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• is it possible to write data to a collection in wpf?

  - by randyc

  Hello. In looking through samples I have seen a number of examples where it is possible to present data within a wpf applicaiton by binding to collections. However I was wondering is it possible to write to a collection from an applicaiton. Say for example i have 2 or more fields such as names and I wanted to have hte ability to add up to three names in my application ( all stored in memory). Will collections serve this purpose. In the past with asp.net I have done this by creating data tables and storing values on the fly or during the session. I am trying to learn WPF and I was wondering if collections work in the same fashion? If so could you please post an example or point me to references that show examples of this? Thank you in advance.

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• Correct way to clear/release an array of arrays

  - by iFloh

  And again my array of arrays .... When I have an array "x" that contains multiple instances of an array "y", how do I clear/release it without risking memory leaks? are the following calls sufficient? (a) clearing the array [x removeAllObjects]; (b) releasing the array [x release]; or do I need to enumerate the array, such as: (c) clearing the array for(int i=0;i<x.count;i++) [[x objectAtIndex:i] release]; [x removeAllObjects]; (d) releasing the array for(int i=0;i<x.count;i++) [[x objectAtIndex:i] release]; [x release]; thanks in advance

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• Hibernate Hql find result size for paginator

  - by KCore

  Hi, I need to add paginator for my Hibernate application. I applied it to some of my database operations which I perform using Criteria by setting Projection.count().This is working fine. But when I use hql to query, I can't seem to get and efficient method to get the result count. If I do query.list().size() it takes lot of time and I think hibernate does load all the objects in memory. Can anyone please suggest an efficient method to retrieve the result count when using hql?

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• Undocumented feature of Dictionary?

  - by Jon

  Dictionary<string, int> testdic = new Dictionary<string, int>(); testdic.Add("cat", 1); testdic.Add("dog", 2); testdic.Add("rat", 3); testdic.Remove("cat"); testdic.Add("bob", 4); Fill the dictionary and then remove the first element. Then add a new element. Bob then appears at position 1 instead of at the end, therefore it seems to remember removed entries and re-uses that memory space? Is this documented anywhere because I can't see it on MSDN and has caused me a day of grief because I assumed it would just keep adding to the end.

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• Reading files with Java

  - by sikas

  I would like to know how can I read a file byte by byte then perform some operation every n bytes. for example: Say I have a file of size = 50 bytes, I want to divide it into blocks each of n bytes. Then each block is sent to a function for some operations to be done on those bytes. The blocks are to be created during the read process and sent to the function when the block reaches n bytes so that I don`t use much memory for storing all blocks. I want the output of the function to be written/appended on a new file. This is what I've reached to read, yet I don't know it it is right: fc = new JFileChooser(); File f = fc.getSelectedFile(); FileInputStream in = new FileInputStream(f); byte[] b = new byte[16]; in.read(b); I haven't done anything yet for the write process.

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• XNA Multi-Thread Jitters

  - by Ice Phoenix

  Hi guys, brand new question. Just implemented multi-threading into my XNA game as it was unable to keep up with using 1 processor. MT is all implemented fine and everything, however the player seems to jitter all over the spot every now and then. I originally thought it was a loss of data between the update and render, but even when i did the player update in the render it did the same thing. It's not a memory/processor issue as i'm no where near maxing out my RAM or processors. It's strange aswell because none of the other entities in the game seem to have any of these issues. Any ideas at all??

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• How to find root cause for "too many connections" error in MySQL/PHP

  - by Nir

  I'm running a web service which runs algorithms that serve millions of calls daily and run some background processing as well. Every now and than I see "Too many connections" error in attempts to connect to the MySQL box" for a few seconds. However this is not necessarily attributed to high traffic times or anything I can put my finger on. I want to find the bottleneck causing it. Other than in the specific times this happens the server isn't too loaded in terms of CPU and Memory, and has 2-3 connections (threads) open and everything works smoothly. (I use Zabbix for monitoring) Any creative ideas on how to trace it?

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• Save NSCache Contents to Disk

  - by Cory Imdieke

  I'm writing an app that needs to keep an in-memory cache of a bunch of objects, but that doesn't get out of hand so I'm planning on using NSCache to store it all. Looks like it will take care of purging and such for me, which is fantastic. I'd also like to persist the cache between launches, so I need to write the cache data to disk. Is there an easy way to save the NSCache contents to a plist or something? Are there perhaps better ways to accomplish this using something other than NSCache? This app will be on the iPhone, so I'll need only classes that are available in iOS 4+ and not just OS X. Thanks!

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• Can I force MySQL to output results before query is completed?

  - by Gordon Royle

  I have a large MySQL table (about 750 million rows) and I just want to extract a couple of columns. SELECT id, delid FROM tbl_name; No joins or selection criteria or anything. There is an index on both fields (separately). In principle, it could just start reading the table and spitting out the values immediately, but in practice the whole system just chews up memory and basically grinds to a halt. It seems like the entire query is being executed and the output stored somewhere before ANY output is produced... I've searched on unbuffering, turning off caches etc, but just cannot find the answer. (mysqldump is almost what I want except it dumps the whole table - but at least it just starts producing output immediately)

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• Modify input stream data on the fly

  - by Frizi

  I would like to implement a std::stream modifier/parser, that is doing data manipulation on the fly. Is it possible to create it in form of stream manipulator? For example, i want to strip all the line comments (from any // to the end of line) out of the stdin and pass it to stdout. string str; istream strippingCin = cin >> stripcomments; while(strippingCin.good()) { strippingCin >> str; cout << str; } There may be also a large file input instead of cin, so i don't want to load full stream data into memory at once. Is it possible without writing my own stream class? Maybe is there another route i should take instead?

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• Problem with increment in inline ARM assembly

  - by tech74

  Hi , i have the following bit of inline ARM assembly, it works in a debug build but crashes in a release build of iphone sdk 3.1. The problem is the add instructions where i am incrementing the address of the C variables output and x by 4 bytes, this is supposed to increment by the size of a float. I think when i increment at some such stage i am overwriting something, can anyone say which is the best way to handle this Thanks C code that the asm is replacing, sum,output and x are all floats for(int i = 0; i< count; i++) sum+= output[i]* (*x++) asm volatile( ".align 4 \n\t" "mov r4,%3 \n\t" "flds s0,[%0] \n\t" "0: \n\t" "flds s1,[%2] \n\t" //"add %3,%3,#4 \n\t" "flds s2,[%1] \n\t" //"add %2,%2,#4 \n\t" "subs r4,r4, #1 \n\t" "fmacs s0, s1, s2 \n\t" "bne 0b \n\t" "fsts s0,[%0] \n\t" : : "r" (&sum), "r" (output), "r" (x),"r" (count) : "r0","r4","cc", "memory", "s0","s1","s2" );

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• Clojure for a lisp illiterate

  - by dbyrne

  I am a lifelong object-oriented programmer. My job is primarily java development, but I have experience in a number of languages. Ruby gave me my first real taste of functional programming. I loved the features Ruby borrowed from the functional paradigm such as closures and continuations. Eventually, I graduated to Scala. This has been a great way to gradually learn to approach non-trivial problems in a functional manner. Now I am interested in Clojure. I know all the sexy features that make it enticing (software transactional memory, macros, etc.), but I just can't get used to "thinking in lisp". I've seen Rich Hickey's screencasts aimed at java programmers, but they are geared towards explaining language features and not approaching real world problems. I am looking for any advice or resources which have made this transition easier for others.

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• SQL Server Compact Edition 3.5 performance

  - by Wili

  I am using SQL Server CE 3.5 SP1 in one of my client applications. When a user loads the program and starts using it, performance is fine. If the user lets the program sit idle for a while, it takes a considerable amount of time (10 or more seconds) for the program to respond. Every time the user asks for a new screen, a call is made to the SQL CE database to get the data for that screen. It seems like the hard drive may be going to sleep and then when the database is accessed, the hard drive has to wake back up. Is it possible to load the entire database into memory and work from that? Are there any other suggestions on how to increase performance?

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• What is the best way to do multiple listviews in android?

  - by Nicos

  Hi all, i am writing a software that i have to drill down on content a lot. For example when the program starts a listview is displayed. When user clicks on an item, then a second listview must be displayed. For example: Select Continent Select Country Select State Select City Select Address What is the best way to do this (less memory, faster, easier to code etc)? To create multiple listviews with multiple adapters? Or 1 listview with multiple Adapters? Lists are loaded from an external XML File. So far i am creating a new adapter and setting it to the listview. How do i create a second listview and after clicking on 1st listview displaying the second one, with animation. Any examples? Extend my class to ListActivity or Activity? Best regards and thanks for helping, Nicos

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• DataSet XML export is empty

  - by Shaine

  I've got in-memory dataset with couple of tables that is populated in code. Data-bound grids on the gui show table contents without a problem. Then I try to export the dataset into XML: ds.WriteXml(fdSave.FileName, XmlWriteMode.WriteSchema); and get empty XML (with couple of lines regarding dataset names but without any tables) If I export table directly I've got all the data but dataset name is obviously wrong: ds.Fields.WriteXml(fdSave.FileName, XmlWriteMode.WriteSchema); What am I missing? Is there any reasonable way to write the whole dataset into file?

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• Strange "cache" effect between client and server

  - by mark

  I use a Socket-based connection between Client and server with ObjectOutputStream. The objects serialized and exchanged have this structure: public class RichiestaSalvataggioArticolo implements Serializable { private ArticoloDati articolo; public RichiestaSalvataggioArticolo(ArticoloDati articolo) { this.articolo = articolo; } @Override public void ricevi(GestoreRichieste gestore) throws Exception { gestore.interpreta(this); } public ArticoloDati getArticolo() { return articolo; } } the issue is that when I try to exchange messages between C/S with incapsulated content very similar (ArticoloDati whom differ only in 2 fields out of 10), the Client sends an ArticoloDati, but the Server receives the previous one. Does the ObjectOutputStream implement some kind of cache or memory between the calls, that fails to recognize that my 2 objects are different because they are very similar?

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• Improving the performance of an nHibernate Data Access Layer.

  - by Amitabh

  I am working on improving the performance of DataAccess Layer of an existing Asp.Net Web Application. The scenerios are. Its a web based application in Asp.Net. DataAccess layer is built using NHibernate 1.2 and exposed as WCF Service. The Entity class is marked with DataContract. Lazy loading is not used and because of the eager-fetching of the relations there is huge no of database objects are loaded in the memory. No of hits to the database is also high. For example I profiled the application using NHProfiler and there were about 50+ sql calls to load one of the Entity object using the primary key. I also can not change code much as its an existing live application with no NUnit test cases at all. Please can I get some suggestions here?

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• Intercommunication between Java Chat Servers

  - by Pravingate

  I have a application in which I am using socket programming , having this(image) scenario. Where number of clients will try to connect Broadcast server. Now here I am managing load through LVS(Load balancer). so as a example shown in image, suppose 200 clients will wish to login for broadcast they will be distributed as 100 users on server 1 and another 100 users on server 2.clients will get connected to servers using TCP connection. Now I am maintaining user information on server side in arraylist which will be stored in heap memory,Now the problem is if client wish to broadcast to all logged in users, but that particular client is logged in server 1. and so client will not be able to broadcast another 100 users from server 2. Because both ther servers are unaware about each others state. please suggest to solve this scenario by whatever means you want.

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• Offline navigation software for Android - what is out there?

  - by Ted

  Im looking for navigation software for the Android platform and I have a few requirements: Offline maps. The maps should be stored on the device/memory card so no Internet-connection is required There should be some way to interact with the application "through code"; sending route requests, getting current location perhaps, bringing app to foreground/background, etc. An API so it can be controlled from another application. No monthly fees The only one I found so far to match the above is Sygic Navigation. However, I havent yet been able to communication with the app even though they say that it can be done. Still investigating that...

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• Do you know of a C dictionary that supports COW transactions?

  - by Tim Post

  I'm looking for a key - value dictionary library written in C that supports a theoretically unlimited number of cheap transactions. I'd like to have one dictionary in memory, with hundreds of threads starting transactions, possibly modifying the dictionary, ending (completing) the transaction or potentially aborting the transaction. Only 50% of the time will these threads actually modify the dictionary. Most dictionary transaction implementations that I've seen copy always, instead of copying on write, whenever a transaction is started. Given the expected size ( 1GB) of the dictionary, I'm hoping to find something that COWs only when something is actually changed during a transaction. I'm also hoping for something that is packaged by most major GNU/Linux distributions. Any suggestions or links are very much appreciated.

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• std::make_shared as a default argument does not compile

  - by Mark Bryant

  In Visual C++ (2008 and 2010), the following code does not compile with the following error: #include <memory> void Foo( std::shared_ptr< int > test = ::std::make_shared< int >( 5 ) ) { } class P { void Foo( std::shared_ptr< int > test = ::std::make_shared< int >( 5 ) ) { } }; error C2039: 'make_shared' : is not a member of '`global namespace'' error C3861: 'make_shared': identifier not found It is complaining about the definition of P::Foo() not ::Foo(). Does anybody know why it is valid for Foo() to have a default argument with std::make_shared but not P::Foo()?

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• What is tha CAUSE of Error 523 and Error 200 in Blackberry handhelds

  - by voipsecuritydigest.com

  I'm Blackberry developer, customers using my application experiencing Error 523 and Error 200. Remedies to those errors are in first case - remove application, my application. In second case totally reload OS! This is very bad, and customers blame me! But this is I don't do anything illegal to make blackberry crash. I just used a lot of memory, which is obvious because customer want that. Everywhere including Blackberry knowledge base people talking how to fix the problem, which may happened to everybody using application from well known brands, for example Yahoo! finances. But nobody explains what is the mechanism behind this, and if it is possible to avoid the problem. I would like to know what is that CAUSE of Error 523 and Error 200?

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• How do I read UTF-8 characters via a pointer?

  - by Jen

  Suppose I have UTF-8 content stored in memory, how do I read the characters using a pointer? I presume I need to watch for the 8th bit indicating a multi-byte character, but how exactly do I turn the sequence into a valid Unicode character? Also, is wchar_t the proper type to store a single Unicode character? This is what I have in mind: wchar_t readNextChar (char** p) { char ch = *p++; if (ch & 128) { // This is a multi-byte character, what do I do now? // char chNext = *p++; // ... but how do I assemble the Unicode character? ... } ... }

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• Which class will be instantiated

  - by Michael

  Say I have 2 subclasses from UIViewController, class A and class B. In Main nib file an object is representing class A and it is set to load file from Secondary nib file. The owner of Secondary nib is of class B. The question is - from which class an object in Main nib file will be instanciated once the nib files unarchived in the memory? The reason this question arised is that I have to take care myself if such reference to external NIB file present, to ensure that the first nib's object and second nib's owner is same. Please correct me if my statement is wrong.

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• Reaplaceing the Import Table in PE file by standart LoadLibrary...

  - by user308368

  Hello. I have an executable (PE) file that load a dll file as represented in the Import table... let say: PEFile.exe Modules.dll my question is how can i remove Modules.dll's import_descriptor from the imports and do its work by loadLibrary without the rely on the import table and without destroy the file???... My bigger problem his i could not understand exactly how the Import thing works... after the loader read the information he needs to do the import's thing, i believe he use the LoadLibrary, GetProcAddress APIs... but i couldn't understated what he doing with the pointers he get... he putting them somewhere in memory... and then what just call them?!? all the papers i found in the net explain the structure of the import table, but i didn't found a paper that explain how it is really work and get used... i hope you cold understand my Gibberish English... Thank you!

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