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• Which is the "best" data access framework/approach for C# and .NET?

  - by Frans

  (EDIT: I made it a community wiki as it is more suited to a collaborative format.) There are a plethora of ways to access SQL Server and other databases from .NET. All have their pros and cons and it will never be a simple question of which is "best" - the answer will always be "it depends". However, I am looking for a comparison at a high level of the different approaches and frameworks in the context of different levels of systems. For example, I would imagine that for a quick-and-dirty Web 2.0 application the answer would be very different from an in-house Enterprise-level CRUD application. I am aware that there are numerous questions on Stack Overflow dealing with subsets of this question, but I think it would be useful to try to build a summary comparison. I will endeavour to update the question with corrections and clarifications as we go. So far, this is my understanding at a high level - but I am sure it is wrong... I am primarily focusing on the Microsoft approaches to keep this focused. ADO.NET Entity Framework Database agnostic Good because it allows swapping backends in and out Bad because it can hit performance and database vendors are not too happy about it Seems to be MS's preferred route for the future Complicated to learn (though, see 267357) It is accessed through LINQ to Entities so provides ORM, thus allowing abstraction in your code LINQ to SQL Uncertain future (see Is LINQ to SQL truly dead?) Easy to learn (?) Only works with MS SQL Server See also Pros and cons of LINQ "Standard" ADO.NET No ORM No abstraction so you are back to "roll your own" and play with dynamically generated SQL Direct access, allows potentially better performance This ties in to the age-old debate of whether to focus on objects or relational data, to which the answer of course is "it depends on where the bulk of the work is" and since that is an unanswerable question hopefully we don't have to go in to that too much. IMHO, if your application is primarily manipulating large amounts of data, it does not make sense to abstract it too much into objects in the front-end code, you are better off using stored procedures and dynamic SQL to do as much of the work as possible on the back-end. Whereas, if you primarily have user interaction which causes database interaction at the level of tens or hundreds of rows then ORM makes complete sense. So, I guess my argument for good old-fashioned ADO.NET would be in the case where you manipulate and modify large datasets, in which case you will benefit from the direct access to the backend. Another case, of course, is where you have to access a legacy database that is already guarded by stored procedures. ASP.NET Data Source Controls Are these something altogether different or just a layer over standard ADO.NET? - Would you really use these if you had a DAL or if you implemented LINQ or Entities? NHibernate Seems to be a very powerful and powerful ORM? Open source Some other relevant links; NHibernate or LINQ to SQL Entity Framework vs LINQ to SQL

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• What was your "aha moment" in understanding delegates?

  - by CM90

  Considering the use of delegates in C#, does anyone know if there is a performance advantage or if it is a convenience to the programmer? If we are creating an object that holds a method, it sounds as if that object would be a constant in memory to be called on, instead of loading the method every time it is called. For example, if we look at the following Unity3D-based code: public delegate H MixedTypeDelegate<G, H>(G g) public class MainParent : MonoBehaviour // Most Unity classes inherit from M.B. { public static Vector3 getPosition(GameObject g) { /* GameObject is a Unity class, and Vector3 is a struct from M.B. The "position" component of a GameObject is a Vector3. This method takes the GameObject I pass to it & returns its position. */ return g.transform.position; } public static MixedTypeDelegate<GameObject, Vector3> PositionOf; void Awake( ) // Awake is the first method called in Unity, always. { PositionOf = MixedTypeDelegate<GameObject, Vector3>(getPosition); } } public class GameScript : MainParent { GameObject g = new GameObject( ); Vector3 whereAmI; void Update( ) { // Now I can say: whereAmI = PositionOf(g); // Instead of: whereAmI = getPosition(g); } } . . . But that seems like an extra step - unless there's that extra little thing that it helps. I suppose the most succinct way to ask a second question would be to say: When you had your aha moment in understanding delegates, what was the context/scenario/source? Thank you!

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• Failed to create a 'System.Windows.RoutedEventHandler' from the text 'Button_Click'

  - by ay89

  In my windows phone 8 application, while trying to create a dependency property I am always getting this exception. what I am doing wrong, plz guide me. {System.Windows.Markup.XamlParseException: Failed to create a 'System.Windows.RoutedEventHandler' from the text 'Button_Click'. [Line: 108 Position: 66] at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator) at com.sap.View.HomePage.InitializeComponent() at com.sap.View.HomePage..ctor()} this is code-behind of Header public static readonly DependencyProperty MenuClickProperty = DependencyProperty.Register("MenuClick", typeof(RoutedEventHandler), typeof(Header), new PropertyMetadata(OnMenuClickHandlerChanged)); public RoutedEventHandler MenuClick { get { return (RoutedEventHandler)GetValue(MenuClickProperty); } set { SetValue(MenuClickProperty, new RoutedEventHandler(value)); } } private static void OnMenuClickHandlerChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { Header header = d as Header; header.OnMenuClickHandlerPropertyChanged(e); } private void OnMenuClickHandlerPropertyChanged(DependencyPropertyChangedEventArgs e) { MenuButton.Click += MenuClick; } this is in my user control (Header) <Button Click="{Binding Path=MenuClick, Source={RelativeSource Mode=Self}}" /> this is how i am including control on my Page: <myControls:Header Title="{Binding Title}" MenuClick="Button_Click" /> this is in code-behind: public void Button_Click(object sender, RoutedEventArgs e) { OpenSettings(); }

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• How to create a horizontal scrollable list?

  - by Thomas Joos

  hi all, I am wondering what the best approach is for creating a horizontal list with custom buttons. I read there is no native control for that: I am considering a UIView with a scroll view inside. On this scrollview I visualize my array of button objects. Any thoughts?

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• Where can I find good ajax support in Java/Python ?

  - by HJ-INCPP

  Hello, I want a framework (or anything) that helps me make rich client guis. I know my server-side, but I don't like programming in ajax, javascript, css etc. Something that wraps the ajax code in some objects/methods with clean syntax, would do the trick. I want to write code in java instead of defining css and html tags. Does Java Spring, JSF, Django support this ? Languages: Java, Python Thank you

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• Binding between Usercontrol with listbox and parent control (MVVM)

  - by walkor

  I have a UserControl which contains a listbox and few buttons. <UserControl x:Class="ItemControls.ListBoxControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"> <Grid> <ListBox:ExtendedListBox SelectionMode="Single" ItemsSource="{Binding LBItems}" Height="184"> <ListBox.ItemTemplate> <DataTemplate> <CheckBox Content="{Binding}"/> </DataTemplate> </ListBox.ItemTemplate> </ListBox> <Button Command="RemoveCommand"/> </Grid> </UserControl> And the code behind: public static readonly DependencyProperty RemoveCommandProperty = DependencyProperty.Register("RemoveCommand", typeof(ICommand), typeof(ListBoxControl), null); public ICommand RemoveCommand { get { return (ICommand)GetValue(RemoveCommandProperty); } set { SetValue(RemoveCommandProperty, value); } } public static readonly DependencyProperty LBItemsProperty = DependencyProperty.Register("LBItems", typeof(IEnumerable), typeof(ListBoxControl), null); public IEnumerable LBItems { get { return (IEnumerable)GetValue(LBItemsProperty); } set { SetValue(LBItemsProperty, value); } } I'm using this control in the view like this: <ItemControls:ListBoxControl Height="240" Width="350" LBItems="{Binding Items, Converter={StaticResource ItemsConverter}, Mode=TwoWay}" RemoveCommand="{Binding RemoveCommand}"/> The command works fine, though the listbox binding doesn't. My question is - WHY?

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• Iterating through child components

  - by ken

  I have button-group component which contains a set of button-element components. The template is defined as: {{#each buttons}} {{button-element titleBinding="title" action="buttonAction"}} {{/each}} I'd like the buttonAction() method in the button-group component to have easy access to the set of button-element components and iterate through them. What's the easiest way to do this? I know I could use a jQuery/DOM approach like: this.$('.btn').doSomething(); But I'd like to address the component objects not the DOM directly.

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• Model Binding with Parent/Child Relationship

  - by user296297

  I'm sure this has been answered before, but I've spent the last three hours looking for an acceptable solution and have been unable to find anything, so I apologize for what I'm sure is a repeat. I have two domain objects, Player and Position. Player's have a Position. My domain objects are POCOs tied to my database with NHibernate. I have an Add action that takes a Player, so I'm using the built in model binding. On my view I have a drop down list that lets a user select the Position for the Player. The value of the drop down list is the Id of the position. Everything gets populated correctly except that my Position object fails validation (ModelState.IsValid) because at the point of model binding it only has an Id and none of it's other required attributes. What is the preferred solution for solving this with ASP.NET MVC 2? Solutions I've tried... Fetch the Position from the database based on the Id before ModelState.IsValid is called in the Add action of my controller. I can't get the model to run the validation again, so ModelState.IsValid always returns false. Create a custom ModelBinder that inherits from the default binder and fetch the Position from the database after the base binder is called. The ModelBinder seems to be doing the validation so if I use anything from the default binder I'm hosed. Which means I have to completely roll my own binder and grab every value from the form...this seems really wrong and inefficient for such a common use-case. Solutions I think might work, I just can't figure out how to do... Turn off the validation for the Position class when used in Player. Write a custom ModelBinder leverages the default binder for most of the property binding, but lets me get the Position from the database BEFORE the default binder runs validation. So, how do the rest of you solve this? Thanks, Dan P.S. In my opinion having a PositionId on Player just for this case is not a good solution. There has to be solvable in a more elegant fashion.

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• pthread_join from a signal handler

  - by liv2hak

  I have a capture program which in addition do capturing data and writing it into a file also prints some statistics.The function that prints the statistics static void* report(void) { /*Print statistics*/ } is called roughly every second using an ALARM that expires every second.So The program is like void capture_program() { pthread_t report_thread while(!exit_now) { if(pthread_create(&report_thread,NULL,report,NULL)){ fprintf(stderr,"Error creating reporting thread! \n"); } /* Capturing code -------------- -------------- */ if(doreport) usleep(5); } } void *report(void *param) { while(true) { if(doreport) { doreport = 0 //access some register from hardware usleep(5) } } } The expiry of the timer sets the doreport flag.If this flag is set report() is called which clears the flag.I am using usleep to alternate between two threads in the program.This seems to work fine. I also have a signal handler to handle SIGINT (i.e CTRL+C) static void anysig(int sig) { if (sig != SIGINT) dagutil_set_signal_handler(SIG_DFL); /* Tell the main loop to exit */ exit_now = 1; return; } My question: 1) Is it safe to call pthread_join from inside the signal handler? 2) Should I use exit_now flag for the report thread as well?

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• MS Exam 70-536 - How to throw and handle exception from thread?

  - by Max Gontar

  Hello! In MS Exam 70-536 .Net Foundation, Chapter 7 "Threading" in Lesson 1 Creating Threads there is a text: Be aware that because the WorkWithParameter method takes an object, Thread.Start could be called with any object instead of the string it expects. Being careful in choosing your starting method for a thread to deal with unknown types is crucial to good threading code. Instead of blindly casting the method parameter into our string, it is a better practice to test the type of the object, as shown in the following example: ' VB Dim info As String = o as String If info Is Nothing Then Throw InvalidProgramException("Parameter for thread must be a string") End If // C# string info = o as string; if (info == null) { throw InvalidProgramException("Parameter for thread must be a string"); } So, I've tried this but exception is not handled properly (no console exception entry, program is terminated), what is wrong with my code (below)? class Program { static void Main(string[] args) { Thread thread = new Thread(SomeWork); try { thread.Start(null); thread.Join(); } catch (InvalidProgramException ex) { Console.WriteLine(ex.Message); } finally { Console.ReadKey(); } } private static void SomeWork(Object o) { String value = (String)o; if (value == null) { throw new InvalidProgramException("Parameter for "+ "thread must be a string"); } } } Thanks for your time!

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• communication between remote servlets

  - by Venkatesh

  I have two web applications say App1 and App2. I want to call a servlet which is in App2 from a servlet in App1. I'm using URLConnection for this. I'm able to pass parameters to the servlet in App2 also and I'm also able to receive response from the servlet as string. But I want to send java objects from the servlet in App2 and receive them in servlet of App1. How to achieve this?

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• UML - Object Method Returns a Collection

  - by derekerdmann

  How can I indicate that a method will return a collection of objects in UML? Is there a better way to explain the relationship than to have a collection class as a return type?

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• How do I pass three arrays from on method to another?

  - by user2966716

  I have a method studentSummary, that scans the input and creates three arrays examMark,courseworkMark and courseworkWeight. I need these arrays passing over to a different method, so I can use them to calculate moduleResult. heres my code: public static int[] studentSummary(int[] courseworkWeight2, int [] examMark2 , int [] courseworkMark2){ int examMark[] = { 0, 0, 0, 0, 0, 0 }; int courseworkMark[] = { 0, 0, 0, 0, 0, 0 }; Scanner resultInput = new Scanner(System.in); int courseworkWeight[] = { 0, 0, 0, 0, 0, 0 }; for (int k = 1; k < 7; k++) { System.out.print("Please enter exam marks for module " + k + ":"); examMark[k - 1] = resultInput.nextInt(); System.out.print("Please enter Coursework marks for module " + k + ":"); courseworkMark[k - 1] = resultInput.nextInt(); System.out.print("Please enter Coursework weighting for module " + k + ":"); courseworkWeight[k - 1] = resultInput.nextInt(); } Calculator method: public static int[] markCalculator() { int[] courseworkWeight = new int [6]; int[] courseworkMark = new int [6]; int[] examMark = new int [6]; for (int i = 0; i < 6; i++) { computedModuleMark = ((courseworkMark[i] * courseworkWeight[i]) + (examMark[i] * (100 - courseworkWeight[i]))) / 100; if ((computedModuleMark) < 35) { if (examMark[i]<35){ } } moduleMark[i] = computedModuleMark; } computeResult(moduleMark); StudentChart.draw(moduleMark); StudentChart.printSummary(moduleMark); return moduleMark; }

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• I am validating for RegEx errors -- how can I return which keyword, it failed on?

  - by Trip

  I'm passing new objects through this set of regex : (?i)exp\s|(?i)expire\s|(?i)print|(?i)mention|(?i)spring|(?i)summer|(?i)winter|(?i)jan(\s|\.)|(?i)january|(?i)february|(?i)feb(\.|\s)|(?i)march|mar(\.|\s)|(?i)april|(?i)june|(?i)july|(?i)august|(?i)aug(\s|\.)|(?i)september|(?i)sept(\.|\s)|(?i)november|(?i)nov(\.|\s)|(?i)december|(?i)dec(\.|\s)|(?i)holiday|(?i)christmas|(?i)holloween|(?i)easter|(?i)season|(?i)ends|(?i)end If it errors, for example on the word christmas , how can I dynamically pull the word it errors on, and display it as the cause of the error?

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• Inject Javascript into iFrame generated by TinyMCE/YUI?

  - by user365804

  I'm trying to insert/load javascript (e.g. prototype/jquery) into the iFrame generated by TinyMCE (tinymce.moxiecode.com) or YUI's text editor (http://developer.yahoo.com/yui/editor/) so as to better manipulate the objects/images/DIVs inside it. Any thoughts?

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• Error while reading custom configuration file(app.config)

  - by Newbie

  I am making a custom configuration in my winform application. (It will represent a country-corrency list) First the CountryList class namespace UtilityMethods { public class CountryList : ConfigurationSection { public CountryList() { // // TODO: Add constructor logic here // } [ConfigurationProperty("CountryCurrency", IsRequired = true)] public Hashtable CountryCurrencies { get { return CountryCurrency.GetCountryCurrency(); } } } } The GetCountryCurrency() method is defined in CountryCurrency class as under namespace UtilityMethods { public static class CountryCurrency { public static Hashtable GetCountryCurrency() { Hashtable ht = new Hashtable(); ht.Add("India", "Rupees"); ht.Add("USA", "Dollar"); return ht; } } } The app.config file looks like <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name ="CountryList1" type ="UtilityMethods.CountryList,CountryList,Version=2.0.0.0, Culture=neutral"/> </configSections> <appSettings /> </configuration> And I am calling this from a button_click's event as try { CountryList cList = ConfigurationManager.GetSection("CountryList") as CountryList; Hashtable ht = cList.CountryCurrencies; } catch (Exception ex) { string h = ex.Message; } Upon running the application and clicking on the button I am getting this error Could not load type 'UtilityMethods.CountryList' from assembly 'System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' Please help (dotnet framework : 3.5 Language: C#)

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• T4 trouble compiling transformation

  - by John Leidegren

  I can't figure this one out. Why doesn't T4 locate the IEnumerable type? I'm using Visual Studio 2010. And I just hope someone knows why? <#@ template debug="true" hostspecific="false" language="C#" #> <#@ assembly name="System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" #> <#@ import namespace="System" #> <#@ import namespace="System.Data" #> <#@ import namespace="System.Data.SqlClient" #> <#@ output extension=".cs" #> public static class Tables { <# var q = @" SELECT tbl.name 'table', col.name 'column' FROM sys.tables tbl INNER JOIN sys.columns col ON col.object_id = tbl.object_id "; // var source = Execute(q); #> } <#+ static IEnumerable Execute(string cmdText) { using (var conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=t4build;Integrated Security=True;")) { conn.Open(); var cmd = new SqlCommand(cmdText, conn); using (var reader = cmd.ExecuteReader()) { while (reader.Read()) { } } } } #> Error 2 Compiling transformation: The type or namespace name 'IEnumerable' could not be found (are you missing a using directive or an assembly reference?) c:\Projects\T4BuildApp\T4BuildApp\TextTemplate1.tt 26 9

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• GridView ObjectDataSource LINQ Paging and Sorting using multiple table query.

  - by user367426

  I am trying to create a pageing and sorting object data source that before execution returns all results, then sorts on these results before filtering and then using the take and skip methods with the aim of retrieving just a subset of results from the database (saving on database traffic). this is based on the following article: http://www.singingeels.com/Blogs/Nullable/2008/03/26/Dynamic_LINQ_OrderBy_using_String_Names.aspx Now I have managed to get this working even creating lambda expressions to reflect the sort expression returned from the grid even finding out the data type to sort for DateTime and Decimal. public static string GetReturnType<TInput>(string value) { var param = Expression.Parameter(typeof(TInput), "o"); Expression a = Expression.Property(param, "DisplayPriceType"); Expression b = Expression.Property(a, "Name"); Expression converted = Expression.Convert(Expression.Property(param, value), typeof(object)); Expression<Func<TInput, object>> mySortExpression = Expression.Lambda<Func<TInput, object>>(converted, param); UnaryExpression member = (UnaryExpression)mySortExpression.Body; return member.Operand.Type.FullName; } Now the problem I have is that many of the Queries return joined tables and I would like to sort on fields from the other tables. So when executing a query you can create a function that will assign the properties from other tables to properties created in the partial class. public static Account InitAccount(Account account) { account.CurrencyName = account.Currency.Name; account.PriceTypeName = account.DisplayPriceType.Name; return account; } So my question is, is there a way to assign the value from the joined table to the property of the current table partial class? i have tried using. from a in dc.Accounts where a.CompanyID == companyID && a.Archived == null select new { PriceTypeName = a.DisplayPriceType.Name}) but this seems to mess up my SortExpression. Any help on this would be much appreciated, I do understand that this is complex stuff.

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• Why do you have to call URLConnection#getInputStream to be able to write out to URLConnection#getOutputStream?

  - by John

  I'm trying to write out to URLConnection#getOutputStream, however, no data is actually sent until I call URLConnection#getInputStream. Even if I set URLConnnection#doInput to false, it still will not send. Does anyone know why this is? There's nothing in the API documentation that describes this. Java API Documentation on URLConnection: http://download.oracle.com/javase/6/docs/api/java/net/URLConnection.html Java's Tutorial on Reading from and Writing to a URLConnection: http://download.oracle.com/javase/tutorial/networking/urls/readingWriting.html import java.io.IOException; import java.io.OutputStreamWriter; import java.net.URL; import java.net.URLConnection; public class UrlConnectionTest { private static final String TEST_URL = "http://localhost:3000/test/hitme"; public static void main(String[] args) throws IOException { URLConnection urlCon = null; URL url = null; OutputStreamWriter osw = null; try { url = new URL(TEST_URL); urlCon = url.openConnection(); urlCon.setDoOutput(true); urlCon.setRequestProperty("Content-Type", "text/plain"); //////////////////////////////////////// // SETTING THIS TO FALSE DOES NOTHING // //////////////////////////////////////// // urlCon.setDoInput(false); osw = new OutputStreamWriter(urlCon.getOutputStream()); osw.write("HELLO WORLD"); osw.flush(); ///////////////////////////////////////////////// // MUST CALL THIS OTHERWISE WILL NOT WRITE OUT // ///////////////////////////////////////////////// urlCon.getInputStream(); ///////////////////////////////////////////////////////////////////////////////////////////////////////// // If getInputStream is called while doInput=false, the following exception is thrown: // // java.net.ProtocolException: Cannot read from URLConnection if doInput=false (call setDoInput(true)) // ///////////////////////////////////////////////////////////////////////////////////////////////////////// } catch (Exception e) { e.printStackTrace(); } finally { if (osw != null) { osw.close(); } } } }

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• OOP/MVC advice on where to place a global helper function

  - by franko75

  Hi, I have a couple of controllers on my site which are handling form data. The forms use AJAX and I have quite a few methods across different controllers which are having to do some specific processing to return errors in a JSON encoded format - see code below. Obviously this isn't DRY and I need to move this code into a single helper function which I can use globally, but I'm wondering where this should actually go! Should I create a static helper class which contains this function (e.g Validation::build_ajax_errors()), or as this code is producing a format which is application specific and tied into the jQuery validation plugin I'm using, should it be a static method stored in, for example, my main Website controller which the form handling controllers extend from? //if ajax request, output errors if (request::is_ajax()) { //need to build errors into array form for javascript validation - move this into a helper method accessible globally $errors = $post->errors('form_data/form_error_messages'); $i = 0; $new_errors = array(); foreach ($errors as $key => $value) { $new_errors[$i][0] = '#' . $key; $new_errors[$i][1] = $value; $new_errors[$i][2] = "error"; $i++; } echo '{"jsonValidateReturn":' . json_encode($new_errors) . '}'; return; }

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• non contiguous String object C#.net

  - by Kazoom

  By what i understand String and StringBuilder objects both allocate contiguous memory underneath. My program runs for days buffering several output in a String object. This sometimes cause outofmemoryexception which i think is because of non availability of contiguous memory. my string size can go upto 100MBs and i m concatenating new string frequently this causes new string object being allocated. i can reduce new string object creation by using Stringbuilder but that would not solve my problem entirely Is there an alternative to a contiguous string object?

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• C# Convert string to nullable type (int, double, etc...)

  - by Nathan Koop

  I am attempting to do some data conversion. Unfortunately, much of the data is in strings, where it should be int's or double, etc... So what I've got is something like: double? amount = Convert.ToDouble(strAmount); The problem with this approach is if strAmount is empty, if it's empty I want it to amount to be null, so when I add it into the database the column will be null. So I ended up writing this: double? amount = null; if(strAmount.Trim().Length>0) { amount = Convert.ToDouble(strAmount); } Now this works fine, but I now have five lines of code instead of one. This makes things a little more difficult to read, especially when I have a large amount of columns to convert. I thought I'd use an extension to the string class and generic's to pass in the type, this is because it could be a double, or an int, or a long. So I tried this: public static class GenericExtension { public static Nullable<T> ConvertToNullable<T>(this string s, T type) where T: struct { if (s.Trim().Length > 0) { return (Nullable<T>)s; } return null; } } But I get the error: Cannot convert type 'string' to 'T?' Is there a way around this? I am not very familiar with creating methods using generics.

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• How to create a String Array and link it to a Grade array

  - by user1861544

  I have a project that I need to create 2 Arrays, one to hold Student Names and one to hold Student Scores. The user inputs the size of the array, and the array needs to be sorted using BubbleSort (putting the high scores at the top). I have started the project, created the first array for scores, I have successfully done bubble sort and sorted the grades. Now I can't figure out how to make an array for Names, and once I do how do I make the names array correspond to the Grades array BubbleSort? Here is the code I have so far. import java.util.Scanner; public class Grades { public static void main(String[]args){ { Scanner UserIn = new Scanner(System.in); System.out.print( "How many students are there? " ); int[]GradeArray = new int[UserIn.nextInt()]; for( int i=0 ; i<GradeArray.length ; i++ ) { System.out.print( "Enter Grade for Student " + (i+1) + ": " ); GradeArray[i] = UserIn.nextInt(); } bubbleSort(GradeArray); for( int i : GradeArray ) System.out.println( i ); System.out.println(); } } private static void bubbleSort(int[]GradeArray){ int n = GradeArray.length; int temp = 0; String temp2; for(int i=0; i<n; i++){ for(int j=1; j<(n-i);j++){ if(GradeArray[j-1]<GradeArray[j]){ //swap temp=GradeArray[j-1]; GradeArray[j-1]=GradeArray[j]; GradeArray[j]=temp; } } } } } Also how do I change the grades to Double? I started with Int and when I try to change everything to double I get an error saying "Found Double, expected Int".

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• Cast exception being generated when using the same type of object

  - by David Tunnell

  I was previously using static variables to hold variable data that I want to save between postbacks. I was having problems and found that the data in these variables is lost when the appdomain ends. So I did some research and decided to go with ViewStates: static Dictionary<string, linkButtonObject> linkButtonDictonary; protected void Page_Load(object sender, EventArgs e) { if (ViewState["linkButtonDictonary"] != null) { linkButtonDictonary = (Dictionary<string, linkButtonObject>)ViewState["linkButtonDictonary"]; } else { linkButtonDictonary = new Dictionary<string, linkButtonObject>(); } } And here is the very simple class I use: [Serializable] public class linkButtonObject { public string storyNumber { get; set; } public string TaskName { get; set; } } I am adding to linkButtonDictionary as a gridview is databound: protected void hoursReportGridView_OnRowDataBound(Object sender, GridViewRowEventArgs e) { if (e.Row.RowType == DataControlRowType.DataRow) { LinkButton btn = (LinkButton)e.Row.FindControl("taskLinkButton"); linkButtonObject currentRow = new linkButtonObject(); currentRow.storyNumber = e.Row.Cells[3].Text; currentRow.TaskName = e.Row.Cells[5].Text; linkButtonDictonary.Add(btn.UniqueID, currentRow); } } It appears that my previous issues are resolved however a new one has arisin. Sometime when I postback I am getting this error: [A]System.Collections.Generic.Dictionary2[System.String,linkButtonObject] cannot be cast to [B]System.Collections.Generic.Dictionary2[System.String,linkButtonObject]. Type A originates from 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'LoadNeither' at location 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. Type B originates from 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'LoadNeither' at location 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. I don't understand how there can be a casting issue when I am using the same class everywhere. What am I doing wrong and how do I fix it?

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• Decide which caching startegy to use ?

  - by hib

  Hi all, I want to cache my loaded data so that I can reduce my application start time . I know several strategies to store application data i.e. core data, nsuserdefaults , archiving . Now my scenario is that suppose that I have array of maximum 10 objects each object having 5 fields . So I can not decide which strategy to store this array an later retrieving the same . Thanks .

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