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  • LINQ - Splitting up a string with maximum length, but not chopping words apart.

    - by Stacey
    I have a simple LINQ Extension Method... public static IEnumerable<string> SplitOnLength(this string input, int length) { int index = 0; while (index < input.Length) { if (index + length < input.Length) yield return input.Substring(index, length); else yield return input.Substring(index); index += length; } } This takes a string, and it chops it up into a collection of strings that do not exceed the given length. This works well - however I'd like to go further. It chops words in half. I don't need it to understand anything complicated, I just want it to be able to chop a string off 'early' if cutting it at the length would be cutting in the middle of text (basically anything that isn't whitespace). However I suck at LINQ, so I was wondering if anyone had an idea on how to go about this. I know what I am trying to do, but I'm not sure how to approach it. So let's say I have the following text. This is a sample block of text that I would pass through the string splitter. I call this method SplitOnLength(6) I would get the following. This i s a sa mple b lock o f text that I would pass t hrough the s tring splitt er. I would rather it be smart enough to stop and look more like .. This is a sample // bad example, since the single word exceeds maximum length, but the length would be larger numbers in real scenarios, closer to 200. Can anyone help me?

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  • std::map keys in C++

    - by Soumava
    I have a requirement to create two different maps in C++. The Key is of type CHAR * and the Value is a pointer to a struct. I am filling 2 maps with these pairs, in separate iterations. After creating both maps I need find all such instances in which the value of the string referenced by the CHAR * are same. For this i am using the following code : typedef struct _STRUCTTYPE { .. } STRUCTTYPE, *PSTRUCTTYPE; typedef pair {CHAR *,PSTRUCTTYPE} kvpair; .. CHAR *xyz; PSTRUCTTYPE abc; after filling the information; Map.insert (kvpair(xyz,abc)); the above is repeated x times for the first map, and y times for the second map. after both are filled out; std::map {CHAR *, PSTRUCTTYPE} :: iterator Iter,findIter; for (Iter=iteratedMap-begin();Iter!=iteratedMap-end();mapIterator++) { char *key = Iter-first; printf("%s\n",key); findIter=otherMap-find(key); //printf("%u",findIter-second); if (findIter!=otherMap-end()) { printf("Match!\n"); } } The above code does not show any match, although the list of keys in both maps show obvious matches. My understanding is that the equals operator for CHAR * just equates the memory address of the pointers. My question is, what should i do to alter the equals operator for this type of key or could I use a different datatype for the string? *note : {} has been used instead of angle brackets as the content inside angle brackets was not showing up in the post.

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  • MySQL: Limit rows linked to each joined row

    - by SolidSnakeGTI
    Hello, Specifications: MySQL 4.1+ I've certain situation that requires certain result set from MySQL query, let's see the current query first & then ask my question: SELECT thread.dateline AS tdateline, post.dateline AS pdateline, MIN(post.dateline) FROM thread AS thread LEFT JOIN post AS post ON(thread.threadid = post.threadid) LEFT JOIN forum AS forum ON(thread.forumid = forum.forumid) WHERE post.postid != thread.firstpostid AND thread.open = 1 AND thread.visible = 1 AND thread.replycount >= 1 AND post.visible = 1 AND (forum.options & 1) AND (forum.options & 2) AND (forum.options & 4) AND forum.forumid IN(1,2,3) GROUP BY post.threadid ORDER BY tdateline DESC, pdateline ASC As you can see, mainly I need to select dateline of threads from 'thread' table, in addition to dateline of the second post of each thread, that's all under the conditions you see in the WHERE CLAUSE. Since each thread has many posts, and I need only one result per thread, I've used GROUP BY CLAUSE for that purpose. This query will return only one post's dateline with it's related unique thread. My questions are: How to limit returned threads per each forum!? Suppose I need only 5 threads -as a maximum- to be returned for each forum declared in the WHERE CLAUSE 'forum.forumid IN(1,2,3)', how can this be achieved. Is there any recommendations for optimizing this query (of course after solving the first point)? Notes: I prefer not to use sub-queries, but if it's the only solution available I'll accept it. Double queries not recommended. I'm sure there's a smart solution for this situation. Appreciated advice in advance :)

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  • How can multiple variables be passed to a function cleanly in C?

    - by aquanar
    I am working on an embedded system that has different output capabilities (digital out, serial, analog, etc). I am trying to figure out a clean way to pass many of the variables that will control those functions. I don't need to pass ALL of them too often, but I was hoping to have a function that would read the input data (in this case from a TCP network), and then parse the data (IE, the 3rd byte contains the states of 8 of the digital outputs (according to which bit in that byte is high or low)), and put that into a variable where I can then use elsewhere in the program. I wanted that function to be separate from the main() function, but to do so would require passing pointers to some 20 or so variables that it would be writing to. I know I could make the variables global, but I am trying to make it easier to debug by making it obvious when a function is allowed to edit that variable, by passing it to the function. My best idea was a struct, and just pass a pointer to it, but wasn't sure if there was a more efficient way, especially since there is only really 1 function that would need to access all of them at once, while most others only require parts of the information that will be stored in this bunch of state variables. So anyway, is there a clean way to send many variables between functions at once that need to be edited?

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  • Number of characters recommended for a statement

    - by liaK
    Hi, I have been using Qt 4.5 and so do C++. I have been told that it's a standard practice to maintain the length of each statement in the application to 80 characters. Even in Qt creator we can make a right border visible so that we can know whether we are crossing the 80 characters limit. But my question is, Is it really a standard being followed? Because in my application, I use indenting and all, so it's quite common that I cross the boundary. Other cases include, there might be a error statement which will be a bit explanatory one and which is in an inner block of code, so it too will cross the boundary. Usually my variable names look bit lengthier so as to make the names meaningful. When I call the functions of the variable names, again I will cross. Function names will not be in fewer characters either. I agree a horizontal scroll bar shows up and it's quite annoying to move back and forth. So, for function calls including multiple arguments, when the boundary is reached I will make the forth coming arguments in the new line. But besides that, for a single statement (for e.g a very long error message which is in double quotes " " or like longfun1()->longfun2()->...) if I use an \ and split into multiple lines, the readability becomes very poor. So is it a good practice to have those statement length restrictions? If this restriction in statement has to be followed? I don't think it depends on a specific language anyway. I added C++ and Qt tags since if it might. Any pointers regarding this are welcome.

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  • Is there a way to create subdatabases as a kind of subfolders in sql server?

    - by user193655
    I am creating an application where there is main DB and where other data is stored in secondary databases. The secondary databases follow a "plugin" approach. I use SQL Server. A simple installation of the application will just have the mainDB, while as an option one can activate more "plug-ins" and for every plug-in there will be a new database. Now why I made this choice is because I have to work with an exisiting legacy system and this is the smartest thing I could figure to implement the plugin system. MainDB and Plugins DB have exactly the same schema (basically Plugins DB have some "special content", some important data that one can use as a kind of template - think to a letter template for example - in the application). Plugin DBs are so used in readonly mode, they are "repository of content". The "smart" thing is that the main application can also be used by "plugin writers", they just write a DB inserting content, and by making a backup of the database they creaetd a potential plugin (this is why all DBs has the same schema). Those plugins DB are downloaded from internet as there is a content upgrade available, every time the full PlugIn DB is destroyed and a new one with the same name is creaetd. This is for simplicity and even because the size of this DBs is generally small. Now this works, anyway I would prefer to organize the DBs in a kind of Tree structure, so that I can force the PlugIn DBs to be "sub-DBs" of the main application DB. As a workaround I am thinking of using naming rules, like: ApplicationDB (for the main application DB) ApplicationDB_PlugIn_N (for the N-th plugin DB) When I search for plugin 1 I try to connect to ApplicationDB_PlugIn_1, if I don't find the DB i raise an error. This situation can happen for example if som DBA renamed ApplicationDB_Plugin_1. So since those Plugin DBs are really dependant on ApplicationDB only I was trying to "do the subfolder trick". Can anyone suggest a way to do this? Can you comment on this self-made plugin approach I decribed above?

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  • Need a Java based interruptible timer thread

    - by LambeauLeap
    I have a Main Program which is running a script on the target device(smart phone) and in a while loop waiting for stdout messages. However in this particular case, some of the heartbeat messages on the stdout could be spaced almost 45secs to a 1minute apart. something like: stream = device.runProgram(RESTORE_LOGS, new String[] {}); stream.flush(); String line = stream.readLine(); while (line.compareTo("") != 0) { reporter.commentOnJob(jobId, line); line = stream.readLine(); } So, I want to be a able to start a new interruptible thread after reading line from stdout with a required a sleep window. Upon being able to read a new line, I want to be able to interrupt/stop(having trouble killing the process), handle the newline of stdout text and restart a process. And it the event I am not able to read a line within the timer window(say 45secs) I want to a way to get out of my while loop either. I already tried the thread.run, thread.interrupt approach. But having trouble killing and starting a new thread. Is this the best way out or am I missing something obvious?

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  • Bind to a collection's view and just call ToString() in WPF

    - by womp
    I'm binding a GridView to a collection of objects that look like this: public class Transaction { public string PersonName { get; set; } public DateTime TransactionDate { get; set; } public MoneyCollection TransactedMoney { get; set;} } MoneyCollection simply inherits from ObservableCollection<T>, and is a collection of MyMoney type object. In my GridView, I just want to bind a column to the MoneyCollection's ToString() method. However, binding it directly to the TransactedMoney property makes every entry display the text "(Collection)", and the ToString() method is never called. Note that I do not want to bind to the items in MoneyCollection, I want to bind directly to the property itself and just call ToString() on it. I understand that it is binding to the collection's default view. So my question is - how can I make it bind to the collection in such a way that it calls the ToString() method on it? This is my first WPF project, so I know this might be a bit noobish, but pointers would be very welcome.

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  • C++ reference variable again!!!

    - by kumar_m_kiran
    Hi All, I think most would be surprised about the topic again, However I am referring to a book "C++ Common Knowledge: Essential Intermediate Programming" written by "Stephen C. Dewhurst". In the book, he quotes a particular sentence (in section under Item 5. References Are Aliases, Not Pointers), which is as below A reference is an alias for an object that already exists prior to the initialization of the reference. Once a reference is initialized to refer to a particular object, it cannot later be made to refer to a different object; a reference is bound to its initializer for its whole lifetime Can anyone please explain the context of "cannot later be made to refer to a different object" Below code works for me, #include <iostream> using namespace std; int main(int argc, char *argv[]) { int i = 100; int& ref = i; cout<<ref<<endl; int k = 2000; ref = k; cout<<ref<<endl; return 0; } Here I am referring the variable ref to both i and j variable. And the code works perfectly fine. Am I missing something? I have used SUSE10 64bit linux for testing my sample program. Thanks for your input in advance.

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  • To display the images in mobile devices is it necessary that the images should resides on device in

    - by Shailesh Jaiswal
    I am devloping smart device application in C#. In this application I have some images in my application which I used to dispay on emulator from my application. To display the images on emulator I need to create the one folder of images which resides on the emulator. Only after that I am able to display the images in emulator. I am able to create the folder in emulator by using File-Configure-General-Shared Folder. For sharing the folder I am giving the path of the folder which contains the images. Once I share the folder the folder of images which resides in my application will get copied in emulator with the name "Storage Card". Now I need to use the path as Bitmap bmp=new Bitmap(@"/Storage Card/ImageName.jpg"); Now I am able to display the images in emulator. Can we display the images in the emulator without any image folder which resides on emultor (so that we dont need to place the image folder in emulator as in the above case by sharing the folder) ? If the answere is no then to run the application on different mobile devices we need to place the folder which contains the images on different mobile devices. Isnt it? If the answere is yes then how we can display the images on different mobile device from our application without placing any folder of images on mobile devices?

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  • operator overloading and inheritance

    - by user168715
    I was given the following code: class FibHeapNode { //... // These all have trivial implementation virtual void operator =(FibHeapNode& RHS); virtual int operator ==(FibHeapNode& RHS); virtual int operator <(FibHeapNode& RHS); }; class Event : public FibHeapNode { // These have nontrivial implementation virtual void operator=(FibHeapNode& RHS); virtual int operator==(FibHeapNode& RHS); virtual int operator<(FibHeapNode& RHS); }; class FibHeap { //... int DecreaseKey(FibHeapNode *theNode, FibHeapNode& NewKey) { FibHeapNode *theParent; // Some code if (theParent != NULL && *theNode < *theParent) { //... } //... return 1; } }; Much of FibHeap's implementation is similar: FibHeapNode pointers are dereferenced and then compared. Why does this code work? (or is it buggy?) I would think that the virtuals here would have no effect: since *theNode and *theParent aren't pointer or reference types, no dynamic dispatch occurs and FibHeapNode::operator< gets called no matter what's written in Event.

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  • C++ ulong to class method pointer and back

    - by Simone Margaritelli
    Hi guys, I'm using a hash table (source code by Google Inc) to store some method pointers defined as: typedef Object *(Executor::*expression_delegate_t)( vframe_t *, Node * ); Where obviously "Executor" is the class. The function prototype to insert some value to the hash table is: hash_item_t *ht_insert( hash_table_t *ht, ulong key, ulong data ); So basically i'm doing the insert double casting the method pointer: ht_insert( table, ASSIGN, reinterpret_cast<ulong>( (void *)&Executor::onAssign ) ); Where table is defined as a 'hash_table_t *' inside the declaration of the Executor class, ASSIGN is an unsigned long value, and 'onAssign' is the method I have to map. Now, Executor::onAssign is stored as an unsigned long value, its address in memory I think, and I need to cast back the ulong to a method pointer. But this code: hash_item_t* item = ht_find( table, ASSIGN ); expression_delegate_t delegate = reinterpret_cast < expression_delegate_t > (item->data); Gives me the following compilation error : src/executor.cpp:45: error: invalid cast from type ‘ulong’ to type ‘Object* (Executor::*)(vframe_t*, Node*)’ I'm using GCC v4.4.3 on a x86 GNU/Linux machine. Any hints?

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  • Unit testing a 'legacy' WPF Application

    - by sc_ray
    The product I have been working on has been in development for the past six years. It started as a generic data entry portal into an insanely complex part WPF/part legacy application. The system has been developed for all these years without a single Unit test in its fold. Now, the point has been raised for a comprehensive unit testing framework. I have been recruited recently to work on this product and have been tasked to get the 'Testing' in order. Since the team that worked on the product for the last six years adopted 'Agile', the project lacks any documentation of the business rules or any design documents. I have been trying to write unit tests for some of the modules. But I am not sure what to Mock, how to setup my Test fixture and eventually what to Test for, since a casual glance of the methods does not reveal its intentions. Also, it has come to my attention that the code was not developed with a particular methodology in mind. Given the situation, I was wondering if the good people of Stackoverflow could provide me with some advise on how to salvage this situation. I have heard about the book 'Working with Legacy Code' that has something to say about this general situation but I was thinking about getting some pointers from individuals who have encountered similar situations within the technology stack(C#,VB,C++,.NET 3.5,WCF,SQL Server 2005).

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  • Porting Perl to C++ `print "\x{2501}" x 12;`

    - by jippie
    I am porting a program from Perl to C++ as a learning objective. I arrived at a routine that draws a table with commands like the following: Perl: print "\x{2501}" x 12; And it draws 12 times a '?' ("box drawings heavy horizontal"). Now I figured out part of the problem already: Perl: \x{}, \x00 Hexadecimal escape sequence; C++: \unnnn To print a single Unicode character: C++: printf( "\u250f\n" ); But does C++ have a smart equivalent for the 'x' operator or would it come down to a for loop? UPDATE Let me include the full source code I am trying to compile with the proposed solution. The compiler does throw an errors: g++ -Wall -Werror project.cpp -o project project.cpp: In function ‘int main(int, char**)’: project.cpp:38:3: error: ‘string’ is not a member of ‘std’ project.cpp:38:15: error: expected ‘;’ before ‘s’ project.cpp:39:3: error: ‘cout’ is not a member of ‘std’ project.cpp:39:16: error: ‘s’ was not declared in this scope #include <stdlib.h> #include <stdint.h> #include <stdio.h> #include <string.h> int main ( int argc, char *argv[] ) { if ( argc != 2 ) { fprintf( stderr , "usage: %s matrix\n", argv[0] ); exit( 2 ); } else { //std::string s(12, "\u250f" ); std::string s(12, "u" ); std::cout << s; } }

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  • C++/Qt - Memory allocation question

    - by HardCoder1986
    Hello! I recently started investigating Qt for myself and have the following question: Suppose I have some QTreeWidget* widget. At some moment I want to add some items to it and this is done via the following call: QList<QTreeWidgetItem*> items; // Prepare the items QTreeWidgetItem* item1 = new QTreeWidgetItem(...); QTreeWidgetItem* item2 = new QTreeWidgetItem(...); items.append(item1); items.append(item2); widget->addTopLevelItems(items); So far it looks ok, but I don't actually understand who should control the objects' lifetime. I should explain this with an example: Let's say, another function calls widget->clear();. I don't know what happens beneath this call but I do think that memory allocated for item1 and item2 doesn't get disposed here, because their ownage wasn't actually transfered. And, bang, we have a memory leak. The question is the following - does Qt have something to offer for this kind of situation? I could use boost::shared_ptr or any other smart pointer and write something like shared_ptr<QTreeWidgetItem> ptr(new QTreeWidgetItem(...)); items.append(ptr.get()); but I don't know if the Qt itself would try to make explicit delete calls on my pointers (which would be disastrous since I state them as shared_ptr-managed). How would you solve this problem? Maybe everything is evident and I miss something really simple?

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  • Write file need to optimised for heavy traffic part 2

    - by Clayton Leung
    For anyone interest to see where I come from you can refer to part 1, but it is not necessary. write file need to optimised for heavy traffic Below is a snippet of code I have written to capture some financial tick data from the broker API. The code will run without error. I need to optimize the code, because in peak hours the zf_TickEvent method will be call more than 10000 times a second. I use a memorystream to hold the data until it reaches a certain size, then I output it into a text file. The broker API is only single threaded. void zf_TickEvent(object sender, ZenFire.TickEventArgs e) { outputString = string.Format("{0},{1},{2},{3},{4}\r\n", e.TimeStamp.ToString(timeFmt), e.Product.ToString(), Enum.GetName(typeof(ZenFire.TickType), e.Type), e.Price, e.Volume); fillBuffer(outputString); } public class memoryStreamClass { public static MemoryStream ms = new MemoryStream(); } void fillBuffer(string outputString) { byte[] outputByte = Encoding.ASCII.GetBytes(outputString); memoryStreamClass.ms.Write(outputByte, 0, outputByte.Length); if (memoryStreamClass.ms.Length > 8192) { emptyBuffer(memoryStreamClass.ms); memoryStreamClass.ms.SetLength(0); memoryStreamClass.ms.Position = 0; } } void emptyBuffer(MemoryStream ms) { FileStream outStream = new FileStream("c:\\test.txt", FileMode.Append); ms.WriteTo(outStream); outStream.Flush(); outStream.Close(); } Question: Any suggestion to make this even faster? I will try to vary the buffer length but in terms of code structure, is this (almost) the fastest? When memorystream is filled up and I am emptying it to the file, what would happen to the new data coming in? Do I need to implement a second buffer to hold that data while I am emptying my first buffer? Or is c# smart enough to figure it out? Thanks for any advice

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  • Emailing a fixed document through Outlook

    - by MoominTroll
    I've added functionality to an application that prints out a bunch of information to a FixedDOcument and sends this off to the printer. This works just fine, however the request is that there be an in application function that emails the document using OUtlook and its here that I come unstuck. I'd very much like to just reuse the class that makes the fixed document for printing to generate the text for email, but I'm struggling to do this. I've tried the following... Microsoft.Office.Interop.Outlook.Application oApp = new Microsoft.Office.Interop.Outlook.Application(); MailItem email = (MailItem)(oApp.CreateItem(OlItemType.olMailItem)); email.Recipients.Add("[email protected]"); email.Subject = "Hello"; email.Body = "TEST"; FixedDocument doc = CreateReport(); //make my fixed document //this doesn't work, and the parameters it takes suggest it never will email.Attachments.Add(doc, OlAttachmentType.olByValue, 1, null); email.Send(); I can't help but think I'm on completely the wrong tack here, but I don't really want to have to write a bunch of new text formatting (since email.Body only takes a string) when I've already got the content formatted how I want it. Note that the content is all textual, so I don't really care if it gets sent as an attachment or as text in the emails body. Ideally if its sent as an attachment it won't be saved anywhere permanently. Any pointers?

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  • Can I create an activity for a particular task without that task coming to the foreground?

    - by Neil Traft
    Here's my use case: The app starts at a login screen. You enter your credentials and hit the "Login" button. Then a progress dialog appears and you wait for some stuff to download. Once the stuff has downloaded, you are taken to a new activity. Exactly which activity you are taken to depends on the server response. Here's my problem: If you go HOME during this login/download process, at some point in the near future your download will complete and will invoke startActivity(). So then the new activity will be pushed to the foreground, rudely interrupting the user. I can't start the activity before I start the download, because, as I mentioned earlier, the activity I start depends on the result of the download. I would obviously not like to interrupt the user like this. One way to solve this is to refrain from calling startActivity() until the user returns to the app. I can do this by keeping track of the LoginActivity's onStop() and onRestart(). But I'm wondering, is there any way to create the activity while it is in the background? That way the user returns to the app and he is ready to go... otherwise he would have to wait for the new activity to be created (which could take some time because the new activity also has to download and display some data). Update: Guess what? I LIED! I could have sworn that starting this activity was causing it to come to the foreground, but I went back to test it again and the problem has magically disappeared. I tested in both 1.6 and 2.0.1 and both OSes were smart enough not to bring a backgrounded task to the front.

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  • Extract information from a Func<bool, T> or alike lambda

    - by Syska
    I''m trying to build a generic cache layer. ICacheRepository Say I have the following: public class Person { public int PersonId { get; set; } public string Firstname { get; set; } public string Lastname { get; set; } public DateTime Added { get; set; } } And I have something like this: list.Where(x => x.Firstname == "Syska"); Here I want to extract the above information, to see if the query supplied the "PersonId" which it did not, so I dont want to cache it. But lets say I run a query like this: list.Where(x => x.PersonId == 10); Since PersonId is my key ... I want to cache it. with the key like "Person_10" and I later can fetch it from the cache. I know its possible to extract the information with Expression<Func<>> but there seems to be a big overhead of doing this (when running compile and extract the Constant values etc. and a bunch of cache to be sure to parse right) Are there a framework for this? Or some smart/golden way of doing this ?

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  • When asked "How do I make a website?" how do you answer?

    - by Luke CK
    A (non-technical) friend of mine has asked me how to make a website. I get this question all the time. After a few questions I found out that she has an idea that could turn into a commercial site. I described three options to her: a) Get a book/enroll in a class/follow some online tutorials and learn how to do it. She's pretty smart and her personality seems like a good match for this sort of thing so I'm sure she could learn but she doesn't have a lot of time spare. Maybe if she started with one of those WYSIWYG editors at first? I stressed that this would take a longer than a couple of weekends of playing around. b) Hire someone to build it. Ranges from ultra cheap to ultra expensive, crappy to good and everything in between. I didn't mention sites like Rentacoder because she hasn't worked on a project like this before and doesn't know what to ask for. At this stage she'd likely ask for a Youtube-MySpace-Google for a few hundred bucks because she doesn't yet understand just how much is involved. c) Find someone technical and partner up with them. I explained that this can either work really well or be a disaster because she'd have to give up some of her ownership of the idea. How do you respond in these situations?

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  • What is the optimal way to animate a drawable within a view using the animator classes?

    - by littleFluffyKitty
    I have read about Property Animation and Hardware Acceleration but I am still uncertain what is the most efficient way to use the animator classes. (For the sake of this question I don't need to support devices before Honeycomb. So I want to use the animator classes.) For example, say I have a View. In this view I have a BitmapDrawable that I want to fade in. There are also many other elements within the view that won't change. What property or object would be best to use with the animator? The drawable? A paint that I am drawing the bitmap with in onDraw? Something else? How can this be done to be most efficient with hardware acceleration? Will this require calling invalidate for each step of the animation or is there a way to animate just the drawable and not cause the rest of the view to be redrawn completely for each step of the animation? I guess I imagine an optimal case would be the rest of the view not having to be completely redrawn in software, but rather hardware acceleration efficiently fading the drawable. Any suggestions or pointers to recommended approaches? Thanks!

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  • Lucene raise document score if sibling entity matches query

    - by Pitagoras
    I have the following design situation. I use hibernate search (lucene in the back). Tha application manages ITEMs which have title, description and tags. These are full text indexed. On the other hand, we have COLLECTION of ITEMs. The user can create a COLLECTION and add as many ITEMs as she wants. ITEMs can also belong to many COLLECTIONs. I have a boosted query so that search terms that appear in the tags are more important than in the title, and lastly in the description. But I need an additional matching criteria: for a given ITEM, it whould rank better if other documents in some COLLECTION where the ITEM belongs, also match the query. This is like to say: the title/tags/description of "fellow" items (i.e. items in some shared collection) make the item rank better. I was thinking that adding an ITEM to a COLLECTION would add something like "extra tags" to every other ITEM in the collection, being these extra tags the elements to match in the added ITEM. I feel a more clever solution lucene-wise should exists. Any ideas/pointers are welcome. Thanks.

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  • C++ universal data type

    - by Gokul
    I have a universal data type, which is passed by value, but does not maintain the type information. We store only pointers and basic data types(like int, float etc) inside this. Now for the first time, we need to store std::string inside this. So we decided to convert it into std::string* and store it. Then comes the problem of destruction. We don't like to copy the std::string every time. So i am thinking of an approach like this. Say the data type looks like this class Atom { public : enum flags { IS_STRING, IS_EMPTY, HAS_GOT_COPIED, MARKER }; private: void* m_value; std::bitset<MARKER> m_flags; public: ..... Atom( Atom& atm ) { atm.m_flags.set( HAS_GOT_COPIED ); ..... } ..... ~Atom() { if( m_flags.test(IS_STRING) && !m_flags.test(HAS_GOT_COPIED) ) { std::string* val = static_cast<std::string*>(m_value); delete val; } } }; Is this a good approach to find out whether there is no more reference to std::string*? Any comments.. Thanks, Gokul.

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  • Faster or more memory-efficient solution in Python for this Codejam problem.

    - by jeroen.vangoey
    I tried my hand at this Google Codejam Africa problem (the contest is already finished, I just did it to improve my programming skills). The Problem: You are hosting a party with G guests and notice that there is an odd number of guests! When planning the party you deliberately invited only couples and gave each couple a unique number C on their invitation. You would like to single out whoever came alone by asking all of the guests for their invitation numbers. The Input: The first line of input gives the number of cases, N. N test cases follow. For each test case there will be: One line containing the value G the number of guests. One line containing a space-separated list of G integers. Each integer C indicates the invitation code of a guest. Output For each test case, output one line containing "Case #x: " followed by the number C of the guest who is alone. The Limits: 1 = N = 50 0 < C = 2147483647 Small dataset 3 = G < 100 Large dataset 3 = G < 1000 Sample Input: 3 3 1 2147483647 2147483647 5 3 4 7 4 3 5 2 10 2 10 5 Sample Output: Case #1: 1 Case #2: 7 Case #3: 5 This is the solution that I came up with: with open('A-large-practice.in') as f: lines = f.readlines() with open('A-large-practice.out', 'w') as output: N = int(lines[0]) for testcase, i in enumerate(range(1,2*N,2)): G = int(lines[i]) for guest in range(G): codes = map(int, lines[i+1].split(' ')) alone = (c for c in codes if codes.count(c)==1) output.write("Case #%d: %d\n" % (testcase+1, alone.next())) It runs in 12 seconds on my machine with the large input. Now, my question is, can this solution be improved in Python to run in a shorter time or use less memory? The analysis of the problem gives some pointers on how to do this in Java and C++ but I can't translate those solutions back to Python.

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  • Receiving "expected expression before" Error When Using A Struct

    - by Zach Dziura
    I'm in the process of creating a simple 2D game engine in C with a group of friends at school. I'd like to write this engine in an Object-Oriented way, using structs as classes, function pointers as methods, etc. To emulate standard OOP syntax, I created a create() function which allocates space in memory for the object. I'm in the process of testing it out, and I'm receiving an error. Here is my code for two files that I'm using to test: test.c: #include <stdio.h> int main() { typedef struct { int i; } Class; Class *test = (Class*) create(Class); test->i = 1; printf("The value of \"test\" is: %i\n", test->i); return 0; } utils.c: #include <stdio.h> #include <stdlib.h> #include "utils.h" void* create(const void* class) { void *obj = (void*) malloc(sizeof(class)); if (obj == 0) { printf("Error allocating memory.\n"); return (int*) -1; } else { return obj; } } void destroy(void* object) { free(object); } The utils.h file simply holds prototypes for the create() and destroy() functions. When I execute gcc test.c utils.c -o test, I'm receiving this error message: test.c: In function 'main': test.c:10:32: error: expected expression before 'Class' I know it has something to do with my typedef at the beginning, and how I'm probably not using proper syntax. But I have no idea what that proper syntax is. Can anyone help?

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