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• parsing the output of the 'w' command?

  - by Blackbinary

  I'm writing a program which requires knowledge of the current load on the system, and the activity of any users (it's a load balancer). This is a university assignment, and I am required to use the w command. I'm having a hard time parsing this command because it is very verbose. Any suggestions on what I can do would be appreciated. This is a small part of the program, and I am free to use whatever method i like. The most condensed version of w which still has the information I require is `w -u -s -f' which produces this: 10:13:43 up 9:57, 2 users, load average: 0.00, 0.00, 0.00 USER TTY IDLE WHAT fsm tty7 22:44m x-session-manager fsm pts/0 0.00s w -u -s -f So out of that, I am interested in the first number after load average and the smallest idle time (so i will need to parse them all). My background process will call w, so the fact that w is the lowest idle time will not matter (all i will see is the tty time). Do you have any ideas? Thanks (I am allowed to use alternative unix commands, like grep, if that helps).

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• Expand chaining hashtable. Errors on code.

  - by FILIaS

  Expanding a hashtable with linked lists there are some errors and warnings. I wanna make sure that the following code is right (expand method) and find out what happens that raise these warnings/errors typedef struct { int length; struct List *head; struct List *tail; } HashTable; //resolving collisions using linked lists - chaining typedef struct { char *number; char *name; int time; struct List *next; }List; //on the insert method i wanna check hashtable's size, //if it seems appropriate there is the following code: //Note: hashtable variable is: Hashtable * ...... hashtable = expand(hashtable,number,name,time); /**WARNING**:assignment makes pointer from integer without a cast*/ HashTable* expand( HashTable* h ,char number[10],char* name,int time) /**error**: conflicting types for ‘expand’ previous implicit declaration of ‘expand’ was here*/ { HashTable* new; int n; clientsList *node,*next; PrimesIndex++; int new_size= primes[PrimesIndex]; /* double the size,odd length */ if (!(new=malloc((sizeof( List*))*new_size))) return NULL; for(n=0; n< h->length; ++n) { for(node=h[n].head; node; node=next) { add (&new, node->number, node->name,node->time); next=node->next;//// free(node); } } free(h); return new; }

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• Python: Access dictionary value inside of tuple and sort quickly by dict value

  - by Aquat33nfan

  I know that wasn't clear. Here's what I'm doing specifically. I have my list of dictionaries here: dict = [{int=0, value=A}, {int=1, value=B}, ... n] and I want to take them in combinations, so I used itertools and it gave me a tuple (Well, okay it gave me a memory object that I then used enumerate on so I could loop over it and enumerate gave ma tuple): for (index, tuple) in enumerate(combinations(dict, 2)): and this is where I have my problem. I want to identify which of the two items in the combination has the bigger 'int' value and which has the smaller value and assign them to variables (I'm actually using more than 2 in the combination so I can't just say if tuple[0]['int'] tuple[1]['int'] and do the assignment because I'd have to list this out a bunch of times and that's hard to manage). I was going to assign each 'int' value to a variable, sort it in a list, index the 'int' value in the list by 1, 2, 3, 4, 5 ... etc., then go back and access the dictionary I wanted by the int value and then assign the dictionary to a variable so I knew which was bigger. But I have a big list and lists and variable assignments are resource intensive and this is taking a long time (I had only a little bit of that written and it was taking forever to run). So I was hoping someone knew a fast way to do this. I actually could list out every possible combination of assignmnets using the if/thens but it's just like 5 pages of if/thens and assignments and is hard to read and manage when I want to change it. You've probably gathered this, but I"m new at programming. thx

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• Static code analysis for new language. Where to start?

  - by tinny

  I just been given a new assignment which looks like its going to be an interesting challenge. The customer is wanting a code style checking tool to be developed for their internal (soon to be open sourced) programming language which runs on the JVM. The language syntax is very Java like. The customer basically wants me to produce something like checkstyle. So my question is this, how would you approach this problem? Given a clean slate what recommendations would you make to the customer? I think I have 3 options Write something from scratch. Id prefer not to do this as it seems like this sort of code analysis tool problem has been solved so many times that there must be a more "framework" or "platform" orientated approach. Fork an existing code style checking tool and modify the parsing to fit with this new language etc etc Extend or plug into an existing static code analysis tool. (maybe write a plugin for Yasca?) Maybe you would like to share your experiences in this area? Thanks for reading

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• Reduce function calls

  - by Curious2learn

  Hello, I profiled my python program and found that the following function was taking too long to run. Perhaps, I can use a different algorithm and make it run faster. However, I have read that I can also possibly increase the speed by reducing function calls, especially when it gets called repeatedly within a loop. I am a python newbie and would like to learn how to do this and see how much faster it can get. Currently, the function is: def potentialActualBuyers(setOfPeople,theCar,price): count=0 for person in setOfPeople: if person.getUtility(theCar) >= price and person.periodCarPurchased==None: count += 1 return count where setOfPeople is a list of person objects. I tried the following: def potentialActualBuyers(setOfPeople,theCar,price): count=0 Utility=person.getUtility for person in setOfPeople: if Utility(theCar) >= price and person.periodCarPurchased==None: count += 1 return count This, however, gives me an error saying local variable 'person' referenced before assignment Any suggestions, how I can reduce function calls or any other changes that can make the code faster. Again, I am a python newbie and even though I may possibly be able to use a better algorithm, it is still worthwhile learning the answer to the above question. Thanks very much.

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• how to return a list using SwingWorker

  - by Ender

  I have an assignment where i have to create an Image Gallery which uses a SwingWorker to load the images froma a file, once the image is load you can flip threw the image and have a slideshow play. I am having trouble getting the list of loaded images using SwingWorker. This is what happens in the background it just publishes the results to a TextArea // In a thread @Override public List<Image> doInBackground() { List<Image> images = new ArrayList<Image>(); for (File filename : filenames) { try { //File file = new File(filename); System.out.println("Attempting to add: " + filename.getAbsolutePath()); images.add(ImageIO.read(filename)); publish("Loaded " + filename); System.out.println("Added file" + filename.getAbsolutePath()); } catch (IOException ioe) { publish("Error loading " + filename); } } return images; } } when it is done I just insert the images in a List<Image> and that is all it does. // In the EDT @Override protected void done() { try { for (Image image : get()) { list.add(image); } } catch (Exception e) { } } Also I created an method that returns the list called getImages() what I need to get is the list from getImages() but doesn't seam to work when I call execute() for example MySwingWorkerClass swingworker = new MySwingWorkerClass(log,list,filenames); swingworker.execute(); imageList = swingworker.getImage() Once it reaches the imageList it doesn't return anything the only way I was able to get the list was when i used the run() instead of the execute() is there another way to get the list or is the run() method the only way?. or perhaps i am not understanding the Swing Worker Class.

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• Need Help finding an appropriate task asignment algoritm for a collage project involving coordinatin

  - by Trif Mircea

  Hello. I am a long time lurker here and have found over time many answers regarding jquery and web development topics so I decided to ask a question of my own. This time I have to create a c++ project for collage which should help manage the workflow of a company providing all kinds of services through in the field teams. The ideas I have so far are: client-server application; the server is a dispatcher where all the orders from clients get and the clients are mobile devices (PDAs) each team in the field having one a order from a client is a task. Each task is made up of a series of subtasks. You have a database with estimations on how long a task should take to complete you also know what tasks or subtasks each team on the field can perform based on what kind of specialists made up the team (not going to complicate the problem by adding needed materials, it is considered that if a member of a team can perform a subtask he has the stuff needed) Now knowing these factors, what would a good task assignment algorithm be? The criteria is: how many tasks can a team do, how many tasks they have in the queue, it could also be location, how far away are they from the place but I don't think I can implement that.. It needs to be efficient and also to adapt quickly is the human dispatcher manually assigns a task. Any help or leads would be really appreciated. Also I'm not 100% sure in the idea so if you have another way you would go about creating such an application please share, even if it just a quick outline. I have to write a theoretical part too so even if the ideas are far more complex that what i outlined that would be ok ; I'd write those and implement what I can.

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• How to do timer with Nios II assembly?

  - by Nick Rosencrantz

  I've got an assignment in a computer engineering course that I don't fully understand since it is so large. Anyway I started coding the parts of it and it seems we should make code for some sort of timer. I've started put together the subroutine for snaptime but I'm not sure what I want: .equ timer, 0x920 .global snaptime .text .align 2 snaptime: movia r8,timer # basadressen till timern stw r0,12(r8) # sparar 0 till snapl movi r9,0b0110 # spara 6 i r9 stw r9,16(r8) # spara r9 movi ... ? andi r10,r10,0xFFFF The manual for Nios II assembly is here and the C code for what I'm trying to do is: #define TIMER_1_BASE ((volatile unsigned int*) 0x920) int snaptime (void) { int snaphight; int snaplow; int snap; TIMER_1_BASE[4]=0; snaphigh = TIMER_1_BASE[5] & 0xffffff; snaplow = TIMER_1_BASE[4] & 0xffffff; snap = snaphigh*65536+snaplow; return (snap); } Perhaps you can inspect the C which should be properly defined and see how I make it with assembly since the spec says it should be assembly.

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• Parse a CSV file using python (to make a decision tree later)

  - by Margaret

  First off, full disclosure: This is going towards a uni assignment, so I don't want to receive code. :). I'm more looking for approaches; I'm very new to python, having read a book but not yet written any code. The entire task is to import the contents of a CSV file, create a decision tree from the contents of the CSV file (using the ID3 algorithm), and then parse a second CSV file to run against the tree. There's a big (understandable) preference to have it capable of dealing with different CSV files (I asked if we were allowed to hard code the column names, mostly to eliminate it as a possibility, and the answer was no). The CSV files are in a fairly standard format; the header row is marked with a # then the column names are displayed, and every row after that is a simple series of values. Example: # Column1, Column2, Column3, Column4 Value01, Value02, Value03, Value04 Value11, Value12, Value13, Value14 At the moment, I'm trying to work out the first part: parsing the CSV. To make the decisions for the decision tree, a dictionary structure seems like it's going to be the most logical; so I was thinking of doing something along these lines: Read in each line, character by character If the character is not a comma or a space Append character to temporary string If the character is a comma Append the temporary string to a list Empty string Once a line has been read Create a dictionary using the header row as the key (somehow!) Append that dictionary to a list However, if I do things that way, I'm not sure how to make a mapping between the keys and the values. I'm also wondering whether there is some way to perform an action on every dictionary in a list, since I'll need to be doing things to the effect of "Everyone return their values for columns Column1 and Column4, so I can count up who has what!" - I assume that there is some mechanism, but I don't think I know how to do it. Is a dictionary the best way to do it? Would I be better off doing things using some other data structure? If so, what?

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• Programming help Loop adding

  - by Deonna

  I know this probably really simple but Im not sure what im doing wrong... The assignment states: For the second program for this lab, you are to have the user enter an integer value in the range of 10 to 50. You are to verify that the user enters a value in that range, and continue to prompt him until he does give you a value in that range. After the user has successfully entered a value in that range, you are to display the sum of all the integers from 1 to the value entered. I have this so far: #include <iostream.h> int main () { int num, sum; cout << "do-while Loop Example 2" << endl << endl; do { cout << "Enter a value from 10 to 50: "; cin >> num; if (num < 10 || num > 50) cout << "Out of range; Please try again..." << endl; } while (num < 10 || num > 50); { int i; int sum = 0; for (num = 1; num <= 50; num ++) sum = sum + num; } cout << endl << "The sum is " << sum << endl; return 0; } Im just not sure exactly what i'm doing wrong... I keep getting the wrong sum for the total...

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• Domain model for an optional many-many relationship

  - by Greg

  Let's say I'm modeling phone numbers. I have one entity for PhoneNumber, and one for Person. There's a link table that expresses the link (if any) between the PhoneNumber and Person. The link table also has a field for DisplayOrder. When accessing my domain model, I have several Use Cases for viewing a Person. I can look at them without any PhoneNumber information. I can look at them for a specific PhoneNumber. I can look at them and all of their current (or past) PhoneNumbers. I'm trying to model Person, not only for the standard CRUD operations, but for the (un)assignment of PhoneNumbers to a Person. I'm having trouble expressing the relationship between the two, especially with respects to the DisplayOrder property. I can think of several solutions but I'm not sure of which (if any) would be best. A PhoneNumberPerson class that has a Person and PhoneNumber property (most closely resembles database design) A PhoneCarryingPerson class that inherits from Person and has a PhoneNumber property. A PhoneNumber and/or PhoneNumbers property on Person (and vis-a-versa, a Person property on PhoneNumber) What would be a good way to model this that makes sense from a domain model perspective? How do I avoid misplaced properties (DisplayOrder on Person) or conditionally populated properties?

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• Properly maintain sorted state of Array/Set

  - by Jeff

  I'm trying to get data out of my MOC and then create some new objects based on those objects, and put it all back together, while keeping my sort state. The securities come out of the MOC in proper order. And everything seems to be fine until I do the assignment to the game at the bottom from setWithArray. The documentation says that setWithArray removed the duplicate objects, if there are any. I'm wonder if that's messing up my data, but I don't see a good alternative. The data is ultimately being pulled out into a UITableView. When I add items to the game manually, then they stay sorted, so I don't think the breaking of the sort is beyond the scope of what I've included here. NSError *error; NSArray *allTheSecurities = [managedObjectContext executeFetchRequest:request error:&error]; if (allTheSecurities == nil) { // Handle the error. } [request release]; /**/ NSLog( @"Enumerate..." ); NSEnumerator *enumerator = [allTheSecurities objectEnumerator]; id anObject; NSMutableArray *portfolioStocks = [[NSMutableArray alloc] init]; while (anObject = [enumerator nextObject]) { NSLog( @"Iteration... %@", [anObject name] ); NSLog( @"Build a stock..." ); PortfolioStocks *this_stock = (PortfolioStocks *)[NSEntityDescription insertNewObjectForEntityForName:@"PortfolioStocks" inManagedObjectContext:context]; NSLog( @"Set a value..." ); [this_stock setSecurity:(Security *)anObject]; [this_stock setQuantity:[NSNumber numberWithInt:0]]; NSLog( @"Add to portfolioStocks..." ); [portfolioStocks addObject:this_stock]; } //Sorted properly up to here! NSLog( @"Add to portfolio..." ); [game setPortfolio:[NSSet setWithArray:portfolioStocks]]; // <-- This is where it's not sorted anymore.

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• Basic question on retain/release semantics from Apple's reference library

  - by davetron5000

  I have done Objective-C way back when, and have recently (i.e. just now) read the documentation on Apple's site regarding the use of retain and release. However, there is a bit of code in their Creating an iPhone Application page that has me a bit confused: - (void)setUpPlacardView { // Create the placard view -- it calculates its own frame based on its image. PlacardView *aPlacardView = [[PlacardView alloc] init]; self.placardView = aPlacardView; [aPlacardView release]; // What effect does this have on self.placardView?! placardView.center = self.center; [self addSubview:placardView]; } Not seeing the entire class, it seems that self.placardView is also a PlacardView * and the assignment of it to aPlacardView doesn't seem to indicate it will retain a reference to it. So, it appears to me that the line I've commented ([aPlacardView release];) could result in aPlacardView having a retain count of 0 and thus being deallocated. Since self.placardView points to it, wouldn't that now point at deallocated memory and cause a problem?

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• W3 xHTML Validation Errors on jQuery code!

  - by Chris

  I have some jQuery code that, without it in the document it passes validation fine, but with it in it causes errors. The code in question is here: $.ajax({ type: "GET", url: "data.xml", dataType: "xml", success: function(xml) { //Update error info errors = $(xml).find("Errors").find("*").filter(function () { return $(this).children().length === 0; }); if (errors.length == 0) { statuscontent = "<img src='/web/resources/graphics/accept.png' alt='' /> System OK"; } else { statuscontent = "<img src='/web/resources/graphics/exclamation.png' alt='' /> "+errors.length+" System error"+(errors.length>1?"s":""); } $("#top-bar-systemstatus a").html(statuscontent); //Update timestamp $("#top-bar-timestamp").html($(xml).find("Timestamp").text()); //Update storename $("#top-bar-storename").html("Store: "+$(xml).find("StoreName").text()); } }); There are loads of other jQuery code on the page which all works fine and causes no errors so I cannot quite understand what is wrong with this. The page isn't "live" so cannot provide a link to it unfortunately. The error it lists is document type does not allow element "img" here And the line of code it points to is here: statuscontent = "<img src='/web/resources/graphics/accept.png' alt='' /> System OK"; It also has an issue with the next assignment to statuscontent

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• Running an RMI registry on one computer and connecting to it from another

  - by Hippopotamus

  Hello. I am doing a student assignment, using java RMI. I've programmed a simple RMI-server application that provides method which return some strings to the client. When I start the server on localhost and connect to it by client on the same computer, everything goes well. However, I am not able to do this between two computers on home network. The computers both have no trouble of connecting by a simple C program with similar functionality, so I guess the problem is with JVM here. I am binding the class to rmiregistry with try{ ComputeImpl R = new ComputeImpl(); Naming.rebind("rmi://localhost/ComputeService",R); } catch(Exception e){ System.out.println("Trouble: " +e); } And I'm doing the lookup for RMI registry in the client application with providing the argument while launching the application: StringBuffer rmi_address = new StringBuffer(); rmi_address.append("rmi://").append(args[1]).append("/ComputeService"); Compute R = (Compute) Naming.lookup(rmi_address.toString()); Is the problem with my code or with JVM? Thanks in advance.

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• Controlling Movie Clips from the main time line instead of using their individual time lines?

  - by Jess

  I have a Flash website template (four pages) that I made using AS 3.0 and Flash CS4. It is for an assignment involving movie clips. Currently on the main time line there is only one frame, and three layers: actions/menu/content. The actionscript on the main time line is simply: content_mc.stop (); There is a movie clip on the stage called “Content” that contains the content for each of the pages. Inside of that there is a “Menu” movie clip that contains and controls all of the navigation buttons. The actionscript for the Menu movie clip is: function homeBtnPress (event:MouseEvent):void{ //comments here //comments here MovieClip(parent).content_mc.gotoAndStop("home"); } function aboutBtnPress (event:MouseEvent): void{ MovieClip(parent).content_mc.gotoAndStop ("about"); } function servicesBtnPress (event:MouseEvent): void{ MovieClip (parent).content_mc.gotoAndStop ("services"); } function contactBtnPress (event:MouseEvent): void{ MovieClip (parent).content_mc.gotoAndStop ("contact"); } function portfolioBtnPress (event:MouseEvent): void{ MovieClip (parent).content_mc.gotoAndStop ("portfolio"); } home.addEventListener(MouseEvent.CLICK, homeBtnPress); about.addEventListener(MouseEvent.CLICK, aboutBtnPress); services.addEventListener(MouseEvent.CLICK, servicesBtnPress); contact.addEventListener(MouseEvent.CLICK, contactBtnPress); portfolio.addEventListener(MouseEvent.CLICK, portfolioBtnPress); So everything works fine, but my instructor wants me to control the menu/content from the main time line by using the target path tool. What exactly would I target – just the “menu” and “content” movie clips, and what code would I use? Sorry if I'm not explaining very well, I'm pretty confused. Here is the feedback from my instructor: “While we learned how to control the main timeline and the timeline of another movie clip from within a movie clip, this is not the most intuitive way to script and makes for difficult debugging. So you will need to explore how to target your buttons inside of your menu movie clip and the frames within the content movie clip from the main timeline. “ Thanks so much in advance!

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• structDelete doesn't affect the shallow copy?

  - by Travis

  I was playing around onError so I tried to create an error using a large xml document object. <cfset XMLByRef = variables.parsedXML.XMLRootElement.XMLChildElement> <cfset structDelete(variables.parsedXML, "XMLRootElement")> <cfset startXMLShortLoop = getTickCount()> <cfloop from = "1" to = "#arrayLen(variables.XMLByRef)#" index = "variables.i"> <cfoutput>#variables.XMLByRef[variables.i].id.xmltext#</cfoutput><br /> </cfloop> <cfset stopXMLShortLoop = getTickCount()> I expected to get an error because I deleted the structure I was referencing. From LiveDocs: Variable Assignment - Creates an additional reference, or alias, to the structure. Any change to the data using one variable name changes the structure that you access using the other variable name. This technique is useful when you want to add a local variable to another scope or otherwise change a variable's scope without deleting the variable from the original scope. instead I got 580df1de-3362-ca9b-b287-47795b6cdc17 25a00498-0f68-6f04-a981-56853c0844ed ... ... ... db49ed8a-0ba6-8644-124a-6d6ebda3aa52 57e57e28-e044-6119-afe2-aebffb549342 Looped 12805 times in 297 milliseconds <cfdump var = "#variables#"> Shows there's nothing in the structure, just parsedXML.xmlRoot.xmlName with the value of XMLRootElement. I also tried <cfset structDelete(variables.parsedXML.XMLRootElement, "XMLChildElement")> as well as structClear for both. More information on deleting from the xml document object. http://help.adobe.com/en_US/ColdFusion/9.0/Developing/WSc3ff6d0ea77859461172e0811cbec22c24-78e3.html Can someone please explain my faulty logic? Thanks.

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• Writing to the DataContext

  - by user738383

  I have a function. This function takes an IEnumerable<Customer> (Customer being an entity). What the function needs to do is tell the DataContext (which has a collection of Customers as a property) that its Customers property needs to be overwritten with this passed in IEnumerable<Customer>. I can't use assignment because DomainContext.Customers cannot be assigned to, as it is read only. I guess it's not clear what I'm asking, so I suppose I should say... how do I do that? So we have DataContext.Customers (of type System.Data.Linq.Table) which wants to be replaced with a System.Collections.Generic.IEnumerable. I can't just assign the latter to the former because DataContext's properties are read only. But there must be a way. Edit: here's an image: Further edit: Yes, this image does not feature a collection of the type 'Customer' but rather 'Connection'. It doesn't matter though, they are both created from tables within the linked SQL database. So there is a dc.Connections, a dc.Customers, a dc.Media and so on. Thanks in advance.

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• Encapsulating user input of data for a class (C++)

  - by Dr. Monkey

  For an assignment I've made a simple C++ program that uses a superclass (Student) and two subclasses (CourseStudent and ResearchStudent) to store a list of students and print out their details, with different details shown for the two different types of students (using overriding of the display() method from Student). My question is about how the program collects input from the user of things like the student name, ID number, unit and fee information (for a course student) and research information (for research students): My implementation has the prompting for user input and the collecting of that input handled within the classes themselves. The reasoning behind this was that each class knows what kind of input it needs, so it makes sense to me to have it know how to ask for it (given an ostream through which to ask and an istream to collect the input from). My lecturer says that the prompting and input should all be handled in the main program, which seems to me somewhat messier, and would make it trickier to extend the program to handle different types of students. I am considering, as a compromise, to make a helper class that handles the prompting and collection of user input for each type of Student, which could then be called on by the main program. The advantage of this would be that the student classes don't have as much in them (so they're cleaner), but also they can be bundled with the helper classes if the input functionality is required. This also means more classes of Student could be added without having to make major changes to the main program, as long as helper classes are provided for these new classes. Also the helper class could be swapped for an alternative language version without having to make any changes to the class itself. What are the major advantages and disadvantages of the three different options for user input (fully encapsulated, helper class or in the main program)?

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• Within an aray of objects can one create a new instance of an object at an index?

  - by David

  Here's the sample code: class TestAO { int[] x; public TestAO () { this.x = new int[5] ; for (int i = 0; i<x.length; i++) x[i] = i; } public static void main (String[]arg) { TestAO a = new TestAO (); System.out.println (a) ; TestAO c = new TestAO () ; c.x[3] = 35 ; TestAO[] Z = new TestAO[3] ; Z[0] = a ; Z[1] = (TestAO b = new TestAO()) ; Z[2] = c ; } } When i try to compile this i get an error message at the line Z[1] which reads as follows: TestAO.java:22: ')' expected Z[1] = (TestAO b = new TestAO()) ; ^ What i'm trying to do here is create an instance of the object TestAO that i want to be in that index within the assignment of the value at that index instead of creating the instance of the object outside of the array like i did with a. Is this legal and i'm just making some syntax error that i can't see (thus causing the error message) or can what i'm trying to do just not be done?

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• String Manipulation in C

  - by baris_a

  Hi guys, I am helping my nephew for his C lab homework, it is a string manipulation assignment and applying Wang's algorithm. Here is the BNF representation for the input. <sequent> ::= <lhs> # <rhs> <lhs> ::= <formulalist>| e <rhs> ::= <formulalist>| e <formulalist> ::= <formula>|<formula> , <formulalist> <formula> ::= <letter>| - <formula>| (<formula><in?xop><formula>) <in?xop> ::= & | | | > <letter> ::= A | B | ... | Z What is the best practice to handle and parse this kind of input in C? How can I parse this structure without using struct? Thanks in advance.

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• How to enforce users to create objects of class derived from mine with "new" only?

  - by sharptooth

  To implement reference counting we use an IUnknown-like interface and a smart pointer template class. The interface has implementation for all the reference-count methods, including Release(): void IUnknownLike::Release() { if( --refCount == 0 ) { delete this; } } The smart pointer template class has a copy constructor and an assignment operator both accepting raw pointers. So users can do the following: class Class : public IUnknownLike { }; void someFunction( CSmartPointer<Class> object ); //whatever function Class object; someFunction( &object ); and the program runs into undefined behavior - the object is created with reference count zero, the smart pointer is constructed and bumps it to one, then the function returns, smart pointer is destroyed, calls Release() which leads to delete of a stack-allocated variable. Users can as well do the following: struct COuter { //whatever else; Class inner;// IUnknownLike descendant }; COuter object; somefunction( &object.Inner ); and again an object not created with new is deleted. Undefined behavior at its best. Is there any way to change the IUnknownLike interface so that the user is forced to use new for creating all objects derived from IUnknownLike - both directly derived and indirectly derived (with classes in between the most derived and the base)?

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• Prolog singleton variables in Python

  - by Rubens

  I'm working on a little set of scripts in python, and I came to this: line = "a b c d e f g" a, b, c, d, e, f, g = line.split() I'm quite aware of the fact that these are decisions taken during implementation, but shouldn't (or does) python offer something like: _, _, var_needed, _, _, another_var_needed, _ = line.split() as well as Prolog does offer, in order to exclude the famous singleton variables. I'm not sure, but wouldn't it avoid unnecessary allocation? Or creating references to the result of the split call does not count up as overhead? EDIT: Sorry, my point here is: in Prolog, as far as I'm concerned, in an expression like: test(L, N) :- test(L, 0, N). test([], N, N). test([_|T], M, N) :- V is M + 1, test(T, V, N). The variable represented by _ is not accessible, for what I suppose the reference to the value that does exist in the list [_|T] is not even created. But, in Python, if I use _, I can use the last value assigned to _, and also, I do suppose the assignment occurs for each of the variables _ -- which may be considered an overhead. My question here is if shouldn't there be (or if there is) a syntax to avoid such unnecessary attributions.

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• Bubble sort dropped images based on their names

  - by user2259784

  I have written a simple bubble sort function that sort an array of Image objects based on image names. For some reason my function is not swapping the elements of array when needed ( basically new assignment is not working) Here is my code : listOfFiles = event.dataTransfer.files; sortImages(listOfFiles); function sortImages(listOfFiles) { var re = /[0-9]/; var temp; for( var index=0; index < listOfFiles.length ; index++) { for ( var index2=0; index2 < listOfFiles.length-1 ; index2++) { var one = parseFloat(re.exec(listOfFiles[index2].name )); var two = parseFloat(re.exec(listOfFiles[index2+1].name)); console.log(one + " : " + two); if (one > two) { console.log(listOfFiles[index2+1]); console.log(listOfFiles[index2]); //following three lines don't work temp = listOfFiles[index2+1]; listOfFiles[index2+1] = listOfFiles[index2]; listOfFiles[index2] = temp; console.log(listOfFiles[index2+1]); console.log(listOfFiles[index2]); } } } }

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• Unable to pass variables from one view to another

  - by jerincbus

  I have a detail view that includes three UIButtons, each of which pushes a different view on to the stack. One of the buttons is connected to a MKMapView. When that button is pushed I need to send the latitude and longitude variables from the detail view to the map view. I'm trying to add the string declaration in the IBAction: - (IBAction)goToMapView { MapViewController *mapController = [[MapViewController alloc] initWithNibName:@"MapViewController" bundle:nil]; mapController.address = self.address; mapController.Title = self.Title; mapController.lat = self.lat; mapController.lng = self.lng; //Push the new view on the stack [[self navigationController] pushViewController:mapController animated:YES]; [mapController release]; mapController = nil; } But I get this when I try to build: 'error: incompatible types in assignment' for both lat and lng variables. So my questions are am I going about passing the variables from one view to another the right way? And does the MKMapView accept latitude and longitude as a string or a number?

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