Search Results

Search found 21759 results on 871 pages for 'int 0'.

Page 484/871 | < Previous Page | 480 481 482 483 484 485 486 487 488 489 490 491  | Next Page >

  • Retrieve only the superclass from a class hierarchy

    - by user1792724
    I have an scenario as the following: @Entity @Table(name = "ANIMAL") @Inheritance(strategy = InheritanceType.JOINED) public class Animal implements Serializable { @Id @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "S_ANIMAL") @SequenceGenerator(name = "S_ANIMAL", sequenceName = "S_ANIMAL", allocationSize = 1) public int getNumero() { return numero; } public void setNumero(int numero) { this.numero = numero; } . . . } and as the subclass: @Entity @Table(name = "DOG") public class Dog extends Animal { private static final long serialVersionUID = -7341592543130659641L; . . . } I have a JPA Select statement like this: SELECT a FROM Animal a; I'm using Hibernate 3.3.1 As I can see the framework retrieves instances of Animal and also of Dog using a left outer join. Is there a way to Select only the "part" Animal? I mean, the previous Select will get all the Animals, those that are only Animals but not Dogs and those that are Dogs. I want them all, but in the case of Dogs I want to only retrieve the "Animal part" of them. I found the @org.hibernate.annotations.Entity(polymorphism = PolymorphismType.EXPLICIT) but as I could see this only works if Animal isn't an @Entity. Thanks a lot.

    Read the article

  • Animate and form rows, arrays, AS3

    - by VideoDnd
    Question How can I animate and form rows together? Explanation One 'for loop' is for animation, the other 'for loop' is for making rows. I want to understand how to use arrays and create a row of sprite animations. 'for loop' for animation //FRAMES ARRAY //THIS SETS UP MY ANIMATION FOR TIMER EVENT var frames:Array = [ new Frame1(), new Frame2(), new Frame3(), new Frame4(), new Frame5(), new Frame6(), new Frame7(), new Frame8(), new Frame9(), new Frame0(), ]; for each (var frame:Sprite in frames) { addChild(frame); } 'for loop' for rows //THIS MAKES A ROW OF DISPLAY OBJECTS var numberOfClips:Number = 11; var xStart:Number = 0; var yStart:Number = 0; var xVal:Number = xStart; var xOffset:Number = 2; for (var $:Number=0; $<numberOfClips; $++) { //DUDE ARRAY var dude:Array = frames; dude.y = yStart +11; dude.x = xVal +55; xVal = dude.x + dude.width + this.xOffset; } timer var timer:Timer = new Timer(100); timer.addEventListener(TimerEvent.TIMER, countdown); function countdown(event:TimerEvent) { var currentFrame:int = timer.currentCount % frames.length; for (var i:int = 0; i < frames.length; ++i) { frames[i].visible = (i == currentFrame); } } timer.start(); counter experiment My new class I'm working on loops through 10 different display objects that are numbers. For those following, I'm trying to make something like NumbersView.

    Read the article

  • Trying to output a list using class

    - by captain morgan
    Am trying to get the moving average of a price..but i keep getting an attribute error in my Moving_Average class. ('Moving_Average' object has no attribute 'days'). Here is what I have: class Moving_Average: def calculation(self, alist:list,days:int): m = self.days prices = alist[1::2] average = [0]* len(prices) signal = ['']* len(prices) for m in range(0,len(prices)-days+1): average[m+2] = sum(prices[m:m+days])/days if prices[m+2] < average[m+2]: signal[m+2]='SELL' elif prices[m+2] > average[m+2] and prices[m+1] < average[m+1]: signal[m+2]='BUY' else: signal[m+2] ='' return average,signal def print_report(symbol:str,strategy:str): print('SYMBOL: ', symbol) print('STRATEGY: ', strategy) print('Date Closing Strategy Signal') def user(): strategy = ''' Which of the following strategy would you like to use? * Simple Moving Average [S] * Directional Indicator[D] Please enter your choice: ''' if signal_strategy in 'Ss': days = input('Please enter the number of days for the average') days = int(days) strategy = 'Simple Moving Average {}-days'.format(str(days)) m = Moving_Average() ma = m.calculation(gg, days) print(ma) gg is an list that contains date and prices. [2013-10-01,60,2013-10-02,60] The output is supposed to look like: Date Price Average Signal 2013-10-01 60.0 2013-10-02 60.0 60.00 BUY

    Read the article

  • Nullable<T> as a parameter

    - by ferch
    I alredy have this: public static object GetDBValue(object ObjectEvaluated) { if (ObjectEvaluated == null) return DBNull.Value; else return ObjectEvaluated; } used like: List<SqlParameter> Params = new List<SqlParameter>(); Params.Add(new SqlParameter("@EntityType", GetDBValue(EntityType))); Now i wanted to keep the same interface but extend that to use it with nullable public static object GetDBValue(int? ObjectEvaluated) { if (ObjectEvaluated.HasValue) return ObjectEvaluated.Value; else return DBNull.Value; } public static object GetDBValue(DateTime? ObjectEvaluated) {...} but i want only 1 function GetDBValue for nullables. How do I do that and keep the call as is is? Is that possible at all? I can make it work like: public static object GetDBValue<T>(Nullable<T> ObjectEvaluated) where T : struct { if (ObjectEvaluated.HasValue) return ObjectEvaluated.Value; else return DBNull.Value; } But the call changes to: Params.Add(new SqlParameter("@EntityID ", GetDBValue<int>(EntityID)));

    Read the article

  • How to get spacing between characters printed using TextOut ?

    - by life-warrior
    I'm trying to calcuate size of each cell (containing text like "ff" or "a0"), so that 32 cells will fit into window by width. However, charWidth*2 doesn' represent the width of a cell, since it doesn't take spacing between characters in the account. How can I obtain size of a font so that 32 cells each is two chars like "ff" fit exactly into window's client area ? Curier is fixed-width font. RECT rect; ::GetClientRect( hWnd, &rect ); LONG charWidth = (rect.right-rect.left)/BLOCK_SIZE/2-2; int oldMapMode = ::SetMapMode( hdc, MM_TEXT ); HFONT font = CreateFont( charWidth*2, charWidth, 0, 0, FW_DONTCARE, FALSE, FALSE, FALSE, DEFAULT_CHARSET, OUT_OUTLINE_PRECIS, CLIP_DEFAULT_PRECIS, CLEARTYPE_QUALITY, FF_ROMAN, _T("Courier") ); HGDIOBJ oldFont = ::SelectObject( hdc, font ); for( int i = 0; i < BLOCK_SIZE; ++i ) { CString str; str.Format( _T("%.2x"), (unsigned char)*(g_memAddr+i) ); SIZE size; ::TextOut( hdc, (size.cx+2)*i+1, 1, str, _tcslen((LPCTSTR)str) ); }

    Read the article

  • Flex 4 Button state in a HGroup

    - by chchrist
    Hi all, I have a HGroup with some buttons inside which is my application's menu. <s:HGroup id="nav"> <s:Button id="homeButton" label="Home" /> <s:Button id="showroomButton" label="Showroom" /> <s:Button label="Catalogue" /> <s:Button label="Offers" /> <s:Button label="My Account" /> <s:Button label="My Orders" /> </s:HGroup> What I want is when I click for example the #homeButton to change it's state to "over", become disabled and reset all other buttons to the "up" state. I've written this function private function resetNavState():void { for(var i:int = 0,ii:int = nav.numChildren-1;i<ii;i++) { Button(nav.getChildAt(i)).mouseEnabled = true; Button(nav.getChildAt(i)).skin.setCurrentState("up",true); } } And then on the homeButton click handler for example i use protected function homeButton_clickHandler(event:MouseEvent):void { resetNavState(); currentState = "home"; homeButton.skin.setCurrentState("over",true); homeButton.mouseEnabled = false; } I resets the states of the #nav buttons but it doesn't change the state of the pressed button. Any ideas? Thanx in advance

    Read the article

  • How to store an interger value of 4 bytes in a memory of chunk which is malloced as type char

    - by Adi
    Dear all, Hello Guys!! This is my first post in the forum . I am really looking forward to having good fun in this site. My question is : int mem_size = 10; char *start_ptr; if((start_ptr= malloc(mem_size*1024*1024*sizeof(char)))==NULL) {return -1;} I have allocated a chunk of memory of type char and size is say 10 MB (i.e mem_size = 10 ); Now I want to store the size information in the header of the memory chunk, To make myself more clear Lets Say : start_ptr = 0xaf868004 (This is the value I got from my execution, it changes every time) Now I want to put the size information in the start of this pointer.. i.e *start_ptr = mem_size*1024*1024; But I am not able to put this information in the start_ptr. I think the reason is because my ptr is of type char which only takes one byte but I am trying to store int which takes 4 bytes, is the problem . I am not sure how to fix this problem.. I would greatly appreciate your suggestions. Cheers!! Aditya

    Read the article

  • What's the best way of accessing a DRb object (e.g. Ruby Queue) from Scala (and Java)?

    - by Tom Morris
    I have built a variety of little scripts using Ruby's very simple Queue class, and share the Queue between Ruby and JRuby processes using DRb. It would be nice to be able to access these from Scala (and maybe Java) using JRuby. I've put together something Scala and the JSR-223 interface to access jruby-complete.jar. import javax.script._ class DRbQueue(host: String, port: Int) { private var engine = DRbQueue.factory.getEngineByName("jruby") private var invoker = engine.asInstanceOf[Invocable] engine.eval("require \"drb\" ") private var queue = engine.eval("DRbObject.new(nil, \"druby://" + host + ":" + port.toString + "\")") def isEmpty(): Boolean = invoker.invokeMethod(this.queue, "empty?").asInstanceOf[Boolean] def size(): Long = invoker.invokeMethod(this.queue, "length").asInstanceOf[Long] def threadsWaiting: Long = invoker.invokeMethod(this.queue, "num_waiting").asInstanceOf[Long] def offer(obj: Any) = invoker.invokeMethod(this.queue, "push", obj.asInstanceOf[java.lang.Object]) def poll(): Any = invoker.invokeMethod(this.queue, "pop") def clear(): Unit = { invoker.invokeMethod(this.queue, "clear") } } object DRbQueue { var factory = new ScriptEngineManager() } (It conforms roughly to java.util.Queue interface, but I haven't declared the interface because it doesn't implement the element and peek methods because the Ruby class doesn't offer them.) The problem with this is the type conversion. JRuby is fine with Scala's Strings - because they are Java strings. But if I give it a Scala Int or Long, or one of the other Scala types (List, Set, RichString, Array, Symbol) or some other custom type. This seems unnecessarily hacky: surely there has got to be a better way of doing RMI/DRb interop without having to use JSR-223 API. I could either make it so that the offer method serializes the object to, say, a JSON string and takes a structural type of only objects that have a toJson method. I could then write a Ruby wrapper class (or just monkeypatch Queue) to would parse the JSON. Is there any point in carrying on with trying to access DRb from Java/Scala? Might it just be easier to install a real message queue? (If so, any suggestions for a lightweight JVM-based MQ?)

    Read the article

  • Using an element against an entire list in Haskell

    - by Snick
    I have an assignment and am currently caught in one section of what I'm trying to do. Without going in to specific detail here is the basic layout: I'm given a data element, f, that holds four different types inside (each with their own purpose): data F = F Float Int, Int a function: func :: F -> F-> Q Which takes two data elements and (by simple calculations) returns a type that is now an updated version of one of the types in the first f. I now have an entire list of these elements and need to run the given function using one data element and return the type's value (not the data element). My first analysis was to use a foldl function: myfunc :: F -> [F] -> Q myfunc y [] = func y y -- func deals with the same data element calls myfunc y (x:xs) = foldl func y (x:xs) however I keep getting the same error: "Couldn't match expected type 'F' against inferred type 'Q'. In the first argument of 'foldl', namely 'myfunc' In the expression: foldl func y (x:xs) I apologise for such an abstract analysis on my problem but could anyone give me an idea as to what I should do? Should I even use a fold function or is there recursion I'm not thinking about?

    Read the article

  • Strange problem with simple multithreading program in Java

    - by Elizabeth
    Hello, I am just starting play with multithreading programming. I would like to my program show alternately character '-' and '+' but it doesn't. My task is to use synchronized keyword. As far I have: class FunnyStringGenerator{ private char c; public FunnyStringGenerator(){ c = '-'; } public synchronized char next(){ if(c == '-'){ c = '+'; } else{ c = '-'; } return c; } } class ThreadToGenerateStr implements Runnable{ FunnyStringGenerator gen; public ThreadToGenerateStr(FunnyStringGenerator fsg){ gen = fsg; } @Override public void run() { for(int i = 0; i < 10; i++){ System.out.print(gen.next()); } } } public class Main{ public static void main(String[] args) throws IOException { FunnyStringGenerator FSG = new FunnyStringGenerator(); ExecutorService exec = Executors.newCachedThreadPool(); for(int i = 0; i < 20; i++){ exec.execute(new ThreadToGenerateStr(FSG)); } } } EDIT: I also testing Thread.sleep in run method instead for loop.

    Read the article

  • How to get address of va_arg?

    - by lionbest
    I hack some old C API and i got a compile error with the following code: void OP_Exec( OP* op , ... ) { int i; va_list vl; va_start(vl,op); for( i = 0; i < op->param_count; ++i ) { switch( op->param_type[i] ) { case OP_PCHAR: op->param_buffer[i] = va_arg(vl,char*); // ok it works break; case OP_INT: op->param_buffer[i] = &va_arg(vl,int); // error here break; // ... more here } } op->pexec(op); va_end(vl); } The error with gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu9) was: main.c|55|error: lvalue required as unary ‘&’ operand So why exactly it's not possible here to get a pointer to argument? How to fix it? This code is executed very often with different OP*, so i prefer to not allocate extra memory. Is it possible to iterate over va_list knowing only the size of arguments?

    Read the article

  • PowerShell function arguments: Can the first one be optional first?

    - by Johannes Rössel
    I have an advanced function in PowerShell, which roughly looks like this: function Foo { [CmdletBinding] param ( [int] $a = 42, [int] $b ) } The idea is that it can be run with either two, one or no arguments. However, the first argument to become optional is the first one. So the following scenarios are possible to run the function: Foo a b # the normal case, both a and b are defined Foo b # a is omitted Foo # both a and b are omitted However, normally PowerShell tries to fit the single argument into a. So I thought about specifying the argument positions explicitly, where a would have position 0 and b position 1. However, to allow for only b specified I tried putting a into a parameter set. But then b would need a different position depending on the currently-used parameter set. Any ideas how to solve this properly? I'd like to retain the parameter names (which aren't a and b actually), so using $args is probably a last resort. I probably could define two parameter sets, one with two mandatory parameters and one with a single optional one, but I guess the parameter names have to be different in that case, then, right?

    Read the article

  • Query String to Object with strongly typed properties

    - by Kamar
    Let’s say we track 20 query string parameters in our site. Each request which comes will have only a subset of those 20 parameters. But we definitely look for all/most of the parameters which comes in each request. We do not want to loop through the collection each time we are looking for a particular parameter initially or somewhere down the pipeline in the code. So we loop once through the query string collection, convert string values to their respective types (enums, int, string etc.), populate to QueryString object which is added to the context. After that wherever its needed we will have a strongly typed properties in the QueryString object which is easy to use and we maintain a standard. public class QueryString { public int Key1{ get; private set; } public SomeType Key2{ get; private set; } private QueryString() { } public static QueryString GetQueryString() { QueryString l_QS = new QueryString(); foreach (string l_Key in HttpContext.Current.Request.QueryString.AllKeys) { switch (l_Key) { case "key1": l_QS.Key1= DoSomething(l_Key, HttpContext.Current.Request.QueryString[l_Key]); break; case "key2": l_QS.Key2 = DoAnotherThing(l_Key, HttpContext.Current.Request.QueryString[l_Key]); break; } } return l_QS; } } Any other solution to achieve this?

    Read the article

  • How to get the compression ratio for a GZipped file ?

    - by Enigma
    Here is how I compressed the data: <%@ page import="javax.servlet.jsp.*,java.io.*,java.util.zip.*" %> <% String encodings = request.getHeader("Accept-Encoding"); PrintWriter outWriter = null; if ((encodings != null) && (encodings.indexOf("gzip") != -1)) { OutputStream outA = response.getOutputStream(); outWriter = new PrintWriter(new GZIPOutputStream(outA), false); response.setHeader("Content-Encoding", "gzip"); int a = response.getBufferSize(); System.out.println("ZIPPED VERSION BF:"+a); } else { System.out.println("UN-ZIPPED VERSION"); outWriter = new PrintWriter(response.getOutputStream(), false); } outWriter.println("<HTML><BODY>"); for(int i=0; i<1000; i++) { outWriter.println(" blah blah blah<br>"); } outWriter.println("</BODY></HTML>"); outWriter.close(); %>

    Read the article

  • Lucene DuplicateFilter question

    - by chardex
    Hi, Why DuplicateFilter doesn't work together with other filters? For example, if a little remake of the test DuplicateFilterTest, then the impression that the filter is not applied to other filters and first trims results: public void testKeepsLastFilter() throws Throwable { DuplicateFilter df = new DuplicateFilter(KEY_FIELD); df.setKeepMode(DuplicateFilter.KM_USE_LAST_OCCURRENCE); Query q = new ConstantScoreQuery(new ChainedFilter(new Filter[]{ new QueryWrapperFilter(tq), // new QueryWrapperFilter(new TermQuery(new Term("text", "out"))), // works right, it is the last document. new QueryWrapperFilter(new TermQuery(new Term("text", "now"))) // why it doesn't work? It is the third document. }, ChainedFilter.AND)); ScoreDoc[] hits = searcher.search(q, df, 1000).scoreDocs; assertTrue("Filtered searching should have found some matches", hits.length > 0); for (int i = 0; i < hits.length; i++) { Document d = searcher.doc(hits[i].doc); String url = d.get(KEY_FIELD); TermDocs td = reader.termDocs(new Term(KEY_FIELD, url)); int lastDoc = 0; while (td.next()) { lastDoc = td.doc(); } assertEquals("Duplicate urls should return last doc", lastDoc, hits[i].doc); } }

    Read the article

  • Asp MVC - "The Id field is required" validation message on Create; Id not set to [Required]

    - by Dann
    This is happening when I try to create the entity using a Create style action in Asp.Net MVC 2. The POCO has the following properties: public int Id {get;set;} [Required] public string Message {get; set} On the creation of the entity, the Id is set automatically, so there is no need for it on the Create action. The ModelState says that "The Id field is required", but I haven't set that to be so. Is there something automatic going on here? EDIT - Reason Revealed The reason for the issue is answered by Brad Wilson via Paul Speranza in one of the comments below where he says (cheers Paul): You're providing a value for ID, you just didn't know you were. It's in the route data of the default route ("{controller}/{action}/{id}"), and its default value is the empty string, which isn't valid for an int. Use the [Bind] attribute on your action parameter to exclude ID. My default route was: new { controller = "Customer", action = "Edit", id = " " } // Parameter defaults EDIT - Update Model technique I actually changed the way I did this again by using TryUpdateModel and the exclude parameter array asscoiated with that. [HttpPost] public ActionResult Add(Venue collection) { Venue venue = new Venue(); if (TryUpdateModel(venue, null, null, new[] { "Id" })) { _service.Add(venue); return RedirectToAction("Index", "Manage"); } return View(collection); }

    Read the article

  • Find Adjacent Nodes A Star Path-Finding C++

    - by Infinity James
    Is there a better way to handle my FindAdjacent() function for my A Star algorithm? It's awfully messy, and it doesn't set the parent node correctly. When it tries to find the path, it loops infinitely because the parent of the node has a pent of the node and the parents are always each other. Any help would be amazing. This is my function: void AStarImpl::FindAdjacent(Node* pNode) { for (int i = -1; i <= 1; i++) { for (int j = -1; j <= 1; j++) { if (pNode->mX != Map::GetInstance()->mMap[pNode->mX + i][pNode->mY + j].mX || pNode->mY != Map::GetInstance()->mMap[pNode->mX + i][pNode->mY + j].mY) { if (pNode->mX + i <= 14 && pNode->mY + j <= 14) { if (pNode->mX + i >= 0 && pNode->mY + j >= 0) { if (Map::GetInstance()->mMap[pNode->mX + i][pNode->mY + j].mTypeID != NODE_TYPE_SOLID) { if (find(mOpenList.begin(), mOpenList.end(), &Map::GetInstance()->mMap[pNode->mX + i][pNode->mY + j]) == mOpenList.end()) { Map::GetInstance()->mMap[pNode->mX+i][pNode->mY+j].mParent = &Map::GetInstance()->mMap[pNode->mX][pNode->mY]; mOpenList.push_back(&Map::GetInstance()->mMap[pNode->mX+i][pNode->mY+j]); } } } } } } } mClosedList.push_back(&Map::GetInstance()->mMap[pNode->mX][pNode->mY]); } If you'd like any more code, just ask and I can post it.

    Read the article

  • problem finding a header with a c++ makefile

    - by Max
    Hi. I've started working with my first makefile. I'm writing a roguelike in C++ using the libtcod library, and have the following hello world program to test if my environment's up and running: #include "libtcod.hpp" int main() { TCODConsole::initRoot(80, 50, "PartyHack"); TCODConsole::root->printCenter(40, 25, TCOD_BKGND_NONE, "Hello World"); TCODConsole::flush(); TCODConsole::waitForKeypress(true); } My project directory structure looks like this: /CppPartyHack ----/libtcod-1.5.1 # this is the libtcod root folder --------/include ------------libtcod.hpp ----/PartyHack --------makefile --------partyhack.cpp # the above code (while we're here, how do I do proper indentation? Using those dashes is silly.) and here's my makefile: SRCDIR = . INCDIR = ../libtcod-1.5.1/include CFLAGS = $(FLAGS) -I$(INCDIR) -I$(SRCDIR) -Wall CC = gcc CPP = g++ .SUFFIXES: .o .h .c .hpp .cpp $(TEMP)/%.o : $(SRCDIR)/%.cpp $(CPP) $(CFLAGS) -o $@ -c $< $(TEMP)/%.o : $(SRCDIR)/%.c $(CC) $(CFLAGS) -o $@ -c $< CPP_OBJS = $(TEMP)partyhack.o all : partyhack partyhack : $(CPP_OBJS) $(CPP) $(CPP_OBJS) -o $@ -L../libtcod-1.5.1 -ltcod -ltcod++ -Wl,-rpath,. clean : \rm -f $(CPP_OBJS) partyhack I'm using Ubuntu, and my terminal gives me the following errors: max@max-desktop:~/Desktop/Development/CppPartyhack/PartyHack$ make g++ -c -o partyhack.o partyhack.cpp partyhack.cpp:1:23: error: libtcod.hpp: No such file or directory partyhack.cpp: In function ‘int main()’: partyhack.cpp:5: error: ‘TCODConsole’ has not been declared partyhack.cpp:6: error: ‘TCODConsole’ has not been declared partyhack.cpp:6: error: ‘TCOD_BKGND_NONE’ was not declared in this scope partyhack.cpp:7: error: ‘TCODConsole’ has not been declared partyhack.cpp:8: error: ‘TCODConsole’ has not been declared make: * [partyhack.o] Error 1 So obviously, the makefile can't find libtcod.hpp. I've double checked and I'm sure the relative path to libtcod.hpp in INCDIR is correct, but as I'm just starting out with makefiles, I'm uncertain what else could be wrong. My makefile is based off a template that the libtcod designers provided along with the library itself, and while I've looked at a few online makefile tutorials, the code in this makefile is a good bit more complicated than any of the examples the tutorials showed, so I'm assuming I screwed up something basic in the conversion. Thanks for any help.

    Read the article

  • Android: Defined array resource not found ?!

    - by David
    Hi, i have a strange (?) error in my android application. I have defined some arrays in values/arrays.xml the following way: <?xml version="1.0" encoding="utf-8"?> <resources> <array name="perimeter"> <item>10 miles</item> <item>20 miles</item> <item>30 miles</item> </array> <array name="regvalues"> <item>1</item> <item>2</item> <item>3</item> </array> </resources> Now I want to use them in a ListPreference for a PreferenceActivity (defined by an xml file). So i set android:entries="@array/perimeter" android:entryValues="@array/regvalues" for this ListPreference. When I try to use this on my device the app crashes. (NullPointer in Dialog.close()) If I try to use the regvalues-items as Entries for the ListPreference i get a NullPointer in ArrayAdapter.createViewFromResource(int, View, ViewGroup, int) line: 355 So there seems to be sth wrong with the regvalues array. But what ?!? Eclipse shows me no errors at compile time. So everything in the xml-file and java-code is written correctly and there are no typos. Where is the problem?!?

    Read the article

  • Haskell Cons Operator (:)

    - by Carson Myers
    I am really new to Haskell (Actually I saw "Real World Haskell" from O'Reilly and thought "hmm, I think I'll learn functional programming" yesterday) and I am wondering: I can use the construct operator to add an item to the beginning of a list: 1 : [2,3] [1,2,3] I tried making an example data type I found in the book and then playing with it: --in a file data BillingInfo = CreditCard Int String String | CashOnDelivery | Invoice Int deriving (Show) --in ghci $ let order_list = [Invoice 2345] $ order_list [Invoice 2345] $ let order_list = CashOnDelivery : order_list $ order_list [CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, ...- etc... it just repeats forever, is this because it uses lazy evaluation? -- EDIT -- okay, so it is being pounded into my head that let order_list = CashOnDelivery:order_list doesn't add CashOnDelivery to the original order_list and then set the result to order_list, but instead is recursive and creates an infinite list, forever adding CashOnDelivery to the beginning of itself. Of course now I remember that Haskell is a functional language and I can't change the value of the original order_list, so what should I do for a simple "tack this on to the end (or beginning, whatever) of this list?" Make a function which takes a list and BillingInfo as arguments, and then return a list? -- EDIT 2 -- well, based on all the answers I'm getting and the lack of being able to pass an object by reference and mutate variables (such as I'm used to)... I think that I have just asked this question prematurely and that I really need to delve further into the functional paradigm before I can expect to really understand the answers to my questions... I guess what i was looking for was how to write a function or something, taking a list and an item, and returning a list under the same name so the function could be called more than once, without changing the name every time (as if it was actually a program which would add actual orders to an order list, and the user wouldn't have to think of a new name for the list each time, but rather append an item to the same list).

    Read the article

  • GetAccessControl error with NTAccount

    - by Adam Witko
    private bool HasRights(FileSystemRights fileSystemRights_, string fileName_, bool isFile_) { bool hasRights = false; WindowsIdentity WinIdentity = System.Security.Principal.WindowsIdentity.GetCurrent(); WindowsPrincipal WinPrincipal = new WindowsPrincipal(WinIdentity); AuthorizationRuleCollection arc = null; if (isFile_) { FileInfo fi = new FileInfo(@fileName_); arc = fi.GetAccessControl().GetAccessRules(true, true, typeof(NTAccount)); } else { DirectoryInfo di = new DirectoryInfo(@fileName_); arc = di.GetAccessControl().GetAccessRules(true, true, typeof(NTAccount)); } foreach (FileSystemAccessRule rule in arc) { if (WinPrincipal.IsInRole(rule.IdentityReference.Value)) { if (((int)rule.FileSystemRights & (int)fileSystemRights_) > 0) { if (rule.AccessControlType == AccessControlType.Allow) hasRights = true; else if (rule.AccessControlType == AccessControlType.Deny) { hasRights = false; break; } } } } return hasRights; } The above code block is causing me problems. When the WinPrincipal.IsInRole(rule.IdentityReference.Value) is executed the following exception occurs: "The trust relationship between the primary domain and the trusted domain failed.". I'm very new to using identities, principles and such so I don't know what's the problem. I'm assuming it's with the use of NTAccount? Thanks

    Read the article

  • How to display panels with component in frame

    - by terence6
    Why my JFrame 'frame' is diplaying empty window, when it should give me 3 menu buttons and my own painted JComponent below ? What am I missing here ? import java.awt.*; import javax.swing.*; public class Eyes extends JFrame { public static void main(String[] args) { final JFrame frame = new JFrame("Eyes"); frame.setPreferredSize(new Dimension(450, 300)); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel players = new JPanel(new GridLayout(1, 3)); players.add(new JButton("Eyes color")); players.add(new JButton("Eye pupil")); players.add(new JButton("Background color")); JPanel eyes = new JPanel(); eyes.add(new MyComponent()); JPanel content = new JPanel(); content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS)); content.add(players); content.add(eyes); frame.getContentPane(); frame.pack(); frame.setVisible(true); } } class MyComponent extends JComponent { public MyComponent(){ } @Override public void paint(Graphics g) { int height = 120; int width = 120; Graphics2D g2d = (Graphics2D) g; g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON); BasicStroke bs = new BasicStroke(3.0f); g2d.setStroke(bs); g2d.setColor(Color.yellow); g2d.fillOval(200, 200, height, width); g2d.setColor(Color.black); g2d.drawOval(60, 60, height, width); } }

    Read the article

  • Convert C function to Objective C or alternative way to include C library?

    - by Moshe
    Background: I'm new to Objective-C and I've never touched C before. I'm trying to include a C library in my iPhone/iPod Touch project and I could not successfully compile the library's source code using the included instructions, so I've resorted to including the .h and .c files in Xcode. The library is for Hebrew Dates and corresponding Jewish Holidays. It can be found here: http://sourceforge.net/projects/libhdate/ I cannot seem to import the .c files into my implementation files. I can import the .h files though. When I try to use #import "file.c", where file.c is a file that is in XCode, it doesn't work. Why not? I've considered just writing the functions over in Objective-C, albeit only my needed functions and not the whole library. How can I make the following C function work in Objective-C? Are there other things that need to be included/re-coded/compiled? How so? I am almost certain something is missing, but I'm not sure what. Code: int hdate_get_omer_day(hdate_struct const * h) { int omer_day; hdate_struct sixteen_nissan; hdate_set_hdate(&sixteen_nissan, 16, 7, h->hd_year); omer_day = h->hd_jd - sixteen_nissan.hd_jd + 1; if ((omer_day > 49) || (omer_day < 0)) omer_day = 0; return omer_day; } So... should I be converting it, or trying somehow to compile to an appropriate format and how so? (I don't know what format a static library should be in, by the way, or if it should be static... - I'm so lost here....) I appreciate the help!

    Read the article

  • Is unnecessary error handling recommended in business logic? eg. Null check/Percentage limit check etc

    - by novice_at_work
    We usually put unnecessary checks in our business logic to avoid failures. Eg. 1. public ObjectABC funcABC(){ ObjectABC obj = new ObjectABC; .......... .......... //its never set to null here. .......... return obj; } ObjectABC o = funABC(); if(o!=null){ //do something } Why do we need this null check if we are sure that it will never be null? Is it a good practice or not? 2. int pplReached = funA(..,..,..); int totalPpl = funB(..,..,..); funA() just puts a few more restriction over result of funB(). Double percentage = (totalPpl==0||totalPpl<pplReached) ? 0.0 : pplReached/totalPpl; Do we again need this check? The questions is: Aren't we swallowing some fundamental issue by putting such checks? Issues which should be shown ideally, are avoided by putting these checks. What is the recommended way?

    Read the article

  • binary_search not working for a vector<string>

    - by VaioIsBorn
    #include <iostream> #include <string> #include <vector> #include <algorithm> using namespace std; int main(void) { string temp; vector<string> encrypt, decrypt; int i,n, co=0; cin >> n; for(i=0;i<n;i++) { cin >> temp; encrypt.push_back(temp); } for(i=0;i<n;i++) { cin >> temp; decrypt.push_back(temp); } for(i=0;i<n;i++) { temp = encrypt[i]; if((binary_search(decrypt.begin(), decrypt.end(), temp)) == true) ++co; } cout << co << endl; return 0; } It reads two equal lists of strings and should print out how many of the words in the first list are also found in the second list, simple. Not giving me the expexted results and i think the problem is in binary_search. Can you tell me why ?

    Read the article

< Previous Page | 480 481 482 483 484 485 486 487 488 489 490 491  | Next Page >