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  • How can I declare a pointer structure?

    - by Y_Y
    This probably is one of the easiest questions ever in C programming language... I have the following code: typedef struct node { int data; struct node * after; struct node * before; }node; struct node head = {10,&head,&head}; Is there a way I can make head to be *head [make it a pointer] and still have the availability to use '{ }' [{10,&head,&head}] to declare an instance of head?

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  • Simulating a missing gem in Ruby unit tests

    - by ktex
    Is there any way to simulate the absence of a gem for certain unit tests, short of actually uninstalling and then reinstalling the gem during testing? I am writing a command line utility, and want to make sure that my tests cover cases where a user may not have all of the gems that I support. For instance, I am using fsevents — a Leopard-specific package for monitoring filesystem events — that will never be present on other systems, as well as a growl gem that's purely optional.

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  • Explicitly accessing banked registers on ARM

    - by Demiurg
    According to the ARM manual, it should be possible to access the banked registers for a specific CPU mode as, for instance, "r13_svc". When I try to do this gcc yells at me with the following error: immediate expression requires a # prefix -- `mov r2,sp_svc' What's wrong?

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  • empty sharepoint user profile property throw an exception

    - by James123
    I have a user profile property. user not assigned any value that property. If I use below code. It is thorwing exception " object reference not set to an instance of an object " userprof["OptOut"].ToString() I tried all types like if (userprof["OptOut"] != null) OR if(userprof["OptOut"].Value != null) nothing worked out for me. Here userProf object has value. userprof["OptOut"].Value is null How to handle this?

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  • Are comonads a good fit for modeling the Wumpus world?

    - by Tim Stewart
    I'm trying to find some practical applications of a comonad and I thought I'd try to see if I could represent the classical Wumpus world as a comonad. I'd like to use this code to allow the Wumpus to move left and right through the world and clean up dirty tiles and avoid pits. It seems that the only comonad function that's useful is extract (to get the current tile) and that moving around and cleaning tiles would not use be able to make use of extend or duplicate. I'm not sure comonads are a good fit but I've seen a talk (Dominic Orchard: A Notation for Comonads) where comonads were used to model a cursor in a two-dimensional matrix. If a comonad is a good way of representing the Wumpus world, could you please show where my code is wrong? If it's wrong, could you please suggest a simple application of comonads? module Wumpus where -- Incomplete model of a world inhabited by a Wumpus who likes a nice -- tidy world but does not like falling in pits. import Control.Comonad -- The Wumpus world is made up of tiles that can be in one of three -- states. data Tile = Clean | Dirty | Pit deriving (Show, Eq) -- The Wumpus world is a one dimensional array partitioned into three -- values: the tiles to the left of the Wumpus, the tile occupied by -- the Wumpus, and the tiles to the right of the Wumpus. data World a = World [a] a [a] deriving (Show, Eq) -- Applies a function to every tile in the world instance Functor World where fmap f (World as b cs) = World (fmap f as) (f b) (fmap f cs) -- The Wumpus world is a Comonad instance Comonad World where -- get the part of the world the Wumpus currently occupies extract (World _ b _) = b -- not sure what this means in the Wumpus world. This type checks -- but does not make sense to me. extend f w@(World as b cs) = World (map world as) (f w) (map world cs) where world v = f (World [] v []) -- returns a world in which the Wumpus has either 1) moved one tile to -- the left or 2) stayed in the same place if the Wumpus could not move -- to the left. moveLeft :: World a -> World a moveLeft w@(World [] _ _) = w moveLeft (World as b cs) = World (init as) (last as) (b:cs) -- returns a world in which the Wumpus has either 1) moved one tile to -- the right or 2) stayed in the same place if the Wumpus could not move -- to the right. moveRight :: World a -> World a moveRight w@(World _ _ []) = w moveRight (World as b cs) = World (as ++ [b]) (head cs) (tail cs) initWorld = World [Dirty, Clean, Dirty] Dirty [Clean, Dirty, Pit] -- cleans the current tile cleanTile :: Tile -> Tile cleanTile Dirty = Clean cleanTile t = t Thanks!

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  • Add a datatable to a data set

    - by Jibu P C_Adoor
    Hii... I have a data table 'dt1' that is belongs to 'ds1'. I have created another instance of dataset 'ds2' and try to add the datatable 'dt1' to 'ds2'. Now i got one exception 'DataTable already belongs to another data set'. Is there any reliable way to add the dt1 to ds2?

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  • Make OS open directory in Python

    - by Vidar
    I am writing a program in Python, and want to get it to make the OS open the current working directory, making for instance Windows open explorer.exe and navigating to the wanted directory. Any ideas on how to do this? The directory is already given by os.getcwd. Cross platform methods preferred :)

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  • What is sender?

    - by marty
    I can't find this answer anywhere. What does it mean when there's a sender parameter in a method header? Does it represent the instance that called it, or the method that called it?

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  • KeyNotFound Exception in Dictionary(of T)

    - by C Patton
    I'm about ready to bang my head against the wall I have a class called Map which has a dictionary called tiles. class Map { public Dictionary<Location, Tile> tiles = new Dictionary<Location, Tile>(); public Size mapSize; public Map(Size size) { this.mapSize = size; } //etc... I fill this dictionary temporarily to test some things.. public void FillTemp(Dictionary<int, Item> itemInfo) { Random r = new Random(); for(int i =0; i < mapSize.Width; i++) { for(int j=0; j<mapSize.Height; j++) { Location temp = new Location(i, j, 0); int rint = r.Next(0, (itemInfo.Count - 1)); Tile t = new Tile(new Item(rint, rint)); tiles[temp] = t; } } } and in my main program code Map m = new Map(10, 10); m.FillTemp(iInfo); Tile t = m.GetTile(new Location(2, 2, 0)); //The problem line now, if I add a breakpoint in my code, I can clearly see that my instance (m) of the map class is filled with pairs via the function above, but when I try to access a value with the GetTile function: public Tile GetTile(Location location) { if(this.tiles.ContainsKey(location)) { return this.tiles[location]; } else { return null; } } it ALWAYS returns null. Again, if I view inside the Map object and find the Location key where x=2,y=2,z=0 , I clearly see the value being a Tile that FillTemp generated.. Why is it doing this? I've had no problems with a Dictionary such as this so far. I have no idea why it's returning null. and again, when debugging, I can CLEARLY see that the Map instance contains the Location key it says it does not... very frustrating. Any clues? Need any more info? Help would be greatly appreciated :)

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  • New to MVC. Actionscript 3.0 Appreciate your help.

    - by Combustion007
    Hello Everyone, I am new to design patterns and am trying to learn the MVC implementation. I have written four classes: DataModel DataView DataController Main Main serves as the application facade. The main FLA is called HelloWorld. I have a symbol called "Box" in HelloWorld. I just would like to add an instance of the "Box" on the stage. Eventually I would like to place a button and when the button is clicked, the Box instance color will be changed. I would appreciate any help, please help me figure out what am I doing wrong. Here are my Classes: DATAMODEL CLASS: package { import flash.events.*; public class DataModel extends EventDispatcher { public static const UPDATE:String = "modelUpdate"; private var _color:Number = (Math.round(Math.random()* 0xffffff)); public function DataModel() { trace("DATA MODEL INIT"); } public function get color():Number { return _color; } public function set color(p:Number):void { _color = p; notifyObserver(); } public function notifyObserver():void { dispatchEvent(new Event(DataModel.UPDATE)); } } } //DATACONTROLLER CLASS: package { import flash.events.; import flash.display.; import flash.errors.*; public class DataController { private var _model:DataModel; public function DataController(m:DataModel) { trace("DATACONTROLLER INIT"); _model = m; } } } DATAVIEW CLASS: package { import flash.events.; import flash.display.; import flash.errors.*; public class DataView extends Sprite { private var _model:DataModel; private var _controller:DataController; private var b:Box; public function DataView(m:DataModel, c:DataController) { _model = m; _controller = c; b = new Box(); b.x = b.y = 100; addChild(b); } } } And Finally THE FACADE: package { import flash.display.; import flash.events.; import flash.text.; import flash.errors.; public class Main extends Sprite { private var _model:DataModel; private var _controller:DataController; private var _view:DataView; public function Main(m:DataModel, c:DataController, v:DataView) { _model = m; _controller = c; _view = v; addChild(v); } } } When I test the movie: I get this error: ArgumentError: Error #1063: Argument count mismatch on Main(). Expected 3, got 0. Thanks alot.

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  • rotate image with php - any degree

    - by Luis
    How to rotate an image with PHP, any degree, without having the filled space? For instance, if I rotate an image 10 degrees, the image rotates fine but the container around (square) gets filled with black. Is it possible to get rid of this, when for example merging 2 images?

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  • Serialize an object using DataContractJsonSerializer as a json array

    - by rekna
    I have a class which contains a list of items. I want to serialize an instance of this class to json using the DataContractJsonSerializer as a json array. eg. class MyClass { List<MyItem> _items; } class MyItem { public string Name {get;set;} public string Description {get;set;} } When serialized to json it should be like this : [{"Name":"one","Description":"desc1"},{"Name":"two","Description":"desc2"}]

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  • Does UIScrollView have a special content view for making the scrolling possible?

    - by mystify
    I wonder if UIScrollView has got an "hidden" subview acting as an container for the content. If I scroll a scroll view, is that content view moved up/down in the scroll view? Or is the scrolling offset applied to the bounds of that UIScrollView instance? Or: Does UIScrollView use an additional view as container, or is all content added directly to the view? The documentation doesn't tell much about wether it has a content container or not.

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  • Understanding java's native threads and the jvm

    - by Moev4
    I understand that the jvm is itself an application that turns the bytecode of the java executable into native machine code, but when using native threads I have some questions that I just cannot seem to answer. Does every thread create their own instance of the jvm to handle their particular execution? If not then does the jvm have to have some way to schedule which thread it will handle next, if so wouldn't this render the multi-threaded nature of java useless since only one thread can be ran at a time?

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  • Is it possible to do DNS-based ACLs on a Cisco ASA?

    - by pickles
    Short of using static IP addresses, is it possible to have a Cisco ASA use a DNS name rather than an IP address? For instance, if I want to limit a host in the DMZ to access only one particular web service, but that web service might be globally load balanced or using DynDNS or cloud, how can the ACL be expressed so that a fixed IP address isn't used and the admin doesn't have to keep opening and closing down IP addresses?

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