And since each dropdown is inside of a user control I can search for those dropdowns beginning with "usrControl" $('select[id ^="usrControl"'].each(function(){ var selectedValue = $(this).val() $(this).val(selectedValue) }); Something like this is what I have in mind. Thanks

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• Complex SQL queries (DELETE)?

  - by Joe

  Hello all, I'm working with three tables, and for simplicity's sake let's call them table A, B, and C. Both tables A and B have a column called id, as well as one other column, Aattribute and Battribute, respectively. Column c also has an id column, and two other columns which hold values for A.id and B.id. Now, in my code, I have easy access to values for both Aattribute and Battribute, and want to delete the row at C, so effectively I want to do something like this: DELETE FROM C WHERE aid=(SELECT id FROM A WHERE Aattribute='myvalue') AND bid=(SELECT id FROM B WHERE Battribute='myothervalue') But this obviously doesn't work. Is there any way to make a single complex query, or do I have to run three queries, where I first get the value of A.id using a SELECT with 'myvalue', then the same for B.id, then use those in the final query? [Edit: it's not letting me comment, so in response to the first comment on this: I tried the above query and it did not work, I figured it just wasn't syntactically correct. Using MS Access, for what it's worth. ]

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• checkbox dynamic create for jquery

  - by user1397840

  How do i create multiple checkbox for jquery to identify it? example i have a html page with this is call new.html <div id =new> <input type=checkbox"></div> at create.html i want to use jquery to load multiple checkbox <div id=load> <div> $("#load).load(new.html) so if i use a for loop to loop 10times to create 10 checkbox, how do i identify each checkbox uniquely? for(var i = 0;i<10;i++){ $("#load).load(new.html)}

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• Singleton Creation preference

  - by cwieland

  You can create singletons in a variety of ways. I am wondering which is better between these. +(ServerConnection*)shared{ static dispatch_once_t pred=0; __strong static id _sharedObject = nil; dispatch_once(&pred, ^{ _sharedObject = [[self alloc] init]; // or some other init method }); return _sharedObject; } I could see that this compiles down to something very fast. I would think that checking the predicate would be another function call. The other is: +(ServerConnection*)shared{ static ServerConnection* connection=nil; if (connection==nil) { connection=[[ServerConnection alloc] init]; } return connection; } Are there any major differences between the two? I know these are probably similar enough to not worry about it. But Just wondering.

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• Accessing local variable doesn't improve performance

  - by NicMagnier

  The short version Why is this code: var index = (Math.floor(y / scale) * img.width + Math.floor(x / scale)) * 4; More performant than this one? var index = Math.floor(ref_index) * 4; The long version This week, the author of Impact js published an article about some rendering issue: http://www.phoboslab.org/log/2012/09/drawing-pixels-is-hard In the article there was the source of a function to scale an image by accessing pixels in the canvas. I wanted to suggest some traditional ways to optimize this kind of code so that the scaling would be shorter at loading time. But after testing it my result was most of the time worst that the original function. Guessing this was the JavaScript engine that was doing some smart optimization I tried to understand a bit more what was going on so I did a bunch of test. But my results are quite confusing and I would need some help to understand what's going on. I have a test page here: http://www.mx981.com/stuff/resize_bench/test.html jsPerf: http://jsperf.com/local-variable-due-to-the-scope-lookup To start the test, click the picture and the results will appear in the console. There are three different versions: The original code: for( var y = 0; y < heightScaled; y++ ) { for( var x = 0; x < widthScaled; x++ ) { var index = (Math.floor(y / scale) * img.width + Math.floor(x / scale)) * 4; var indexScaled = (y * widthScaled + x) * 4; scaledPixels.data[ indexScaled ] = origPixels.data[ index ]; scaledPixels.data[ indexScaled+1 ] = origPixels.data[ index+1 ]; scaledPixels.data[ indexScaled+2 ] = origPixels.data[ index+2 ]; scaledPixels.data[ indexScaled+3 ] = origPixels.data[ index+3 ]; } } jsPerf: http://jsperf.com/so-accessing-local-variable-doesn-t-improve-performance One of my attempt to optimize it: var ref_index = 0; var ref_indexScaled = 0 var ref_step = 1 / scale; for( var y = 0; y < heightScaled; y++ ) { for( var x = 0; x < widthScaled; x++ ) { var index = Math.floor(ref_index) * 4; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+1 ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+2 ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+3 ]; ref_index+= ref_step; } } jsPerf: http://jsperf.com/so-accessing-local-variable-doesn-t-improve-performance The same optimized code but with recalculating the index variable each time (Hybrid) var ref_index = 0; var ref_indexScaled = 0 var ref_step = 1 / scale; for( var y = 0; y < heightScaled; y++ ) { for( var x = 0; x < widthScaled; x++ ) { var index = (Math.floor(y / scale) * img.width + Math.floor(x / scale)) * 4; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+1 ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+2 ]; scaledPixels.data[ ref_indexScaled++ ] = origPixels.data[ index+3 ]; ref_index+= ref_step; } } jsPerf: http://jsperf.com/so-accessing-local-variable-doesn-t-improve-performance The only difference in the two last one is the calculation of the 'index' variable. And to my surprise the optimized version is slower in most browsers (except opera). Results of personal testing (not the jsPerf tests): Opera Original: 8668ms Optimized: 932ms Hybrid: 8696ms Chrome Original: 139ms Optimized: 145ms Hybrid: 136ms Safari Original: 433ms Optimized: 853ms Hybrid: 451ms Firefox Original: 343ms Optimized: 422ms Hybrid: 350ms After digging around, it seems an usual good practice is to access mainly local variable due to the scope lookup. Because The optimized version only call one local variable it should be faster that the Hybrid code which call multiple variable and object in addition to the various operation involved. So why the "optimized" version is slower? I thought that it might be because some JavaScript engine don't optimize the Optimized version because it is not hot enough but after using --trace-opt in chrome, it seems all version are properly compiled by V8. At this point I am a bit clueless and wonder if somebody would know what is going on? I did also some more test cases in this page: http://www.mx981.com/stuff/resize_bench/index.html

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• why some mp3s on mime_content_type return application/octet-stream

  - by robertdd

  why on some mp3s file when i call mime_content_type($mp3_file_path) it's return application/octet-stream? i have this: if (!empty($_FILES)) { $tempFile = $_FILES['Filedata']['tmp_name']; $image = getimagesize($tempFile); $mp3_mimes = array('audio/mpeg', 'audio/x-mpeg', 'audio/mp3', 'audio/x-mp3', 'audio/mpeg3', 'audio/x-mpeg3', 'audio/mpg', 'audio/x-mpg', 'audio/x-mpegaudio'); if (in_array(mime_content_type($tempFile), $mp3_mimes)) { echo json_encode("mp3"); } elseif ($image['mime']=='image/jpeg') { echo json_encode("jpg"); } else{ echo json_encode("error"); } }

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• How to simulate Func<T1, T2, TResult> in C++?

  - by Zach

  Hello all, In C#, I use Func to replace Factories. For example: class SqlDataFetcher { public Func<IConnection> CreateConnectionFunc; public void DoRead() { IConnection conn = CreateConnectionFunc(); // call the Func to retrieve a connection } } class Program { public void CreateConnection() { return new SqlConnection(); } public void Main() { SqlDataFetcher f = new SqlDataFetcher(); f.CreateConnectionFunc = this.CreateConnection; ... } } How can I simulate the code above in C++?

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• name of class that manipulates the entities

  - by cyberguest

  hi, i have a general question regarding naming convention. if I separate the data and operations into two separate classes. one has the data elements (entity), the other class manipulates the entity class. what do we usually call that class that manipulates the entity class? (the entity I am referring to has nothing to do with any kind of entity framework) manager? controller? operator? manipulator? thanks in advance

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• .Htaccess & Wildcard Subdomains — Can't get other variables to work!

  - by Justin Scheetz

  It would be absolutely awesome if someone could help me out here. I have a domain, let's call it "example.com". I have wildcard subdomains setup and working great. The only problem is I can't get htaccess to see anything else like subdomain.example.com/profile/some_name/some_id_number/. In fact, I can type any garbage after the domain and it will still just show me the home screen. Here's what's in my htaccess file now: Options +FollowSymLinks Options +Indexes Options -Multiviews RewriteEngine On RewriteCond %{REQUEST_URI} !^/app/index.php RewriteCond %{HTTP_HOST} !^www\.example\.com RewriteCond %{HTTP_HOST} ^([^.]+)\.example\.com RewriteRule (.*) /app/index.php?user%1 [L] I can see why that wouldn't work yet, but I wanted to add something similar to the following: RewriteRule ^profile/([^/]+)/([^/]+) /app/index.php?page=profile&username=$1&user_id=$2 [nc] But it's not working at all. The server doesn't even really show signs that it's even seeing it there. Any ideas?

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• Qt QMainWindow at Close

  - by Cenoc

  Hey, this may seem like a very simple question, but I want to dump some data whenever the QMainWindow closes, so I used the following piece of code: QObject::connect(MainWindow.centralwidget, SIGNAL(destroyed()), this, SLOT(close())); but this doesnt seem to make it call close(). Am I doing this wrong? Isnt the centralwidget suppose to be destroyed? Or perhaps the application closes before close() can be called? Any other ways of doing it then? Thanks in advance!

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• Pushing to an array not working as expected

  - by Ross Attrill

  When I execute the code below, my array 'tasks' ends up with the same last row from the dbi call repeated for each row in the database. require 'dbi' require 'PP' dbh = DBI.connect('DBI:ODBC:Driver={SQL Server Native Client 10.0};Server=localhost,1433;Database=db;Uid=db;Pwd=mypass', 'db', 'mypass') sth = dbh.prepare('select * from TASK') sth.execute tasks = Array.new while row=sth.fetch do p row tasks.push(row) end pp(tasks) sth.finish So if I have two rows in my TASK table, then instead of getting this in the tasks array: [[1, "Task 1"], [2, "Task 2"]] I get this [[2, "Task 2"], [2, "Task 2"]] What am I doing wrong?

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• EXC_BAD_ACCESS when returning a CGRect in iPhone

  - by pabloruiz55

  I have a class which must return a CGRect from one of its methods: -(CGRect)myRect { CGRect rect = CGRectMake(self.mySprite.position.x,self.mySprite.position.y,self.mySprite.textureRect.size.width, self.mySprite.textureRect.size.height); return rect; } I get an exc_bad_access as soon as i try to access the mySprite ivar. Thing is if i call it, the instance variable mySprite is full of garbage. BUT if i change the function to return void, self.mySprite does contain the correct data. -(void)myRect { CGRect rect = CGRectMake(self.mySprite.position.x,self.mySprite.position.y,self.mySprite.textureRect.size.width, self.mySprite.textureRect.size.height); return rect; } that does not crash when accessing mySprite...

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• private virtual function in derived class

  - by user1706047

  class base { public: virtual void doSomething() = 0; }; class derived : public base { **private:** virtual void doSomething(){cout<<"Derived fn"<<endl;} }; now if i do the following: base *b=new child; b->doSomething(); //it calls the derived class fn even if that is private. Question: 1.its able to call the derived class fn even if that is private.How is it possible? Now if i change the inheritance access specifier from public to protected/private then i get compilation error as "'type cast' : conversion from 'Derived *' to 'base *' exists, but is inaccessible" Notes: I am aware on the concepts of the inheritance access specifiers.So in second case as its derived private/protected, its inaccessible. But here it confuses me for the first question. Any input will be highly appreciated

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• Associate a URL with a resource within my application

  - by Horace Loeb

  When I visit http://my-application.com/posts/1 in my browser, Rails knows I'm looking for the Post with id = 1. How can I get my application to do this internally? I.e., I'd like a function (call it associate_with_resource) that takes a string containing a URL as its input and outputs the associated resource. For example: >> associate_with_resource('http://my-application.com/posts/1') => #<Post id: 1, ... > (I'd like to be able to use associate_with_resource throughout my application though -- not only in the console)

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