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• R Tree 50,000 foot overview?

  - by roufamatic

  I'm working on a school project that involves taking a lat/long point and finding the top five closest points in a known list of places. The list is to be stored in memory, with the caveat that we must choose an "appropriate data structure" -- that is, we cannot simply store all the places in an array and compare distances one-by-one in a linear fashion. The teacher suggested grouping the place data by US State to prevent calculating the distance for places that are obviously too far away. I think I can do better. From my research online it seems like an R-Tree or one of its variants might be a neat solution. Unfortunately, that sentence is as far as I've gotten with understanding the actual technique, as the literature is simply too dense for my non-academic head. Can somebody give me a really high overview of what the process is for populating an R-Tree with lat/long data, and then traversing the tree to find those 5 nearest neighbors of a given point? Additionally the project is in C, and I don't have to reinvent the wheel on this, so if you've used an existing open source C implementation of an R Tree I'd be interested in your experiences.

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• ASP ListView - Eval() as formatted number, Bind() as unformatted?

  - by chucknelson

  I have an ASP ListView, and have a very simple requirement to display numbers as formatted w/ a comma (12,123), while they need to bind to the database without formatting (12123). I am using a standard setup - ListView with a datasource attached, using Bind(). I converted from some older code, so I'm not using ASP.NET controls, just form inputs...but I don't think it matters for this: <asp:SqlDataSource ID="MySqlDataSource" runat="server" ConnectionString='<%$ ConnectionStrings:ConnectionString1 %>' SelectCommand="SELECT NUMSTR FROM MY_TABLE WHERE ID = @ID" UpdateCommand= "UPDATE MY_TABLE SET NUMSTR = @NUMSTR WHERE ID = @ID"> </asp:SqlDataSource> <asp:ListView ID="MyListView" runat="server" DataSourceID="MySqlDataSource"> <LayoutTemplate> <div id="itemplaceholder" runat="server"></div> </LayoutTemplate> <ItemTemplate> <input type="text" name="NUMSTR" ID="NUMSTR" runat="server" value='<%#Bind("NUMSTR")%>' /> <asp:Button ID="UpdateButton" runat="server" Text="Update" Commandname="Update" /> </ItemTemplate> </asp:ListView> In the example above, NUMSTR is a number, but stored as a string in a SqlServer 2008 database. I'm also using the ItemTemplate as read and edit templates, to save on duplicate HTML. In the example, I only get the unformatted number. If I convert the field to an integer (via the SELECT) and use a format string like Bind("NUMSTR", "{0:###,###}"), it writes the formatted number to the database, and then fails when it tries to read it again (can't convert with the comma in there). Is there any elegant/simple solution to this? It's so easy to get the two-way binding going, and I would think there has to be a way to easily format things as well... Oh, and I'm trying to avoid the standard ItemTemplate and EditItemTemplate approach, just for sheer amount of markup required for that. Thanks!

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• Unable to Get values from Web Form to a PHP Class to Display

  - by kentrenholm

  I am having troubles getting the value from my variables submitted via a web form using a PHP class file. Here is my structure of the web page: Order Form Page Process.php Page Book.php Page I can easily get the user data entered (on Order Form Page), process, and display it on the Process.php page. The issue is that I must create a Book class and print the details of the data using the Book class. I have an empty constructor printing out "created" so I know my constructor is being called. I also am able to print the word "title" so I know I can print to the screen by using the Book class. My issue is that I can't get values in my variables in the Book class. Here is my variable declaration: private $title; Here is my printDetails function: public function printDetails () { echo "Title: " . $this->title . "<br />"; } Here is my new instance of the book class: $bookNow = new book; Here are my get and set functions: function __getTitle($title) { return $this->$title; } function __setTitle($title,$value) { $this->$title = $value; } I do have four other variables that I'm looking to display as well. Each of those have their own variable declaration, a line in printDetails, and their own setter and getter. Lastly, I also have a call to the Book class in my process PHP. It looks like this: function __autoload($book) { include $book . '.php'; } $bookNow = new book(); Any help, much appreciated. It must be something so very small (I'm hoping).

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• variables in abstract classes C++

  - by wyatt

  I have an abstract class CommandPath, and a number of derived classes as below: class CommandPath { public: virtual CommandResponse handleCommand(std::string) = 0; virtual CommandResponse execute() = 0; virtual ~CommandPath() {} }; class GetTimeCommandPath : public CommandPath { int stage; public: GetTimeCommandPath() : stage(0) {} CommandResponse handleCommand(std::string); CommandResponse execute(); }; All of the derived classes have the member variable 'stage'. I want to build a function into all of them which manipulates 'stage' in the same way, so rather than defining it many times I thought I'd build it into the parent class. I moved 'stage' from the private sections of all of the derived classes into the protected section of CommandPath, and added the function as follows: class CommandPath { protected: int stage; public: virtual CommandResponse handleCommand(std::string) = 0; virtual CommandResponse execute() = 0; std::string confirmCommand(std::string, int, int, std::string, std::string); virtual ~CommandPath() {} }; class GetTimeCommandPath : public CommandPath { public: GetTimeCommandPath() : stage(0) {} CommandResponse handleCommand(std::string); CommandResponse execute(); }; Now my compiler tells me for the constructor lines that none of the derived classes have a member 'stage'. I was under the impression that protected members are visible to derived classes? The constructor is the same in all classes, so I suppose I could move it to the parent class, but I'm more concerned about finding out why the derived classes aren't able to access the variable. Also, since previously I've only used the parent class for pure virtual functions, I wanted to confirm that this is the way to go about adding a function to be inherited by all derived classes.

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• C++ and Dependency Injection in unit testing

  - by lhumongous

  Suppose I have a C++ class like so: class A { public: A() { } void SetNewB( const B& _b ) { m_B = _b; } private: B m_B; } In order to unit test something like this, I would have to break A's dependency on B. Since class A holds onto an actual object and not a pointer, I would have to refactor this code to take a pointer. Additionally, I would need to create a parent interface class for B so I can pass in my own fake of B when I test SetNewB. In this case, doesn't unit testing with dependency injection further complicate the existing code? If I make B a pointer, I'm now introducing heap allocation, and some piece of code is now responsible for cleaning it up (unless I use ref counted pointers). Additionally, if B is a rather trivial class with only a couple of member variables and functions, why introduce a whole new interface for it instead of just testing with an instance of B? I suppose you could make the argument that it would be easier to refactor A by using an interface. But are there some cases where two classes might need to be tightly coupled?

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• Getting setting cookies on different domains, with javascript or other

  - by Luca Matteis

  Haven't been able to find anything particular to this situation online so here i go... I need to set/get the cookies stored at "first.com" while browsing "second.com", I have full access of "first.com" but i only have javascript access (can manipulate the DOM as i want) on "second.com". My first approach was to create an iframe on second.com (with js) that loaded a page like "first.com/doAjax?setCookie=xxx" and that did an ajax call to say "first.com/setCookie?cookieData=xxx" which would set the cookie on "first.com" with the data we passed around. That pretty much worked fine for setting the cookie on first.com from second.com - for getting a cookie I basically followed the same procedure, created the iframe that loaded "first.com/doAjax?getCookie" and that would do an ajax call to say "first.com/getCookie" which would read the cookie info on first.com and return it as a JSON object. The problem is that I'm unable to bring that JSON cookie object back to "second.com" so I can read it, well maybe i could just bring it when the Ajax call is complete using "window.top" but there's timing issues because its not relative to when the iframe has been loaded. I hope i am clear and was wondering if there's an easier solution rather than this crazy iframe-ajax crap, also seems like this wont even work for getting cookies in SAFARI.

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• Asynchronous URL connection objective C

  - by tweety

  I created an asynchronous URL connection to call a web service using HTTP POST method. after I am pinging the web i set an NSTimerInterval in the completion handler. my problem is when I'm trying to display the time on the view controller it is not doing promptly. I know block is stored in the heap and gets executed later on anytime and probably that's why i'm not getting prompt answer. I was wondering is there any other way to do this? Thanks in advance. my code: __block NSDate *start= [NSDate date]; __block NSDate *end; __block double miliseconds; __block NSTimeInterval time; [NSURLConnection sendAsynchronousRequest:urlRequest queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) { if([data length]==0 && error==nil){ end=[NSDate date]; time=[end timeIntervalSinceDate:start]; NSLog(@"Successfully Pinged"); miliseconds = time; // calling a method to display ping time [self label:miliseconds]; } -(void) label:(double) mili{ double miliseconds=mili*1000; self.timeDisplay.text=[NSString stringWithFormat:@"Time: %.3f ms", miliseconds];

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• Preprocessor #define vs. function pointer - best practice?

  - by Dustin

  I recently started a small personal project (RGB value to BGR value conversion program) in C, and I realised that a function that converts from RGB to BGR can not only perform the conversion but also the inversion. Obviously that means I don't really need two functions rgb2bgr and bgr2rgb. However, does it matter whether I use a function pointer instead of a macro? For example: int rgb2bgr (const int rgb); /* * Should I do this because it allows the compiler to issue * appropriate error messages using the proper function name, * not to mention possible debugging benefits? */ int (*bgr2rgb) (const int bgr) = rgb2bgr; /* * Or should I do this since it is merely a convenience * and they're really the same function anyway? */ #define bgr2rgb(bgr) (rgb2bgr (bgr)) I'm not necessarily looking for a change in execution efficiency as it's more of a subjective question out of curiosity. I am well aware of the fact that type safety is neither lost nor gained using either method. Would the function pointer merely be a convenience or are there more practical benefits to be gained of which I am unaware?

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• how to emulate thread local storage at user space in C++ ?

  - by vprajan

  I am working on a mobile platform over Nucleus RTOS. It uses Nucleus Threading system but it doesn't have support for explicit thread local storage i.e, TlsAlloc, TlsSetValue, TlsGetValue, TlsFree APIs. The platform doesn't have user space pthreads as well. I found that __thread storage modifier is present in most of the C++ compilers. But i don't know how to make it work for my kind of usage. How does __thread keyword can be mapped with explicit thread local storage? I read many articles but nothing is so clear for giving me the following basic information will __thread variable different for each thread ? How to write to that and read from it ? does each thread has exactly one copy of the variable ? following is the pthread based implementation: pthread_key_t m_key; struct Data : Noncopyable { Data(T* value, void* owner) : value(value), owner(owner) {} int* value; }; inline ThreadSpecific() { int error = pthread_key_create(&m_key, destroy); if (error) CRASH(); } inline ~ThreadSpecific() { pthread_key_delete(m_key); // Does not invoke destructor functions. } inline T* get() { Data* data = static_cast<Data*>(pthread_getspecific(m_key)); return data ? data->value : 0; } inline void set(T* ptr) { ASSERT(!get()); pthread_setspecific(m_key, new Data(ptr, this)); } How to make the above code use __thread way to set & get specific value ? where/when does the create & delete happen? If this is not possible, how to write custom pthread_setspecific, pthread_getspecific kind of APIs. I tried using a C++ global map and index it uniquely for each thread and retrieved data from it. But it didn't work well.

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• PHP: Extract direct sub directory from path string

  - by Nebs

  I need to extract the name of the direct sub directory from a full path string. For example, say we have: $str = "dir1/dir2/dir3/dir4/filename.ext"; $dir = "dir1/dir2"; Then the name of the sub-directory in the $str path relative to $dir would be "dir3". Note that $dir never has '/' at the ends. So the function should be: $subdir = getsubdir($str,$dir); echo $subdir; // Outputs "dir3" If $dir="dir1" then the output would be "dir2". If $dir="dir1/dir2/dir3/dir4" then the output would be "" (empty). If $dir="" then the output would be "dir1". Etc.. Currently this is what I have, and it works (as far as I've tested it). I'm just wondering if there's a simpler way since I find I'm using a lot of string functions. Maybe there's some magic regexp to do this in one line? (I'm not too good with regexp unfortunately). function getsubdir($str,$dir) { // Remove the filename $str = dirname($str); // Remove the $dir if(!empty($dir)){ $str = str_replace($dir,"",$str); } // Remove the leading '/' if there is one $si = stripos($str,"/"); if($si == 0){ $str = substr($str,1); } // Remove everything after the subdir (if there is anything) $lastpart = strchr($str,"/"); $str = str_replace($lastpart,"",$str); return $str; } As you can see, it's a little hacky in order to handle some odd cases (no '/' in input, empty input, etc). I hope all that made sense. Any help/suggestions are welcome.

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• Looping through NSArray while subtracting values from each object? [on hold]

  - by Julian

  I have NSNumber objects stored in an NSMutableArray. I am attempting to perform a calculation on each object in the array. What I want to do is: 1) Take a random higher number variable and keep subtracting a smaller number variable in increments until the value of the variable is equal to the value in the array. For example: NSMutableArray object is equal to 2.50. I have an outside variable of 25 that is not in the array. I want to subtract 0.25 multiple times from the variable until I reach less than or equal to 2.50. I also need a parameter so if the number does not divide evenly and goes below the array value, it resorts to the original array value of 2.50. Lastly, for each iteration, I want to print the values as they are counting down as a string. I was going to provide code, but I don't want to make this more confusing than it has to be. So my output would be: VALUE IS: 24.75 VALUE IS: 24.50 VALUE IS: 24.25 … VALUE IS: 2.50 END

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• Dynamically adjust padding on an image?

  - by Cory

  What I'm basically attempting to do is dynamically change a padding value for a scrubber image based on player position data provided by an app. I have been able to leverage the provided number to dynamically increase the width of a progress overlay image and create a progress bar, but I would like a scrubber diamond at the leading edge of the progress bar. To do this, I have positioned the scrubber diamond at the same starting point as the progress overlay and would like to increase the padding on the diamond at the same rate as the width is increasing for the progress overlay, allowing them to pace each other with the scrubber diamond moving as the song plays. Any help with the script necessary to manipulate padding-left dynamically would be very much appreciated. var progress = Ecoute.playerPosition(); var width = 142.5 / length * progress + 1.63; EcouteSel('Progression').width = width.toString(); EcouteSel('Scrubber').style('padding-left', 'width'); We define progress as the player position, width as a function of the progress and then apply that function to the ID applied to the progress over lay image. But how do I accomplish that for padding-left? style.paddingLeft ...based functions have broken the controller outright. I'm at a loss and any help would be appreciated.

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• Java Graphics not displaying on successive function calls, why?

  - by primehunter326

  Hi, I'm making a visualization for a BST implementation (I posted another question about it the other day). I've created a GUI which displays the viewing area and buttons. I've added code to the BST implementation to recursively traverse the tree, the function takes in coordinates along with the Graphics object which are initially passed in by the main GUI class. My idea was that I'd just have this function re-draw the tree after every update (add, delete, etc...), drawing a rectangle over everything first to "refresh" the viewing area. This also means I could alter the BST implementation (i.e by adding a balance operation) and it wouldn't affect the visualization. The issue I'm having is that the draw function only works the first time it is called, after that it doesn't display anything. I guess I don't fully understand how the Graphics object works since it doesn't behave the way I'd expect it to when getting passed/called from different functions. I know the getGraphics function has something to do with it. Relevant code: private void draw(){ Graphics g = vPanel.getGraphics(); tree.drawTree(g,ORIGIN,ORIGIN); } vPanel is what I'm drawing on private void drawTree(Graphics g, BinaryNode<AnyType> n, int x, int y){ if( n != null ){ drawTree(g, n.left, x-10,y+10 ); if(n.selected){ g.setColor(Color.blue); } else{ g.setColor(Color.gray); } g.fillOval(x,y,20,20); g.setColor(Color.black); g.drawString(n.element.toString(),x,y); drawTree(g,n.right, x+10,y+10); } } It is passed the root node when it is called by the public function. Do I have to have: Graphics g = vPanel.getGraphics(); ...within the drawTree function? This doesn't make sense!! Thanks for your help.

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• zend-framework doctrine, and mvc pattern: what should connect data between models and forms?

  - by Skirmantas

  I am learning Zend Framework and Doctrine. I am wondering what is the best practice to connect forms to models and vice versa. I don't know where I should put my code. I have seen in Zendcast video tutorials where author creates methods like mapFormToRecord and mapRecordToForm in form class. Well I guess it is very handy when form is sophisticated and uses many records. Is it a good practice? I somehow believe that form-class should not need to know about data-records. And sometimes we might have model which is used in many forms. So It would be handy to have few functions in that model which would help to prepare data for forms. For example to give an array of id=name pairs so that it might be used in Zend_Form_Element_Select. However I would like to have a consistency. So I don't want to put this code nor in model nor in form because on different situations I act different. So only controller is what is left to deal it. However this will result in code duplication if one form will be used more than in one controller. Moreover controller gets bloated if form is not from the simple ones. Or maybe there is a consistent pattern in those data conversions between forms and models? I think that there is. At least in my simple cases. So maybe a separate class could be a solution? Where should I put such class and how should I name it? Another question: Zend_Form has validators and filter. Doctrine has validators and filters too. Which do we use and when? What is your way of dealing the connections between forms and models? (Sorry if it was hard for you to read my text. I don't have enough knowledge of English language to express myself freely)

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• "2d Search" in Solr or how to get the best item of the multivalued field 'items'?

  - by Karussell

  The title is a bit awkward but I couldn't found a better one. My problem is as follows: I have several users stored as documents and I am storing several key-value-pairs or items (which have an id) for each document. Now, if I apply highlighting I can get the first n items. If you have several hundreds of such items this highlighting is necessary and works nicely. But there are two problems: The highlighted text won't contain the id and so retrieving additional information of the highlighted item text is ugly. E.g. you need to store the id in the text so that the highlighter returns it. Adding the id to the hl.fl parameter does not help. You will not get the most relevant n-items. You will get the first n items ... So how can I find the best items of a documents with multiple such items? I will now add my own findings as answers, but as I will point out. Each of them has its drawbacks. Hopefully anyone of you can point me to a better solution.

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• Zend Framework-where do calls to my methods go? Controller of Model?

  - by Joel

  Hi guys, I'm confused about exactly what I should have in my controller and what in my method. Specifically, I have this in the action method: public function upcomingshowsAction() { $gcal = $this->_validateCalendarConnection(); $uncleanedFeedArray = $this->_getCalendarFeed($gcal); $finishedFeedArray = $this->_cleanFeed($uncleanedFeedArray); $this->view->googleArray = $finishedFeedArray; } And then (incorrectly I know), I have my methods still in the bottom of my controller. So what I'm wondering, is for those methods in the upcomingshowsAction method, should all the actual methods just be in one model and then I'd have something like this: public function upcomingshowsAction() { $finishedFeedArray = new Application_Model_calendarModelPage(); $this->view->googleArray = $finishedFeedArray; } And then something like this in the model: class Application_Model_CalendarModelPage { $gcal = $this->_validateCalendarConnection(); $uncleanedFeedArray = $this->_getCalendarFeed($gcal); $finishedFeedArray = $this->_cleanFeed($uncleanedFeedArray); public functions { ... ... ... } } Am I on the right track here? Thanks!

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• LINQ to SQL - Lightweight O/RM?

  - by CoffeeAddict

  I've heard from some that LINQ to SQL is good for lightweight apps. But then I see LINQ to SQL being used for Stackoverflow, and a bunch of other .coms I know (from interviewing with them). Ok, so is this true? for an e-commerce site that's bringing in millions and you're typically only doing basic CRUDs most the time with the exception of an occasional stored proc for something more complex, is LINQ to SQL complete enough and performance-wise good enough or able to be tweaked enough to run happily on an e-commerce site? I've heard that you just need to tweak performance on the DB side when using LINQ to SQL for a better approach. So there are really 2 questions here: 1) Meaning/scope/definition of a "Lightweight" O/RM solution: What the heck does "lightweight" mean when people say LINQ to SQL is a "lightweight O/RM" and is that true??? If this is so lightweight then why do I see a bunch of huge .coms using it? Is it good enough to run major .coms (obviously it looks like it is) and what determines what the context of "lightweight" is...it's such a generic statement. 2) Performance: I'm working on my own .com and researching different O/RMs. I'm not really looking at the Entity Framework (yet), just want to figure out the LINQ to SQL basics here and determine if it will be efficient enough for me. The problem I think is you can't tweak or control the SQL it generates...

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• Is there a way to receive data as unsigned char over UDP on Qt?

  - by user269037

  I need to send floating point numbers using a UDP connection to a Qt application. Now in Qt the only function available is qint64 readDatagram ( char * data, qint64 maxSize, QHostAddress * address = 0, quint16 * port = 0 ) which accepts data in the form of signed character buffer. I can convert my float into a string and send it but it will obviously not be very efficient converting a 4 byte float into a much longer sized character buffer. I got hold of these 2 functions to convert a 4 byte float into an unsinged 32 bit integer to transfer over network which works fine for a simple C++ UDP program but for Qt I need to receive the data as unsigned char. Is it possible to avoid converting the floatinf point data into a string and then sending it? uint32_t htonf(float f) { uint32_t p; uint32_t sign; if (f < 0) { sign = 1; f = -f; } else { sign = 0; } p = ((((uint32_t)f)&0x7fff)<<16) | (sign<<31); // Whole part and sign. p |= (uint32_t)(((f - (int)f) * 65536.0f))&0xffff; // Fraction. return p; } float ntohf(uint32_t p) { float f = ((p>>16)&0x7fff); // Whole part. f += (p&0xffff) / 65536.0f; // Fraction. if (((p>>31)&0x1) == 0x1) { f = -f; } // Sign bit set. return f; }

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• Application logic for invoicing and subscriptions?

  - by Industrial

  Hi everyone, We're just in the planning stage of a web app that offers subscriptions to our customers. The subscription periods varies and can be prolonged indefinitely by our customers, but are always at least one month (30 days). When a customer signs up, the customer information (billing address, phone number and so on) are stored in a customers table and a subscription is created in the subscriptions table: id | start_date | end_date | customer_id -------------------------------------------------------- 1 | 2010-12-31 | 2011-01-31 | 1 Every month we'll loop through the subscriptions table (cronjob preferably) and create invoices for the past subscription period, which are housed in their own table - invoices. Depending on the customer, invoices are manually printed out and sent by mail, or just emailed to the customer. Due to the nature of our customers and the product, we need to offer a variety of different payment alternatives including wire transfer and card payments, hence some invoices may need to be manually handled and registered as paid by our staff. The 15th every month, the invoices table are looped through and if no payment has been marked for the actual invoice, the according subscription will be removed. If there's a payment registered, the end_date in the subscriptions table is incremented by another 30 days (or what now our period our customer has chosen). Are we looking at headaches by incrementing dates forwards and backwards to handle non-paying customers and extending subscriptions? Would it be a better idea to add new subscriptions as customers extends their subscription?

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• Making a visual bar timer for iPhone

  - by Ohmnastrum

  I've looked up all results for progress bars and changing the width of an image but it only refers to scaling, and the progress bars aren't customizable so that they fit other functions or design schemes... unless I missed that part. I'm trying to make a bar timer that crops off of the right over a period of time. I tried using an NStimer so that it would subtract from a value each time its function is called. the Timerbar function gets called as a result of another timer invalidating and it works. What doesn't work is that the width isn't changing just the position. further more I keep getting values like Inf and 0 for power and pwrBarWidth I was sure that the changes would occur when Mult was plugged into the equation. it seems like casting mult as an int is causing problems but i'm not sure exactly how. int pwrBarMaxWidth = 137; int pwrBarWidth 0; int limit = 1; float mult; float power = 0; -(void) Timerbar:(NSTimer *)barTimer { if(!waitForPlayer) { [barTimer invalidate]; } if(mult > 0.0) { mult -= 0.001 * [colorChoices count]; if(mult < 0.0) { mult = 0.0; } } power = (mult * 10) / pwrBarMaxWidth; pwrBarWidth = (int)power % limit; // causes the bar to repeat after it reaches a certain point //At this point however the variable Power is always "inf" and PwrBarWidth is always 0. [powerBar setBounds:CGRectMake(powerBar.frame.origin.x, powerBar.frame.origin.y,pwrBarWidth,20)]; //supposed to change the crop of the bar } Any reason why I'm getting inf as a value for power, 0 as a value for pwrBarWidth, and the bar itself isn't cropping? if this question is a bit vague i'll provide more information as needed.

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• How to implement a grapher in C#

  - by iansinke

  So I'm writing a graphing calculator. So far I have a semi-functional grapher, however, I'm having a hard time getting a good balance between accurate graphs and smooth looking curves. The current implementation (semi-pseudo-code) looks something like this: for (float i = GraphXMin; i <= GraphXMax; i++) { PointF P = new PointF(i, EvaluateFunction(Function, i) ListOfPoints.Add(P) } Graphics.DrawCurve(ListOfPoints) The problem with this is since it only adds a point at every integer value, graphs end up distorted when their turning points don't fall on integers (e.g. sin(x)^2). I tried incrementing i by something smaller (like 0.1), which works, but the graph looks very rough. I am using C# and GDI+. I have SmoothingMethod set to AntiAlias, so that's not the problem, as you can see from the first graph. Is there some sort of issue with drawing curves with a lot of points? Should the points perhaps be positioned exactly on pixels? I'm sure some of you have worked on something very similar before, so any suggestions? While you're at it, do you have any suggestions for graphing functions with asymptotes? e.g. 1/x^2 P.S. I'm not looking for a library that does all this - I want to write it myself.

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• Find telephonenumbers - finding number with and without an phone extension

  - by nWorx

  Hello there I've a table with about 130 000 records with telephonenumbers. The numbers are all formated like this +4311234567. The numbers always include international country code, local area code and then the phonenumber and sometimes an extension. There is a webservice which checks for the caller's number in the table. That service works already. But now the client wants that also if someone calls from a company which number is already in the database but not his extension, that the service will return some result. Example for table. **id** | **telephonenumber** | **name** | 1 | +431234567 | company A | 2 | +431234567890 | employee in company A | 3 | +4398765432 | company b now if somebody from company A calls with a different extension for example +43123456777, than it should return id1. But the problem is, that I don't know how many digits the extensions have. It could have 3,4 or more digits. Are there any patterns for string kind of matchings? The data is stored in a sql2005 database. Thanks

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• calling constructor of the class in the destructor of the same class

  - by dicaprio

  Experts !! I know this question is one of the lousy one , but still I dared to open my mind , hoping I would learn from all. I was trying some examples as part of my routine and did this horrible thing, I called the constructor of the class from destructor of the same class. I don't really know if this is ever required in real programming , I cant think of any real time scenarios where we really need to call functions/CTOR in our destructor. Usually , destructor is meant for cleaning up. If my understanding is correct, why the compiler doesn't complain ? Is this because it is valid for some good reasons ? If so what are they ? I tried on Sun Forte, g++ and VC++ compiler and none of them complain about it. using namespace std; class test{ public: test(){ cout<<"CTOR"<<endl; } ~test() {cout<<"DTOR"<<endl; test(); }};

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• Speed/expensive of SQLite query vs. List.contains() for "in-set" icon on list rows

  - by kpdvx

  An application I'm developing requires that the app main a local list of things, let's say books, in a local "library." Users can access their local library of books and search for books using a remote web service. The app will be aware of other users of the app through this web service, and users can browse other users' lists of books in their library. Each book is identified by a unique bookId (represented as an int). When viewing books returned through a search result or when viewing another user's book library, the individual list row cells need to visually represent if the book is in the user's local library or not. A user can have at most 5,000 books in the library, stored in SQLite on the device (and synchronized with the remote web service). My question is, to determine if the book shown in the list row is in the user's library, would it be better to directly ask SQLite (via SELECT COUNT(*)...) or to maintain, in-memory, a List or int[] array of some sort containing the unique bookIds. So, on each row display do I query SQLite or check if the List or int[] array contains the unique bookId? Because the user can have at most 5,000 books, each bookId occupies 4 bytes so at most this would use ~ 20kB. In thinking about this, and in typing this out, it seems obvious to me that it would be far better for performance if I maintained a list or int[] array of in-library bookIds vs. querying SQLite (the only caveat to maintaining an int[] array is that if books are added or removed I'll need to grow or shrink the array by hand, so with this option I'll most likely use an ArrayList or Vector, though I'm not sure of the additional memory overhead of using Integer objects as opposed to primitives). Opinions, thoughts, suggestions?

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• How to delete ProgIDs from other user accounts when uninstalling from Windows?

  - by Mordachai

  I've been investigating "how should a modern windows c++ application register its file types" with Windows (see http://stackoverflow.com/questions/2828637/c-how-do-i-correctly-register-and-unregister-file-type-associations-for-our-ap). And having combed through the various MSDN articles on the subject, the summary appears to be as follows: The installer (elevated) should register the global ProgID HKLM\Software\Classes\my-app.my-doc[.version] (e.g. HKLM\Software\Classes\TextPad.text) The installer also configures default associations for its document types (e.g. .myext) and points this to the aforementioned global ProgID in HKLM. NOTE: a user interface should be provided here to allow the user to either accept all default associations, or to customize which associations should be set. The application, running standard (unelevated), should provide a UI for allowing the current user to set their personal associations as is available in the installer, except that these associations are stored in HKCU\Software\Classes (per user, not per machine). The UN-installer is then responsible for deleting all registered ProgIDs (but should leave the actual file associations alone, as Windows is smart enough to handle associations pointing to missing ProgIDs, and this is the specified desired behavior by MSDN). So that schema sounds reasonable to me, except when I consider #4: How does an uninstaller, running elevated for a given user account, delete any per-user ProgIDs created in step #3 for other users? As I understand things, even in elevated mode, an uninstaller cannot go into another user's registry hive and delete items? Or can it? Does it have to load each given user hive first? What are the rules here? Thanks for any insight you might have to offer! EDIT: See below for the solution (My question was founded in confusion)

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