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• Problem with Boost::Asio for C++

  - by Martin Lauridsen

  Hi there, For my bachelors thesis, I am implementing a distributed version of an algorithm for factoring large integers (finding the prime factorisation). This has applications in e.g. security of the RSA cryptosystem. My vision is, that clients (linux or windows) will download an application and compute some numbers (these are independant, thus suited for parallelization). The numbers (not found very often), will be sent to a master server, to collect these numbers. Once enough numbers have been collected by the master server, it will do the rest of the computation, which cannot be easily parallelized. Anyhow, to the technicalities. I was thinking to use Boost::Asio to do a socket client/server implementation, for the clients communication with the master server. Since I want to compile for both linux and windows, I thought windows would be as good a place to start as any. So I downloaded the Boost library and compiled it, as it said on the Boost Getting Started page: bootstrap .\bjam It all compiled just fine. Then I try to compile one of the tutorial examples, client.cpp, from Asio, found (here.. edit: cant post link because of restrictions). I am using the Visual C++ compiler from Microsoft Visual Studio 2008, like this: cl /EHsc /I D:\Downloads\boost_1_42_0 client.cpp But I get this error: /out:client.exe client.obj LINK : fatal error LNK1104: cannot open file 'libboost_system-vc90-mt-s-1_42.lib' Anyone have any idea what could be wrong, or how I could move forward? I have been trying pretty much all week, to get a simple client/server socket program for c++ working, but with no luck. Serious frustration kicking in. Thank you in advance.

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• Hashtable is that fast

  - by Costa

  Hi s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]. Is the hash function of the java string, I assume the rest of languages is similar or close to this implementation. If we have hash-Table and a list of 50 elements. each element is 7 chars ABCDEF1, ABCDEF2, ABCDEF3..... ABCDEFn If each bucket of hashtable contains 5 strings (I think this function will make it one string per bucket, but let us assume it is 5). If we call col.Contains("ABCDEFn"); // will do 6 comparisons and discover the difference on the 7th. The hash-table will take around 70 operations (multiplication and additions) to get the hashcode and to compare with 5 strings in bucket. and BANG it found. For list it will take around 300 comparisons to find it. for the case that there is only 10 elements, the list will take around 70 operations but the Hashtable will take around 50 operations. and note that hashtable operations are more time consuming (it is multiplications). I conclude that HybirdDictionary in .Net probably is the best choice for that most cases that require Hashtable with unknown size, because it will let me use a list till the list becomes more than 10 elements. still need something like HashSet rather than a Dictionary of keys and values, I wonder why there is no HybirdSet!! So what do u think? Thanks

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• Returning c_str from a function

  - by user199421

  This is from a small library that I found online: const char* GetHandStateBrief(const PostFlopState* state) { static std::ostringstream out; ... rest of the function ... return out.str().c_str() Now in my code I am doing this: const char *d = GetHandStateBrief(&post); std::cout<< d << std::endl; Now, at first d contained garbage. I then realized that the c string I am getting from the function is destroyed when the function returns because std::ostringstream is allocated on the stack. So I added: return strdup( out.str().c_str()); And now I can get the text I need from the function. I have two questions: 1) Am I understanding this correctly? 2) I later noticed that the ostringstream was was allocated with static storage. Doesn't that mean that the object is supposed to stay in memory until the program terminates? and if so , then why can't I access the string?

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• Expanding DIV slides behind DIV beneath it...

  - by Paddy

  I'm not sure that I'm going to get an answer here, as I'd need to post a lot of CSS and html to get a working recreation, however... I have structure something like this: <fieldset> <legend>Test A</legend> <h3>Test A</h3> <p> Something here. </p> <div style="display:hidden;">I'm dynamically displayed</div> </fieldset> <fieldset> <legend>Test B</legend> <h3>Test B</h3> <p> Something B here. </p> </fieldset> I have code that toggles the display of my hidden div using jQuery and .show(). This works fine in IE8, firefox and Safari, but when I stick IE8 into compatibility mode, then the first fieldset (Test A) will expand, but the expansion happens behind the second fieldset, which doesn't move (i.e. it slides down behind it). I have quite a bit of CSS in use here, and I'm going to have to go back and unpick the whold lot, which isn't a fun idea. If anybody has any idea of one of the IE7 rendering issues that might be affecting this, then I'd very much appreciate it. (note that there is more to the content in these fieldsets than shown, including floated divs). Quick note - if I stick IE7 into quirks mode, it works (but wrecks the rest of my layout) - in standards mode, I get the above behaviour.

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• Managing inverse relationships without CoreData

  - by Nathaniel Martin

  This is a question for Objective-J/Cappuccino, but I added the cocoa tag since the frameworks are so similar. One of the downsides of Cappuccino is that CoreData hasn't been ported over yet, so you have to make all your model objects manually. In CoreData, your inverse relationships get managed automatically for you... if you add an object to a to-many relationship in another object, you can traverse the graph in both directions. Without CoreData, is there any clean way to setup those inverse relationships automatically? For a more concrete example, let's take the typical Department and Employees example. To use rails terminology, a Department object has-many Employees, and an Employee belongs-to a Department. So our Department model has an NSMutableSet (or CPMutableSet ) "employees" that contains a set of Employees, and our Employee model has a variable "department" that points back to the Department model that owns it. Is there an easy way to make it so that, when I add a new Employee model into the set, the inverse relationship (employee.department) automatically gets set? Or the reverse: If I set the department model of an employee, then it automatically gets added to that department's employee set? Right know I'm making an object, "ValidatedModel" that all my models subclass, which adds a few methods that setup the inverse relationships, using KVO. But I'm afraid that I'm doing a lot of pointless work, and that there's already an easier way to do this. Can someone put my concerns to rest?

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• Ruby: how does constant-lookup work in instance_eval/class_eval?

  - by Alan O'Donnell

  I'm working my way through Pickaxe 1.9, and I'm a bit confused by constant-lookup in instance/class_eval blocks. I'm using 1.9.2. It seems that Ruby handles constant-lookup in *_eval blocks the same way it does method-lookup: look for a definition in receiver.singleton_class (plus mixins); then in receiver.singleton_class.superclass (plus mixins); then continue up the eigenchain until you get to #<Class:BasicObject>; whose superclass is Class; and then up the rest of the ancestor chain (including Object, which stores all the constants you define at the top-level), checking for mixins along the way Is this correct? The Pickaxe discussion is a bit terse. Some examples: class Foo CONST = 'Foo::CONST' class << self CONST = 'EigenFoo::CONST' end end Foo.instance_eval { CONST } # => 'EigenFoo::CONST' Foo.class_eval { CONST } # => 'EigenFoo::CONST', not 'Foo::CONST'! Foo.new.instance_eval { CONST } # => 'Foo::CONST' In the class_eval example, Foo-the-class isn't a stop along Foo-the-object's ancestor chain! And an example with mixins: module M CONST = "M::CONST" end module N CONST = "N::CONST" end class A include M extend N end A.instance_eval { CONST } # => "N::CONST", because N is mixed into A's eigenclass A.class_eval { CONST } # => "N::CONST", ditto A.new.instance_eval { CONST } # => "M::CONST", because A.new.class, A, mixes in M

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• segmentation fault in file operations in c

  - by mekasperasky

  #include<stdio.h> /* this is a lexer which recognizes constants , variables ,symbols, identifiers , functions , comments and also header files . It stores the lexemes in 3 different files . One file contains all the headers and the comments . Another file will contain all the variables , another will contain all the symbols. */ int main() { int i; char a,b[20],c; FILE *fp1; fp1=fopen("source.txt","r"); //the source file is opened in read only mode which will passed through the lexer //now lets remove all the white spaces and store the rest of the words in a file if(fp1==NULL) { perror("failed to open source.txt"); //return EXIT_FAILURE; } i=0; while(1) { a=fgetc(fp1); if(a !="") { b[i]=a; } else { fprintf(fp1, "%.20s\n", b); i=0; continue; } i=i+1; /*Switch(a) { case EOF :return eof; case '+':sym=sym+1; case '-':sym=sym+1; case '*':sym=sym+1; case '/':sym=sym+1; case '%':sym=sym+1; case ' */ } return 0; } how does this code end up in segmentation fault?

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• Servlet send image from server and save in client

  - by sangi

  Hi, I'm new and just developing on J2EE. I am modifying an existing application (an OpenSource project). I need to save an image on a client sent by the server, but I do not know how. This activity must be done in a transparent manner without affecting the existing operation of the application. From the tests done I get this error: java.lang.IllegalStateException: getWriter () has Already Been Called for this response. How should carry out this task, according to your own opinion? How do I save on the client, locally, the image? Update: Thanks for the answers. My problem is that: the image is generated on the server, but not for direct client request (there is no link to click on web page), the picture is composed using other services on the Internet. reconstruct the image on the server. This image must be sent to the client to be saved locally. so I'd like it to appear a window where you assign the destination image plus I'd like the rest of the application were not affected by this activity. The application is yet on production. Thank you very much for your response.

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• Programming exercises in Java inheritance for intern

  - by Tenner

  I work for a small software development team, working primarily in Java, for a very large company. Our new intern showed up sight-unseen (not uncommon in my company). He has some C++ experience but no Java. Worse, he's never worked with inheritance in C++. Our code has a great deal of abstraction and a heavy reliance on inheritance. We need to get him up to speed as quickly as possible. Of course the rest of the team is busy, and so we can't take the time out of our day to teach a one-student 200-level CS course. Instead, I'd like to give him an actual programming project to work on which highlights how classes, interfaces, method overrides, etc. work. I've had him look at Project Euler, but most of the solutions end up being procedural, and not object-oriented programs. Do any of you have any somewhat-straightforward (and relatively quick) projects which you would give to an intern in this situation? Or, any recent (or current) students have a school project they'd be willing to share? Anyone else had this experience?

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• How to copy generically superclass instances to subclass instances?

  - by gerry

  Hi @all, I have a class hierarchy / inheritance like this: public class A { private String name; // with getters & setters public void doAWithName(){ ... } } public class B extends A { public void doBWithName(){ // a differnt implementation to what I do in class A } } public class C extends B { public void doCWithName(){ // a differnt implementation to what I do in class A and B } } So at one time there is a instance of class A with the initialized field "name". Later I want this instance of A get wrapped into instance of B or C. So the superclasses should be get wrapped with a subclass! How can I make this most efficent with respect to DRY? I've thought about a constructor that does some copying with the getters/setters. But in this case I have to repeat myself - and this doesn't respect anymore to my initial requirement of DRY! So, how can I warp A to B by just initializing B's new fields (with default values) and delegating the rest to a method in A (which knows more than B about which fields of A should be accessed...). In the same way: If A should be wrapped into C only a method in c should init C's 'new' fields, delegate to B's wrap method (which therefore inits B's 'new' fields in C) and at last B delegates to A which copies it's fields to the fields of C). So in the end I have a new instance of C which has the values of A wrapped (and some default init values to the fields which the inheritance hierarchy has added).

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• SCJP Book, IO section: Is this a typo or is there a reason it would look like this?

  - by iamchuckb

  My question is about line 4, where the new PrintWriter is created with the constructor taking the FileWriter fw as a parameter. I don't understand the use of chaining the BufferedWriter bw to FileWriter if it isn't used later on in the actual writing. Can Java apply chaining in a way that bw still somehow affects the rest of the program? 16. try { 17. FileWriter fw = new FileWriter(test); 18. BufferedWriter bw = new BufferedWriter(fw, 1024); 19. PrintWriter out = new PrintWriter(fw); 20. out.println("<html><body><h1>"); 21. out.println(args[0]); 22. out.println("</h1></body></html>"); 23. out.close(); 24. bw.close(); 25. fw.close(); 26. }catch(IOException e) { 27. e.printStackTrace(); 28. } I think it is probably a typo and they meant to use bw as the parameter for PrintWriter out but like the title says, I'm new to this. Thanks to all in advance.

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• JQuery drag, drop and save via cookie - how to?

  - by RussP

  Sorry to be back folks, but you guys & girls seem to know much more about this than I do ... anyhow, here is my question/problem I want to use drag, drop, sort (the interface plugin does me even though I have read it's out of date? but have looked at UI and to be honest is not clear and to me appears heavier than interface?) Anyhow, how do I set a cookie to save positions from this: $(document).ready( function () { $('a.closeEl').bind('click', toggleContent); $('div.groupWrapper').Sortable( { accept: 'groupItem', helperclass: 'sortHelper', activeclass : 'sortableactive', hoverclass : 'sortablehover', handle: 'div.itemHeader', tolerance: 'pointer', onChange : function(ser) { }, onStart : function() { $.iAutoscroller.start(this, document.getElementsByTagName('body')); }, onStop : function() { $.iAutoscroller.stop(); } } ); } ); var toggleContent = function(e) { var targetContent = $('div.itemContent', this.parentNode.parentNode); if (targetContent.css('display') == 'none') { targetContent.slideDown(300); $(this).html('[-]'); } else { targetContent.slideUp(300); $(this).html('[+]'); } return false; }; var ser = function (s) { serial = $.SortSerialize(s); alert(serial.hash); }; which is the "standard" interface demo, PLUS How do I then get to read that cookie so that when I next visit the page the order is as I set it in the cookie? Hopefully from that I can work out the rest .......? Thanks for help in advance.

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• Migrate Data and Schema from MySQL to MSSQL

  - by colithium

  Are there any free solutions for automatically migrating a database from MySQL to MSSQL Server that "just works"? I've been attempting this simple (at least I thought so) task all day now. I've tried: MSSQL Server Management Studio's Import Data feature Create an empty database Tasks - Import Data... .NET Framework Data Provider for Odbc Valid DSN (verified it connects) Copy data from one or more tables or views Check 1 VERY simple table Click Preview Get Error: The preview data could not be retrieved. ADDITIONAL INFORMATION: ERROR [42000] [MySQL][ODBC 5.1 Driver][mysqld-5.1.45-community]You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '"table_name"' at line 1 (myodbc5.dll) A similar error occurs if I go through the rest of the wizard and perform the operation. The failed step is "Setting Source Connection" the error refers to retrieving column information and then lists the above error. It can retrieve column information just fine when I modify column mappings so I really don't know what the issue is. I've also tried getting various MySql tools to output ddl statements that MSSQL understand but haven't succeeded. I've tried with MySQL v5.1.11 to SQL Server 2005 and with MySQL v5.1.45 to SQL Server 2008 (with ODBC drivers 3.51.27.00 and 5.01.06.00 respectively)

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• What database strategy to choose for a large web application

  - by Snoopy

  I have to rewrite a large database application, running on 32 servers. The hardware is up to date, each machine has two quad core Xeon and 32 GByte RAM. The database is multi-tenant, each customer has his own file, around 5 to 10 GByte each. I run around 50 databases on this hardware. The app is open to the web, so I have no control on the load. There are no really complex queries, so SQL is not required if there is a better solution. The databases get updated via FTP every day at midnight. The database is read-only. C# is my favourite language and I want to use ASP.NET MVC. I thought about the following options: Use two big SQL servers running SQL Server 2012 to serve the 32 servers with data. On the 32 servers running IIS hosting providing REST services. Denormalize the database and use Redis on each webserver. Use booksleeve as a Redis client. Use a combination of SQL Server and Redis Use SQL Server 2012 together with Hadoop Use Hadoop without SQL Server What is the best way for a read-only database, to get the best performance without loosing maintainability? Does Map-Reduce make sense at all in such a scenario? The reason for the rewrite is, the old app written in C++ with ISAM technology is too slow, the interfaces are old fashioned and not nice to use from an website, especially when using ajax. The app uses a relational datamodel with many tables, but it is possible to write one accerlerator table where all queries can be performed on, and all other information from the other tables are possible by a simple key lookup.

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• Database contents setting themselves to 0

  - by Luis Armando

  I have a Database that contains 4 tables, however I'm using 1 of them which is separated from the others. In this table I have 4 fields which are varchar and the rest are ints (11 other fields), when the users fill up the DB everything gets saved correctly, however it has happened 3 times so far that the database values for the int's reset to 0 without any apparent reason. At first, I thought, it was because those fields (where the numbers should go) were varchars not ints. However since I changed it, it happened again. I've already double checked my code and I have nothing that even updates or inserts a 0 value. Also I'm using codeigniter and active records which protect against SQL injections AND have XSS filtering enabled, could anyone point out something I might be missing or a reason for this to be happening? Also, I'm pretty sure about the answer of this but, is there ANY way to recover some data?? Other than having to ask everyone to fill in everything again.. =/ ** EDIT ** The Storage Engine is MyISAM and Collation is latin1_swedish_ci, Pack Keys are default, for all intents and purposes it's a normal DB

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• Truncating a string while storing it in an array in c

  - by Nick

  I am trying to create an array of 20 character strings with a maximum of 17 characters that are obtained from a file named "words.dat". After that the program should truncate the string only showing the first 17 characters and completely ignore the rest of that string. However My question is: I am not quite sure how to accomplish this, can anyone give me some insight on how to accomplish this task? Here is my current code as is: #include <stdio.h> #include <stdlib.h> #define WORDS 20 #define LENGTH 18 char function1(char[WORDS][LENGTH]); int main( void ) { char word_array [WORDS] [LENGTH]; function1(word_array); return ( 0 ) ; } char function1(char word_array[WORDS][LENGTH]) { FILE *wordsfile = fopen("words.dat", "r"); int i = 0; if (wordsfile == NULL) printf("\nwords.dat was not properly opened.\n"); else { for (i = 0; i < WORDS; i++) { fscanf(wordsfile, "%17s", word_array[i]); printf ("%s \n", word_array[i]); } fclose(wordsfile); } return (word_array[WORDS][LENGTH]); } words.dat file: Ninja DragonsFury failninja dragonsrage leagueoflegendssurfgthyjnu white black red green yellow green leagueoflegendssughjkuj dragonsfury Sword sodas tiger snakes Swords Snakes sage Sample output: blahblah@fang:~>a.out Ninja DragonsFury failninja dragonsrage leagueoflegendssu rfgthyjnu white black red green yellow green leagueoflegendssu ghjkuj dragonsfury Sword sodas tiger snakes Swords blahblah@fang:~> What will be accomplished afterwards with this program is: After function1 works properly I will then create a second function name "function2" that will look throughout the array for matching pairs of words that match "EXACTLY" including case . After I will create a third function that displays the 20 character strings from the words.dat file that I previously created and the matching words.

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• Rails can't find my route but it exists!

  - by DJTripleThreat

  Ok I have events that I want to publish/unpublish with an extra action (nonRESTful) I watched Ryan Bates' railscast on this: http://railscasts.com/episodes/35-custom-rest-actions and it got me most of the way. I think the problem is that my route is nested in an /admin section so even though when I run rake routes and get: publish_admin_event PUT /admin/events/:id/publish(.:format) {:controller=>"event_services", :action=>"publish"} This won't work in my /views/admin/index.html.erb file: <%= link_to 'Publish', publish_admin_event(event), :method => :put %> because it claims that path doesn't exist! And neither will this: <%= link_to 'Publish', {:controller => :event_services, :action => :publish}, {:method => :put, :id => event} %> and says that "No route matches {:controller=>"event_services", :action=>"publish"}" so what gives? (And I've tried restarting my server so that isn't it.) EDIT: This DOES work: <%= link_to 'Publish', "/admin/events/" + event.id.to_s + "/publish", :method => :put %> But I'd rather NOT do this.

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• Deserialize json with json.net c#

  - by 76mel

  Hi, am new to Json so a little green. I have a Rest Based Service that returns a json string; {"treeNode":[{"id":"U-2905","pid":"R","userId":"2905"}, {"id":"U-2905","pid":"R","userId":"2905"}]} I have been playing with the Json.net and trying to Deserialize the string into Objects etc. I wrote an extention method to help. public static T DeserializeFromJSON<T>(this Stream jsonStream, Type objectType) { T result; using (StreamReader reader = new StreamReader(jsonStream)) { JsonSerializer serializer = new JsonSerializer(); try { result = (T)serializer.Deserialize(reader, objectType); } catch (Exception e) { throw; } } return result; } I was expecting an array of treeNode[] objects. But its seems that I can only deserialize correctly if treeNode[] property of another object. public class treeNode { public string id { get; set; } public string pid { get; set; } public string userId { get; set; } } I there a way to to just get an straight array from the deserialization ? Cheers

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• SQL Server INSERT, Scope_Identity() and physical writing to disc

  - by TheBlueSky

  Hello everyone, I have a stored procedure that does, among other stuff, some inserts in different table inside a loop. See the example below for clearer understanding: INSERT INTO T1 VALUES ('something') SET @MyID = Scope_Identity() ... some stuff go here INSERT INTO T2 VALUES (@MyID, 'something else') ... The rest of the procedure These two tables (T1 and T2) have an IDENTITY(1, 1) column in each one of them, let's call them ID1 and ID2; however, after running the procedure in our production database (very busy database) and having more than 6250 records in each table, I have noticed one incident where ID1 does not match ID2! Although normally for each record inserted in T1, there is record inserted in T2 and the identity column in both is incremented consistently. The "wrong" records were something like that: ID1 Col1 ---- --------- 4709 data-4709 4710 data-4710 ID2 ID1 Col1 ---- ---- --------- 4709 4710 data-4709 4710 4709 data-4710 Note the "inverted", ID1 in the second table. Knowing not that much about SQL Server underneath operations, I have put the following "theory", maybe someone can correct me on this. What I think is that because the loop is faster than physically writing to the table, and/or maybe some other thing delayed the writing process, the records were buffered. When it comes the time to write them, they were wrote in no particular order. Is that even possible if no, how to explain the above mentioned scenario? If yes, then I have another question to rise. What if the first insert (from the code above) got delayed? Doesn't that mean I won't get the correct IDENTITY to insert into the second table? If the answer of this is also yes, what can I do to insure the insertion in the two tables will happen in sequence with the correct IDENTITY? I appreciate any comment and information that help me understand this. Thanks in advance.

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• How can I render an in-memory UIViewController's view Landscape?

  - by Aaron

  I'm trying to render an in-memory (but not in hierarchy, yet) UIViewController's view into an in-memory image buffer so I can do some interesting transition animations. However, when I render the UIViewController's view into that buffer, it is always rendering as though the controller is in Portrait orientation, no matter the orientation of the rest of the app. How do I clue this controller in? My code in RootViewController looks like this: MyUIViewController* controller = [[MyUIViewController alloc] init]; int width = self.view.frame.size.width; int height = self.view.frame.size.height; int bitmapBytesPerRow = width * 4; unsigned char *offscreenData = calloc(bitmapBytesPerRow * height, sizeof(unsigned char)); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef offscreenContext = CGBitmapContextCreate(offscreenData, width, height, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast); CGContextTranslateCTM(offscreenContext, 0.0f, height); CGContextScaleCTM(offscreenContext, 1.0f, -1.0f); [(CALayer*)[controller.view layer] renderInContext:offscreenContext]; At that point, the offscreen memory buffers contents are portrait-oriented, even when the window is in landscape orientation. Ideas?

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• remove duplicated array values in a function PHP

  - by Deividas Juškevicius

  I read all topics related to this question in stackoverflow and whole internet and cant find working sollution... Each owner has his item and when someone buy his item, owner gets an confirmation email, but when in cart is few same owner items, he gets several same email letters, so I need to remove dublicated array entries. I have tried to use DISTINCT and array_uniques functions but no luck. Any advices? I have an array and function to send mail.. function email($mail_array) { foreach(array_unique($mail_array) as $field => $value) { $result = mysql_query("select email from users where $field='$value'"); $row = mysql_fetch_array($result); $maail = mysql_real_escape_string($row['email']); $email_to = "".$maail.""; // rest of mail formatting code // create email headers $headers = 'From: '.$email_from."\r\n" . 'Reply-To: '.$email_from."\r\n" . 'X-Mailer: PHP/' . phpversion(); @mail($email_to, $email_subject, $email_message, $headers); } for ($i = 0; $i < $max; $i++) { $pid = $_SESSION['cart'][$i]['productid']; $owner = get_owner($pid); $mail_array = array( 'name' => $owner ); email($mail_array) //call function to send mail }

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• How do I find all paths through a set of given nodes in a DAG?

  - by Hanno Fietz

  I have a list of items (blue nodes below) which are categorized by the users of my application. The categories themselves can be grouped and categorized themselves. The resulting structure can be represented as a Directed Acyclic Graph (DAG) where the items are sinks at the bottom of the graph's topology and the top categories are sources. Note that while some of the categories might be well defined, a lot is going to be user defined and might be very messy. Example: On that structure, I want to perform the following operations: find all items (sinks) below a particular node (all items in Europe) find all paths (if any) that pass through all of a set of n nodes (all items sent via SMTP from example.com) find all nodes that lie below all of a set of nodes (intersection: goyish brown foods) The first seems quite straightforward: start at the node, follow all possible paths to the bottom and collect the items there. However, is there a faster approach? Remembering the nodes I already passed through probably helps avoiding unnecessary repetition, but are there more optimizations? How do I go about the second one? It seems that the first step would be to determine the height of each node in the set, as to determine at which one(s) to start and then find all paths below that which include the rest of the set. But is this the best (or even a good) approach? The graph traversal algorithms listed at Wikipedia all seem to be concerned with either finding a particular node or the shortest or otherwise most effective route between two nodes. I think both is not what I want, or did I just fail to see how this applies to my problem? Where else should I read?

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• Python: Errors saving and loading objects with pickle module

  - by Peterstone

  Hi, I am trying to load and save objects with this piece of code I get it from a question I asked a week ago: Python: saving and loading objects and using pickle. The piece of code is this: class Fruits: pass banana = Fruits() banana.color = 'yellow' banana.value = 30 import pickle filehandler = open("Fruits.obj","wb") pickle.dump(banana,filehandler) filehandler.close() file = open("Fruits.obj",'rb') object_file = pickle.load(file) file.close() print(object_file.color, object_file.value, sep=', ') At a first glance the piece of code works well, getting load and see the 'color' and 'value' of the saved object. But, what I pursuit is to close a session, open a new one and load what I save in a past session. I close the session after putting the line filehandler.close() and I open a new one and I put the rest of your code, then after putting object_file = pickle.load(file) I get this error: Traceback (most recent call last): File "<pyshell#5>", line 1, in <module> object_file = pickle.load(file) File "C:\Python31\lib\pickle.py", line 1365, in load encoding=encoding, errors=errors).load() AttributeError: 'module' object has no attribute 'Fruits' Can anyone explain me what this error message means and telling me how to solve this problem? Thank so much and happy new year!!

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• Display Yearly Report When Data Not Available (CI, PHP, MySQL)

  - by tegaralaga

  First of all, i do apologize for my bad english, cos english isn't my native language. I want to display yearly report based on month, let say i got order on January, August, December, but the rest there's no order. So in MySQL database only have 3 order (Jan,Aug,Dec). When i query use CI ( select month(order_date) as month_name , count(order_id) as amount from order where year(order_date)=2011 group by month(order_date) ) there's only 3 data let say the 3 data is (use $query-result_array()) Array ( [0] => Array ( [month_num] => 1 [amount] => 4 ) [1] => Array ( [month_num] => 8 [amount] => 1 ) [2] => Array ( [month_num] => 12 [amount] => 19 ) ) how to make it to 12 data (12 Month) the array become like this (when data not available the amount is 0) Array ( [0] => Array ( [month_num] => 1 [amount] => 4 ) [1] => Array ( [month_num] => 2 [amount] => 0 ) [2] => Array ( [month_num] => 3 [amount] => 0 ) etc ) Thanks in advance :)

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• pure/const functions in C++

  - by Albert

  Hi, I'm thinking of using pure/const functions more heavily in my C++ code. (pure/const attribute in GCC) However, I am curious how strict I should be about it and what could possibly break. The most obvious case are debug outputs (in whatever form, could be on cout, in some file or in some custom debug class). I probably will have a lot of functions, which don't have any side effects despite this sort of debug output. No matter if the debug output is made or not, this will absolutely have no effect on the rest of my application. Or another case I'm thinking of is the use of my own SmartPointer class. In debug mode, my SmartPointer class has some global register where it does some extra checks. If I use such an object in a pure/const function, it does have some slight side effects (in the sense that some memory probably will be different) which should not have any real side effects though (in the sense that the behaviour is in any way different). Similar also for mutexes and other stuff. I can think of many complex cases where it has some side effects (in the sense of that some memory will be different, maybe even some threads are created, some filesystem manipulation is made, etc) but has no computational difference (all those side effects could very well be left out and I would even prefer that). How does it work out in practice? If I mark such functions as pure/const, could it break anything (considering that the code is all correct)?

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