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C_sharp : Entity Framework Core introduced the methods HasServiceTier and HasPerformanceLevel to change the edition of an Azure SQL server . You can use them in OnModelCreating like this : If you use Add-Migration Add-Migration you get a migration like this : This seems to work fine but when I try to apply this migrati...
Specify Azure SQL server edition in EF Core without breaking local development
C_sharp : I have the exact situation described in this question : Device Hub communication with printer queueDue to the question having neither an accepted , nor an acceptable answer , I am asking the question again.I have configured DeviceHub with Acumatica , and my printer is shown . I am sending the print job via a ...
Printer fails to receive job from DeviceHub
C_sharp : I have the following ActionLink : yet when I hover over the link , the url displayed in the browser is http : //localhost:44334/Upload . Where is the controller in this url ? Strangely , clicking the url takes me to my File/Upload view , and yet stranger , the url displayed in the browser 's address bar is ht...
I 'm seeing strange ActionLink behaviour , why is the url displayed in the browser not displaying the seemingly correct controller ?
C_sharp : I have the feeling I 'm not looking at this issue from the right angle here , and I 'm just not thinking of other solution.Assuming this generic class ; It is used to define `` ports '' in a graph-node editor . A port can transfer a object/value from one node to another , but they also need to be `` type-safe...
Invoking generic method/delegate from a non-generic base class
C_sharp : I need some help . I am creating a SelectItem class like this : I would like the following code to be validInstead of having to do this : How can I accomplish this ? <code> public class SelectItem < T > where T : class { public bool IsChecked { get ; set ; } public T Item { get ; set ; } } SelectItem < String...
Implicit operator ?
C_sharp : I hit a bizarre problem earlier which I have replicated in a new console application . I wonder , can anyone explain why this occurs ? You get an error on the DoSomething line : Error 1 The call is ambiguous between the following methods or properties : 'DoSomething ( int ? ) ' and 'DoSomething ( MyEnum ) ' H...
Can anyone explain this interesting C # problem ?
C_sharp : Imagine the code above being used in the following case : It looks like it 's perfectly safe to inline y , but it 's actually not . This inconsistency in the language itself is counter-intuitive and is plain dangerous . Most programmers would simply inline y , but you 'd actually end up with an integer overfl...
Integral type promotion inconsistency
C_sharp : BackgroundOur site is a press site and is viewed by many people around the globe . Obviously this means that we will be localising the site in as many languages as possible . A professional translator will be hired for each language.How our site works currentlyThe way we have planned to do this is by storing ...
Does the way we translate our website result in performance issues ?
C_sharp : I 'm writing a desktop application in C # that should be able to access all users on a Google Apps `` account '' an retrieve calendar-events for each user . I have added the Calendar API and the Admin SDK to my `` project '' .Both methods ( below ) works fine on their own but when I want to authorize my app f...
Multiple Google access permissions for a desktop application
C_sharp : I 've been struggling a lot lately to find decent solution which has authentication mechanism for server and client API's.I put alot of effort trying to find working ( ! ) code samples , but could n't find any.The code from DotNetOpenAuth does n't work for me - im using vs 2010 .net 4 webformAnyway , I ca n't...
OpenID API for both asp.net and JavaScript support ?
C_sharp : List < T > derives from the following interfaces : I just wonder , why it needs all these interfaces ( in the class declaration ) ? IList itself already derives from ICollection < T > , IEnumerable < T > und IEnumerable.So why is the following not enough ? I hope you can solve my confusion . <code> public cla...
Why does List < T > implement so many interfaces ?
C_sharp : I have following LINQ statement and I want to rewrite it using extension methods.One possible solution is : However this is everything but elegant . Do you any idea how to improve beauty of second expression ? <code> from x in efrom y in efrom z in eselect new { x , z } e.Join ( e , x = > 42 , y = > 42 , ( x ...
What 's elegant way to rewrite following LINQ statement using extension methods ?
C_sharp : I 'm finding that ValueTuples evaluate differently when I access their properties from a collection.Why do these two highlighted lines evaluate differently and how can I change `` MyList [ 0 ] .c '' to get the value correctly ? <code> public static List < Tuple < string , bool > > MyTupleList = new List < Tup...
Why does the Visual Studio watch window show wrong values for ValueTuples in a collection ?
C_sharp : I have two functions that have different enough logic but pretty much the same exception handling : It is not possible to use a single entry point for DoIt1 and DoIt2 , because they are called in from outside.Is Copy/Pase ( for the exception block ) the best approach ? <code> public void DoIt1 // DoIt2 has di...
What is the best way to re-use exception handling logic in C # ?
C_sharp : I am developing a WinRT app using XAML and MVVM Light . This app is meant to make it easier to do data collection while the users are out in the field . I have a section of my app where users will need to enter in a bunch of information about several different items . These items are defined as classes that i...
Multiple input forms with same xaml file and different DataContexts
C_sharp : I 'm creating a reusable library that targets several platforms ( .NET 4.0 , .NET 4.5 , .NETStandard 1.0 and .NETStandard 1.3 ) . The .NET 4.5 version of this project contains some features that are not available under the .NET 4.0 version . The unit test project that references this library project has one s...
How to let a Visual Studio 2015 xproject ( project.json ) reference the highest framework of a depending project
C_sharp : I have a class called Message which overloads these operators : I want the == and ! = operators keep comparing references of the types other than String and Message but , gives me this : The call is ambiguous between the following methods or properties : 'Message.operator == ( Message , Message ) ' and 'Messa...
Overloading == operator for null
C_sharp : I have came across this question : What does the [ Flags ] Enum Attribute mean in C # ? And one thing I have been wondering , using the accepted answer 's example , what will happen if I declare : Will the following steps in that example resulting an error ? If no , how can I get to MyColors.Red ? <code> [ Fl...
What happens if we declare [ Flags ] enum in order ?
C_sharp : My OM has a 'product ' object.Each product has a 'manufacturer id ' ( property , integer ) .When I have a list of products to display , the first three are displayed as the 'featured products'.The list is already sorted in a specific sort order , putting the 'featured ' products first in the list . However , ...
LINQ Sorting - First three need to be different manufacturers
C_sharp : This is a very uncommon problem and there are definetly many workarounds , but I would like to understand what is actually going on and why it 's not working.So I have 3 assemblies in a test solution , first assembly has type ClassA : Second assembly references first assembly and has ClassB : which has an exp...
Explicit cast operator fails with `` assembly is not referenced '' error
C_sharp : I have a x64 crash dump of a managed ( C # ) application that p/invokes to native code . The dump was taken after the native code attempted to dereference a bad memory location , and after the .NET marshaler had turned it into an AccessViolationException . As a result , the stack frame where the error occurre...
How do I retrieve Register Context from AccessViolationException ?
C_sharp : A part of my ( C # 3.0 .NET 3.5 ) application requires several lists of strings to be maintained . I declare them , unsurprisingly , as List < string > and everything works , which is nice.The strings in these Lists are actually ( and always ) Fund IDs . I 'm wondering if it might be more intention-revealing ...
Are there drawbacks to creating a class that encapsulates Generic Collection ?
C_sharp : I have the following code snippet in C # : It 's running fine , but I am not getting the result I expect.Actual result9,9,9Expected result1,4,9Why am I not getting the result I expect ? <code> var actions = new List < Func < int > > ( ) ; IEnumerable < int > values = new List < int > { 1 , 2 , 3 } ; foreach (...
Why am I getting wrong results when calling Func < int > ?
C_sharp : I am working with ComboBox elements that often contain very large quantities of data ; ~250000 data entries.This works fine when a ComboBox is set up a little like this.However , some custom modifications of the ComboBox I am working with require the ComboBoxItem elements to not be focusable . I achieved this...
None focusable ComboBoxItem
C_sharp : I want to capture the selected date on my DropDown list , where there are five days will display on DropdownList.I 'm usually putting the default value on DropDown , but not this time because in the drop down list I want it always display the current date and the next five days . But I do n't know how to capt...
Capture a value from a dropdownlist where the display dropdownlist is not default
C_sharp : I am using an asp.net webapi controller , and in my project I have a dll that I built myself . The dll is being used to validate if the person that the user is typing in actually exists.Here is my controller method : Now the two conditional statements above that have EmpData.. EmpData is from my dll.Here is t...
AJAX error not returning jqXHR.responseText.modelState when using custom dll
C_sharp : Okay I have a derived class that has an overload to a method that 's on my base class . I call what I think would match the method signature of the base class but instead my derived classes implementation is called . ( The code below always prints out `` MyDerived '' ) Why is this ? <code> public class MyBase...
Compiler picking the wrong overload
C_sharp : I am trying to call IEnumerable.Contains ( ) with a dynamic argument , but I am getting the error 'IEnumerable ' does not contain a definition for 'Contains ' and the best extension method overload 'Queryable.Contains ( IQueryable , TSource ) ' has some invalid argumentsI 've noticed that I can either cast th...
Why do I need to cast a dynamic object when calling IEnumerable.Contains ( ) ?
C_sharp : Just wondering why Enumerable.Range implements IDisposable.I understand why IEnumerator < T > does , but IEnumerable < T > does n't require it . ( I discovered this while playing with my .Memoise ( ) implementation , which has statement like in its `` source finished '' method that I had placed a breakpoint o...
Why does Enumerable.Range Implement IDisposable ?
C_sharp : Is there way to do something along these lines ? I do n't care about the type of the properties , I just need the properties to be available . This does n't have to be implemented with an interface , just using that as an example . <code> interface Iface { [ anytype ] Prop1 { get ; } [ anytype ] Prop2 { get ;...
C # Interface without static typing
C_sharp : I 've got something like this : I have to make SomeDataBlob public so that it can be used as a member of the public interface method ExternalPlugin.DoStuff . However , I would not like to allow clients to inherit from that class and thus be susceptible to the brittle base class problem . ( All derivatives of ...
Can I disallow other assemblies from inheriting from a class ?
C_sharp : I am migrating a project from .Net 4.6.2 into .Net Core 2.0 . What is the replacement for RoleProvider in Net Core ? The type or namespace name 'RoleProvider ' could not be found ( are you missing a using directive or an assembly reference ? ) New code looks like this , received errorUpdate : Answer from John...
Net Core : Type or namespace name 'RoleProvider ' could not be found
C_sharp : In this threadHow to get null instead of the KeyNotFoundException accessing Dictionary value by key ? in my own answer I used explicit interface implementation to change the basic dictionary indexer behaviour not to throw KeyNotFoundException if the key was not present in the dictionary ( since it was convini...
Is there a built-in generic interface with covariant type parameter returned by an indexer ?
C_sharp : The issue I 'm currently facing is that I 'm unable to get my C # program to write the file I want to send in the response ( I 'm writing the bytes of the file ) and have a valid HTTP response , the browser I 'm testing it with is saying ERR_INVALID_HTTP_RESPONSE if I have appended the file to the response.Or...
C # How do you send a file via TCP for HTTP ?
C_sharp : I have found huge amounts of information ( ie , this ) on how to handle unexpected errors in ASP.NET , using the Page_Error and Application_Error methods as well as the customErrors directive in Web.config.However , my question is what is the best way to handle EXPECTED errors . For example , I have a page to...
Displaying expected errors to users in ASP.NET
C_sharp : I 've got a DataGridView that is backed by a SortableBindingList as described by this article.This is essentially a BindingList whose Data source is a list of custom objects . The underlying custom objects are updated programatically.My SortableBindingList allows me to sort each column in Ascending or Descend...
Keeping a DataGridView autosorted
C_sharp : I have a generic class which could use a generic OrderBy argumentthe class is as followsThe orderBy could be of various typese.g . The goal is to make the orderBy an argument rather than bake it inany ideas ? <code> class abc < T > where T : myType { public abc ( ... .. , orderBy_Argument ) { ... } void someM...
Linq and order by
C_sharp : Given the following C # code : And its counterpart in VB.NET : It appears that VB.NET is able to correctly infer type of a = Object ( ) , while C # complains until the above is fixed to : Is there a way to auto-infer type in C # for the above scenario ? EDIT : Interesting observation after playing with differ...
Type inference in C # not working ?
C_sharp : I came across the following code , all in a single file/class . I 'm leaving out the details , its the construct I 'm interested in . Why are there two different declarations for the same class and how are they different ? What 's the purpose of the syntax for the second declaration ? <code> public abstract c...
What is this C # construct doing and why ? MyClass < TMyClass > : MyClass where
C_sharp : First time poster here , but I have been using stackoverflow this entire quarter to help me along in my intro to C # class . Generally , I can find what I 'm looking for if I look hard enough , but I have been unable to find anyone that has already answered my question.I have an assignment that wants me to di...
How to properly align a 5x10 2-d array with random data in console ?
C_sharp : This is the first time I face a problem like this . Not being this my profession but only my hobby , I have no previous references.In my program I have added one by one several functions to control a machine . After I added the last function ( temperature measurement ) , I have started experiencing problems o...
Multithreading or something different
C_sharp : I 'm forwarding type definitions for our legacy support . I 'm using following syntax to do so : problem I 'm having is that I ca n't find correct syntax for generic type definitions ( it should be possible based on Eric Lippert 's post and many other places ) .What I would expect as working solution isAny id...
Forward generic type definition
C_sharp : I have a vertically and horizontally scrollable DataGridView on a form.I use virtual mode because the underlying datatable is huge.When I scroll right , if the last column is not fully shown in the view , then I see repeated calls to CellValueNeeded.How can I fix this ? My thoughts : Why is CellValueNeed bein...
Repeated calls to CellValueNeeded
C_sharp : I am trying to serialize a List to a file in C # with JSON.NET.I want to be able to add values to the list and serialize that change.I do not want to serialize the list all over again , since it can grow pretty big.Is something like that possible with JSON.NET ? this way it would only be possible to `` Reseri...
continuous serialization of a list with JSON.NET
C_sharp : Here 's the Lambda expression I am using to try and include the User table , which throws an error.The include statement gives this error The Include path expression must refer to a navigation property defined on the type . Use dotted paths for reference navigation properties and the Select operator for colle...
Include Derived Models Related Class
C_sharp : What I want to do is combine lambda syntax with `` params '' to carry out an action on a series of object.Let 's say I want to make a bunch of controls invisible.After a bit of fiddling I ended up with an extension method : and then I can create an action : and then call it : This is n't very nice syntax thou...
C # syntax for applying an action to a varying number of objects
C_sharp : I have the follwoing code and I would like to write it in a way that I have minimum lines of code and the work is done the same way . How can I do that ? <code> List < Category > categoryList = new List < Category > ( ) ; categoryList = Category.LoadForProject ( project.ID ) .ToList ( ) ; List < string > cate...
How can I avoid code duplication
C_sharp : I am reading some x and y coordinates from an XML file.The coordinates look like this 3.47 , -1.54 , .. and so on.When I assign the value to a double variable byThe Value becomes 3470.00Why is this the case ? <code> double x , y ; x = Convert.ToDouble ( reader [ `` X '' ] ) ; // X Value : 3.47
Why does Convert.ToDouble change my Value by factor 1000 ?
C_sharp : I want to create a copy my object in my DB with using Entity Frameworkfirst I got my `` Book '' from DBthen , I tried to add this object as a new objectAlso I trid to initilize EntityKey of Bookit didnt workIs there any way doing this without creating new Book and copy properties from old one ? Thanks <code> ...
How to Add existing entity as a new Entity with Entity Framework
C_sharp : I am converting a codebase to C # 8 with nullable reference types . I came across the a method similar to the one in this question but async.T may be any type , including nullable reference types or nullable value types.To be clear , I understand WHY this method triggers a warning . What I 'd like to know is ...
Proper nullable annotation for async generic method that may return default ( T )
C_sharp : The BackgroundI have converted the C # code below ( found in TreeViewAdv file TreeColumn.cs ) into VB.net code using the converter found at DeveloperFusion.com . C # VBThe ProblemAccess to TreeColumn.TreeColumnConverter in this line of the C # code is fine . [ TypeConverter ( typeof ( TreeColumn.TreeColumnCon...
`` Private '' visibility modifier - how to handle differences when converting C # to VB ?
C_sharp : What I basically wish to do is design a generic interface that , when implemented , results in a class that can behave exactly like T , except that it has some additional functionality . Here is an example of what I 'm talking about : And this is all well and good , but in order to use CoolInt , I need to do ...
C # Interfaces : Is it possible to refer to the type that implements the interface within the interface itself ?
C_sharp : To my surprise , this one compiles and runs : The method is public whereas the default value `` redirects '' to a constant private variable.My question : What is/was the idea behind this `` concept '' ? My understanding ( until today ) was , that something public can only be used if all other `` referenced ''...
What 's the idea behind allowing private constant to be used as default parameters for public methods ?
C_sharp : What happens if I pass a data member by reference to a function , and while that function is running , the Garbage Collector starts running and moves the object containing the data member in memory ? How does the CLR make sure reference parameters do n't become invalid during Garbage Collection ? Are they adj...
passing data members by reference
C_sharp : I have a little C # problem . I have two classes ClassA and ClassB defined in this way : As you can see , ClassA has an instance of ClassB.The thing is , from a list of ClassA instances , I want to access to a list of the corresponding ClassB instances . I suppose it would look like this : The solution is pro...
Class associations and lists
C_sharp : I was browsing the source of the PluralizationService when I noticed something odd . In the class there are a couple of private dictionaries reflecting different pluralisation rules . For example : What are the groups of four dashes in the strings ? I did not them see handled in the code , so they 're not som...
What are the groups of four dashes in the .NET reference source code ?
C_sharp : Is there a mechanism for the new c # 8 using statement to work without a local variable ? Given ScopeSomething ( ) returns a IDisposable ( or null ) ... Previously : However in C # 8 with the using statement , it requires a variable name : The _ here is not treated as a discard.I would have expected this to h...
using statement in C # 8 without a variable
C_sharp : What happens when I add a method to existing delegate ? I mean when I added the method1 to del , del holds the address of method1 . When I add method2 afterwards , del still points to Method1 and Method 2 address is inserted on the bottom of it . Does n't this mean I changed the delegate ? If I can change thi...
Delegates are immutable but how ?
C_sharp : I 'm running into a problem where as I have an implied unsigned hexadecimal number as a string , provided from user input , that needs to be converted into a BigInteger.Thanks to the signed nature of a BigInteger any input where the highest order bit is set ( 0x8 / 1000b ) the resulting number is treated as n...
What is the proper way to construct a BigInteger from an implied unsigned hexadecimal string ?
C_sharp : In my WPF application I have a sort of node graph . I have added a ContextMenu to these nodes , which appears when I right-click on stuff and so on.The commands in the context menu come from a Service ( Microsoft.Practices.ServiceLocation.ServiceLocator ) with DelegateCommands , and those commands are updated...
RaiseCanExecuteChanged delay with ContextMenu
C_sharp : I am trying to write the following : I would like to write a method `` A '' which takes as parameter another method `` B '' as well as an unknown number of parameters for this method B . ( params object [ ] args ) . Now , inside method A i would like to make a call to B with the parameters args . B will now r...
C # Method that executes a given Method
C_sharp : I was surprised that there would be any runtime difference between these two delegates ( fn1 and fn2 ) : But apparently the second lambda is treated like an instance method , because its Target property is non-null . And it was treated differently before I switched to Visual Studio 2015 ( in VS2012 , I am pre...
Lambda treated as a closed delegate in Roslyn
C_sharp : When running We see a difference when using different framework versions.vsAlso why would I see different a NumberFormat.CurrencyPositivePattern between machines . Is it framework specific or related to the OS ? 40,00 kr . vs kr . 20,00 <code> var x = 10.0M ; Console.WriteLine ( typeof ( Program ) .Assembly.I...
What controls the CurrencyPositivePattern in .NET
C_sharp : I want to create a wrapper around this existing helper : How can I create a helper to wrap this and add a parameter to it ? My Controller has a property : I want to somehow reference this value from my controller and use it like : How can I do this ? Is the only way to add IsAdmin to my ViewModel ? <code> @ C...
How to create a wrapper helper around Url.Content helper function ?
C_sharp : I have static e paper but i want to develop dynamic e-paper like below urlhttps : //epaper.dawn.com/ ? page=15_04_2019_001I have no idea to start e paper dynamic below is my whole html codei am not getting any idea to implement dynamic , i have to take repeater control or grid view control to achieve dynamic ...
Trying to make epaper dynamic using C # asp.net web form
C_sharp : I do n't understand why it 's working ... The IL code : It compiles to bool Object.Equals ( Object , Object ) , but why ? <code> class Program { static void Main ( string [ ] args ) { IComparable.Equals ( 12 , 3 ) ; } } .method private hidebysig static void Main ( string [ ] args ) cil managed { .entrypoint /...
IComparable magic - why it 's a valid statement ?
C_sharp : why does n't the element get swappedeven if the parameter is without a ref modifier the array does n't change.a copy of the reference is passed as a parameter right ? <code> public static void SwapArray ( int [ , ] arr ) { for ( int i = 0 ; i < arr.GetLength ( 0 ) ; i++ ) { for ( int j = 0 ; j < arr.GetLength...
basic c # question
C_sharp : I am going through the Head First C # book and I ca n't figure out why they used the following way to create a property . It just seems inconsistent with the convention I 'm seeing everywhere else and in the book itself too . I understand that the pattern for creating properties is : Based on the above patter...
Head First C # : strange way to create a read-only property
C_sharp : I have an application where you can select between different objects in a ListBox . When you select an object , it changes the viewmodel for a control . The control utlizes the Timeline Control from CodePlex , and because of this , I have the StartDate and EndDate for the timeline data bound to ViewModel . Wh...
OnPropertyChange Firing Order
C_sharp : Is this kind of if-testing necessary when removing an item ? And , what about this test ? <code> if ( _items.Contains ( item ) ) { _items.Remove ( item ) ; } if ( ! _items.Contains ( item ) ) { _items.Add ( item ) ; }
C # List < T > Contains test
C_sharp : The code below is part of authorization . I am trying to mentally imaging what it actually does but could not somehow . Could anyone explain this lambda expression to me ? Thanks ! Edit : IsAuthorized is a delegate type . The previous programmer who code this seems want to keep it secret by putting delegate t...
Could anyone explain this lambda expression to me ? It 's kind getting me crazy
C_sharp : Like there are many Applications which are just basic but you can have install add-ins for it which extends its functionality in that Application . For example : How do they design such applications and how does the application accept the module and how can it automatically integrate.Secondly I do not know if...
Designing Application that can accept add ins
C_sharp : I 've simple Linq2Sql query : The problem is that it seems that new SomeLinq2SqlEntity ( ) is executed only once for the sequence , so all instances of MyViewModelClass in result of the query share the link to one object.Update : Here is how I quickly check it : Using debugger I can check that MyField was set...
`` new '' inside concrete type projection is only called once
C_sharp : Does Linq use any sorting or other mechanisms to make a group join more efficient so it does n't have to loop through an entire collection for every unmatched item ? In other words , Is this : more efficient than this : <code> var x = listA.GroupJoin ( listB , a = > a.prop , b = > b.prop , ( a , b ) = > new {...
Efficiency of Linq GroupJoin vs. Linq All in Select
C_sharp : We 've got a slight performance issue in a section of code that 's using LINQ and it 's raised a question about how LINQ works in terms of lookupsMy question is this ( please note that I have changed all the code so this is an indicative example of the code , not the real scenario ) : GivenIf I had a list of ...
Does this LINQ code perform multiple lookups on the original data ?
C_sharp : Suppose we had the following : I am using Autofac to register all of my components that implement IFoo : When I later resolve my dependencies with : I should get all of the classes that implement IFoo except the contract class ( es ) . How do I prevent all of my contract classes from resolving without moving ...
Autofac and Contract classes
C_sharp : Here is my code which is used widely in project , and I 'm wondering can I refactor this somehow so I might avoid == null checks all the time ? Thanks guysCheers <code> ActiveCompany = admin.Company == null ? false : admin.Company.Active
How could I avoid == null checking ?
C_sharp : I have a simple object that looks like this : I tried this code I found somewhere on the net : But somehow the returning byte array has a size of 248 bytes.I would expect it to be 4 bytes x 4 fields = 16 bytes.QUESTION : What 's the cleanest way to convert a fixed object into a byte array ? And should the res...
Fixed Object to Byte Array
C_sharp : Consider the following code ( for the sake of this test , it does n't do anything of particular use - it 's just to demonstrate the error that occurs ) I want to wrap Dictionary < string , dynamic > using inheritance : Here is the examle above using this derived class : This happens ... Any ideas on what is c...
C # compilation error with LINQ and dynamic inheritance
C_sharp : I have the following code : and when I run the test `` TestFoo ( ) '' , the console output is `` Foo - string '' . How does the compiler decide which method to call ? <code> [ TestMethod ] public void TestFoo ( ) { Foo ( null ) ; } private void Foo ( object bar ) { Console.WriteLine ( `` Foo - object '' ) ; }...
How does the compiler choose which method to call when a parameter type is ambiguous ?
C_sharp : Basically , is it better practice to store a value into a variable at the first run through , or to continually use the value ? The code will explain it better : or <code> TextWriter tw = null ; if ( ! File.Exists ( ConfigurationManager.AppSettings [ `` LoggingFile '' ] ) ) { // ... tw = File.CreateText ( Con...
Read a value multiple times or store as a variable first time round ?
C_sharp : I have the following code in my .Net 4 app : This givens me an ensures unproven warning at compile time : What is going on ? This works fine if S is an integer . It also works if I change the Ensure to S == Contract.OldValue ( S + `` 1 '' ) , but that 's not what I want to do . <code> static void Main ( strin...
Why is this string-based Contract.Ensure call unproven ?
C_sharp : i have a path data that i coppy it from syncfusion program.i have a path with that data in my page and want to animate my object exact on path way ( in mid of path line ) but the problem is the object move on outline ( surroundings ) of path .here is code : Edit 1 : my animation go wrong way . i want my Recta...
MatrixAnimationUsingPath animate on surroundings ( outline ) of path
C_sharp : I have been working a little bit with LINQ recently , and thanks to the help of some StackOverflowers I was able to get this statement working : However , I am confused because the piece that makes it work is the if ( traceJob.Count ( ) ==1 ) . If I remove that section , then I get an ObjectNullRef error sayi...
Why does an IF Statement effect the outcome of my LINQ Statement ?
C_sharp : I have this simple LINQ query , which executes for 8395 ms : Its IL : when it executes , it generates the following SQL query , which takes 661 ms to execute : What was Entity Framework ( version= '' 6.1.0.133 '' ) doing all that time ? Little change to the LINQ query , namely removing ToString ( ) call in th...
Why does ToString ( ) degrade Entity Framework 's performance so dramatically
C_sharp : Why ca n't I use code like this ? 12And should write like this12PS : I can use if-else statement without { } . Why should I use them with try-catch ( -finally ) statement ? Is there any meaningful reason ? Is it only because that some people think that code is hard to read ? Several months ago I asked that qu...
Why does it not allowed to use try-catch statement without { } ?
C_sharp : Possible Duplicate : “ new ” keyword in property declaration Pardon me if this is C # 101 , but I am trying to understand the code below : Why does the indexer have new in front of it ? By the way , Rabbit is a class defined in another file . Thanks ! <code> using System ; using System.Collections.Generic ; u...
Why does this code have new in the collections indexer
C_sharp : Specifically , if you create an instance of a Timer in the local scope , and then return from that scope:1 ) Will the timer still execute ? 2 ) When would it be garbage collected ? I offer these two scenarios : And <code> Timer timer = new Timer ( new TimerCallback ( ( state ) = > { doSomething ( ) ; } ) ) ; ...
What is the expected behavior of a locally scoped Timer ?
C_sharp : I 'm stuck with a weird problem ( which is probably my lack of knowledge ) , I present the offending code : f and fTemp are FileInfo objects . So if I run this with code where f is a video file playing in a mediaplayer it throws the exception . That works fine and as expected . Now when I close the mediaplaye...
Delete functions deletes even when calling app is closed
C_sharp : I 've this piece of code : If I build my application in Debug mode everything is ok , test index pre prints 12 and test index post prints 14. the same in Release mode with Optimize code unchecked . if i test with Optimize code checked test index post prints 18 instead of 14.Same result if I replace index += e...
RyuJIT C # wrong sum result with /optimize
C_sharp : Why is it when I turn on `` check for arithmetic underflow/overflow '' under C # Project Properties > Build > Advanced , that the following code runs faster ( 138 ms ) than if I turn the option off ( 141 ms ) ? Test Run # 1 : 138ms with checked arithmetic , 141ms withoutOn the other hand , if you comment out ...
Why is checked arithmetic in .NET sometimes faster than unckecked ?
C_sharp : Let 's say you wrote a custom enumerator for the code below : And then in the client code , you did this : Then , set a break-point on the MoveNext method implementation of your StudentEnumerator class.Then when you run the code and the debugger breaks after constructing the query / IEnumerable in this case ,...
How does Visual Studio evaluate the IEnumerable without breaking into its IEnumerator < T > 's MoveNext ?
C_sharp : Consider these two definitions for GetWindowText . One uses a string for the buffer , the other uses a StringBuilder instead : Here 's how you call them : They both seem to work correctly whether I pass in a string , or a StringBuilder . However , all the examples I 've seen use the StringBuilder variant . Ev...
For C # , is there a down-side to using 'string ' instead of 'StringBuilder ' when calling Win32 functions such as GetWindowText ?
C_sharp : I have discovered that if i run following lines of code.No boxing is done , but if i call i.GetType ( ) ( another derived function from System.Object ) in place of GetHashCode ( ) , a boxing will be required to call GetType ( ) , Why its not possible to call GetType ( ) on primitive type instance directly , w...
Why calling some functions of the Object class , on a primitive type instance , need boxing ?
C_sharp : As I do n't know how my problem is called , I can not guarantee , that nobody has asked the same question recently or at all.I did notice , however that there are quite a few threads with a similar title , but they do n't seem to be relevant to my problem.I have a custom list class , that implements Generics....
About Generics and Inheritance ( forgive my bad title )
C_sharp : The following is a code snippet about covariance in C # . I have some understanding about how to apply covariance , but there is some detailed technical stuff that I have hard time grasping.Invoking IExtract < object > .Extract ( ) invokes IExtract < string > .Extract ( ) , as evidenced by the output . While ...
C # covariance confusion
C_sharp : I have a troublesome query to write . I 'm currently writing some nasty for loops to solve it , but I 'm curious to know if Linq can do it for me.I have : and a list that contains these structs . Let 's say it 's ordered this way : If you put the orderedList struct dates in a set they will always be contiguou...
How can I use `` Linq to Objects '' to put a set of contiguous dates in one group ?
C_sharp : I have a .dll and a console app that uses the said .dll but does n't reference directly , it loads it via reflection . The console app calls a method of a class inside the .dll.The method signature is IEnumerable < Customer > GetAll ( ) ; In the .dll I have done this : In the Console app I 've done this : Now...
Access to type T properties of IEnumerable < T > returned from a method called via reflection
C_sharp : The following codeThrows a run-time KeyNotFoundException , albeit that { 1 } is a perfectly well-formed array ( i.e . int [ ] a = { 1,2,3,4 } being valid code ) . Changing the TValue of the Dictionary to int [ ] , throws a compile-time CS1061 , but this does not ( note the added new [ ] array-allocation ) : W...
Reason for KeyNotFoundException in Dictionary initialization
C_sharp : Do I need to add a lock block here if I want to be sure that instance will be created only 1 time ? Since there is only 1 instruction within the IF I 'm not 100 % sure . In a case like below , I 'm sure I 'd need it but I wanted to double check if the same applies for the code above.EDITYes , I assume multith...
Do I need a lock here ?