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  • Communicating Between .NET Programs

    - by IronManIngellis
    I wanted to set up a simple data communication between two C# applications, and I'm not sure what the best method is in doing so. I've previously used Java Sockets and ServerSockets to get the job done, but I'm new to C#, so I've come for advice :) It's going to be two way communication with two clients exchanging strings or something of the like.

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  • && Operation in .NET

    - by Ram
    Which one out of the following two should be preferred while doing && operation on two values. if (!StartTime.Equals(DateTime.MinValue) && !CreationTime.Equals(DateTime.MinValue)) Or if (!(StartTime.Equals(DateTime.MinValue) && CreationTime.Equals(DateTime.MinValue)) What is the difference between the two?

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  • Thousands separator in .Net/F#

    - by rwallace
    What's the recommended way to print an integer with thousands separator? Best I've come up with so far is let thousands(x:int64) = String.Format("{0:0,0}", x) Which works in most cases, but prints zero as 00.

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  • code needed in ASP.NET [closed]

    - by user333366
    1) how to write a code to close a conform box by pressing esc key. 2) how to write a code to save a data what ever we entered in the present web form if we press yes in conform box.... if press no need to be in same web form..

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  • Asp.net with MVC multiple model in one view (create, update)

    - by Abdalmohaymen
    I have problem in asp.ne Mvc with multiple model in one view on create and update I 'm work on exams system class Questions and class Answers Question is aparent class and Answers is a child class [Bind(exclude("id"))] class Quesions { public string question{get; set;} public Datetime Timepostquestion{get; set;} } [Bind(exclude("id"))] class Answers { public string answer{get; set;} public Datetime Timepostanswer{get; set;} public questionId {get; set;} } in a view I use two classes how to use classes in insert and update what a way which I have to solve my problem

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  • .Net file writing and string splitting issues

    - by sagar
    I have a requirement where the file should be split using a given character. Default splitting options are CRLF and LF In both these cases I am splitting the line by \r\n and \r respectively. Also I have requirement where any size of file should be processed. (Processing is basically inserting the given string in a file at given position). For this I am reading the file in chunk of 1024 bytes. Then I am applying the string.Split() method. Split() method gives options for ignoring white spaces and none. I have to add back these line break characters to the line. for this I am using a binary writer and I am writing the byte array to the new file. Issue:- 1) When line break is CRLF, and the split option is NONE, while spaces are also added in the splitted array. Second option is given (to ignore white spaces) CRLF works properly. 2)Bit ignoring white space option creates other problems, as I am reading the file byte by byte I can't ignore a white space. 3)When line break characters are other than default(e.g. '|', a null value is prepended to the resulting line. Can anybody give solution to my issues?

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  • asp.net mvc postback

    - by user266909
    I have a controller with the following two Edit methods. The edit form displays correctly with all additional dropdown lists from the FormViewModel. However, when I changed some field values and submitted the form. None of the changed fields were saved. The fields in the postbask collection have default or null values. I have another edit form which update another table. On submit, the changed values are saved. Does anyone know why? // GET: /Transfers/Edit/5 public ActionResult Edit(int id) { Transfer transfer = myRepository.GetTransfer(id); if (transfer == null) return View("NotFound"); return View(new TransferFormViewModel(transfer)); } // // POST: /Transfers/Edit/5 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, Transfer collection) { Transfer transfer = vetsRepository.GetTransfer(id); if (transfer == null) return View("NotFound"); else { try { UpdateModel(transfer); vetsRepository.Save(); return RedirectToAction("Details", new { id = transfer.TransfersID }); } catch { ModelState.AddModelErrors(transfer.GetRuleViolations()); return View(new TransferFormViewModel(transfer)); } } }

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  • .net File.Copy very slow when copying many small files (not over network)

    - by Guavaman
    I'm making a simple folder sync backup tool for myself and ran into quite a roadblock using File.Copy. Doing tests copying a folder of ~44,000 small files (Windows mail folders) to another drive in my system, I found that using File.Copy was over 3x slower than using a command line and running xcopy to copy the same files/folders. My C# version takes over 16+ minutes to copy the files, whereas xcopy takes only 5 minutes. I've tried searching for help on this topic, but all I find is people complaining about slow file copying of large files over a network. This is neither a large file problem nor a network copying problem. I found an interesting article about a better File.Copy replacement, but the code as posted has some errors which causes problems with the stack and I am nowhere near knowledgeable enough to fix the problems in his code. Are there any common or easy ways to replace File.Copy with something more speedy?

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  • Can i do this in javascript ?(ASP.NET MVC)

    - by user1710716
    <script type="text/javascript"> function CheckData(e) { var form = e.form; var dataItem = e.dataItem; var r = <%=Session["count"] %>; var s = []; var t = []; for (i=1;i<r;i++) { s.push(<%=Session["level"+i] %>; } for(i=1;i<r;i++) { t.push(<%=Session["level"+i+"val"] %> } if(e.mode="edit") { } } </script> I try to combind session in to variable in JavaScript but my session has dynamic session this code get error when I try to build.

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  • [ASP.NET] <%# %> vs <%= %>

    - by Bart
    Hello I am wondering what is the difference between <%# ... % and <%= ... % and <%$ ... % ? I couldn't find anything abt it, cause it's impossible to find <%= in search engine;/ Does these constructions have name to look for it? Could you explain pls? Cheers

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  • Windows Phone 7 development: reading RSS feeds

    - by DigiMortal
    One limitation on Windows Phone 7 is related to System.Net namespace classes. There is no convenient way to read data from web. There is no WebClient class. There is no GetResponse() method – we have to do it all asynchronously because compact framework has limited set of classes we can use in our applications to communicate with internet. In this posting I will show you how to read RSS-feeds on Windows Phone 7. NB! This is my draft code and it may contain some design flaws and some questionable solutions. This code is intended to use as test-drive for Windows Phone 7 CTP developer tools and I don’t suppose you are going to use this code in production environment. Current state of my RSS-reader Currently my RSS-reader for Windows Phone 7 is very simple, primitive and uses almost all defaults that come out-of-box with Windows Phone 7 CTP developer tools. My first goal before going on with nicer user interface design was making RSS-reading work because instead of convenient classes from .NET Framework we have to use very limited classes from .NET Framework CE. This is why I took the reading of RSS-feeds as my first task. There are currently more things to solve regarding user-interface. As I am pretty new to all this Silverlight stuff I am not very sure if I can modify default controls easily or should I write my own controls that have better look and that work faster. The image on right shows you how my RSS-reader looks like right now. Upper side of screen is filled with list that shows headlines from this blog. The bottom part of screen is used to show description of selected posting. You can click on the image to see it in original size. In my next posting I will show you some improvements of my RSS-reader user interface that make it look nicer. But currently it is nice enough to make sure that RSS-feeds are read correctly. FeedItem class As this is most straight-forward part of the following code I will show you RSS-feed items class first. I think we have to stop on it because it is simple one. public class FeedItem {     public string Title { get; set; }     public string Description { get; set; }     public DateTime PublishDate { get; set; }     public List<string> Categories { get; set; }     public string Link { get; set; }       public FeedItem()     {         Categories = new List<string>();     } } RssClient RssClient takes feed URL and when asked it loads all items from feed and gives them back to caller through ItemsReceived event. Why it works this way? Because we can make responses only using asynchronous methods. I will show you in next section how to use this class. Although the code here is not very good but it works like expected. I will refactor this code later because it needs some more efforts and investigating. But let’s hope I find excellent solution. :) public class RssClient {     private readonly string _rssUrl;       public delegate void ItemsReceivedDelegate(RssClient client, IList<FeedItem> items);     public event ItemsReceivedDelegate ItemsReceived;       public RssClient(string rssUrl)     {         _rssUrl = rssUrl;     }       public void LoadItems()     {         var request = (HttpWebRequest)WebRequest.Create(_rssUrl);         var result = (IAsyncResult)request.BeginGetResponse(ResponseCallback, request);     }       void ResponseCallback(IAsyncResult result)     {         var request = (HttpWebRequest)result.AsyncState;         var response = request.EndGetResponse(result);           var stream = response.GetResponseStream();         var reader = XmlReader.Create(stream);         var items = new List<FeedItem>(50);           FeedItem item = null;         var pointerMoved = false;           while (!reader.EOF)         {             if (pointerMoved)             {                 pointerMoved = false;             }             else             {                 if (!reader.Read())                     break;             }               var nodeName = reader.Name;             var nodeType = reader.NodeType;               if (nodeName == "item")             {                 if (nodeType == XmlNodeType.Element)                     item = new FeedItem();                 else if (nodeType == XmlNodeType.EndElement)                     if (item != null)                     {                         items.Add(item);                         item = null;                     }                   continue;             }               if (nodeType != XmlNodeType.Element)                 continue;               if (item == null)                 continue;               reader.MoveToContent();             var nodeValue = reader.ReadElementContentAsString();             // we just moved internal pointer             pointerMoved = true;               if (nodeName == "title")                 item.Title = nodeValue;             else if (nodeName == "description")                 item.Description =  Regex.Replace(nodeValue,@"<(.|\n)*?>",string.Empty);             else if (nodeName == "feedburner:origLink")                 item.Link = nodeValue;             else if (nodeName == "pubDate")             {                 if (!string.IsNullOrEmpty(nodeValue))                     item.PublishDate = DateTime.Parse(nodeValue);             }             else if (nodeName == "category")                 item.Categories.Add(nodeValue);         }           if (ItemsReceived != null)             ItemsReceived(this, items);     } } This method is pretty long but it works. Now let’s try to use it in Windows Phone 7 application. Using RssClient And this is the fragment of code behing the main page of my application start screen. You can see how RssClient is initialized and how items are bound to list that shows them. public MainPage() {     InitializeComponent();       SupportedOrientations = SupportedPageOrientation.Portrait | SupportedPageOrientation.Landscape;     listBox1.Width = Width;       var rssClient = new RssClient("http://feedproxy.google.com/gunnarpeipman");     rssClient.ItemsReceived += new RssClient.ItemsReceivedDelegate(rssClient_ItemsReceived);     rssClient.LoadItems(); }   void rssClient_ItemsReceived(RssClient client, IList<FeedItem> items) {     Dispatcher.BeginInvoke(delegate()     {         listBox1.ItemsSource = items;     });            } Conclusion As you can see it was not very hard task to read RSS-feed and populate list with feed entries. Although we are not able to use more powerful classes that are part of full version on .NET Framework we can still live with limited set of classes that .NET Framework CE provides.

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  • C#/.NET Fundamentals: Choosing the Right Collection Class

    - by James Michael Hare
    The .NET Base Class Library (BCL) has a wide array of collection classes at your disposal which make it easy to manage collections of objects. While it's great to have so many classes available, it can be daunting to choose the right collection to use for any given situation. As hard as it may be, choosing the right collection can be absolutely key to the performance and maintainability of your application! This post will look at breaking down any confusion between each collection and the situations in which they excel. We will be spending most of our time looking at the System.Collections.Generic namespace, which is the recommended set of collections. The Generic Collections: System.Collections.Generic namespace The generic collections were introduced in .NET 2.0 in the System.Collections.Generic namespace. This is the main body of collections you should tend to focus on first, as they will tend to suit 99% of your needs right up front. It is important to note that the generic collections are unsynchronized. This decision was made for performance reasons because depending on how you are using the collections its completely possible that synchronization may not be required or may be needed on a higher level than simple method-level synchronization. Furthermore, concurrent read access (all writes done at beginning and never again) is always safe, but for concurrent mixed access you should either synchronize the collection or use one of the concurrent collections. So let's look at each of the collections in turn and its various pros and cons, at the end we'll summarize with a table to help make it easier to compare and contrast the different collections. The Associative Collection Classes Associative collections store a value in the collection by providing a key that is used to add/remove/lookup the item. Hence, the container associates the value with the key. These collections are most useful when you need to lookup/manipulate a collection using a key value. For example, if you wanted to look up an order in a collection of orders by an order id, you might have an associative collection where they key is the order id and the value is the order. The Dictionary<TKey,TVale> is probably the most used associative container class. The Dictionary<TKey,TValue> is the fastest class for associative lookups/inserts/deletes because it uses a hash table under the covers. Because the keys are hashed, the key type should correctly implement GetHashCode() and Equals() appropriately or you should provide an external IEqualityComparer to the dictionary on construction. The insert/delete/lookup time of items in the dictionary is amortized constant time - O(1) - which means no matter how big the dictionary gets, the time it takes to find something remains relatively constant. This is highly desirable for high-speed lookups. The only downside is that the dictionary, by nature of using a hash table, is unordered, so you cannot easily traverse the items in a Dictionary in order. The SortedDictionary<TKey,TValue> is similar to the Dictionary<TKey,TValue> in usage but very different in implementation. The SortedDictionary<TKey,TValye> uses a binary tree under the covers to maintain the items in order by the key. As a consequence of sorting, the type used for the key must correctly implement IComparable<TKey> so that the keys can be correctly sorted. The sorted dictionary trades a little bit of lookup time for the ability to maintain the items in order, thus insert/delete/lookup times in a sorted dictionary are logarithmic - O(log n). Generally speaking, with logarithmic time, you can double the size of the collection and it only has to perform one extra comparison to find the item. Use the SortedDictionary<TKey,TValue> when you want fast lookups but also want to be able to maintain the collection in order by the key. The SortedList<TKey,TValue> is the other ordered associative container class in the generic containers. Once again SortedList<TKey,TValue>, like SortedDictionary<TKey,TValue>, uses a key to sort key-value pairs. Unlike SortedDictionary, however, items in a SortedList are stored as an ordered array of items. This means that insertions and deletions are linear - O(n) - because deleting or adding an item may involve shifting all items up or down in the list. Lookup time, however is O(log n) because the SortedList can use a binary search to find any item in the list by its key. So why would you ever want to do this? Well, the answer is that if you are going to load the SortedList up-front, the insertions will be slower, but because array indexing is faster than following object links, lookups are marginally faster than a SortedDictionary. Once again I'd use this in situations where you want fast lookups and want to maintain the collection in order by the key, and where insertions and deletions are rare. The Non-Associative Containers The other container classes are non-associative. They don't use keys to manipulate the collection but rely on the object itself being stored or some other means (such as index) to manipulate the collection. The List<T> is a basic contiguous storage container. Some people may call this a vector or dynamic array. Essentially it is an array of items that grow once its current capacity is exceeded. Because the items are stored contiguously as an array, you can access items in the List<T> by index very quickly. However inserting and removing in the beginning or middle of the List<T> are very costly because you must shift all the items up or down as you delete or insert respectively. However, adding and removing at the end of a List<T> is an amortized constant operation - O(1). Typically List<T> is the standard go-to collection when you don't have any other constraints, and typically we favor a List<T> even over arrays unless we are sure the size will remain absolutely fixed. The LinkedList<T> is a basic implementation of a doubly-linked list. This means that you can add or remove items in the middle of a linked list very quickly (because there's no items to move up or down in contiguous memory), but you also lose the ability to index items by position quickly. Most of the time we tend to favor List<T> over LinkedList<T> unless you are doing a lot of adding and removing from the collection, in which case a LinkedList<T> may make more sense. The HashSet<T> is an unordered collection of unique items. This means that the collection cannot have duplicates and no order is maintained. Logically, this is very similar to having a Dictionary<TKey,TValue> where the TKey and TValue both refer to the same object. This collection is very useful for maintaining a collection of items you wish to check membership against. For example, if you receive an order for a given vendor code, you may want to check to make sure the vendor code belongs to the set of vendor codes you handle. In these cases a HashSet<T> is useful for super-quick lookups where order is not important. Once again, like in Dictionary, the type T should have a valid implementation of GetHashCode() and Equals(), or you should provide an appropriate IEqualityComparer<T> to the HashSet<T> on construction. The SortedSet<T> is to HashSet<T> what the SortedDictionary<TKey,TValue> is to Dictionary<TKey,TValue>. That is, the SortedSet<T> is a binary tree where the key and value are the same object. This once again means that adding/removing/lookups are logarithmic - O(log n) - but you gain the ability to iterate over the items in order. For this collection to be effective, type T must implement IComparable<T> or you need to supply an external IComparer<T>. Finally, the Stack<T> and Queue<T> are two very specific collections that allow you to handle a sequential collection of objects in very specific ways. The Stack<T> is a last-in-first-out (LIFO) container where items are added and removed from the top of the stack. Typically this is useful in situations where you want to stack actions and then be able to undo those actions in reverse order as needed. The Queue<T> on the other hand is a first-in-first-out container which adds items at the end of the queue and removes items from the front. This is useful for situations where you need to process items in the order in which they came, such as a print spooler or waiting lines. So that's the basic collections. Let's summarize what we've learned in a quick reference table.  Collection Ordered? Contiguous Storage? Direct Access? Lookup Efficiency Manipulate Efficiency Notes Dictionary No Yes Via Key Key: O(1) O(1) Best for high performance lookups. SortedDictionary Yes No Via Key Key: O(log n) O(log n) Compromise of Dictionary speed and ordering, uses binary search tree. SortedList Yes Yes Via Key Key: O(log n) O(n) Very similar to SortedDictionary, except tree is implemented in an array, so has faster lookup on preloaded data, but slower loads. List No Yes Via Index Index: O(1) Value: O(n) O(n) Best for smaller lists where direct access required and no ordering. LinkedList No No No Value: O(n) O(1) Best for lists where inserting/deleting in middle is common and no direct access required. HashSet No Yes Via Key Key: O(1) O(1) Unique unordered collection, like a Dictionary except key and value are same object. SortedSet Yes No Via Key Key: O(log n) O(log n) Unique ordered collection, like SortedDictionary except key and value are same object. Stack No Yes Only Top Top: O(1) O(1)* Essentially same as List<T> except only process as LIFO Queue No Yes Only Front Front: O(1) O(1) Essentially same as List<T> except only process as FIFO   The Original Collections: System.Collections namespace The original collection classes are largely considered deprecated by developers and by Microsoft itself. In fact they indicate that for the most part you should always favor the generic or concurrent collections, and only use the original collections when you are dealing with legacy .NET code. Because these collections are out of vogue, let's just briefly mention the original collection and their generic equivalents: ArrayList A dynamic, contiguous collection of objects. Favor the generic collection List<T> instead. Hashtable Associative, unordered collection of key-value pairs of objects. Favor the generic collection Dictionary<TKey,TValue> instead. Queue First-in-first-out (FIFO) collection of objects. Favor the generic collection Queue<T> instead. SortedList Associative, ordered collection of key-value pairs of objects. Favor the generic collection SortedList<T> instead. Stack Last-in-first-out (LIFO) collection of objects. Favor the generic collection Stack<T> instead. In general, the older collections are non-type-safe and in some cases less performant than their generic counterparts. Once again, the only reason you should fall back on these older collections is for backward compatibility with legacy code and libraries only. The Concurrent Collections: System.Collections.Concurrent namespace The concurrent collections are new as of .NET 4.0 and are included in the System.Collections.Concurrent namespace. These collections are optimized for use in situations where multi-threaded read and write access of a collection is desired. The concurrent queue, stack, and dictionary work much as you'd expect. The bag and blocking collection are more unique. Below is the summary of each with a link to a blog post I did on each of them. ConcurrentQueue Thread-safe version of a queue (FIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentStack Thread-safe version of a stack (LIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentBag Thread-safe unordered collection of objects. Optimized for situations where a thread may be bother reader and writer. For more information see: C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection ConcurrentDictionary Thread-safe version of a dictionary. Optimized for multiple readers (allows multiple readers under same lock). For more information see C#/.NET Little Wonders: The ConcurrentDictionary BlockingCollection Wrapper collection that implement producers & consumers paradigm. Readers can block until items are available to read. Writers can block until space is available to write (if bounded). For more information see C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection Summary The .NET BCL has lots of collections built in to help you store and manipulate collections of data. Understanding how these collections work and knowing in which situations each container is best is one of the key skills necessary to build more performant code. Choosing the wrong collection for the job can make your code much slower or even harder to maintain if you choose one that doesn’t perform as well or otherwise doesn’t exactly fit the situation. Remember to avoid the original collections and stick with the generic collections.  If you need concurrent access, you can use the generic collections if the data is read-only, or consider the concurrent collections for mixed-access if you are running on .NET 4.0 or higher.   Tweet Technorati Tags: C#,.NET,Collecitons,Generic,Concurrent,Dictionary,List,Stack,Queue,SortedList,SortedDictionary,HashSet,SortedSet

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