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  • Strings in ASP?

    - by TSL
    Hi All, I have some APSX code that I am trying to modify for a programmer that is out on medicaly leave. I am not an ASP guy, but rather C++ So what I want to do is delare a string, check the first 4 characters and if it is 'http' do something, if not, something else. Here is what I have: string strYT= Left(objFile, 4); if (strYT=="http") { pnlYT.Visible = true; pnlIntro.Visible = false; pnlVideo.Visible = false; } else { pnlYT.Visible = false; pnlIntro.Visible = false; pnlVideo.Visible = true; PrintText(objFile); } But I get errors like: Compiler Error Message: CS0103: The name 'Left' does not exist in the class or namespace 'ASP.zen_aspx' My googling turns up many examples of doing it just like this.....

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  • How to strip debug code during compile time in C++?

    - by juvenis
    Say I have a C++ function debugPrint(int foo). How can I most conveniently strip that from release builds? I do not want to surround every call to debugPrint with #ifdefs as it would be really time consuming. On the other hand, I want to be 100% sure that the compiler strips all the calls to that function, and the function itself from release builds. The stripping should happen also, if it's called with a parameter that results from a function call. E.g., debugPrint(getFoo());. In that case I want also the getFoo() call to be stripped. I understand that function inlining could be an option, but inlining is not guaranteed to be supported.

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  • C# Generics Multiple Inheritance Problem

    - by Ciemnl
    Can any one help me with this syntax issue with C#? I have no idea how to do it. class SomeClass<T> : SomeOtherClass<T> where T : ISomeInterface , IAnotherInterface { ... } I want SomeClass to inherit from SomeOtherClass and IAnotherInterface and for T to inherit ISomeInterface only It seems the problem is that the where keyword screws everything up so that the compiler thinks both ISomeInterface and IAnotherInterface should both be inherited by T. This problem is very annoying and I think the solution is some kind of parenthesis but I have tried and failed finding one that works. Also, switching around the order of the two items inherited from SomeClass does not work because the class inherited always has to come before any interfaces. I couldn't find any solutions on the MSDN C# generics pages and I can't beleive I'm the first person to have this problem. Thanks, any help is much appreciated!

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  • What's the outcome if I use free with new or delete with malloc?

    - by skydoor
    It is a compiler error or runtime error? The code below can be compiled! class Base{ void g(); void h(); }; int main() { Base* p = new Base(); free(p); return 0; } However it can't be compiled with a virtual function if I declare the class Base like this class Base{ virtual void g(); void h(); }; The code below can be compiled all the time, no matter the function is virtual or not. class Base{ void g(); void h(); }; int main() { Base* p = (Base*)malloc(sizeof(Base)); delete p; return 0; }

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  • what is the best approach for to use openGL in the web?

    - by Y_Y
    I wrote a program in C++/OpenGL (using Dev-C++ compiler) for my calculus 2 class. The teacher liked the program and he requested me to somehow put it online so that instead of downloading the .exe file and run it the web browser will run it automatically just like a java applet. The question is: How if possible, can I display a C++/OpenGL program in a web browser? I am thinking of moving to JOGL which is a java interpretation of OpenGL but I rather stay in C++ since I am more familiar with it. Also is there any other better and easier 3D web base API that I can consider?

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  • I want to make a wrapped acces type for certain internals of one of classes and I have some performa

    - by Alex
    I am writing an abstract matrix class (and some concrete subclasses) for use on very differing hardwares/architectures, etc. and I want to write a row and column type that provides a transparent reference to the rows and columns of the matrix. However, I want to tune for performance, so I'd like this class to be essentially a compiler construct. In other words, I'm willing to sacrifice some dev time to making the overhead of these classes as small as possible. I assume all (small) methods would want to be virtual? Keep the structure small? Any other suggestions?

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  • Typecasting doesn't work. How to convert an object?

    - by Nastase Ion
    Hi everyone! I need to convert a custom object to a different object. How can I do that? I know that typecasting doesn't work (the only thing is does is "shuts the compiler warnings off", but nothing more). Here is a sample code: MyType* obj1; MyOtherType* obj2; obj1 = [MyType initWithData: 1]; obj2 = (MyOtherType*) obj1; if ([obj2 isMemberOfClass: [MyOtherType class]]) { NSLog(@"OK"); } else if ([obj2 isMemberOfClass: [MyType class]]) { NSLog(@"Nope"); } The result is: Nope What can I do??

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  • Why Do try ... catch Blocks Require Braces?

    - by Bidou
    Hello. While in other statements like if ... else you can avoid braces if there is only one instruction in a block, you cannot do that with try ... catch blocks: the compiler doesn't buy it. For instance: try do_something_risky(); catch (...) std::cerr << "Blast!" << std::endl; With the code above, g++ simply says it expects a '{' before do_something_risky(). Why this difference of behavior between try ... catch and, say, if ... else ? Thanks!

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  • Tracking Useful Information

    - by Steve M
    What do the clever programmers here do to keep track of handy programming tricks and useful information they pick up over their many years of experience? Things like useful compiler arguments, IDE short-cuts, clever code snippets, etc. I sometimes find myself frustrated when looking up something that I used to know a year or two ago. My IE favourites probably represent a good chunk of the Internet in the late 1990s, so clearly that isn't effective (at least for me). Or am I just getting old? So.. what do you do?

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  • question about copy constructor

    - by lego69
    I have this class: class A { private: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); ~A(); void foo() const; }; and I have function which contains this row: A *pa1 = new A(a2); can somebody please explain what exactly is going on, when I call A(a2) compiler calls copy constructor or constructor, thanks in advance

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  • C++ template + typedef

    - by MMS
    What is wrong in the following code: Point2D.h template <class T> class Point2D { private: T x; T y; ... }; PointsList.h template <class T> class Point2D; template <class T> struct TPointsList { typedef std::vector <Point2D <T> > Type; }; template <class T> class PointsList { private: TPointsList <T>::Type points; //Compiler error ... }; I would like to create new user type TPointsList without direct type specification...

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  • How to make Eclipse compile with Java 1.5 in Mac OS X Leopard (10.5)?

    - by whiskeyspider
    I have been developing in Snow Leopard (10.6). I believe I have some Java6-only API features and I'd like to find these. I moved my project to Leopard (10.5) -- since Snow Leopard does not support Java 1.5 -- but I am so far unable to make Eclipse give compile errors for a Java API call which I know to have been added in 1.6. Here is what I have done: Project properties - Java Compiler - set everything to 1.5. Preferences - Java - Installed JREs - selected JVM 1.5.0. Project properties - Java Build Path - Libraries - says JRE System Library [JVM 1.5.0] What am I missing? Is there another way to find Java API calls added in 1.6 when using Eclipse in Snow Leopard? Thanks.

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  • Testing IPhone code on Windows

    - by steve
    I'm picking up a new Dell laptop. My primary machine is a IMac. I will most likely have to write some IPhone projects for someone in the future. While I do most of my work on the IMac there would be maybe 25% of the time where I work from my laptop. Can anyone tell me if I use objective C / IPhone SDK's if there is a generic objective C compiler I can use to see if my code would in theroy work? Not looking to do hackintosh or anything like that. My other option is to just get a discounted mac mini (Think this is most likely) as well as the Dell. Thanks for any advice

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  • XCode Project Code Changes Not Updating 100% After Save-Build-Run

    - by Greg
    When I make code changes to my iPhone game project in XCode, and then do CMD-B + Enter, I expect the project to be saved, build and run on the simulator with the latest. What is happening though, sometimes, is that it doesn't pick up a small change I make unless I clean the project and then build. I'm a long time Java person and newish to C-based languages and it's compiler. Can someone explain to me what is cached after each build that does this and how to change my project settings to avoid having to clean everytime? Or tell me the bad news that this is part of C development? Not trying to bash it - I get compiled JSPs stuck in the working cache often in Java, too. :P

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  • Can we overload a function based on only whether a parameter is a value or a reference?

    - by skydoor
    I got the answer NO! Because passing by value and passing by reference looks identical to the caller. However, the code below compiles right class A { public: void f(int i) {} void f(int& i) {} }; But when I try to use it, there is compile error. int main () { A a; int i = 9; int& j = i; a.f(1); a.f(i); a.f(j); return 0; } Why does not the compiler disable it even without knowing it is going to be used?

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  • @MustOverride annotation?

    - by Harrypotter2k5
    In .NET, one can specify a "mustoverride" attribute to a method in a particular superclass to ensure that subclasses override that particular method. I was wondering whether anybody has a custom java annotation that could achieve the same effect. Essentially what i want is to push for subclasses to override a method in a superclass that itself has some logic that must be run-through. I dont want to use abstract methods or interfaces, because i want some common functionality to be run in the super method, but more-or-less produce a compiler warning/error denoting that derivative classes should override a given method.

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  • Generics not so generic !!

    - by Aymen
    Hi I tried to implement a generic binary search algorithm in scala. Here it is : type Ord ={ def <(x:Any):Boolean def >(x:Any):Boolean } def binSearch[T <: Ord ](x:T,start:Int,end:Int,t:Array[T]):Boolean = { if (start > end) return false val pos = (start + end ) / 2 if(t(pos)==x) true else if (t(pos) < x) binSearch(x,pos+1,end,t) else binSearch(x,start,pos-1,t) } everything is OK until I tried to actually use it (xD) : binSearch(3,0,4,Array(1,2,5,6)) the compiler is pretending that Int not a member of Ord, well what shall I do to solve this ? Thanks

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  • Returning a struct from a class method

    - by tree
    I have a header file that looks something like the following: class Model { private: struct coord { int x; int y; } xy; public: .... coord get() const { return xy; } }; And in yet another file (assume ModelObject exists): struct c { int x; int y; void operator = (c &rhs) { x = rhs.x; y = rhs.y; }; } xy; xy = ModelObject->get(); The compiler throws an error that says there is no known covnersion from coord to c. I believe it is because it doesn't know about coord type because it is declared inside of a class header. I can get around that by declaring the struct outside of the class, but I was wondering if it is possible to do the way I am, or is this generally considered bad practice

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  • Java Basics: create class object

    - by user1767853
    In C++: class Rectangle { int x, y; public: void set_values (int,int); int area () {return (x*y);} }; int main () { Rectangle rect; rect.set_values (3,4); } In Java: class Rectangle { int x, y; void set_values (int x,int y); int area () {return (x*y);} } public static void main(String[] args) { Rectangle rect=new Rectangle(3,4); } In C++ compiler will create rect object & reserve memory 4 bytes. I want to know How Java is creating object?

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  • printf("... %c ...",'\0') and family - what will happen?

    - by SF.
    How will various functions that take printf format string behave upon encountering the %c format given value of \0/NULL? How should they behave? Is it safe? Is it defined? Is it compiler-specific? e.g. sprintf() - will it crop the result string at the NULL? What length will it return? Will printf() output the whole format string or just up to the new NULL? Will va_args + vsprintf/vprintf be affected somehow? If so, how? Do I risk memory leaks or other problems if I e.g. shoot this NULL at a point in std::string.c_str()? What are the best ways to avoid this caveat (sanitize input?)

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  • Getting Started with ASP.NET Membership, Profile and RoleManager

    - by Ben Griswold
    A new ASP.NET MVC project includes preconfigured Membership, Profile and RoleManager providers right out of the box.  Try it yourself – create a ASP.NET MVC application, crack open the web.config file and have a look.  First, you’ll find the ApplicationServices database connection: <connectionStrings>   <add name="ApplicationServices"        connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true"        providerName="System.Data.SqlClient"/> </connectionStrings>   Notice the connection string is referencing the aspnetdb.mdf database hosted by SQL Express and it’s using integrated security so it’ll just work for you without having to call out a specific database login or anything. Scroll down the file a bit and you’ll find each of the three noted sections: <membership>   <providers>     <clear/>     <add name="AspNetSqlMembershipProvider"          type="System.Web.Security.SqlMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"          connectionStringName="ApplicationServices"          enablePasswordRetrieval="false"          enablePasswordReset="true"          requiresQuestionAndAnswer="false"          requiresUniqueEmail="false"          passwordFormat="Hashed"          maxInvalidPasswordAttempts="5"          minRequiredPasswordLength="6"          minRequiredNonalphanumericCharacters="0"          passwordAttemptWindow="10"          passwordStrengthRegularExpression=""          applicationName="/"             />   </providers> </membership>   <profile>   <providers>     <clear/>     <add name="AspNetSqlProfileProvider"          type="System.Web.Profile.SqlProfileProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"          connectionStringName="ApplicationServices"          applicationName="/"             />   </providers> </profile>   <roleManager enabled="false">   <providers>     <clear />     <add connectionStringName="ApplicationServices" applicationName="/" name="AspNetSqlRoleProvider" type="System.Web.Security.SqlRoleProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />     <add applicationName="/" name="AspNetWindowsTokenRoleProvider" type="System.Web.Security.WindowsTokenRoleProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />   </providers> </roleManager> Really. It’s all there. Still don’t believe me.  Run the application, walk through the registration process and finally login and logout.  Completely functional – and you didn’t have to do a thing! What else?  Well, you can manage your users via the Configuration Manager which is hiding in Visual Studio behind Projects > ASP.NET Configuration. The ASP.NET Web Site Administration Tool isn’t MVC-specific (neither is the Membership, Profile or RoleManager stuff) but it’s neat and I hardly ever see anyone using it.  Here you can set up and edit users, roles, and set access permissions for your site. You can manage application settings, establish your SMTP settings, configure debugging and tracing, define default error page and even take your application offline.  The UI is rather plain-Jane but it works great. And here’s the best of all.  Let’s say you, like most of us, don’t want to run your application on top of the aspnetdb.mdf database.  Let’s suppose you want to use your own database and you’d like to add the membership stuff to it.  Well, that’s easy enough. Take a look inside your [drive:]\%windir%\Microsoft.Net\Framework\v2.0.50727\ folder.  Here you’ll find a bunch of files.  If you were to run the InstallCommon.sql, InstallMembership.sql, InstallRoles.sql and InstallProfile.sql files against the database of your choices, you’d be installing the same membership, profile and role artifacts which are found in the aspnet.db to your own database.  Too much trouble?  Okay. Run [drive:]\%windir%\Microsoft.Net\Framework\v2.0.50727\aspnet_regsql.exe from the command line instead.  This will launch the ASP.NET SQL Server Setup Wizard which walks you through the installation of those same database objects into the new or existing database of your choice. You may not always have the luxury of using this tool on your destination server, but you should use it whenever you can.  Last tip: don’t forget to update the ApplicationServices connectionstring to point to your custom database after the setup is complete. At the risk of sounding like a smarty, everything I’ve mentioned in this post has been around for quite a while. The thing is that not everyone has had the opportunity to use it.  And it makes sense. I know I’ve worked on projects which used custom membership services.  Why bother with the out-of-the-box stuff, right?   And the .NET framework is so massive, who can know it all. Well, eventually you might have a chance to architect your own solution using any implementation you’d like or you will have the time to play around with another aspect of the framework.  When you do, think back to this post.

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  • MVC Razor Engine For Beginners Part 1

    - by Humprey Cogay, C|EH, E|CSA
    I. What is MVC? a. http://www.asp.net/mvc/tutorials/older-versions/overview/asp-net-mvc-overview II. Software Requirements for this tutorial a. Visual Studio 2010/2012. You can get your free copy here Microsoft Visual Studio 2012 b. MVC Framework Option 1 - Install using a standalone installer http://www.microsoft.com/en-us/download/details.aspx?id=30683 Option 2 - Install using Web Platform Installer http://www.microsoft.com/web/handlers/webpi.ashx?command=getinstallerredirect&appid=MVC4VS2010_Loc III. Creating your first MVC4 Application a. On the Visual Studio click file new solution link b. Click Other Project Type>Visual Studio Solutions and on the templates window select blank solution and let us name our solution MVCPrimer. c. Now Click File>New and select Project d. Select Visual C#>Web> and select ASP.NET MVC 4 Web Application and Enter MyWebSite as Name e. Select Empty, Razor as view engine and uncheck Create a Unit test project f. You can now view a basic MVC 4 Application Structure on your solution explorer g. Now we will add our first controller by right clicking on the controllers folder on your solution explorer and select Add>Controller h. Change the name of the controller to HomeController and under the scaffolding options select Empty MVC Controller. i. You will now see a basic controller with an Index method that returns an ActionResult j. We will now add a new View Folder for our Home Controller. Right click on the views folder on your solution explorer and select Add> New Folder> and name this folder Home k. Add a new View by right clicking on Views>Home Folder and select Add View. l. Name the view Index, and select Razor(CSHTML) as View Engine, All checkbox should be unchecked for now and click add. m. Relationship between our HomeController and Home Views Sub Folder n. Add new HTML Contents to our newly created Index View o. Press F5 to run our MVC Application p. We will create our new model, Right click on the models folder of our solution explorer and select Add> Class. q. Let us name our class Customer r. Edit the Customer class with the following code s. Open the HomeController by double clickin HomeController of our Controllers folder and edit the HomeControllerusing System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc;   namespace MyWebSite.Controllers {     public class HomeController : Controller     {         //         // GET: /Home/           public ActionResult Index()         {             return View();         }           public ActionResult ListCustomers()         {             List<Models.Customer> customers = new List<Models.Customer>();               //Add First Customer to Our Collection             customers.Add(new Models.Customer()                     {                         Id = 1,                         CompanyName = "Volvo",                         ContactNo = "123-0123-0001",                         ContactPerson = "Gustav Larson",                         Description = "Volvo Car Corporation, or Volvo Personvagnar AB, is a Scandinavian automobile manufacturer founded in 1927"                     });                 //Add Second Customer to Our Collection             customers.Add(new Models.Customer()                     {                         Id = 2,                         CompanyName = "BMW",                         ContactNo = "999-9876-9898",                         ContactPerson = "Franz Josef Popp",                         Description = "Bayerische Motoren Werke AG,  (BMW; English: Bavarian Motor Works) is a " +                                       "German automobile, motorcycle and engine manufacturing company founded in 1917. "                     });                 //Add Third Customer to Our Collection             customers.Add(new Models.Customer()             {                 Id = 3,                 CompanyName = "Audi",                 ContactNo = "983-2222-1212",                 ContactPerson = "Karl Benz",                 Description = " is a multinational division of the German manufacturer Daimler AG,"             });               return View(customers);         }     } } t. Let us now create a view for this Class, But before continuing Press Ctrl + Shift + B to rebuild the solution, this will make the previously created model on the Model class drop down of the Add View Menu. Right click on the views>Home folder and select Add>View u. Let us name our View as ListCustomers, Select Razor(CSHTML) as View Engine, Put a check mark on Create a strongly-typed view, and select Customer (MyWebSite.Models) as model class. Slect List on the Scaffold Template and Click OK. v. Run the MVC Application by pressing F5, and on the address bar insert Home/ListCustomers, We should now see a web page similar below.   x. You can edit ListCustomers.CSHTML to remove and add HTML codes @model IEnumerable<MyWebSite.Models.Customer>   @{     Layout = null; }   <!DOCTYPE html>   <html> <head>     <meta name="viewport" content="width=device-width" />     <title>ListCustomers</title> </head> <body>     <h2>List of Customers</h2>     <table border="1">         <tr>             <th>                 @Html.DisplayNameFor(model => model.CompanyName)             </th>             <th>                 @Html.DisplayNameFor(model => model.Description)             </th>             <th>                 @Html.DisplayNameFor(model => model.ContactPerson)             </th>             <th>                 @Html.DisplayNameFor(model => model.ContactNo)             </th>         </tr>         @foreach (var item in Model) {         <tr>             <td>                 @Html.DisplayFor(modelItem => item.CompanyName)             </td>             <td>                 @Html.DisplayFor(modelItem => item.Description)             </td>             <td>                 @Html.DisplayFor(modelItem => item.ContactPerson)             </td>             <td>                 @Html.DisplayFor(modelItem => item.ContactNo)             </td>                   </tr>     }         </table> </body> </html> y. Press F5 to run the MVC Application   z. You will notice some @HTML.DisplayFor codes. These are called HTML Helpers you can read more about HTML Helpers on this site http://www.w3schools.com/aspnet/mvc_htmlhelpers.asp   That’s all. You now have your first MVC4 Razor Engine Web Application . . .

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  • SQL Authority News – Download Microsoft SQL Server 2014 Feature Pack and Microsoft SQL Server Developer’s Edition

    - by Pinal Dave
    Yesterday I attended the SQL Server Community Launch in Bangalore and presented on Performing an effective Presentation. It was a fun presentation and people very well received it. No matter on what subject, I present, I always end up talking about SQL. Here are two of the questions I had received during the event. Q1) I want to install SQL Server on my development server, where can we get it for free or at an economical price (I do not have MSDN)? A1) If you are not going to use your server in a production environment, you can just get SQL Server Developer’s Edition and you can read more about it over here. Here is another favorite question which I keep on receiving it during the event. Q2) I already have SQL Server installed on my machine, what are different feature pack should I install and where can I get them from. A2) Just download and install Microsoft SQL Server 2014 Service Pack. Here is the link for downloading it. The Microsoft SQL Server 2014 Feature Pack is a collection of stand-alone packages which provide additional value for Microsoft SQL Server. It includes tool and components for Microsoft SQL Server 2014 and add-on providers for Microsoft SQL Server 2014. Here is the list of component this product contains: Microsoft SQL Server Backup to Windows Azure Tool Microsoft SQL Server Cloud Adapter Microsoft Kerberos Configuration Manager for Microsoft SQL Server Microsoft SQL Server 2014 Semantic Language Statistics Microsoft SQL Server Data-Tier Application Framework Microsoft SQL Server 2014 Transact-SQL Language Service Microsoft Windows PowerShell Extensions for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Shared Management Objects Microsoft Command Line Utilities 11 for Microsoft SQL Server Microsoft ODBC Driver 11 for Microsoft SQL Server – Windows Microsoft JDBC Driver 4.0 for Microsoft SQL Server Microsoft Drivers 3.0 for PHP for Microsoft SQL Server Microsoft SQL Server 2014 Transact-SQL ScriptDom Microsoft SQL Server 2014 Transact-SQL Compiler Service Microsoft System CLR Types for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Remote Blob Store SQL RBS codeplex samples page SQL Server Remote Blob Store blogs Microsoft SQL Server Service Broker External Activator for Microsoft SQL Server 2014 Microsoft OData Source for Microsoft SQL Server 2014 Microsoft Balanced Data Distributor for Microsoft SQL Server 2014 Microsoft Change Data Capture Designer and Service for Oracle by Attunity for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Master Data Service Add-in for Microsoft Excel Microsoft SQL Server StreamInsight Microsoft Connector for SAP BW for Microsoft SQL Server 2014 Microsoft SQL Server Migration Assistant Microsoft SQL Server 2014 Upgrade Advisor Microsoft OLEDB Provider for DB2 v5.0 for Microsoft SQL Server 2014 Microsoft SQL Server 2014 PowerPivot for Microsoft SharePoint 2013 Microsoft SQL Server 2014 ADOMD.NET Microsoft Analysis Services OLE DB Provider for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Analysis Management Objects Microsoft SQL Server Report Builder for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Reporting Services Add-in for Microsoft SharePoint Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL

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  • Imperative Programming v/s Declarative Programming v/s Functional Programming

    - by kaleidoscope
    Imperative Programming :: Imperative programming is a programming paradigm that describes computation in terms of statements that change a program state. In much the same way as the imperative mood in natural languages expresses commands to take action, imperative programs define sequences of commands for the computer to perform. The focus is on what steps the computer should take rather than what the computer will do (ex. C, C++, Java). Declarative Programming :: Declarative programming is a programming paradigm that expresses the logic of a computation without describing its control flow. It attempts to minimize or eliminate side effects by describing what the program should accomplish, rather than describing how to go about accomplishing it. The focus is on what the computer should do rather than how it should do it (ex. SQL). A  C# example of declarative v/s. imperative programming is LINQ. With imperative programming, you tell the compiler what you want to happen, step by step. For example, let's start with this collection, and choose the odd numbers: List<int> collection = new List<int> { 1, 2, 3, 4, 5 }; With imperative programming, we'd step through this, and decide what we want: List<int> results = new List<int>(); foreach(var num in collection) {     if (num % 2 != 0)           results.Add(num); } Here’s what we are doing: *Create a result collection *Step through each number in the collection *Check the number, if it's odd, add it to the results With declarative programming, on the other hand, we write the code that describes what you want, but not necessarily how to get it var results = collection.Where( num => num % 2 != 0); Here, we're saying "Give us everything where it's odd", not "Step through the collection. Check this item, if it's odd, add it to a result collection." Functional Programming :: Functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions.Functional programming has its roots in the lambda calculus. It is a subset of declarative languages that has heavy focus on recursion. Functional programming can be a mind-bender, which is one reason why Lisp, Scheme, and Haskell have never really surpassed C, C++, Java and COBOL in commercial popularity. But there are benefits to the functional way. For one, if you can get the logic correct, functional programming requires orders of magnitude less code than imperative programming. That means fewer points of failure, less code to test, and a more productive (and, many would say, happier) programming life. As systems get bigger, this has become more and more important. To know more : http://stackoverflow.com/questions/602444/what-is-functional-declarative-and-imperative-programming http://msdn.microsoft.com/en-us/library/bb669144.aspx http://en.wikipedia.org/wiki/Imperative_programming   Technorati Tags: Ranjit,Imperative Programming,Declarative programming,Functional Programming

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  • Subterranean IL: Filter exception handlers

    - by Simon Cooper
    Filter handlers are the second type of exception handler that aren't accessible from C#. Unlike the other handler types, which have defined conditions for when the handlers execute, filter lets you use custom logic to determine whether the handler should be run. However, similar to a catch block, the filter block does not get run if control flow exits the block without throwing an exception. Introducing filter blocks An example of a filter block in IL is the following: .try { // try block } filter { // filter block endfilter }{ // filter handler } or, in v1 syntax, TryStart: // try block TryEnd: FilterStart: // filter block HandlerStart: // filter handler HandlerEnd: .try TryStart to TryEnd filter FilterStart handler HandlerStart to HandlerEnd In the v1 syntax there is no end label specified for the filter block. This is because the filter block must come immediately before the filter handler; the end of the filter block is the start of the filter handler. The filter block indicates to the CLR whether the filter handler should be executed using a boolean value on the stack when the endfilter instruction is run; true/non-zero if it is to be executed, false/zero if it isn't. At the start of the filter block, and the corresponding filter handler, a reference to the exception thrown is pushed onto the stack as a raw object (you have to manually cast to System.Exception). The allowed IL inside a filter block is tightly controlled; you aren't allowed branches outside the block, rethrow instructions, and other exception handling clauses. You can, however, use call and callvirt instructions to call other methods. Filter block logic To demonstrate filter block logic, in this example I'm filtering on whether there's a particular key in the Data dictionary of the thrown exception: .try { // try block } filter { // Filter starts with exception object on stack // C# code: ((Exception)e).Data.Contains("MyExceptionDataKey") // only execute handler if Contains returns true castclass [mscorlib]System.Exception callvirt instance class [mscorlib]System.Collections.IDictionary [mscorlib]System.Exception::get_Data() ldstr "MyExceptionDataKey" callvirt instance bool [mscorlib]System.Collections.IDictionary::Contains(object) endfilter }{ // filter handler // Also starts off with exception object on stack callvirt instance string [mscorlib]System.Object::ToString() call void [mscorlib]System.Console::WriteLine(string) } Conclusion Filter exception handlers are another exception handler type that isn't accessible from C#, however, just like fault handlers, the behaviour can be replicated using a normal catch block: try { // try block } catch (Exception e) { if (!FilterLogic(e)) throw; // handler logic } So, it's not that great a loss, but it's still annoying that this functionality isn't directly accessible. Well, every feature starts off with minus 100 points, so it's understandable why something like this didn't make it into the C# compiler ahead of a different feature.

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