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• Confusion in bind call in socket programming

  - by Tarun

  i was learning socket programming in unix using c/c++. I am confused with one function call bind(params..). Actually it takes the adreess structure "sockaddr_in" and we can create the structure in the following way sockaddr_in.*** = somthing.. sockaddr_in..s_addr htonl(INADDR_ANY) **Passing INADDR_ANY will alow to bind all local addresses** My question is , why do we need to use "INADDR_ANY" ? In my knowledge every machine can has only one unique IP Address. In this way there is only one address associated with the machien. Thye bind call should directly bind the socket to the single available address. Please explain what are the different scenarios and why is it so?

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• Fault exception trashes a register causing a crash in [NSInvocation invoke]

  - by Mike Weller

  I have an NSOperation which fetches some objects from a core data persistent store and sums up a few totals. Sometimes an object is deleted while the operation in in progress, so a core data fault exception occurs. I try/catch the exception while summing to ignore it because I just want to skip objects that cannot be faulted in. However, when one of these fault exceptions occurs (and I swallow it) there is a crash after the invocation returns in [NSInvocation invoke]. It's a bad memory access when dereferencing the value in r10 which according to GDB on a successful run points to one of these: (gdb) x 0x38388348 0x38388348 <OBJC_IVAR_$_NSInvocation._retdata>: 0x00000008 If a fault exception occured a value of 0x02 is in the register which causes the crash. A quick google search tells me that r10 should be saved by the callee, meaning it is not being restored by whatever code is changing it when this exception occurs. Can anybody explain this? I'm not an expert when it comes to these kinds of low-level details

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• ASP.NET web services leak memory when (de)serializing disposable objects?

  - by Serilla

  In the following two cases, if Customer is disposable (implementing IDisposable), I believe it will not be disposed by ASP.NET, potentially being the cause of a memory leak: [WebMethod] public Customer FetchCustomer(int id) { return new Customer(id); } [WebMethod] public void SaveCustomer(Customer value) { // save it } This flaw applies to any IDisposable object. So returning a DataSet from a ASP.NET web service, for example, will also result in a memory leak - the DataSet will not be disposed. In my case, Customer opened a database connection which was cleaned up in Dispose - except Dispose was never called resulting in loads of unclosed database connections. I realise there a whole bunch of bad practices being followed here (its only an example anyway), but the point is that ASP.NET - the (de)serializer - is responsible for disposing these objects, so why doesn't it? This is an issue I was aware of for a while, but never got to the bottom of. I'm hoping somebody can confirm what I have found, and perhaps explain if there is a way of dealing with it.

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• Sprintf equivalent in Mathematica?

  - by jxy

  I don't know why Wikipedia lists Mathematica as a programming language with printf. I just couldn't find the equivalent in Mathematica. My specific task is to process a list of data files with padded numbers, which I used to do it in bash with fn=$(printf "filename_%05d" $n) The closest function I found in Mathematica is PaddedForm. And after some trial and error, I got it with "filename_" <> PaddedForm[ Round@#, 4, NumberPadding -> {"0", ""} ]& It is very odd that I have to use the number 4 to get the result similar to what I get from "%05d". I don't understand this behavior at all. Can someone explain it to me? And is it the best way to achieve what I used to in bash?

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• Django template tag basic question

  - by ninja123

  It looks like this template tag works like a charm for most people: http://blog.localkinegrinds.com/2007/09/06/digg-style-pagination-in-django/ For some reason I get this error: Caught an exception while rendering: 'is_paginated' I use this template tag in my template like so: {% load digg_paginator %} {% digg_paginator %} Where digg_paginator.py is in my app/templatetags folder and the included template context digg_paginator.html is in my app/templates folder. The queryset that needs pagination is called 'destinations'. If i just specify {% digg_paginator %}, how does it know what variable to paginate?? I feel I am missing something important here or just plain stupid :P Someone please help, or explain to me how this should be done. Thanks

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• How to Detect Trusted Connection in Crystal Reports using VB.NET?

  - by Michael

  I have some Crystal Reports connecting to a Sql Server db that I would like to detect whether the connection is trusted or whether I need to supply the log on info (reports are not supplied by me so I can't control the connect method). If I just blindly supply login credentials, it won't connect if it is a trusted connection. The following does not work: oRpt = oCR.OpenReport("C:\MyReport.rpt") if oRpt.Database.Tables(1).ConnectionProperties.Item("Integrated Security") = True then 'trusted connection else 'supply login credentials end if It gives the following error: Operator '=' is not defined for type 'IConnectionProperty' and type 'Boolean'. I cannot find how create a construct in vb.net for IConnectionProperty. I can't find any documents from Crystal that explain it. I am using Crystal Reports XI - Developer

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• Css Multiple background-color

  - by Khanh TO

  I'm a novice in Css and it's difficult to search for this specific case on the internet, so I post a question here. I'm working on an existing code base and I see something like this. li { background-color: #000 \9; background-color: rgba(0, 0, 0, 0); } I don't understand the meaning of \9. But it looks to me they are duplicates and I should remove one of them. Could you please explain the \9 and should I remove one of them? Thanks.

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• Need help in downloading file with header() function

  - by riccardo

  Hi. I'm trying to explain as best as I can, sorry for my English. I have a list of links, each linked to a php file with an id by parameters (ex. download.php?id=1 or ?id=2 and so on). This file create a new instance of a class witch return the correct header of the files so it displays the save dialog box of the browser. Now I need to check if the files is already downloaded in past (The first time you downloaded it I add a field on the mysql db). This checks go ahead if you haven't download the files, else return false. Here is the problem, when it returns false or something else the browser redirect me to the download.php file, so I get a blank page or what I'm echoing. I need that if the file is already download it show me a js alert for advice ppl. Hope you can understand what i mean. Thanks for help

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• Is it possible to implement Flex states in Android application.

  - by barmaleikin

  Hi guys, Let me explain what I am want to archive. For example, in Flex I can create page (list of something) with 3 states: Loading state (just display some animation or label with text "Please wait."), No records state (page with text saying that there is no records) and Page with populated list. It is very easy to operate with states in Flex. Is it possible to implement something similar in Android application? I would appreciate if you provide some examples.

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• String intern puzzles

  - by Yob

  On this blog I found interesting String puzzles: --- Quote --- String te = "te", st = "st"; //"test".length(); String username = te + st; username.intern(); System.out.println("String object the same is: " + (username == "test")); prints String object the same is: true but uncomment the "test".length(); line and it prints String object the same is: false --- EoQ --- Being honest I don't understand why the outputs are different. Could you please explain me what's the cause of such behaviour?

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• C++ Pointers to functions.

  - by Andy Leman

  using namespace std; int addition (int a, int b) { return (a+b); } int subtraction (int a, int b) { return (a-b); } int operation (int x, int y, int (*functocall)(int,int)) { int g; g = (*functocall)(x,y); return(g); } int main() { int m,n; int (*minus)(int,int) = subtraction; m = operation (7,5,addition); n = operation (20,m,minus); cout << n; return 0; } Can anybody explain this line for me int (*minus)(int,int) = subtraction; Thanks a lot!

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• SQL Server 2005 Weird varchar Behavior

  - by Tom Tresansky

  This SQL Server 2005 T-SQL code: DECLARE @Test1 varchar; SET @Test1 = 'dog'; DECLARE @Test2 varchar(10); SET @Test2 = 'cat'; SELECT @Test1 AS Result1, @Test2 AS Result2; produces: Result1 = d Result2 = cat I would expect either The assignment SET @Test1 = 'dog'; to fail because there isn't enough room in @Test1 Or the SELECT to return 'dog' in the Result1 column. What is up with @Test1? Could someone please explain this behavior?

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• Problem accessing base member in derived constructor

  - by LeopardSkinPillBoxHat

  Given the following classes: class Foo { struct BarBC { protected: BarBC(uint32_t aKey) : mKey(aKey) mOtherKey(0) public: const uint32_t mKey; const uint32_t mOtherKey; }; struct Bar : public BarBC { Bar(uint32_t aKey, uint32_t aOtherKey) : BarBC(aKey), mOtherKey(aOtherKey) // Compile error here }; }; I am getting a compilation error at the point indicated: error: class `Foo::Bar' does not have any field named `mOtherKey'. Can anyone explain this? I suspect it's a syntactical problem due to my Bar class being defined within the Foo class, but can't seem to find a way around it. This is simple public inheritance, so mOtherKey should be accessible from the Bar constructor. Right? Or is it something to do with the fact that mOtherKey is const and I have already initialised it to 0 in the BarBC constructor?

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• question about c++ template functions taking any type as long that type meets at least one of the re

  - by smerlin

  Since i cant explain this very well, i will start with a small example right away: template <class T> void Print(const T& t){t.print1();} template <class T> void Print(const T& t){t.print2();} This does not compile: error C2995: 'void Print(const T &)' : function template has already been defined So, how can i create a template function which takes any type T as long as that type has a print1 memberfunction OR a print2 memberfunction (no polymorphism) ?

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• SQL Stored Procedure

  - by Nathan

  I am trying to run a stored procedure with a while loop in it using Aqua Data Studio 6.5 and as soon as the SP starts Aqua Data starts consuming an increasing amount of my CPU's memory which makes absolutely no sense to me because everything should be off on the Sybase server I am working with. I have commented out and tested every piece of the SP and narrowed the issue down to the while loop. Can anyone explain to me what is going on? create procedure sp_check_stuff as begin declare @counter numeric (9), @max_id numeric (9), @exists numeric (1), @rows numeric (1) select @max_id = max(id) from my_table set @counter = 0 set @exists = 0 set @rows = 0 while @count <= @max_id begin //More logic which doesn't affect memory usage based //on commenting it out and running the SP set @counter = @counter + 1 set @exists = 0 set @rows = 0 end end return

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• interfacing: simplified

  - by code wombat

  i've been doing some research on interfaces and a simple layman's explanation for what it truly is. For some reason people love using overly complex explanations and jargon to explain truly simple concepts (guess it makes them feel big) and i have a gut feeling it's the same in this case. so from what i could grasp, it seems like interfaces are nothing more than a way to reserve method names, their return type if any, and the type and amount of arguments they accept. so when a class implements an interface (or interfaces) it is forced to define the body of each method from the interface(s). Am i on the nose with this one or do i need to keep digging? p.s. i know javascript doesn't have support for interfaces, but i still need to understand the concept because there are quite a few places where it's shown how to emulate to an extent.

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• Setting a preferred item of a many-to-one in Django

  - by Mike DeSimone

  I'm trying to create a Django model that handles the following: An Item can have several Names. One of the Names for an Item is its primary Name, i.e. the Name displayed given an Item. (The model names were changed to protect the innocent.) The models.py I've got looks like: class Item(models.Model): primaryName = models.OneToOneField("Name", verbose_name="Primary Name", related_name="_unused") def __unicode__(self): return self.primaryName.name class Name(models.Model): item = models.ForeignKey(Item) name = models.CharField(max_length=32, unique=True) def __unicode__(self): return self.name class Meta: ordering = [ 'name' ] The admin.py looks like: class NameInline(admin.TabularInline): model = Name class ItemAdmin(admin.ModelAdmin): inlines = [ NameInline ] admin.site.register(Item, ItemAdmin) It looks like the database schema is working fine, but I'm having trouble with the admin, so I'm not sure of anything at this point. My main questions are: How do I explain to the admin that primaryName needs to be one of the Names of the item being edited? Is there a way to automatically set primaryName to the first Name found, if primaryName is not set, since I'm using inline admin for the names?

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• When to use <strong> and when to use <b>?

  - by metal-gear-solid

  When to use <strong> and when to use <b> or other ways to give look of bold? strong has semantic value ( and useful for screen reader while b is presentation (and even valid in HTML 5). my question is not what is the difference between strong and b. The question is when to use semantic tag and when to use just to make text bold Should I always use <strong> if client's content files (MS word files) has some words bold in content paragraphs? How can we know when client want to give emphasis to text and when he just want to make text bold for presentation/aesthetic purpose? If it's client job to tell us, then how to explain this scenario to client to give us clear info on "when he just want to make text bold for presentation/aesthetic purpose" ?

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• Source control issue with deploying versions

  - by Bonefisher

  Hi all, we have this discussion about how to deploy to production revisions that are UAT closed without revisions with UAT not-closed status. We are using SVN and we figured out that we are not able to just take revisions without prior-revisions on the same file made. Let me explain it on this example: we have 3 revisions made on same file: r1: UAT closed (ready to deploy) r2: UAT not-closed (not ready) r3: UAT closed (ready to deploy) now I want to deploy only my changes for which the UAT is closed (e.g. r1 and r3). In SVN this is not possible because r3 contains also r2 changes.. How do you made this to work? Maybe branching? Or just take r1 and wait until r2 is UAT closed? thanks

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• Balanced Search Tree Query, Asymtotic Analysis..

  - by AGeek

  Hi, The situation is as follows:- We have n number and we have print them in sorted order. We have access to balanced dictionary data structure, which supports the operations serach, insert, delete, minimum, maximum each in O(log n) time. We want to retrieve the numbers in sorted order in O(n log n) time using only the insert and in-order traversal. The answer to this is:- Sort() initialize(t) while(not EOF) read(x) insert(x,t); Traverse(t); Now the query is if we read the elements in time "n" and then traverse the elements in "log n"(in-order traversal) time,, then the total time for this algorithm (n+logn)time, according to me.. Please explain the follow up of this algorithm for the time calculation.. How it will sort the list in O(nlogn) time?? Thanks.

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• How does Play recognize a particular websocket message?

  - by noncom

  I am looking at the websocket-chat example. It unveils much, but I still cannot get something. I understand how messages are received, processed and sent on the web page side. However, Play captures websocket messages by means of the receive method of an Akka actor. In the websocket-chat, there are several cases in this method, but I don't get, how does it know which websocket message should be mapped to which case. In fact, I don't understand the path that a websocket message follows upon entering Play's domain, how is it processed and how can different message types/kinds be sent from the webpage. I have not find any info or sources related to this. Could please someone explain this or point to some kind of a good reference? UPDATE: The link to the original example.

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• Differences between Ruby on Rails versions? Which should I use?

  - by Stephen Kellett

  I first used Rails when it was not so well known about, in 2005. I did some experimental work with it but it has languished due to lack of time. I'm now thinking of persuing the original idea again (with a new implementation) and when researching the latest Ruby and Ruby-on_Rails versions I see Ruby 1.9.2 and a Rails 3.0 beta. I haven't managed to find a concise description of the differences between any of the Rails major versions. I have looked on the official Rails site and a few others as well. No joy. Maybe i'm looking in the wrong places or for the wrong thing? My project isn't commercial in nature (it's a hobby thing) so the beta nature of Rails 3.0 doesn't put me off. I'd just like to know what the differences are. Can anyone explain please? If it makes any odds to the answer, I'll be working on a Linux box and/or a Windows box.

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• The emulator isn't showing the XML contents

  - by Roni Copul

  I have been reading Google's android tutorial (link added in the first comment) and I got a problem... In the tutorial they explain the XML elements (EditText and Button) and in the end they say how to tun the program to see the button + the text field. The problem is, that the emulator doesn't show them.. just a black screen. I even tried adding this line to the onCreate function - System.out.println("Hello World!"); but still the emulator is showing only black screen.. Here's the .java main file - http://pastebin.com/G5J9YjNe And the XML files (I mentioned what code is what file) - http://pastebin.com/VnRwAfMW What should I do? Thanks a lot for everyone who will help!

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• Trouble understanding Java map Entry sets

  - by Jake Sellers

  I'm looking at a java hangman game here: https://github.com/leleah/EvilHangman/blob/master/EvilHangman.java The code in particular is this: Iterator<Entry<List<Integer>, Set<String>>> k = partitions.entrySet().iterator(); while (k.hasNext()) { Entry<?, ?> pair = (Entry<?, ?>)k.next(); int sizeOfSet = ((Set<String>)pair.getValue()).size(); if (sizeOfSet > biggestPartitionSize) { biggestPartitionSize = sizeOfSet; } } Now my question. My google foo is weak I guess, I cannot find much on Entry sets other than the java doc itself. Is is just a temporary copy of the map? And I cannot find any info at all on the syntax: Entry<?, ?> Can anyone explain or point me toward an explanation of what is going on with those question marks? Thanks in advanced.

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• Cannot seem to communicate between views

  - by devnet247

  Hi all I have written a MVVM prototype as a learning exercise and I am struggling to understand how I can communicate between views.Let me explain I have a treeview on the left (leftSideView) ListView on the right (rightSideView) MainWindow (includes the 2 views mentioned above and a splitter) What I have implemented does not work and I would like you if you can point out where I am going wrong or if there is a better way of doing it. you can download the quick prototype from here http://cid-9db5ae91a2948485.skydrive.live.com/self.aspx/.Public/WpfCommunicationBetweenViews.zip For sure I am doing something wrong with the bindind. Also it would be nice to learn how you do it. EG ListBox on left (one view) ListView On the right (another view) how u communicate between the two. Thanks a lot of any suggestions

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