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  • Memory allocated with malloc does not persist outside function scope?

    - by PM
    Hi, I'm a bit new to C's malloc function, but from what I know it should store the value in the heap, so you can reference it with a pointer from outside the original scope. I created a test program that is supposed to do this but I keep getting the value 0, after running the program. What am I doing wrong? int f1(int * b) { b = malloc(sizeof(int)); *b = 5; } int main() { int * a; f1(a); printf("%d\n", a); return 0; }

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  • using "Reference3 Interface" to add desired references to a project

    - by BDotA
    I found this: http://msdn.microsoft.com/en-us/library/vslangproj80.reference3%28VS.80%29.aspx what I have in mind is that many of the references that we add to our project are on a network drive and there are TON of them. Adding references to the project by right clicking on the References in the porject and choosing add reference is a pain. so I was wondering if I can take advantage of something like what I posted the link to it and have a small program,add-in,macro, etc! that we can give it a list of the references that I want and it will add them to the project.

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  • .NET web service call slower when performed asynchronously

    - by joelt
    I have an ASP.NET site, and some pages need to call a web service. I used Visual Studio's "Add Web Reference" to auto-generate classes and methods for the web service. When I call the service synchronously, i.e. objService.MethodName("param1"), a call might take a second or so. When I call it asynchronously, i.e., objService.BeginMethodName("param1", AddressOf MyCallback, Nothing), it typically takes about 6 seconds. When debugging, it appears that the bulk of the time is spent waiting between the completion of the BeginMethodName call and the beginning of MyCallback. Does the thread switching really incur that much overhead? Is there another reason for this?

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  • Is it possible to dynamically change the style/template of a control?

    - by elggarc
    I am creating a UserControl in Silverlight 4 which has a watermarked background. The watermark should change depending on the underlying 'type' the UserControl is representing. The watermark is created using a Path and I have extracted all the properties into a style. I was wondering if it would be possible to change the style of the Path at runtime based on some known value. I am using MVVM and Unity. Perhaps I could bind the style somehow? Or could I inject the style when the view is created? I may have to do this with control templates, hence the reference in the title. Thanks...

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  • Pass C++ object to Lua function

    - by peterdemin
    Hello there. I have a C++ project, where 1 method of a 1 class changes very often. So I want to take that code from C++ to Lua. Note, I'm novice to Lua. The whole task: Bind some class methods to Lua state machine; Pass reference to class object to a function, written in Lua; Operate with passed C++ object in Lua function. I've found how to make first step with Lunar, and can't cope with second and third. I can't use SWIG and boost.

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  • Infinite loop when Selecting a panel?

    - by serhio
    I have a winform in witch I have a custom LongPanel with textboxes. In order to validate an eventually edited textbox when the user click somewhere out of textBoxY I use the following code: Private Sub LongPanel_MouseClick(ByVal sender As Object, _ ByVal e As MouseEventArgs) _ Handles MyBase.MouseClick _AttachedPanel.Select() End Sub In runtime application freezes at the "Select" line... I receive infinite panel Leave events(sender is a panel)... any idea why? EDIT: precision on panels parents: Form => SplitPanel => _AttachedPanel | _LongPanel (_LongPanel contains a reference to _AttachedPanel)

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  • How to handle Foreign Keys with Entity Framework

    - by Jack Marchetti
    I have two entities. Groups. Pools. A Group can create many pools. So I setup my Pool table to have a GroupID foreign key. My code: using (entity _db = new entity()) { Pool p = new Pool(); p.Name = "test"; p.Group.ID = "5"; _db.AddToPool(p); } This doesn't work. I get a null reference exception on p.Group. How do I go about creating a new "Pool" and associating a GroupID?

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  • Accessing primitive properties from objects stored in a NSDictionary

    - by ChrisS
    Apologies if this is a basic question, I am just starting with Objective-C and trying to wrap things around in my head! I have a simple class of the form: @interface Whatever : NSObject { int somePrimitive; SomeObject* someObject; } @property (nonatomic) int somePrimitive; @property (nonatomic, retain) SomeObject* someObject; The class is more involved that this, but this illustrates the purpose. When I store instances of this class in a NSMutableDictionary: Whatever *whatever = [[Whatever alloc] init]; whatever.somePrimitive = 1; whatever.someObject = ...; [myDictionary setObject:whatever forKey:@"someKey"]; and then try to retrieve the object later: Whatever *result = [myDictionary valueForKey:@"someKey"]; then, result.someObject is ok to reference but, result.somePrimitive crashes. Does the NSDictionary not copy over the primitives of the object? Is the rule that the object stored in a dictionary should only contain objects?

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  • Any way to stringify a variable id / symbol in Python?

    - by otz
    I'm wondering if it is possible at all in python to stringify variable id/symbol -- that is, a function that behaves as follows: >>> symbol = 'whatever' >>> symbol_name(symbol) 'symbol' Now, it is easy to do it on a function or a class (if it is a direct reference to the object): >>> def fn(): pass >>> fn.func_name 'fn' But I'm looking for a general method that works on all cases, even for indirect object references. I've thought of somehow using id(var), but no luck yet. Is there any way to do it?

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  • How long people take to learn a new programming language?

    - by Cawas
    In general aspects, this might be a good reference for everyone. Having an idea of how long people take in average for properly learning how to code can give a very good idea on how dense or long is the path. Someone who never programmed should take weeks or months, even years maybe while someone who's already experienced in the area and know at least 2 different languages might take days, hours or even minutes to start coding. But other than being able to write code that runs, there are ways to write the same program, and it's much harder to get deep knowledge on that than actually being able to program. And sometimes languages differ a lot from one to another on that aspect as well. For instance, we should never have to worry with code-injection in JavaScript like we do in C. So, is there any place we can see some good numbers for how long it takes to learn a language, maybe divided into level of knowledge categories, languages and paradigms, etc?

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  • C# thread safety for class instances

    - by Steveng
    I am learning C# and I am confused with the thread safety of the copies of the class instances as below: eg: classA objA; classA objB = objA; objA.field1 = value2; //do I need lock around modification of field1? //let say we pass the objB to another thread objB.field1 = value1 //do I need a lock for objB because of the modification of field1? I am confused because coming from the background of C++, the class in C# is the reference type. If both objA and objB refer to the same memory underlying, then I would need a lock to protect the simultaneous writing to the field1. Could someone confirm with this or am I missing something? Thanks.

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  • Can a SQL Server 2008 database support both a REST and SOAP web services within two different endpoints?

    - by PaulDecember
    Say you have a SQL Server 2008 database. You build a SOAP web service. You then deploy or publish this using Visual Studio 2010 in one website. Now, using the same database, you build a REST web service, in a different solution. You deploy this on another website. Can you consume the endpoints and/or .svc file of both the SOAP and REST web services, though they reference the same SQL Server 2008 database? I don't see why not, but before I go down this path and spend days I'd like to make sure. Also if there's a performance hit to the database if it is running both SOAP and REST at the same time--again, I don't see why it would matter, but I must make sure. Thanks.

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  • Question about r-value in C++0x

    - by Goofy
    Rvalues IMHO are great improvement in C++, but at the beginning the're seems quite. Please look at code below: #include <string> std::string && foo (void) { std::string message ("Hello!"); return std::move (message); } void bar (const std::string &message2) { if (message == "Bye Bye!") return; } int main () { bar (foo ()); } Reference message2 is last owner of original message object returned by foo(), right?

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  • C# background worker and timer loop

    - by Mike
    This is my first attempt of a Timer, if someone could help me out where I am going wrong it would be awesome. I'm trying to use a while loop where if the timer hits 30 seconds try to loop it again. private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) { System.Windows.Forms.Timer my_timer = new System.Windows.Forms.Timer(); my_timer = null; //int restartticker = 30000; while (true) { my_timer.Start(); if (my_timer.Equals(30000)) { watcherprocess1(); } my_timer = null; } } Object reference not set to an instance of an object. my_timer.Start();

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  • What is the right way to implement communication between java objects?

    - by imoschak
    I'm working on an academic project which simulates a rather large queuing procedure in java. The core of the simulator rests within one package where there exist 8 classes, each one implementing a single concept. Every class in the project follows SRP. These classes encapsulate the behavior of the simulator and inter-connect every other class in the project. The problem that has arisen is that most of these 8 classes are, as is logical i think, tightly coupled and each one has to have working knowledge of every other class in this package in order to be able to call methods from it when needed. The application needs only one instance of each class so it might be better to create static fields for each class in a new class and use that to make calls -instead of preserving a reference in each class for every other class in the package (which I'm certain that is incorrect)-, but is this considered a correct design solution? or is there a design pattern maybe that better suits my needs?

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  • Getting facts from documents

    - by dotnetdev
    Hi, I want to be able to get all the facts from webpages. But these have to be related to coding, and not, for example, about something irrelevant. For example: The Engine renders at a decent speed. May be a fact but is not what I am interested in. If the same article states: A class is a reference type. (This is C#) Then I am interested in that as it is coding related. Has an algorithm like this ever been done? How hard would this be? I'm thinking AI would come into play here. Any advice sought. Thanks

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  • Class templating std::set key types

    - by TomFLuff
    I have a class to evaluate set algebra but wish to template it. At the minute it looks a bit like this set.h: template<typename T> class SetEvaluation { public: SetEvaluation<T>(); std::set<T> evaluate(std::string in_expression); } set.cpp template<typename T> std::set<T> SetEvaluation<T>::evaluate(std::string expression) { std::set<T> result; etc etc... } But i'm getting undefined reference errors when compiling. Is it possible to declare the return type as std::set<T> and then pass std::string as the class template param. There are no errors in the class but only when I try to instantiate SetEvaluation<std::string> Can anyone shed light on this problem? thanks

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  • JavaScript prototype(ing) question

    - by OneNerd
    Trying to grasp Prototyping in Javascript. Trying to create my own namespace to extend the String object in JavaScript. Here is what I have so far (a snippet): var ns { alert: function() { alert (this); } } String.prototype.$ns = ns; As you can see, I am trying to place what will be a series of functions into the ns namespace. So I can execute a command like this: "hello world".$ns.alert(); But the problem is, the this doesn't seem to reference the text being sent (in this case, "hello world"). What I get is an alert box with the following: [object Object] Not having a full grasp of the object-oriented nature of JavaScript, I am at a loss, but I am guessing I am missing something simple. Does anyone know how to achieve this? Thanks -

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  • Why don't hardware failures show up at the programming language level?

    - by Julian Cienfuegos
    I am wondering if anyone can give my a good answer, or at least point me in the direction of a good reference to the following question: How come I have never heard of a computer breaking in a very fundamental way? How come when I declare x to be a double it stays as a double? How come there is never a short circuit that robs it of some bytes and makes it an integer? Why do we have faith that when we initialize x to 10, there will never be a power surge that will cause it to become 11, or something similar? I think I need a better understanding of memory. Thanks, and please don't bash me over the head for such a simple/abstract question.

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  • How can i add column name in list generic?

    - by Phsika
    class MyExcelSheets { public List MyColumnNames { get; set; } } how can i add Excel data's column name in "List MyColumnNames ". it returns to me Object reference not set to an instance of an object. i want to use above class in: myexcelSheet = new MyExcelSheets(); myexcelSheet.MyColumnNames = new MyExcelSheets().MyColumnNames; foreach (DataColumn col in dTable.Columns) myexcelSheet.MyColumnNames.Add(col.ColumnName.ToString()); How can i solve it? Error: NullReferenceException

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  • C++ syntax of constructors " 'Object1 a (1, Object1(2))''

    - by osgx
    Hello I have a such syntax in program class Object1 : BaseClass { BaseClass *link; int i; public: Object1(int a){i=a;} Object1(int a, Object1 /*place1*/ o) {i=a; link= &o;} }; int main(){ Object1 a(1, /*place2*/ Object1(2)); ... } What do I need in place1? I want to save a link (pointer) to the second object in the first object. Should I use in place1 reference "&"? What type will have "Object1(2)" in place2? Is it a constructor of the anonymous object? Will it have a "auto" storage type?

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  • c# project cannot find c++ .dll?

    - by flavour404
    I have a working c++ dll that works in one c# project that I am calling via the interop service. I have created another c# project and am trying to call the same .dll but keep getting a generic error message stating that the .dll cannot be found, both project are .net 2.0. What folder, and where do I specify in the project, should I put the .dll file in so that the project can find it? Think of it as a reminder for me... In the previous project I did not have a reference to it, I just had it in the /bin folder and doing the same thing for this project does not work. Thanks R.

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  • Handling orientation changes yourself

    - by synic
    From the documentation regarding the android:configChanges='orientation' attribute of the activity tag in the manifest: Note: Using this attribute should be avoided and used only as a last-resort. Please read Handling Runtime Changes for more information about how to properly handle a restart due to a configuration change. Why does it say this? In the case of threads and networking requests via a service API library, a request could be made with a reference to the original Activity, and then an orientation change could occur, leaving the thread pointing to the old Activity. While this can be fixed, it's tedious and ugly compared to just handling the configuration changes yourself. Why should it be avoided?

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  • how to use constants in SQL CREATE TABLE?

    - by kchiu
    Hi, I have 3 SQL tables, defined as follows: CREATE TABLE organs( abbreviation VARCHAR(16), -- ... other stuff ); CREATE TABLE blocks( abbreviation VARCHAR(16), -- ... other stuff ); CREATE TABLE slides( title VARCHAR(16), -- ... other stuff ); The 3 fields above all use VARCHAR(16) because they're related and have the same length restriction. Is there a (preferably portable) way to put '16' into a constant / variable and reference that instead in CREATE TABLE? eg. something like this would be nice: CREATE TABLE slides( title VARCHAR(MAX_TITLE_LENGTH), -- ... other stuff ); I'm using PostgreSQL 8.4. thanks a lot, and Happy New Year! cheers.

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  • SQL Server 2005 Reporting Services: How to count rows that are not null? Any hints for calculating t

    - by user329266
    Is there a way to count only records that are not null; similar to "COUNTA" in Excel? I would think this would be very simple process, but nothing I have tried has worked. If necessary, I can try to work this into my SQL query, but the query is already incredibly complicated. Also, I've found very little documentation for how to calculate report totals, and how to total from groups. Would anyone have any recommendations on what to use as a reference?

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