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  • php cURL. preg_match , extract text from xhtml

    - by Michael
    I'm trying to extract the price from the bellow html page/link using php cURL and preg_match . Basically I'm expecting for this code to output 4,550 but for some reasons I get Notice: Undefined offset: 1 in C:\wamp\www\test.php on line 22 I think that the pattern is correct because if I put the html itself in a variable and escape the "" it works ! . Also if I output (echo $result;) it displays the html properly grabbed from foxtons website so I just can't figure it out why the whole thing doesn't work . I need to make this work and also I would appreciate if you would tell me why is that notice generated and why my current script doesn't work. $url = "http://www.foxtons.co.uk/search?bedrooms_from=0&property_id=727717"; $ch = curl_init($url); curl_setopt($ch, CURLOPT_HEADER, 0); curl_setopt($ch,CURLOPT_RETURNTRANSFER, 1); $result = curl_exec($ch); curl_exec($ch); curl_close($ch); $result2 = str_replace('"', '\"', $result); $tagname1= ");<\/script "; $tagname2= "<\/noscript per month<\/a"; $pattern = "/$tagname1(.*?)$tagname2/"; preg_match($pattern, $result, $matches); $prices = $matches[1]; print_r($prices); ?

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  • Noise with multi-threaded raytracer

    - by herber88
    This is my first multi-threaded implementation, so it's probably a beginners mistake. The threads handle the rendering of every second row of pixels (so all rendering is handled within each thread). The problem persists if the threads render the upper and lower parts of the screen respectively. Both threads read from the same variables, can this cause any problems? From what I've understood only writing can cause concurrency problems... Can calling the same functions cause any concurrency problems? And again, from what I've understood this shouldn't be a problem... The only time both threads write to the same variable is when saving the calculated pixel color. This is stored in an array, but they never write to the same indices in that array. Can this cause a problem? Multi-threaded rendered image (Spam prevention stops me from posting images directly..) Ps. I use the exactly same implementation in both cases, the ONLY difference is a single vs. two threads created for the rendering.

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  • perl - converting a date into a string

    - by Jason
    I need to convert a date to a string, the date is entered as 07/04/2010 and should then read July 4th 2010. It should also be able to be entered using singe digits instead of double (7 instead of 07, and it needs to add the 20 to the year if the user enters only /10) This is what I have so far - #!/usr/bin/perl use CGI qw(:standard); use strict; #declare variables my ($date, $month, $day, $year); my @months = ("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"); #assign input item to variable $date = param('Date'); #break date apart $date =~ /([0-9]{1,2})\/([0-9]{1,2})\/([0-9]{2,2}|20[0-9]{2,2})/; $month = $1; $day = $2; $year = $3; unless($year =~ /20[0-9]{2,2}/){ $year = "20".$year; } $date = $months[int($1)]." ".$day.", ".$year; #display date print "<HTML><HEAD><TITLE>The Date</TITLE></HEAD>\n"; print "<BODY>\n"; print "The date is: $date\n"; print "</BODY></HTML>\n"; However I keep getting errors Use of uninitialized value in pattern match (m//) at c08ex6.cgi line 14. Use of uninitialized value in pattern match (m//) at c08ex6.cgi line 18. Use of uninitialized value in concatenation (.) or string at c08ex6.cgi line 19. Use of uninitialized value in int at c08ex6.cgi line 21. Use of uninitialized value in concatenation (.) or string at c08ex6.cgi line 21.

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  • c++ floating point precision loss: 3015/0.00025298219406977296

    - by SigTerm
    The problem. Microsoft Visual C++ 2005 compiler, 32bit windows xp sp3, amd 64 x2 cpu. Code: double a = 3015.0; double b = 0.00025298219406977296; //*((unsigned __int64*)(&a)) == 0x40a78e0000000000 //*((unsigned __int64*)(&b)) == 0x3f30945640000000 double f = a/b;//3015/0.00025298219406977296; the result of calculation (i.e. "f") is 11917835.000000000 (*((unsigned __int64*)(&f)) == 0x4166bb4160000000) although it should be 11917834.814763514 (i.e. *((unsigned __int64*)(&f)) == 0x4166bb415a128aef). I.e. fractional part is lost. Unfortunately, I need fractional part to be correct. Questions: 1) Why does this happen? 2) How can I fix the problem? Additional info: 0) The result is taken directly from "watch" window (it wasn't printed, and I didn't forget to set printing precision). I also provided hex dump of floating point variable, so I'm absolutely sure about calculation result. 1) The disassembly of f = a/b is: fld qword ptr [a] fdiv qword ptr [b] fstp qword ptr [f] 2) f = 3015/0.00025298219406977296; yields correct result (f == 11917834.814763514 , *((unsigned __int64*)(&f)) == 0x4166bb415a128aef ), but it looks like in this case result is simply calculated during compile-time: fld qword ptr [__real@4166bb415a128aef (828EA0h)] fstp qword ptr [f] So, how can I fix this problem? P.S. I've found a temporary workaround (i need only fractional part of division, so I simply use f = fmod(a/b)/b at the moment), but I still would like to know how to fix this problem properly - double precision is supposed to be 16 decimal digits, so such calculation isn't supposed to cause problems.

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  • objective-c having issues with an NSDictioary object

    - by Mark
    I have a simple iPhone app that Im learning and I want to have an instance variable called urlLists which is an NSDictionary I have declared it like so: @interface MyViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>{ IBOutlet UIPickerView *pickerView; NSMutableArray *categories; NSDictionary *urlLists; } @property(retain) NSDictionary *urlLists; @end and in the implementation: @implementation MyViewController @synthesize urlLists; ... - (void)viewDidLoad { [super viewDidLoad]; categories = [[NSMutableArray alloc] init]; [categories addObject:@"Sport"]; [categories addObject:@"Entertainment"]; [categories addObject:@"Technology"]; [categories addObject:@"Political"]; NSArray *objects = [NSArray arrayWithObjects:@"value1", @"value2", @"value3", @"value4", nil]; urlLists = [NSDictionary dictionaryWithObjects:objects forKeys:categories]; for (id key in urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } ... @end And, this all works up to here. I have added a UIPicker to my app, and when I select one of the items, I want to Log the one picked and its related entry in my dictionary. -(void) pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger) component { for (id key in self.urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } but I get the old EXC_BAD_ACCESS error... I know Im missing something small, but what? Thanks

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  • Computing, storing, and retrieving values to and from an N-Dimensional matrix

    - by Adam S
    This question is probably quite different from what you are used to reading here - I hope it can provide a fun challenge. Essentially I have an algorithm that uses 5(or more) variables to compute a single value, called outcome. Now I have to implement this algorithm on an embedded device which has no memory limitations, but has very harsh processing constraints. Because of this, I would like to run a calculation engine which computes outcome for, say, 20 different values of each variable and stores this information in a file. You may think of this as a 5(or more)-dimensional matrix or 5(or more)-dimensional array, each dimension being 20 entries long. In any modern language, filling this array is as simple as having 5(or more) nested for loops. The tricky part is that I need to dump these values into a file that can then be placed onto the embedded device so that the device can use it as a lookup table. The questions now, are: What format(s) might be acceptable for storing the data? What programs (MATLAB, C#, etc) might be best suited to compute the data? C# must be used to import the data on the device - is this possible given your answer to #1?

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  • Can I use drawRect to refresh a UIView subclass?

    - by Timbo
    I've created a subclass of UIView called Status which is designed to display a rectangle of a certain size (within a view) depending on the value of a variable. // Interface #import <Foundation/Foundation.h> #import <QuartzCore/QuartzCore.h> @interface Status: UIView { NSString* name; int someVariable; } @property int someVariable; @property (assign) NSString *name; - (void) createStatus: (NSString*)withName; - (void) drawRect:(CGRect)rect; @end // Implementation #import "Status.h" @implementation Status @synthesize name, someVariable; - (void) createStatus: (NSString*)withName { name = withName; someVariable = 10000; } - (void) drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); //Draw Status CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1); // fill CGContextFillRect(context, CGRectMake(0.0, 0.0, someVariable, 40.0)); } //// myviewcontroller implementation - (void) viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; myStatus = [[Status alloc] initWithFrame:CGRectMake(8,8,200,56)]; myStatus.backgroundColor = [UIColor grayColor]; [self.view addSubview:myStatus]; } How do I set this up so I can repeatedly call a refresh of the status bar? I'll probably call the refresh 4 times per second using a NSTimer, I'm just not sure what to call or if I should move this rectangle drawing to a separate function or something... Thanks in advance for your help :)

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  • Best (Java) book for understanding 'under the bonnet' for programming?

    - by Ben
    What would you say is the best book to buy to understand exactly how programming works under the hood in order to increase performance? I've coded in assembly at university, I studied computer architecture and I obviously did high level programming, but what I really dont understand is things like: -what is happening when I perform a cast -whats the difference in performance if I declare something global as opposed to local? -How does the memory layout for an ArrayList compare with a Vector or LinkedList? -Whats the overhead with pointers? -Are locks more efficient than using synchronized? -Would creating my own array using int[] be faster than using ArrayList -Advantages/disadvantages of declaring a variable volatile I have got a copy of Java Performance Tuning but it doesnt go down very low and it contains rather obvious things like suggesting a hashmap instead of using an ArrayList as you can map the keys to memory addresses etc. I want something a bit more Computer Sciencey, linking the programming language to what happens with the assembler/hardware. The reason im asking is that I have an interview coming up for a job in High Frequency Trading and everything has to be as efficient as possible, yet I cant remember every single possible efficiency saving so i'd just like to learn the fundamentals. Thanks in advance

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  • How to manage large amounts of delegates and usercallbacks in C# async http library

    - by Tyler
    I'm coding a .NET library in C# for communicating with XBMC via its JSON RPC interface using HTTP. I coded and released a preliminary version but everything is done synchronously. I then recoded the library to be asynchronous for my own purposes as I was/am building an XBMC remote for WP7. I now want to release the new async library but want to make sure it's nice and tidy before I do. Due to the async nature a user initiates a request, supplies a callback method that matches my delegate and then handles the response once it's been received. The problem I have is that within the library I track a RequestState object for the lifetime of the request, it contains the http request/response as well as the user callback etc. as member variables, this would be fine if only one type of object was coming back but depending on what the user calls they may be returned a list of songs or a list of movies etc. My implementation at the moment uses a single delegate ResponseDataRecieved which has a single parameter which is a simple Object - As this has only be used by me I know which methods return what and when I handle the response I cast said object to the type I know it really is - List, List etc. A third party shouldn't have to do this though - The delegate signature should contain the correct type of object. So then I need a delegate for every type of response data that can be returned to the third party - The specific problem is, how do I handle this gracefully internally - Do I have a bunch of different RequestState objects that each have a different member variable for the different delegates? That doesn't "feel" right. I just don't know how to do this gracefully and cleanly.

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  • In AS3/Flex, how can I get from flat data to hierarchical data?

    - by Dave S
    I have some data that gets pulled out of a database and mapped to an arraycollection. This data has a field called parentid, and I would like to map the data into a new arraycollection with hierarchical information to then feed to an advanced data grid. I think I'm basically trying to take the parent object, add a new property/field/variable of type ArrayCollection called children and then remove the child object from the original list and clone it into the children array? Any help would be greatly appreciated, and I apologize ahead of time for this code: private function PutChildrenWithParents(accountData : ArrayCollection) : ArrayCollection{ var pos_inner:int = 0; var pos_outer:int = 0; while(pos_outer < accountData.length){ if (accountData[pos_outer].ParentId != null){ pos_inner = 0; while(pos_inner < accountData.length){ if (accountData[pos_inner].Id == accountData[pos_outer].ParentId){ accountData.addItemAt( accountData[pos_inner] + {children:new ArrayCollection(accountData[pos_outer])}, pos_inner ); accountData.removeItemAt(pos_outer); accountData.removeItemAt(pos_inner+1); } pos_inner++; } } pos_outer++; } return accountData; }

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  • optimize output value using a class and public member

    - by wiso
    Suppose you have a function, and you call it a lot of times, every time the function return a big object. I've optimized the problem using a functor that return void, and store the returning value in a public member: #include <vector> const int N = 100; std::vector<double> fun(const std::vector<double> & v, const int n) { std::vector<double> output = v; output[n] *= output[n]; return output; } class F { public: F() : output(N) {}; std::vector<double> output; void operator()(const std::vector<double> & v, const int n) { output = v; output[n] *= n; } }; int main() { std::vector<double> start(N,10.); std::vector<double> end(N); double a; // first solution for (unsigned long int i = 0; i != 10000000; ++i) a = fun(start, 2)[3]; // second solution F f; for (unsigned long int i = 0; i != 10000000; ++i) { f(start, 2); a = f.output[3]; } } Yes, I can use inline or optimize in an other way this problem, but here I want to stress on this problem: with the functor I declare and construct the output variable output only one time, using the function I do that every time it is called. The second solution is two time faster than the first with g++ -O1 or g++ -O2. What do you think about it, is it an ugly optimization?

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  • Java: Tracking a user login session - Session EJBs vs HTTPSession

    - by bguiz
    If I want to keep track of a conversational state with each client using my web application, which is the better alternative - a Session Bean or a HTTP Session - to use? Using HTTP Session: //request is a variable of the class javax.servlet.http.HttpServletRequest //UserState is a POJO HttpSession session = request.getSession(true); UserState state = (UserState)(session.getAttribute("UserState")); if (state == null) { //create default value .. } String uid = state.getUID(); //now do things with the user id Using Session EJB: In the implementation of ServletContextListener registered as a Web Application Listener in WEB-INF/web.xml: //UserState NOT a POJO this this time, it is //the interface of the UserStateBean Stateful Session EJB @EJB private UserState userStateBean; public void contextInitialized(ServletContextEvent sce) { ServletContext servletContext = sce.getServletContext(); servletContext.setAttribute("UserState", userStateBean); ... In a JSP: public void jspInit() { UserState state = (UserState)(getServletContext().getAttribute("UserState")); ... } Elsewhere in the body of the same JSP: String uid = state.getUID(); //now do things with the user id It seems to me that the they are almost the same, with the main difference being that the UserState instance is being transported in the HttpRequest.HttpSession in the former, and in a ServletContext in the case of the latter. Which of the two methods is more robust, and why?

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  • Using static variables for Strings

    - by Vivart
    below content is taken from Best practice: Writing efficient code but i didn't understand why private static String x = "example"; faster than private static final String x ="example"; Can anybody explain this. Using static variables for Strings When you define static fields (also called class fields) of type String, you can increase application speed by using static variables (not final) instead of constants (final). The opposite is true for primitive data types, such as int. For example, you might create a String object as follows: private static final String x = "example"; For this static constant (denoted by the final keyword), each time that you use the constant, a temporary String instance is created. The compiler eliminates "x" and replaces it with the string "example" in the bytecode, so that the BlackBerry® Java® Virtual Machine performs a hash table lookup each time that you reference "x". In contrast, for a static variable (no final keyword), the String is created once. The BlackBerry JVM performs the hash table lookup only when it initializes "x", so access is faster. private static String x = "example"; You can use public constants (that is, final fields), but you must mark variables as private.

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  • Using fonts that aren't on iPhone

    - by 4thSpace
    I'd like to use some fonts that aren't part of the iPhone OS. I've seen games that use non standard fonts. I can install the fonts, create images for each one in Photoshop and then use those images in the iPhone app. However, I don't think that is a practical way to go. If the color or tint needs to be adjusted (because of background) or size, I'll have to redesign every font I'm using. Is there a better way to do this? I read this http://stackoverflow.com/questions/360751/can-i-embed-a-custom-font-in-an-iphone-application and downloaded the open source font label app. However, it crashes most of the time when I try using particular fonts. In regards to the last comment about using UIFont with the fontWithName:size, that certainly doesn't work. Your font variable will be nil. Listing all available fonts reveals why - none of the custom fonts are in the list. I've also read http://stackoverflow.com/questions/566054/how-do-i-include-a-font-with-my-iphone-application, which definitely does not work. Same as last comment in above link.

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  • Saving user settings in Metro app using C#

    - by jitendra garg
    I want to write user selected settings in Metro app, in Local Folder. I have done the code as below, but it is not working. The code to save settings: void OnUnloaded(object sender, RoutedEventArgs args) { //code to save app settings. var localSettings = ApplicationData.Current.LocalSettings; localSettings.Values["playerPosition"] = playerPosition; localSettings.Values["aiPosition"] = aiPosition; localSettings.Values["selectedLevel"] = selectedLevel; } The code to read settings: var localSettings = ApplicationData.Current.LocalSettings; if ((localSettings.Values["playerPosition"]) == null) { localSettings.Values["playerPosition"] = 1; localSettings.Values["aiPosition"] = 1; localSettings.Values["selectedLevel"] = "1"; playerPosition = aiPosition = 1; selectedLevel = "1"; } else { playerPosition = (int)localSettings.Values["playerPosition"]; aiPosition = (int)localSettings.Values["aiPosition"]; selectedLevel = (string)localSettings.Values["selectedLevel"]; ---- Clearly I am supposed to save this localSettings variable in a file. But, I am unable to find the code to do that. Also, is Unload event a good place to do it, or should I move it to OnNavigatedFrom event?

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  • Select multi-select form from array

    - by Budove
    Here's the issue. I have a database column called pymnt_meth_pref, which contains a comma separated string of payment methods chosen from a multiselect form. <td>Payment Methods Used:<br /> <input type="checkbox" name="pyment_meth_pref[]" value="Cash">I can pay with cash.<br /> <input type="checkbox" name="pyment_meth_pref[]" value="Check">I can pay by check.<br /> <input type="checkbox" name="pyment_meth_pref[]" value="Credit Card">I can pay by credit card.<br /> <input type="checkbox" name="pyment_meth_pref[]" value="Paypal">I can pay with Paypal.<br /> </td> This array is posted to a variable and turned into a comma separated string if (isset($_POST['pyment_meth_pref'])) $pymntmethpref = implode(", ", $_POST['pyment_meth_pref']); if (isset($_POST['pyment_meth_acc'])) $pymntmethacc = implode(", ", $_POST['pyment_meth_acc']); This is then inserted into the database as a comma separated string. What I would like to do, is take this string and apply the values to the original form when the user goes back to the form as 'pre-selected' checkboxes, indicated that the user has already selected those values previously, and keeping those values in the database if they choose to edit any other information in the form. I'm assuming this would need to be done with javascript but if there is a way to do it with PHP I'd rather do it that way.

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  • Why is PLINQ slower than LINQ for this code?

    - by Rob Packwood
    First off, I am running this on a dual core 2.66Ghz processor machine. I am not sure if I have the .AsParallel() call in the correct spot. I tried it directly on the range variable too and that was still slower. I don't understand why... Here are my results: Process non-parallel 1000 took 146 milliseconds Process parallel 1000 took 156 milliseconds Process non-parallel 5000 took 5187 milliseconds Process parallel 5000 took 5300 milliseconds using System; using System.Collections.Generic; using System.Diagnostics; using System.Linq; namespace DemoConsoleApp { internal class Program { private static void Main() { ReportOnTimedProcess( () => GetIntegerCombinations(), "non-parallel 1000"); ReportOnTimedProcess( () => GetIntegerCombinations(runAsParallel: true), "parallel 1000"); ReportOnTimedProcess( () => GetIntegerCombinations(5000), "non-parallel 5000"); ReportOnTimedProcess( () => GetIntegerCombinations(5000, true), "parallel 5000"); Console.Read(); } private static List<Tuple<int, int>> GetIntegerCombinations( int iterationCount = 1000, bool runAsParallel = false) { IEnumerable<int> range = Enumerable.Range(1, iterationCount); IEnumerable<Tuple<int, int>> integerCombinations = from x in range from y in range select new Tuple<int, int>(x, y); return runAsParallel ? integerCombinations.AsParallel().ToList() : integerCombinations.ToList(); } private static void ReportOnTimedProcess( Action process, string processName) { var stopwatch = new Stopwatch(); stopwatch.Start(); process(); stopwatch.Stop(); Console.WriteLine("Process {0} took {1} milliseconds", processName, stopwatch.ElapsedMilliseconds); } } }

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  • C/C++ macro/template blackmagic to generate unique name.

    - by anon
    Macros are fine. Templates are fine. Pretty much whatever it works is fine. The example is OpenGL; but the technique is C++ specific and relies on no knowledge of OpenGL. Precise problem: I want an expression E; where I do not have to specify a unique name; such that a constructor is called where E is defined, and a destructor is called where the block E is in ends. For example, consider: class GlTranslate { GLTranslate(float x, float y, float z); { glPushMatrix(); glTranslatef(x, y, z); } ~GlTranslate() { glPopMatrix(); } }; Manual solution: { GlTranslate foo(1.0, 0.0, 0.0); // I had ti give it a name ..... } // auto popmatrix Now, I have this not only for glTranslate, but lots of other PushAttrib/PopAttrib calls too. I would prefer not to have to come up with a unique name for each var. Is there some trick involving macros templates ... or something else that will automatically create a variable who's constructor is called at point of definition; and destructor called at end of block? Thanks!

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  • iPhone inputting NSUserDefaults into a UITextField

    - by Rob
    I am writing a program where I where the first time a user runs it - they will have to fill out about 10 different UITextFields. I am trying to save the fields so that on subsequent runs of the program that whatever they previously put will already be displayed in those UITextFields so the wont have to re-input it in - unless they want to edit something in which case they still have that option. I think that I have figured out a good way to save the strings using NSUserDefaults but now I am trying to figure out how to have those fields populate a UITextField - it doesnt seem as easy as if they were UILabels. This is the route I am attempting: // in the viewDidLoad portion. NSUserDefaults *userData = [NSUserDefaults standardUserDefaults]; //Hooks. NSString *placeHolderName = [userData stringForKey:@"name"]; txtName.text = @"%@", placeHolderName; When I do this, it simply displays the '%@' in the textfields. I want whatever variable being held by placeHolderName to be automatically put into that UITextField. Is this possible?

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  • Looking for the log file on iPhone

    - by zp26
    Hi, I have a problem. I have the code below for save a data on file. I build my app on the device, and run. The result variable is TRUE, but i don't find the file on the my iPhone device. Can you help me? Thank and sorry for my english XP -(void)saveXML:(NSString*)name:(float)x:(float)y:(float)z{ NSMutableData *data = [NSMutableData data]; NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]; [archiver setOutputFormat:NSPropertyListXMLFormat_v1_0]; [archiver encodeFloat:x forKey:@"x"]; [archiver encodeFloat:y forKey:@"y"]; [archiver encodeFloat:z forKey:@"z"]; [archiver encodeObject:name forKey:@"name"]; [archiver finishEncoding]; NSString* filePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"XML Position"]; BOOL result = [data writeToFile:filePath atomically:YES]; if(result) [self updateTextView:@"success"]; [archiver release]; }

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  • What is a recommended Android utility class collection?

    - by Sebastian Roth
    I often find myself writing very similar code across projects. And more often than not, I copy stuff over from old projects. Things like: Create images with round corners read density into a static variable & re-use. 4 lines.. disable / hide multiple views / remote views at once. Example: } public static void disableViews(RemoteViews views, int... ids) { for (int id : ids) { views.setInt(id, SET_VISIBILITY, View.GONE); } } public static void showViews(RemoteViews views, int... ids) { for (int id : ids) { views.setInt(id, SET_VISIBILITY, View.VISIBLE); } } I'd love to package these kind of functions into 1 letter / 2 letter class names, i.e. V.showViews(RemoteViews views, int... ids) would be easy to write & remember I hope. I'm searching for Github recommendations, links and if nothing is found, I perhaps will start a small project on github to collect.

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  • Why is it that an int in C++ that isnt initialized (then used) doesn't return an error?

    - by omizzle
    I am new to C++ (just starting). I come from a Java background and I was trying out the following piece of code that would sum the numbers between 1 and 10 (inclusive) and then print out the sum: /* * File: main.cpp * Author: omarestrella * * Created on June 7, 2010, 8:02 PM */ #include <cstdlib> #include <iostream> using namespace std; int main() { int sum; for(int x = 1; x <= 10; x++) { sum += x; } cout << "The sum is: " << sum << endl; return 0; } When I ran it it kept printing 32822 for the sum. I knew the answer was supposed to be 55 and realized that its print the max value for a short (32767) plus 55. Changing int sum; to int sum = 0; would work (as it should, since the variable needs to be initialized!). Why does this behavior happen, though? Why doesnt the compiler warn you about something like this? I know Java screams at you when something isnt initialized. Thank you.

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  • Returning a reference from a Class member?

    - by nebukadnezzar
    Hi, I've a class that basically looks like this: class App { public function newTemplate($filename, $vars=array()) { $smarty = new Smarty; $smarty->compile_dir = $this->template_compile_path; if(count($vars) > 0) { foreach($vars as $v_key => $v_name) { $smarty->assign($v_key, $v_name); } } return $smarty; } } However, when I create a Instance of 'App', the reference to $smarty seems broken, as every call to the membermethods don't seem to do anything: $app = new App; $tpl = $app->newTemplate("index.tmpl"); $tpl->assign("foo", "bar"); // {$foo} does not appear with "bar" in the template Now I wonder why? Of course I tried to use references: ... public function &newTemplate() ... ... But that doesn't work. Variable references don't seem to work either: ... $tpl = &$app->newTemplate("index.tmpl"); ... What is causing PHP here not to return a proper reference? Help is very appreciated!

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  • numpy array assignment problem

    - by Sujan
    Hi All: I have a strange problem in Python 2.6.5 with Numpy. I assign a numpy array, then equate a new variable to it. When I perform any operation to the new array, the original's values also change. Why is that? Please see the example below. Kindly enlighten me, as I'm fairly new to Python, and programming in general. -Sujan >>> import numpy as np >>> a = np.array([[1,2],[3,4]]) >>> b = a >>> b array([[1, 2], [3, 4]]) >>> c = a >>> c array([[1, 2], [3, 4]]) >>> c[:,1] = c[:,1] + 5 >>> c array([[1, 7], [3, 9]]) >>> b array([[1, 7], [3, 9]]) >>> a array([[1, 7], [3, 9]])

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  • Changing type of object in a conditional

    - by David Doria
    I'm having a bit of trouble with dynamic_casting. I need to determine at runtime the type of an object. Here is a demo: include include class PersonClass { public: std::string Name; virtual void test(){}; //it is annoying that this has to be here... }; class LawyerClass : public PersonClass { public: void GoToCourt(){}; }; class DoctorClass : public PersonClass { public: void GoToSurgery(){}; }; int main(int argc, char *argv[]) { PersonClass* person = new PersonClass; if(true) { person = dynamic_cast(person); } else { person = dynamic_cast(person); } person-GoToCourt(); return 0; } I would like to do the above. The only legal way I found to do it is to define all of the objects before hand: PersonClass* person = new PersonClass; LawyerClass* lawyer; DoctorClass* doctor; if(true) { lawyer = dynamic_cast(person); } else { doctor = dynamic_cast(person); } if(true) { lawyer-GoToCourt(); } The main problem with this (besides having to define a bunch of objects that won't be use) is that I have to change the name of the 'person' variable. Is there a better way? (I am not allowed to change any of the classes (Person, Lawyer, or Doctor) because they are part of a library that people who will use my code have and won't want to change). Thanks, Dave

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