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  • Why is my Map broken?

    - by Kirk
    Scenario: Creating a server which has Room objects which contain User objects. I want to store the rooms in a Map of some sort by Id (a string). Desired Behavior: When a user makes a request via the server, I should be able to look up the Room by id from the library and then add the user to the room, if that's what the request needs. Currently I use the static function in my Library.java class where the Map is stored to retrieve Rooms: public class Library { private static Hashtable<String, Rooms> myRooms = new Hashtable<String, Rooms>(); public static addRoom(String s, Room r) { myRooms.put(s, r); } public static Room getRoomById(String s) { return myRooms.get(s); } } In another class I'll do the equivalent of myRoom.addUser(user); What I'm observing using Hashtable, is that no matter how many times I add a user to the Room returned by getRoomById, the user is not in the room later. I thought that in Java, the object that was returned was essentially a reference to the data, the same object that was in the Hashtable with the same references; but, it isn't behaving like that. Is there a way to get this behavior? Maybe with a wrapper of some sort? Am I just using the wrong variant of map? Help?

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  • Updating a DLL in a Production ASP.NET Web Site bin folder

    - by Josh Stodola
    I want to update a class library (a single DLL file) in a production web application. This web app is pre-compiled (published). I read an answer on StackOverflow (sorry, can't seem to find it anymore because the Search function does not work very well), that led me to believe that I could just paste the new DLL in the bin folder and it would be picked up without problems (this would cause the WP to recycle, which is fine with me because we do not use InProc session state). However, when I tried this, my site blows up and gives a FileLoadException saying that the assembly manifest definition does not match the assembly reference. What in the world is this?! Updating the DLL in Visual Studio and re-deploying the entire site works just fine, but it is a huge pain in the rear. What is the point of having a separate DLL if you have to re-deploy the entire site to implement any changes? Here's the question: How can I update a DLL on a production web site without breaking the app and without re-deploying all of the files?

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  • Strange Behaviour in Swift: constant defined with LET but behaving like a variable defined with VAR

    - by Sam
    Stuck on the below for a day! Any insight would be greatly appreciated. The constant in the first block match0 behaves as expected. The constant defined in the second block does not behave as nicely in the face of a change to its "source": var str = "+y+z*1.0*sum(A1:A3)" if let range0 = str.rangeOfString("^\\+|^\\-|^\\*|^\\/", options: NSStringCompareOptions.RegularExpressionSearch){ let match0 = str[range0] println(match0) //yields "+" - as expexted str.removeRange(range0) println(match0) //yields "+" - as expected str.removeRange(range0) println(match0) //yields "+" - as expected } if let range1 = str.rangeOfString("^\\+|^\\-|^\\*|^\\/", options: NSStringCompareOptions.RegularExpressionSearch){ let match1 = str[range1] println(match1) //yields "+" as expected str.removeRange(range1) println(match1) //!@#$ OMG!!!!!!!!!!! a constant variable has changed! This prints "z" } The following are the options I can see: match1 has somehow obtained a reference to its source instead of being copied by value [Problem: Strings are value types in Swift] match1 has somehow obtained a closure to its source instead of just being a normal constant/variable? [Problem: sounds like science fiction & then why does match0 behave so well?] Could there be a bug in the Swift compiler? [Problem: Experience has taught me that this is very very very rarely the solution to your problem...but it is still in beta]

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  • Retaining Managed objects - more general retaining objects

    - by Luuk D. Jansen
    A quick question regarding Managed Objects. I created an Array with Managed Objects (in Object 1: TableViewConbtroller), and pass one of those objects to another class/object (object 2: TableCell). The original array should still be retained in the original caller class. Then Object 2 is released, does that mean that that particular item in the array is released as well, as the reference to it in Object 2 was released? I am trying to better understand how to work with ManagedObjects as I get 'Object was released' errors. [EDIT] After some experimenting I came across the following scenario: I have the main AppDelegate. In a different class I create an AppDelegate to obtain the ManagedObjectContext. appDelegate = (iDomsAppDelegate *)[[UIApplication sharedApplication] delegate]; [self setContext:[appDelegate managedObjectContext]]; When the class is finished, and I release it, the variable in the class 'appDelegate' is also released. But then the ManagedObjectContext is closed, and obvious any future attempt to use it will cause a crash. So should I leave the appDelegate unreleased? This comes to the same question as the above about when and how to release in those situations where an objects is used from another class. I think a way of putting it is, how to know when you own an object and when not.

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  • NullReferenceExeption when reading from a file

    - by Whitey
    I need to read a file structured like this: 01000 00030 00500 03000 00020 And put it in an array like this: int[,] iMap = new int[iMapHeight, iMapWidth] { {0, 1, 0, 0, 0}, {0, 0, 0, 3, 0}, {0, 0, 5, 0, 0}, {0, 3, 0, 0, 0}, {0, 0, 0, 2, 0}, }; Hopefully you see what I'm trying to do here. I was confused how to do this so I asked here on SO, but the code I got from it gets this error: Object reference not set to an instance of an object. I'm pretty new to this so I have no idea how to fix it... I only barely know the code: protected void ReadMap(string mapPath) { using (var reader = new StreamReader(mapPath)) { for (int i = 0; i < iMapHeight; i++) { string line = reader.ReadLine(); for (int j = 0; j < iMapWidth; j++) { iMap[i, j] = (int)(line[j] - '0'); } } } } The line I get the error on is this: iMap[i, j] = (int)(line[j] - '0'); Can anyone provide a solution? Thank you. :)

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  • Am I doing something wrong here (references in C++)?

    - by m4design
    I've been playing around with references (I'm still having issues in this regard). 1- I would like to know if this is an acceptable code: int & foo(int &y) { return y; // is this wrong? } int main() { int x = 0; cout << foo(x) << endl; foo(x) = 9; // is this wrong? cout << x << endl; return 0; } 2- Also this is from an exam sample: Week & Week::highestSalesWeek(Week aYear[52]) { Week max = aYear[0]; for(int i = 1; i < 52; i++) { if (aYear[i].getSales() > max.getSales()) max = aYear[i]; } return max; } It asks about the mistake in this code, also how to fix it. My guess is that it return a local reference. The fix is: Week & max = aYear[0]; Is this correct/enough?

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  • Work with function references

    - by Ockonal
    Hello, I have another one question about functions reference. For example, I have such definition: typedef boost::function<bool (Entity &handle)> behaviorRef; std::map< std::string, ptr_vector<behaviorRef> > eventAssociation; The first question is: how to insert values into such map object? I tried: eventAssociation.insert(std::pair< std::string, ptr_vector<behaviorRef> >(eventType, ptr_vector<behaviorRef>(callback))); But the error: no matching function for call to ‘boost::ptr_vector<boost::function<bool(Entity&)> >::push_back(Entity::behaviorRef&)’ And I undersatnd it, but can't make workable code. The second question is how to call such functions? For example, I have one object of behaviorRef, how to call it with boost::bind with passing my own values?

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  • int foo(type& bar); is a bad practice?

    - by Earlz
    Well, here we are. Yet another proposed practice that my C++ book has an opinion on. It says "a returning-value(non-void) function should not take reference types as a parameter." So basically if you were to implement a function like this: int read_file(int& into){ ... } and used the integer return value as some sort of error indicator (ignoring the fact that we have exceptions) then that function would be poorly written and it should actually be like void read_file(int& into, int& error){ } Now to me, the first one is much clearer and nice to use. If you want to ignore the error value, you do so with ease. But this book suggests the later. Note that this book does not say returning value functions are bad. It rather says that you should either only return a value or you should only use references. What are your thoughts on this? Is my book full of crap? (again)

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  • Changing Value of Array Pointer When Passed to a Function

    - by ZAX
    I have a function which receives both the array, and a specific instance of the array. I try to change the specific instance of the array by accessing one of its members "color", but it does not actually change it, as can be seen by debugging (checking the value of color after function runs in the main program). I am hoping someone can help me to access this member and change it. Essentially I need the instance of the array I'm specifying to be passed by reference if nothing else, but I'm hoping there is an easier way to accomplish what I'm trying to do. Here's the structures: typedef struct adjEdge{ int vertex; struct adjEdge *next; } adjEdge; typedef struct vertex{ int sink; int source; int color; //0 will be white, 1 will be grey, 5 will be black int number; adjEdge *nextVertex; } vertex; And here is the function: void walk(vertex *vertexArray, vertex v, int source, maxPairing *head) { int i; adjEdge *traverse; int moveVertex; int sink; traverse = vertexArray[v.number-1].nextVertex; if(v.color != 5 && v.sink == 5) { sink = v.number; v.color = 5; addMaxPair(head, source, sink); } else { walk(vertexArray, vertexArray[traverse->vertex-1], source, head); } } In particular, v.color needs to be changed to a 5, that way later after recursion the if condition blocks it.

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  • The type 'XXX' is defined in an assembly that is not referenced exception after upgrade to ASP.NET 4

    - by imran_ku07
       Introduction :          I found two posts in ASP.NET MVC forums complaining that they are getting exception, The type XXX is defined in an assembly that is not referenced, after upgrading thier application into Visual Studio 2010 and .NET Framework 4.0 at here and here .   Description :           The reason why they are getting the above exception is the use of new clean web.config without referencing the assemblies which were presents in ASP.NET 3.5 web.config. The quick solution for this problem is to add the old assemblies in new web.config.          <assemblies>             <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>             <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>             <add assembly="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>              <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />              <add assembly="System.Data.Linq, Version=4.0.0.0, Culture=neutral, publicKeyToken=b77a5c561934e089" />          </assemblies>    How It works :            Currently i have not tested the above scenario in ASP.NET 4.0 because i have not yet get it. But the above scenario can easily be tested and verified in VS 2008. Just Open the root web.config and remove           <add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>             Even you add the reference of System.Core in your project, you will still get the above exception because aspx pages are compiled in separate assembly. You can check this yourself by checking Show Detailed Compiler Output: below in the yellow screen of death, you will find something,/out:"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\e907aee4\5fa0acc8\App_Web_y5rd6bdg.dll"             This shows that aspx pages are compiled in separate assembly in Temporary ASP.NET Files.Summary :             After getting the above exception make sure to add the assemblies in web.config or add the Assembly directive at Page level. Hopefully this will helps to solve your problem.       

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  • JS onclick triggers wrong object

    - by Clemens Prerovsky
    Hi guys, what I'm trying to do here is to associate a DOM object with an instance of a JS object, which will provide some meaningfol methods later on ;) At this point I just want to handle my JS object the click event, whilst keeping it's references intact. <?xml version="1.0" encoding="ISO-8859-1" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /> <title>Insert title here</title> <script type="text/javascript"> // my object, which will hold a reference to a single DOM object obj = function(domobj) { this.o = domobj; my = this; var ref = my.click; this.o.onclick = ref; } // my objects click function obj.prototype.click = function() { alert(my.o.innerHTML); } // create objects with references $(document).ready(function() { o1 = new obj(document.getElementById('b1')); o2 = new obj(document.getElementById('b2')); }); </script> </head> <body> <button id="b1">button 1</button> <button id="b2">button 2</button> </body> </html> Expected result: when clicking on button 1, the text "button 1" should be alerted. Current result: when clicking button 1, the text "button 2" is alerted. What I found out so far is that the wrong instance of obj is triggered from the click event, even though o1 and o2 maintain correct references to their corresponding DOM object. Any ideas how to solve this? Thanks for your help! Best regards, Clemens

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  • SQL Server: SELECT rows with MAX(Column A), MAX(Column B), DISTINCT by related columns

    - by z531
    Scenario: Table A MasterID, Added Date, Added By, Updated Date, Updated By, 1, 1/1/2010, 'Fred', null, null 2, 1/2/2010, 'Barney', 'Mr. Slate', 1/7/2010 3, 1/3/2010, 'Noname', null, null Table B MasterID, Added Date, Added By, Updated Date, Updated By, 1, 1/3/2010, 'Wilma', 'The Great Kazoo', 1/5/2010 2, 1/4/2010, 'Betty', 'Dino', 1/4/2010 Table C MasterID, Added Date, Added By, Updated Date, Updated By, 1, 1/5/2010, 'Pebbles', null, null 2, 1/6/2010, 'BamBam', null, null Table D MasterID, Added Date, Added By, Updated Date, Updated By, 1, 1/2/2010, 'Noname', null, null 3, 1/4/2010, 'Wilma', null, null I need to return the max added date and corresponding user, and max updated date and corresponding user for each distinct record when tables A,B,C&D are UNION'ed, i.e.: 1, 1/5/2010, 'Pebbles', 'The Great Kazoo', 1/5/2010 2, 1/6/2010, 'BamBam', 'Mr. Slate', 1/7/2010 3, 1/4/2010, 'Wilma', null, null I know how to do this with one date/user per row, but with two is beyond me. DBMS is SQL Server 2005. T-SQL solution preferred. Thanks in advance, Dave

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  • sql: Group by x,y,z; return grouped by x,y with lowest f(z)

    - by Sai Emrys
    This is for http://cssfingerprint.com I collect timing stats about how fast the different methods I use perform on different browsers, etc., so that I can optimize the scraping speed. Separately, I have a report about what each method returns for a handful of URLs with known-correct values, so that I can tell which methods are bogus on which browsers. (Each is different, alas.) The related tables look like this: CREATE TABLE `browser_tests` ( `id` int(11) NOT NULL AUTO_INCREMENT, `bogus` tinyint(1) DEFAULT NULL, `result` tinyint(1) DEFAULT NULL, `method` varchar(255) DEFAULT NULL, `url` varchar(255) DEFAULT NULL, `os` varchar(255) DEFAULT NULL, `browser` varchar(255) DEFAULT NULL, `version` varchar(255) DEFAULT NULL, `created_at` datetime DEFAULT NULL, `updated_at` datetime DEFAULT NULL, `user_agent` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=33784 DEFAULT CHARSET=latin1 CREATE TABLE `method_timings` ( `id` int(11) NOT NULL AUTO_INCREMENT, `method` varchar(255) DEFAULT NULL, `batch_size` int(11) DEFAULT NULL, `timing` int(11) DEFAULT NULL, `os` varchar(255) DEFAULT NULL, `browser` varchar(255) DEFAULT NULL, `version` varchar(255) DEFAULT NULL, `user_agent` varchar(255) DEFAULT NULL, `created_at` datetime DEFAULT NULL, `updated_at` datetime DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=28849 DEFAULT CHARSET=latin1 (user_agent is broken down pre-insert into browser, version, and os from a small list of recognized values using regex; I keep the original user-agent string just in case.) I have a query like this that tells me the average timing for every non-bogus browser / version / method tuple: select c, avg(bogus) as bog, timing, method, browser, version from browser_tests as b inner join ( select count(*) as c, round(avg(timing)) as timing, method, browser, version from method_timings group by browser, version, method having c > 10 order by browser, version, timing ) as t using (browser, version, method) group by browser, version, method having bog < 1 order by browser, version, timing; Which returns something like: c bog tim method browser version 88 0.8333 184 reuse_insert Chrome 4.0.249.89 18 0.0000 238 mass_insert_width Chrome 4.0.249.89 70 0.0400 246 mass_insert Chrome 4.0.249.89 70 0.0400 327 mass_noinsert Chrome 4.0.249.89 88 0.0556 367 reuse_reinsert Chrome 4.0.249.89 88 0.0556 383 jquery Chrome 4.0.249.89 88 0.0556 863 full_reinsert Chrome 4.0.249.89 187 0.0000 105 jquery Chrome 5.0.307.11 187 0.8806 109 reuse_insert Chrome 5.0.307.11 123 0.0000 110 mass_insert_width Chrome 5.0.307.11 176 0.0000 231 mass_noinsert Chrome 5.0.307.11 176 0.0000 237 mass_insert Chrome 5.0.307.11 187 0.0000 314 reuse_reinsert Chrome 5.0.307.11 187 0.0000 372 full_reinsert Chrome 5.0.307.11 12 0.7500 82 reuse_insert Chrome 5.0.335.0 12 0.2500 102 jquery Chrome 5.0.335.0 [...] I want to modify this query to return only the browser/version/method with the lowest timing - i.e. something like: 88 0.8333 184 reuse_insert Chrome 4.0.249.89 187 0.0000 105 jquery Chrome 5.0.307.11 12 0.7500 82 reuse_insert Chrome 5.0.335.0 [...] How can I do this, while still returning the method that goes with that lowest timing? I could filter it app-side, but I'd rather do this in mysql since it'd work better with my caching.

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  • Wondering about a way to conserve memory in C# using List<> with structs

    - by Michael Ryan
    I'm not even sure how I should phrase this question. I'm passing some CustomStruct objects as parameters to a class method, and storing them in a List. What I'm wondering is if it's possible and more efficient to add multiple references to a particular instance of a CustomStruct if a equivalent instance it found. This is a dummy/example struct: public struct CustomStruct { readonly int _x; readonly int _y; readonly int _w; readonly int _h; readonly Enum _e; } Using the below method, you can pass one, two, or three CustomStruct objects as parameters. In the final method (that takes three parameters), it may be the case that the 3rd and possibly the 2nd will have the same value as the first. List<CustomStruct> _list; public void AddBackground(CustomStruct normal) { AddBackground(normal, normal, normal); } public void AddBackground(CustomStruct normal, CustomStruct hover) { AddBackground(normal, hover, hover); } public void AddBackground(CustomStruct normal, CustomStruct hover, CustomStruct active) { _list = new List<CustomStruct>(3); _list.Add(normal); _list.Add(hover); _list.Add(active); } As the method stands now, I believe it will create new instances of CustomStruct objects, and then adds a reference of each to the List. It is my understanding that if I instead check for equality between normal and hover and (if equal) insert normal again in place of hover, when the method completes, hover will lose all references and eventually be garbage collected, whereas normal will have two references in the List. The same could be done for active. That would be better, right? The CustomStruct is a ValueType, and therefore one instance would remain on the Stack, and the three List references would just point to it. The overall List size is determined not by the object Type is contains, but by its Capacity. By eliminating the "duplicate" CustomStuct objects, you allow them to be cleaned up. When the CustomStruct objects are passed to these methods, new instances are created each time. When the structs are added to the List, is another copy made? For example, if i pass just one CustomStruct, AddBackground(normal) creates a copy of the original variable, and then passes it three times to Addbackground(normal, hover, active). In this method, three copies are made of the original copy. When the three local variables are added to the List using Add(), are additional copies created inside Add(), and does that defeat the purpose of any equality checks as previously mentioned? Am I missing anything here?

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  • Problems getting foreign keys working in MySQL

    - by thehuby
    I've been trying to get a delete to cascade and it just doesn't seem to work. I'm sure I am missing something obvious, can anyone help me find it? I would expect a delete on the 'articles' table to trigger a delete on the corresponding rows in the 'article_section_lt' table. CREATE TABLE articles ( id INTEGER UNSIGNED PRIMARY KEY AUTO_INCREMENT, url_stub VARCHAR(255) NOT NULL UNIQUE, h1 VARCHAR(60) NOT NULL UNIQUE, title VARCHAR(60) NOT NULL, description VARCHAR(150) NOT NULL, summary VARCHAR(150) NOT NULL DEFAULT "", html_content TEXT, date DATE NOT NULL, updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP )ENGINE=INNODB; CREATE TABLE article_sections ( /* blog, news etc */ id INTEGER UNSIGNED PRIMARY KEY AUTO_INCREMENT, url_stub VARCHAR(255) NOT NULL UNIQUE, h1 VARCHAR(60) NOT NULL, title VARCHAR(60) NOT NULL, description VARCHAR(150) NOT NULL, summary VARCHAR(150) NOT NULL DEFAULT "", html_content TEXT NOT NULL DEFAULT "" )ENGINE=INNODB; CREATE TABLE article_section_lt ( fk_article_id INTEGER UNSIGNED NOT NULL REFERENCES articles(id) ON DELETE CASCADE, fk_article_section_id INTEGER UNSIGNED NOT NULL )ENGINE=INNODB;

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  • Django Comments and Users integration

    - by Patrick
    Hi folks, I am new to django. I am trying to use django.contrib.comments, I saw the table in the database like this, but how can I integrate it with user_id, user_photos, user_name, user_email....and those things with the django commenting system? I also tried to use thread-comments, but I can't configure it properly, is the django threadedcomments table similar to following ? Please let me know if any of you have done this before....all I need is a user login, and post comments, and then show list of comments with users' profile photos and username, as well as there comments. I think shouldn't be that hard. Thank you very much again. +-----------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | content_type_id | int(11) | NO | MUL | NULL | | | object_pk | longtext | NO | | NULL | | | site_id | int(11) | NO | MUL | NULL | | | user_id | int(11) | YES | MUL | NULL | | | user_name | varchar(50) | NO | | NULL | | | user_email | varchar(75) | NO | | NULL | | | user_url | varchar(200) | NO | | NULL | | | comment | longtext | NO | | NULL | | | submit_date | datetime | NO | | NULL | | | ip_address | char(15) | YES | | NULL | | | is_public | tinyint(1) | NO | | NULL | | | is_removed | tinyint(1) | NO | | NULL | | +-----------------+--------------+------+-----+---------+----------------+

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  • Cleaning up a dynamic array of Objects in C++

    - by Dr. Monkey
    I'm a bit confused about handling an array of objects in C++, as I can't seem to find information about how they are passed around (reference or value) and how they are stored in an array. I would expect an array of objects to be an array of pointers to that object type, but I haven't found this written anywhere. Would they be pointers, or would the objects themselves be laid out in memory in an array? In the example below, a custom class myClass holds a string (would this make it of variable size, or does the string object hold a pointer to a string and therefore take up a consistent amount of space. I try to create a dynamic array of myClass objects within a myContainer. In the myContainer.addObject() method I attempt to make a bigger array, copy all the objects into it along with a new object, then delete the old one. I'm not at all confident that I'm cleaning up my memory properly with my destructors - what improvements could I make in this area? class myClass { private string myName; public unsigned short myAmount; myClass(string name, unsigned short amount) { myName = name; myAmount = amount; } //Do I need a destructor here? I don't think so because I don't do any // dynamic memory allocation within this class } class myContainer { int numObjects; myClass * myObjects; myContainer() { numObjects = 0; } ~myContainer() { //Is this sufficient? //Or do I need to iterate through myObjects and delete each // individually? delete [] myObjects; } void addObject(string name, unsigned short amount) { myClass newObject = new myClass(name, amount); myClass * tempObjects; tempObjects = new myClass[numObjects+1]; for (int i=0; i<numObjects; i++) tempObjects[i] = myObjects[i]); tempObjects[numObjects] = newObject; numObjects++; delete newObject; //Will this delete all my objects? I think it won't. //I'm just trying to delete the old array, and have the new array hold // all the objects plus the new object. delete [] myObjects; myObjects = tempObjects; } }

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  • C# 4.0 'dynamic' doesn't set ref/out arguments

    - by Buu Nguyen
    I'm experimenting with DynamicObject. One of the things I try to do is setting the values of ref/out arguments, as shown in the code below. However, I am not able to have the values of i and j in Main() set properly (even though they are set correctly in TryInvokeMember()). Does anyone know how to call a DynamicObject object with ref/out arguments and be able to retrieve the values set inside the method? class Program { static void Main(string[] args) { dynamic proxy = new Proxy(new Target()); int i = 10; int j = 20; proxy.Wrap(ref i, ref j); Console.WriteLine(i + ":" + j); // Print "10:20" while expect "20:10" } } class Proxy : DynamicObject { private readonly Target target; public Proxy(Target target) { this.target = target; } public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { int i = (int) args[0]; int j = (int) args[1]; target.Swap(ref i, ref j); args[0] = i; args[1] = j; result = null; return true; } } class Target { public void Swap(ref int i, ref int j) { int tmp = i; i = j; j = tmp; } }

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  • why is there extra using where in execution plan of query

    - by user366534
    I see plan of query: EXPLAIN SELECT * FROM `subscribers` WHERE state =4 AND date_added < '2010-12-23 11:47:45' It shows: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subscribers range state_date_added state_date_added 9 NULL 8 Using where Here is indexes of table: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment subscribers 0 PRIMARY 1 subscriber_id A 382039 NULL NULL BTREE subscribers 0 email_list_id 1 email_address A 191019 NULL NULL BTREE subscribers 0 email_list_id 2 list_id A 382039 NULL NULL BTREE subscribers 1 FK_list_id 1 list_id A 10 NULL NULL BTREE subscribers 1 state_date_added 1 state A 12 NULL NULL BTREE subscribers 1 state_date_added 2 date_added A 8128 NULL NULL BTREE The last two lines describes index what is supposed for the query. Why is there in extra column using where? Even If I fetch only state and date_added column, it has in extra column: Using where; Using index. I understand why it has using index, but I don't understand Using where here.

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  • Very difficult SQL query

    - by db666
    For the following table definitions: Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------ ENUM NOT NULL NUMBER(4) ENUM should not exceed a length of 4. ENAME CHAR(15) ADDRESS CHAR(25) ADDRESS should not exceed 25 characters. SALARY NUMBER(5) OFFICE CHAR(4) DNUM NOT NULL NUMBER(4) Department which this employee belongs to department Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------- DNUM NOT NULL NUMBER(4) DMGR NOT NULL NUMBER(4) Department manager DNAME NOT NULL CHAR(15) project Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------- PNUM NOT NULL NUMBER(4) PMGR NOT NULL NUMBER(4) Project manager PTITLE NOT NULL CHAR(15) emp_proj Name Null? Type ------------------------------- -------- ---- PNUM NOT NULL NUMBER(4) ENUM NOT NULL NUMBER(4) I have to write SQL query which will find the names of employees who do not share an office but work on the same project, and have different salaries... I've spent last three days trying to figure out something, but no idea as far. I will appreciate any advice.

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  • Need MYSQL query for finding lowest score per game player

    - by Chris Barnhill
    I have a game on Facebook called Rails Across Europe. I have a Best Scores page where I show the players with the best 20 scores, which in game terms refers to the lowest winning turn. The problem is that there are a small number of players who play frequently, and their scores dominate the page. I'd like to make the scores page open to more players. So I thought that I could display the single lowest winning turn for each player instead of displaying all of the lowest winning turns for all players. The problem is that the query for this eludes me. So I hope that one of you brilliant StackOverflow folks can help me with this. I have included the relevant MYSQL table schemas below. Here are the the table relationships: player_stats contains statistics for either a game in progress or a completed game. If a game is in progress, winning_turn is zero (which means that games with a winning_turn of zero should not be included in the query). player_stats has a game_player table id reference. game_player contains data describing games currently in progress. game_player has a player table id reference. player contains data describing a person who plays the game. Here's the query I'm currently using: 'SELECT p.fb_user_id, ps.winning_turn, gp.difficulty_level, c.name as city_name, g.name as goods_name, d.cost FROM game_player as gp, player as p, player_stats as ps, demand as d, city as c, goods as g WHERE p.status = "ACTIVE" AND gp.player_id = p.id AND ps.game_player_id = gp.id AND d.id = ps.highest_demand_id AND c.id = d.city_id AND g.id = d.goods_id AND ps.winning_turn > 0 ORDER BY ps.winning_turn ASC, d.cost DESC LIMIT '.$limit.';'; Here are the relevant table schemas: -- -- Table structure for table `player_stats` -- CREATE TABLE IF NOT EXISTS `player_stats` ( `id` int(11) NOT NULL auto_increment, `game_player_id` int(11) NOT NULL, `winning_turn` int(11) NOT NULL, `highest_demand_id` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `game_player_id` (`game_player_id`,`highest_demand_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3814 ; -- -- Table structure for table `game_player` -- CREATE TABLE IF NOT EXISTS `game_player` ( `id` int(10) unsigned NOT NULL auto_increment, `game_id` int(10) unsigned NOT NULL, `player_id` int(10) unsigned NOT NULL, `player_number` int(11) NOT NULL, `funds` int(10) unsigned NOT NULL, `turn` int(10) unsigned NOT NULL, `difficulty_level` enum('STANDARD','ADVANCED','MASTER','ULTIMATE') NOT NULL, `date_last_used` datetime NOT NULL, PRIMARY KEY (`id`), KEY `game_id` (`game_id`,`player_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=3814 ; -- -- Table structure for table `player` -- CREATE TABLE IF NOT EXISTS `player` ( `id` int(11) NOT NULL auto_increment, `fb_user_id` char(255) NOT NULL, `fb_proxied_email` text NOT NULL, `first_name` char(255) NOT NULL, `last_name` char(255) NOT NULL, `birthdate` date NOT NULL, `date_registered` datetime NOT NULL, `date_last_logged_in` datetime NOT NULL, `status` enum('ACTIVE','SUSPENDED','CLOSED') NOT NULL, PRIMARY KEY (`id`), KEY `fb_user_id` (`fb_user_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1646 ;

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  • correct mysql syntax error

    - by user2981651
    please could someone tell me the problem with this syntax because mysql 5.5.32 keeps tell me about an error CREATE TABLE `clients` ( `ID` tinyint(11) NOT NULL auto_increment, `title` varchar(10) NOT NULL default '', `firstName` varchar(30) NOT NULL default '', `lastName` varchar(30) NOT NULL default '', `address1` varchar(100) NOT NULL default '', `address2` varchar(100) NOT NULL default '', `town` varchar(100) NOT NULL default '', `province` varchar(100) NOT NULL default '', `country` varchar(40) NOT NULL default '', `postCode` varchar(20) NOT NULL default '', `telephone` varchar(20) NOT NULL default '', `email` varchar(100) NOT NULL default '', `cardNo` varchar(16) NOT NULL default '0000-00-00', `expiryDate` date NOT NULL default '0000-00-00', PRIMARY KEY (`ID`) ) TYPE=MyISAM COMMENT='customer table' AUTO_INCREMENT=1 ;

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  • Generate a merge statement from table structure

    - by Nigel Rivett
    This code generates a merge statement joining on he natural key and checking all other columns to see if they have changed. The full version deals with type 2 processing and an audit trail but this version is useful. Just the insert or update part is handy too. Change the table at the top (spt_values in master in the version) and the join columns for the merge in @nk. The output generated is at the top and the code to run to generate it below. Output merge spt_values a using spt_values b on a.name = b.name and a.number = b.number and a.type = b.type when matched and (1=0 or (a.low b.low) or (a.low is null and b.low is not null) or (a.low is not null and b.low is null) or (a.high b.high) or (a.high is null and b.high is not null) or (a.high is not null and b.high is null) or (a.status b.status) or (a.status is null and b.status is not null) or (a.status is not null and b.status is null) ) then update set low = b.low , high = b.high , status = b.status when not matched by target then insert ( name , number , type , low , high , status ) values ( b.name , b.number , b.type , b.low , b.high , b.status ); Generator set nocount on declare @t varchar(128) = 'spt_values' declare @i int = 0 -- this is the natural key on the table used for the merge statement join declare @nk table (ColName varchar(128)) insert @nk select 'Number' insert @nk select 'Name' insert @nk select 'Type' declare @cols table (seq int, nkseq int, type int, colname varchar(128)) ;with cte as ( select ordinal_position, type = case when columnproperty(object_id(@t), COLUMN_NAME,'IsIdentity') = 1 then 3 when nk.ColName is not null then 1 else 0 end, COLUMN_NAME from information_schema.columns c left join @nk nk on c.column_name = nk.ColName where table_name = @t ) insert @cols (seq, nkseq, type, colname) select ordinal_position, row_number() over (partition by type order by ordinal_position) , type, COLUMN_NAME from cte declare @result table (i int, j int, k int, data varchar(500)) select @i = @i + 1 insert @result (i, data) select @i, 'merge ' + @t + ' a' select @i = @i + 1 insert @result (i, data) select @i, ' using cte b' select @i = @i + 1 insert @result (i, j, data) select @i, nkseq, ' ' + case when nkseq = 1 then 'on' else 'and' end + ' a.' + ColName + ' = b.' + ColName from @cols where type = 1 select @i = @i + 1 insert @result (i, data) select @i, ' when matched and (1=0' select @i = @i + 1 insert @result (i, j, k, data) select @i, seq, 1, ' or (a.' + ColName + ' b.' + ColName + ')' + ' or (a.' + ColName + ' is null and b.' + ColName + ' is not null)' + ' or (a.' + ColName + ' is not null and b.' + ColName + ' is null)' from @cols where type 1 select @i = @i + 1 insert @result (i, data) select @i, ' )' select @i = @i + 1 insert @result (i, data) select @i, ' then update set' select @i = @i + 1 insert @result (i, j, data) select @i, nkseq, ' ' + case when nkseq = 1 then ' ' else ', ' end + colname + ' = b.' + colname from @cols where type = 0 select @i = @i + 1 insert @result (i, data) select @i, ' when not matched by target then insert' select @i = @i + 1 insert @result (i, data) select @i, ' (' select @i = @i + 1 insert @result (i, j, data) select @i, seq, ' ' + case when seq = 1 then ' ' else ', ' end + colname from @cols where type 3 select @i = @i + 1 insert @result (i, data) select @i, ' )' select @i = @i + 1 insert @result (i, data) select @i, ' values' select @i = @i + 1 insert @result (i, data) select @i, ' (' select @i = @i + 1 insert @result (i, j, data) select @i, seq, ' ' + case when seq = 1 then ' ' else ', ' end + 'b.' + colname from @cols where type 3 select @i = @i + 1 insert @result (i, data) select @i, ' );' select data from @result order by i,j,k,data

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  • CoreData update problems

    - by kpower
    My app makes updates in background thread then saves context changes. And in main context there is a table view that works with NSFetchedResultsController. For some time updates work correctly, but then exception is thrown. To check this I've added NSLog(@"%@", [self.controller fetchedObjects]); to -controllerDidChangeContent:. Here is what I got: "<PRBattle: 0x6d30530> (entity: PRBattle; id: 0x6d319d0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p2> ; data: {\n battleId = \"-1\";\n finishedAt = \"2012-11-06 11:37:36 +0000\";\n opponent = \"0x6d2f730 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p1>\";\n opponentScore = nil;\n score = nil;\n status = 4;\n})", "<PRBattle: 0x6d306f0> (entity: PRBattle; id: 0x6d319f0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p1> ; data: {\n battleId = \"-1\";\n finishedAt = \"2012-11-06 11:37:36 +0000\";\n opponent = \"0x6d2ddb0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p3>\";\n opponentScore = nil;\n score = nil;\n status = 4;\n})", "<PRBattle: 0x6d30830> (entity: PRBattle; id: 0x6d31650 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p11> ; data: <fault>)", "<PRBattle: 0x6d306b0> (entity: PRBattle; id: 0x6d319e0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p5> ; data: {\n battleId = 325;\n finishedAt = nil;\n opponent = \"0x6d2f730 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p1>\";\n opponentScore = 91;\n score = 59;\n status = 3;\n})", "<PRBattle: 0x6d30730> (entity: PRBattle; id: 0x6d31a00 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p6> ; data: {\n battleId = 323;\n finishedAt = nil;\n opponent = \"0x6d2ddb0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p3>\";\n opponentScore = 0;\n score = 0;\n status = 3;\n})", "<PRBattle: 0x6d307b0> (entity: PRBattle; id: 0x6d31630 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p9> ; data: {\n battleId = 370;\n finishedAt = \"2012-11-06 14:24:14 +0000\";\n opponent = \"0x79a8e90 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p2>\";\n opponentScore = 180;\n score = 180;\n status = 4;\n})", "<PRBattle: 0x6d307f0> (entity: PRBattle; id: 0x6d31640 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p10> ; data: {\n battleId = 309;\n finishedAt = \"2012-11-02 01:19:27 +0000\";\n opponent = \"0x79a8e90 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p2>\";\n opponentScore = 120;\n score = 240;\n status = 4;\n})", "<PRBattle: 0x6d30770> (entity: PRBattle; id: 0x6d31620 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p7> ; data: {\n battleId = 315;\n finishedAt = \"2012-11-02 02:26:24 +0000\";\n opponent = \"0x79a8e90 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p2>\";\n opponentScore = 119;\n score = 179;\n status = 4;\n})" ) Faulted object (0xe972610) here causes crash. I've logged data during update & before saving. This object is in updatedObjects only. Why can this method return "bad" object? (Moreover, during updates this object is affected almost each update. And only after some passes becomes "bad" one). P.S.: I use RestKit to manage CoreData. UPDATED: The exception was got, when I did smth. like this: for (PRBattle *battle in [self.controller fetchedObjects) { switch (battle.statusScalar) { case ... default: [battle willAccessValueForKey:nil]; NSAssert1(NO, @"Unexpected battle status found: %@", battle); } } The exception is on line with -willAccessValueForKey:. Scalar status for battle is enum, that is bind to integer values 1..4. I've mentioned all possible values in switch's cases (above default:). And the last one has break;. So this one is possible only when battle.statusScalar returns non-enum value. Status scalar implementation in PRBattle: - (PRBattleStatuses)statusScalar { [self willAccessValueForKey:@"statusScalar"]; PRBattleStatuses result = (PRBattleStatuses)[self.status integerValue]; [self didAccessValueForKey:@"statusScalar"]; return result; } And battle.status has validation rules: - min-value: 1 - max-value: 4 - default: no value And the last thing - debug log: objc[4664]: EXCEPTIONS: throwing 0x7d33f80 (object 0xe67d2a0, a _NSCoreDataException) objc[4664]: EXCEPTIONS: searching through frame [ip=0x97b401 sp=0xbfffd9b0] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: catch(id) objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x97b401 sp=0xbfffd9b0] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: handling exception 0x7d33f60 at 0x97b79f objc[4664]: EXCEPTIONS: rethrowing current exception objc[4664]: EXCEPTIONS: searching through frame [ip=0x97b911 sp=0xbfffd9b0] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: searching through frame [ip=0x9ac8b7 sp=0xbfffdc20] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: searching through frame [ip=0x97ee80 sp=0xbfffdc40] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: searching through frame [ip=0x361d0 sp=0xbfffdc70] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: searching through frame [ip=0xa701d8 sp=0xbfffde10] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: catch(id) objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x97b911 sp=0xbfffd9b0] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: finishing handler objc[4664]: EXCEPTIONS: searching through frame [ip=0x97b963 sp=0xbfffd9b0] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: searching through frame [ip=0x9ac8b7 sp=0xbfffdc20] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: searching through frame [ip=0x97ee80 sp=0xbfffdc40] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: searching through frame [ip=0x361d0 sp=0xbfffdc70] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: searching through frame [ip=0xa701d8 sp=0xbfffde10] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: catch(id) objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x97b963 sp=0xbfffd9b0] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x9ac8b7 sp=0xbfffdc20] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x97ee80 sp=0xbfffdc40] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x361d0 sp=0xbfffdc70] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x3656f sp=0xbfffdc70] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: unwinding through frame [ip=0xa701d8 sp=0xbfffde10] for exception 0x7d33f60 objc[4664]: EXCEPTIONS: handling exception 0x7d33f60 at 0xa701f5 2012-11-07 13:37:55.463 TestApp[4664:fb03] CoreData: error: Serious application error. An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:. CoreData could not fulfill a fault for '0x6d31650 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p10>' with userInfo { NSAffectedObjectsErrorKey = ( "<PRBattle: 0x6d30830> (entity: PRBattle; id: 0x6d31650 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p10> ; data: <fault>)" ); }

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