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• Is there a programmatic way to transform a sequence of image files into a PDF?

  - by Salim Fadhley

  I have a sequence of JPG images. Each of the scans is already cropped to the exact size of one page. They are sequential pages of a valuable and out of print book. The publishing application requires that these pages be submitted as a single PDF file. I could take each of these images and just past them into a word-processor (e.g. OpenOffice) - unfortunately the problem here is that it's a very big book and I've got quite a few of these books to get through. It would obviously be time-consuming. This is volunteer work! My second idea was to use LaTeX - I could make a very simple document that consists of nothing more than a series of in-line image includes. I'm sure that this approach could be made to work, it's just a little on the complex side for something which seems like a very simple job. It occurred to me that there must be a simpler way - so any suggestions? I'm on Ubuntu 9.10, my primary programming language is Python, but if the solution is super-simple I'd happily adopt any technology that works.

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• Basic problems (type inference or something else?) in Objective-C/Cocoa.

  - by Matt

  Hi, Apologies for how basic these questions are to some. Just started learning Cocoa, working through Hillegass' book, and am trying to write my first program (a GUI Cocoa app that counts the number of characters in a string). I tried this: NSString *string = [textField stringValue]; NSUInteger *stringLength = [string length]; NSString *countString = (@"There are %u characters",stringLength); [label setStringValue:countString]; But I'm getting errors like: Incompatible pointer conversion initializing 'NSUInteger' (aka 'unsigned long'), expected 'NSUInteger *'[-pedantic] for the first line, and this for the second line: Incompatible pointer types initializing 'NSUInteger *', expected 'NSString *' [-pedantic] I did try this first, but it didn't work either: [label setStringValue:[NSString stringWithFormat:@"There are %u characters",[[textField stringValue] length]]] On a similar note, I've only written in easy scripting languages before now, and I'm not sure when I should be allocing/initing objects and when I shouldn't. For example, when is it okay to do this: NSString *myString = @"foo"; or int *length = 5; instead of this: NSString *myString = [[NSString alloc] initWithString:"foo"]; And which ones should I be putting into the header files? I did check Apple's documentation, and CocoaDev, and the book I'm working for but without luck. Maybe I'm looking in the wrong places.. Thanks to anyone who takes the time to reply this: it's appreciated, and thanks for being patient with a beginner. We all start somewhere. EDIT Okay, I tried the following again: [label setStringValue:[NSString stringWithFormat:@"There are %u characters",[[textField stringValue] length]]] And it actually worked this time. Not sure why it didn't the first time, though I think I might have typed %d instead of %u by mistake. However I still don't understand why the code I posted at the top of my original post doesn't work, and I have no idea what the errors mean, and I'd very much like to know because it seems like I'm missing something important there.

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• [LaTeX] positions of page numbers, position of chapter headings, chapters AND Table of Contents, Ref

  - by kaikanmonaco

  I am writing my PhD thesis (120+ pages) in latex, the deadline is approaching and I am struggling with layout problems. I am using the documentstyle book. I am posting both problems in this one thread because I am not sure if the solution might be related to both problems or not. Problems are: 1.) The page numbers are mostly located on the top-right of each page (this is correct and where I want them to be). However, only on the first page of chapters and on the first page of what I call "special chapters", the page number is located bottom-centered. With "special chapters" I mean: List of Contents, List of Figures, List of Tables, References, Index. My university will not accept the thesis like this. The page number must ALWAYS be top-right one each page, even if the page is the first page of a chapter or the first page of something like the List of Contents. How can I fix this? 2.) On the first page of chapters and "special chapters" (List of Contents...), the chapter title is located far too low on the page. This is the standard layout of LaTeX with documentstyle book I think. However, the chapter title must start at the very top of the page! I.e. the same height as the normal text on the pages that follow. I mean the chapter title, not the header. I.e., if there is a chapter called "Chapter 1 Dynamics of foobar under mechanical stress" then that text has to start from the top the page, but right now it starts several centimeters below the top. How can I fix this? Have tried all kinds of things to no effect, I'd be very thankful for a solution! Thanks.

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• Haskel dot (.) and dollar ($) composition: correct use.

  - by Robert Massaioli

  I have been reading Real World Haskell and I am nearing the end but a matter of style has been niggling at me to do with the (.) and ($) operators. When you write a function that is a composition of other functions you write it like: f = g . h But when you apply something to the end of those functions I write it like this: k = a $ b $ c $ value But the book would write it like this: k = a . b . c $ value Now to me they look functionally equivalent, they do the exact same thing in my eyes. However, the more I look, the more I see people writing their functions in the manner that the book does: compose with (.) first and then only at the end use ($) to append a value to evaluate the lot (nobody does it with many dollar compositions). Is there a reason for using the books way that is much better than using all ($) symbols? Or is there some best practice here that I am not getting? Or is it superfluous and I shouldn't be worrying about it at all? Thanks.

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• How do i set the Transaction Isolation in EJB?

  - by Nitesh Panchal

  Hello, I am not able to find a way to set TransactionIsolation in ejb. Can anybody tell me how do i set it? I am using persistence. I have looked the following classes : EntityManager , EntityManagerFactory, UserTransaction. None of them seems to have any method like setTransactionIsolation or such. Do we need to change persistence.xml? I just read a book named Mastering EJB 3.0 4th edition. They gave a full 10 page theory about Isolation level that this problems occur and that occurs and such things but at the end they gave this paragraph :- "As we now know, the EJB standard does not deal with isolation levels directly, and rightly so. EJB is a component specification. It defines the behavior and contracts of a business component with clients and middleware infrastructure (containers) such that the component can be rendered as various middleware services properly. EJBs therefore are transactional components that interact with resource managers, such as the JDBC resource manager or JMS resource manager, via JTS, as part of a transaction. They are not, hence, resource components in themselves. Since isolation levels are very specific to the behavior and capabilities of the underlying resources, they should therefore be specified at the resource API levels. " What exactly does it mean? What is meant by resource level APIs? Please help me. If persistence has no way to set Isolation Level then why do they give such huge theory in an EJB book and make it heavy in weight unnecessarily :(

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• What are the best tricks for learning how to -think- in Objective-C?

  - by Braintapper

  Before I get flamed out for not checking previous questions, I have read most of the tutorials, and have Hillegass' book, as well as O'Reilly's book on it. I'm not asking for tips on Cocoa or what IDE to use. Where my issue lies - my 'mental muscle memory' is making it hard for me to read Objective-C code. I have no problems at all reading Java and C code and understanding what's going on. Maybe I'm getting to old to learn a new syntax, but it's a struggle shifting mental gears and looking at Objective-C code and just "getting it" (I thought it might be an isolated case, but I have other friends who are seasoned devs who have said the same thing). Are there any tricks that any non-Objective-C programmers who now know Objective-C used to help process the syntactical differences when learning it? For some reason, I get dyslexic when reading Objective-C code. Maybe I'm not meant to be able to learn it (and that's ok too). I was hoping/wondering if there might be others who have had the same experience.

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• routes as explained in RoR tutorial 2nd Ed?

  - by 7stud

  The author, Michael Hartl, says: Here the rule: get "static_pages/home" maps requests for the URI /static_pages/home to the home action in the StaticPages controller. How? The type of request is given, the url is given, but where is the mapping to a controller and action? My tests all pass, though. I also tried deleting all the actions in the StaticPagesController, which just looks like this: class StaticPagesController < ApplicationController def home end def about end def help end def contact end end ...and my tests still pass, which is puzzling. The 2nd edition of the book(online) is really frustrating. Specifically, the section about making changes to the Guardfile is impossible to follow. For instance, if I instruct you to edit this file: blah blah blah dog dog dog beetle beetle beetle jump jump jump and make these changes: blah blah blah . . . go go go . . . jump jump jump ...would you have any idea where the line 'go go go' should be in the code? And the hint for exercise 3.5-1 is flat out wrong. If the author would put up a comment section at the end of every chapter, the rails community could self-edit the book.

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• How do I Order on common attribute of two models in the DB?

  - by Will

  If i have two tables Books, CDs with corresponding models. I want to display to the user a list of books and CDs. I also want to be able to sort this list on common attributes (release date, genre, price, etc.). I also have basic filtering on the common attributes. The list will be large so I will be using pagination in manage the load. items = [] items << CD.all(:limit => 20, :page => params[:page], :order => "genre ASC") items << Book.all(:limit => 20, :page => params[:page], :order => "genre ASC") re_sort(items,"genre ASC") Right now I am doing two queries concatenating them and then sorting them. This is very inefficient. Also this breaks down when I use paging and filtering. If I am on page 2 of how do I know what page of each table individual table I am really on? There is no way to determine this information without getting all items from each table. I have though that if I create a new Class called items that has a one to one relationship with either a Book or CD and do something like Item.all(:limit => 20, :page => params[:page], :include => [:books, :cds], :order => "genre ASC") However this gives back an ambiguous error. So can only be refined as Item.all(:limit => 20, :page => params[:page], :include => [:books, :cds], :order => "books.genre ASC") And does not interleave the books and CDs in a way that I want. Any suggestions.

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• Haskell function composition (.) and function application ($) idioms: correct use.

  - by Robert Massaioli

  I have been reading Real World Haskell and I am nearing the end but a matter of style has been niggling at me to do with the (.) and ($) operators. When you write a function that is a composition of other functions you write it like: f = g . h But when you apply something to the end of those functions I write it like this: k = a $ b $ c $ value But the book would write it like this: k = a . b . c $ value Now to me they look functionally equivalent, they do the exact same thing in my eyes. However, the more I look, the more I see people writing their functions in the manner that the book does: compose with (.) first and then only at the end use ($) to append a value to evaluate the lot (nobody does it with many dollar compositions). Is there a reason for using the books way that is much better than using all ($) symbols? Or is there some best practice here that I am not getting? Or is it superfluous and I shouldn't be worrying about it at all? Thanks.

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• Can I make an identity field span multiple tables in SQL Server?

  - by johnnycakes

  Can I have an "identity" (unique, non-repeating) column span multiple tables? For example, let's say I have two tables: Books and Authors. Authors AuthorID AuthorName Books BookID BookTitle The BookID column and the AuthorID column are identity columns. I want the identity part to span both columns. So, if there is an AuthorID with a value of 123, then there cannot be a BookID with a value of 123. And vice versa. I hope that makes sense. Is this possible? Thanks. Why do I want to do this? I am writing an APS.NET MVC app. I am creating a comment section. Authors can have comments. Books can have comments. I want to be able to pass an entity ID (a book ID or an author ID) to an action and have the action pull up all the corresponding comments. The action won't care if it's a book or an author or whatever. Sound reasonable?

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• In need of a Smarter Environmental Package Configuration

  - by Jeremy Liberman

  I am trying to set up a package template in SSIS, following the Wrox Programmer to Programmer book, SQL Server 2008 Integration Services: Problem - Design - Solution. I'm really liking this book even though it is 2008 and we're using SQL Server 2005. I've got a working package template that uses an Indirect XML package configuration to identify what environment (local developer, dev, QA, production, etc) the package is being run in. That locates the SQL Server package configuration for the environment. That set-up is great and all except for the environment variable at the very front of it all. My team would prefer it if the package could use the same environment resource locator as all our other applications and tools use, so we don't two environment markers with essentially the same information in them. Normally we look up a registry key in HKey_Local_Machine but the Registry Package Configuration type only lets you look up the HKey_Current_User registries. My first thought was to write a new Package Configuration Type class that extends the Registry type; after all we'd had such luck writing our own custom log provider. SSIS is super extendable, right? So there doesn't seem to be a way to write your own Package Configuration Types. Is there still some way I can configure my SSIS SQL Server package configuration from a HKLM registry key connection string? If this is not possible, what other workarounds are available? My idea is to write a PowerShell script that will create/modify the Environment Variable that the package will use by fetching the connection string from the registry. This way there's still two markers, but at least then it's automatically maintained and automated. Is this kind of workaround necessary? Thank you for your time.

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• Change HTML image into a Button for partial refresh of page

  - by user990951

  I am new to webpage design and MVC. I have a aspx page and I have a html image. I want to change this image and make it clickable so that it will refresh only the bottom half of the page when clicked. I setup my image so that the source of the image is updated by the controller. By using the following src="<%=ViewData["BookImg"] %>" So that the whole story is clear. When a person clicks on the image of the book, it displays on the bottom half of the page information about that book pulled from a sql database. I am thinking that I would need to look into getting ajax implemented so that I can do partial page update. But the question is how do I change that HTML image into a button. Thanks in advance. ---updating per the answer chosen but still having problems--- home.aspx <% Html.RenderPartial("HomePartialView"); %> <img id = "Book_Img" src="<%=ViewData["BookImg"] %>" alt = "click Me" class="imgClick"/> <script src="../../Scripts/jquery-1.5.1.js" type="text/javascript"> $(document).ready(function(){ $(".imgClick").click(function () { $("HomePartialView").load("../../Controllers/HomeController/PartialViewBook"); }); }); </script> ---Controller public ActionResult PartialViewBook() { ViewData[imageBookPressd] = "hello world"; return View("HomePartialView"); }

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• MySQL: SELECT highest column value when WHERE finds similar entries

  - by Ike

  My question is comparable to this one, but not quite the same. I have a database with a huge amount of books, with different editions of some of the same book titles. I'm looking for an SQL statement giving me the highest edition number of each of the titles I'm selecting with a WHERE clause (to find specific book series). Here's what the table looks like: |id|title |edition|year| |--|-------------------------|-------|----| |01|Serie One Title One |1 |2007| |02|Serie One Title One |2 |2008| |03|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |05|Serie One Title Three |1 |2008| |06|Serie One Title Three |2 |2009| |07|Serie One Title Three |3 |2010| |08|Serie One Title Three |4 |2011| |--|-------------------------|-------|----| The result I'm looking for is this: |id|title |edition|year| |--|-------------------------|-------|----| |03|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |08|Serie One Title Three |4 |2011| |--|-------------------------|-------|----| The closest I got was using this statement: select id, title, max(edition), max(year) from books where title like "serie one%" group by name; but it returns the highest edition and year and includes the first id it finds: |--|-----------------------|-------|----| |01|Serie One Title One |3 |2009| |04|Serie One Title Two |1 |2001| |05|Serie One Title Three |4 |2011| |--|-----------------------|-------|----| This fancy join also comes close, but doesn't give the right result: select b.id, b.title, b.edition, b.year from books b inner join (select name, max(edition) as maxedition from books group by title) g on b.edition = g.maxedition where b.title like "serie one%" group by title; Using this I'm getting unique titles, but mostly old editions.

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• How can I perform this query between related tables without using UNION?

  - by jeremy

  Suppose I have two separate tables that I watch to query. Both of these tables has a relation with a third table. How can I query both tables with a single, non UNION based query? I want the result of the search to rank the results by comparing a field on each table. Here's a theoretical example. I have a User table. That User can have both CDs and books. I want to find all of that user's books and CDs with a single query matching a string ("awesome" in this example). A UNION based query might look like this: SELECT "book" AS model, name, ranking FROM book WHERE name LIKE 'Awesome%' UNION SELECT "cd" AS model, name, ranking FROM cd WHERE name LIKE 'Awesome%' ORDER BY ranking DESC How can I perform a query like this without the UNION? If I do a simple left join from User to Books and CDs, we end up with a total number of results equal to the number of matching cds timse the number of matching books. Is there a GROUP BY or some other way of writing the query to fix this?

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• Getting dialogue snippets from text using regular expressions

  - by sheldon

  I'm trying to extract snippets of dialogue from a book text. For example, if I have the string "What's the matter with the flag?" inquired Captain MacWhirr. "Seems all right to me." Then I want to extract "What's the matter with the flag?" and "Seem's all right to me.". I found a regular expression to use here, which is "[^"\\]*(\\.[^"\\]*)*". This works great in Eclipse when I'm doing a Ctrl+F find regex on my book .txt file, but when I run the following code: String regex = "\"[^\"\\\\]*(\\\\.[^\"\\\\]*)*\""; String bookText = "\"What's the matter with the flag?\" inquired Captain MacWhirr. \"Seems all right to me.\""; Pattern p = Pattern.compile(regex); Matcher m = p.matcher(bookText); if(m.find()) System.out.println(m.group(1)); The only thing that prints is null. So am I not converting the regex into a Java string properly? Do I need to take into account the fact that Java Strings have a \" for the double quotes?

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• basic file input using C

  - by user1781966

  So im working on learning how to do file I/O, but the book I'm using is terrible at teaching how to receive input from a file. Below is is their example of how to receive input from a file, but it doesn't work. I have copied it word for word, and it should loop through a list of names until it reaches the end of the file( or so they say in the book), but it doesn't. In fact if I leave the while loop in there, it doesn't print anything. #include <stdio.h> #include <conio.h> int main() { char name[10]; FILE*pRead; pRead=fopen("test.txt", "r"); if (pRead==NULL) { printf("file cannot be opened"); }else printf("contents of test.txt"); fscanf(pRead,"%s",name); while(!feof(pRead)) { printf("%s\n",name); fscanf(pRead, "%s", name); } getch(); } Even online, every beginners tutorial I see does some variation of this, but I can't seem to get it to work even a little bit.

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• C++ reference variable again!!!

  - by kumar_m_kiran

  Hi All, I think most would be surprised about the topic again, However I am referring to a book "C++ Common Knowledge: Essential Intermediate Programming" written by "Stephen C. Dewhurst". In the book, he quotes a particular sentence (in section under Item 5. References Are Aliases, Not Pointers), which is as below A reference is an alias for an object that already exists prior to the initialization of the reference. Once a reference is initialized to refer to a particular object, it cannot later be made to refer to a different object; a reference is bound to its initializer for its whole lifetime Can anyone please explain the context of "cannot later be made to refer to a different object" Below code works for me, #include <iostream> using namespace std; int main(int argc, char *argv[]) { int i = 100; int& ref = i; cout<<ref<<endl; int k = 2000; ref = k; cout<<ref<<endl; return 0; } Here I am referring the variable ref to both i and j variable. And the code works perfectly fine. Am I missing something? I have used SUSE10 64bit linux for testing my sample program. Thanks for your input in advance.

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• UIViewController maintains state after being nilled

  - by Eric

  In my app, I made a BookViewController class that displays and animates the pages of a book and a MainMenuViewController class that displays a set of books the user can read. In the latter class, when the user taps on one of the books, a function is called that should create a completely new instance of BookViewController, but for some reason the instance maintains its state (i.e. it resumes from the page the user left off). How can this be if I set it to nil? What am I missing here? (Note that I'm using ARC). MainMenuViewController.m @interface MainMenuViewController () @property (strong) BookViewController *bookViewController; @end @implementation MainMenuViewController @synthesize bookViewController; -(void)bookTapped:(UIButton *)sender{ NSString *bookTitle; if(sender == book1button) bookTitle = @"book1"; else if(sender == book2button) bookTitle = @"book2"; bookViewController = nil; bookViewController = [[BookViewController alloc] initWithBookTitle:bookTitle]; [self presentViewController:bookViewController animated:YES completion:nil]; } BookViewController.h @interface BookViewController : UIViewController -(id)initWithBookTitle:(NSString *)bookTitle; @end BookViewController.m @implementation BookViewController -(id)initWithBookTitle:(NSString *)theBookTitle{ self = [super init]; if(self){ bookTitle = [NSString stringWithFormat:@"%@", theBookTitle]; [self setModalTransitionStyle:UIModalTransitionStyleCrossDissolve]; NSLog(@"init a BookViewController with bookTitle: %@", bookTitle); } return self; } Every time a book is tapped, bookTapped: is called, and thee console always prints: 2012-08-31 16:29:51.750 AppName[25713:c07] init a BookViewController with bookTitle: book1 So if a new instance of BookViewController is being created, how come it seems to be returning the old one?

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• C# and Excel best practices

  - by rlp

  I am doing a lot of MS Excel interop i C# (Visual Studio 2012) using Microsoft.Office.Interop.Excel. It requires a lot of tiresome manual code to include Excel formulas, doing formatting of text and numbers, and making graphs. I would like it very much if any of you have some input on how I do the task better. I have been looking at Visual Studio Tools for Office, but I am uncertain on its functions. I get it is required to make Excel add-ins, but does it help doing Excel automation? I have desperately been trying to find information on working with Excel in Visual Studio 2012 using C#. I did found some good but short tutorials. However I really would like a book an the subject to learn the field more in depth regarding functionality and best practices. Searching Amazon with my limited knowlegde only gives me book on VSTO using older versions of Visual Studio. I would not like to use VBA. My applications use Excel mainly for visualizing compiled from different sources. I also to data processing where Excel is not required. Futhermore, I can write C# but not VB.

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• possible to make codeigniter work with another framework?

  - by ajsie

  the situation is this. my client (who also is a programmer) asks me to develop an address book (with mysql database) with a lot of functions. then he can interact with some class methods i provide for him. kinda like an API. the situation is that the address book application is getting bigger and bigger, and i feel like its way better to use CodeIgniter to code it with MVC. i wonder if i can use codeigniter, then in some way give him the access to controller methods. eg. in a controller there are some functions u can call with the web browser. public function create_contact($information) {..} public function delete_contact($id) {..} public function get_contact($id) {..} however, these are just callable from web browser. how can i let my client have access to these functions like an API? then in his own application he can use: $result = $address_book-create_contact($information); if($result) { echo "Success"; } $contact = $address_book-get_contact($id); is this possible? cause i just know how to access the controller methods with the webbrowser. and i guess its not an option for him to use header(location) to access them. all suggestions to make this possible are welcomed! thanks

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• .NET Development of iPhone App with MonoTouch - which development environment?

  - by Click Ahead

  Hi All, I'm a .NET developer (C#) with several years developing Windows Mobile Apps. I would like to get into developing iPhone Apps and MonoTouch looks good based on reviews I've read. So I'm going to go with MonoTouch. My understanding is that I'll need a new Mac, but as it happens I also need a new PC for my .NET windows development. My question is should I (a) Purchase a Mac Book Pro and dual boot with Windows 7 (b) Purchase a Mac Pro and dual boot with Windows 7 (c) Purchase a good Dev PC and a slighlty less well spec'd Mac Book Pro or Mac Pro Bear in mind I'm only doing MonoTouch development with the Mac, most of my development (approx. 80% initially) will be done on the Windows side. My budget is approx. €3,000 / $4,000 and I'd like a good, fast development environment.It's purely for development so on the windows side installing SQL 2008/VS 2010/Office and on the OS X side installing MonoTouch. BTW - my budget excludes licensing for VS/MonoTouch/etc, I have a MonoTouch and MSDN license. Any opinions are greatly appreciated. I'm a newbie to Mac's !

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• how can i read the integer value from xml document in objective-c

  - by uttam

  this is my xml document, i want to use the value of id and mlsid in in my viewcontroller. how can i read it. <Table> <ID>1</ID> <MLSID>70980420</MLSID> <STREET_NO>776</STREET_NO> <STREET_NAME>Boylston</STREET_NAME> <AreaName>Back Bay</AreaName <Table> i have created one object file book which store the all value of xml data and then i put that objects in the array . now i am able to retrive the string value but not getting the integer value. this is my object class. @interface Book : NSObject { NSInteger ID; NSInteger MLSID //Same name as the Entity Name. } how to trieve the value of MLSID in the viewcontroller. or how to print it.

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• C vs C++ function questions

  - by james

  I am learning C, and after starting out learning C++ as my first compiled language, I decided to "go back to basics" and learn C. There are two questions that I have concerning the ways each language deals with functions. Firstly, why does C "not care" about the scope that functions are defined in, whereas C++ does? For example, int main() { donothing(); return 0; } void donothing() { } the above will not compile in a C++ compiler, whereas it will compile in a C compiler. Why is this? Isn't C++ mostly just an extension on C, and should be mostly "backward compatible"? Secondly, the book that I found (Link to pdf) does not seem to state a return type for the main function. I check around and found other books and websites and these also commonly do not specify return types for the main function. If I try to compile a program that does not specify a return type for main, it compiles fine (although with some warnings) in a C compiler, but it doesn't compile in a C++ compiler. Again, why is that? Is it better style to always specify the return type as an integer rather than leaving it out? Thanks for any help, and just as a side note, if anyone can suggest a better book that I should buy that would be great!

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• Is this an error in "More Effective C++" in Item28?

  - by particle128

  I encountered a question when I was reading the item28 in More Effective C++ .In this item, the author shows to us that we can use member template in SmartPtr such that the SmartPtr<Cassette> can be converted to SmartPtr<MusicProduct>. The following code is not the same as in the book,but has the same effect. #include <iostream> class Base{}; class Derived:public Base{}; template<typename T> class smart{ public: smart(T* ptr):ptr(ptr){} template<typename U> operator smart<U>() { return smart<U>(ptr); } ~smart(){delete ptr;} private: T* ptr; }; void test(const smart<Base>& ) {} int main() { smart<Derived> sd(new Derived); test(sd); return 0; } It indeed can be compiled without compilation error. But when I ran the executable file, I got a core dump. I think that's because the member function of the conversion operator makes a temporary smart, which has a pointer to the same ptr in sd (its type is smart<Derived>). So the delete directive operates twice. What's more, after calling test, we can never use sd any more, since ptr in sd has already been delete. Now my questions are : Is my thought right? Or my code is not the same as the original code in the book? If my thought is right, is there any method to do this? Thanks very much for your help.

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• Credit card validation with regexp using test()

  - by Matt

  I'm trying to complete some homework and it appears the book might have gotten it wrong. I have a simple html page that allows user to pick a credit card in our case american express. The user then enters a number and evalutes that number based on a regular expression. My question ends up being when test() evaluates the number it returns a boolean or a string? I should then compare that string or boolean? True == true should fire off the code in a nested if statement. Heres what the book gives me as valid code: if(document.forms[0].cardName.value == "American Express") { var cardProtocol = new RegExp("^3[47][0-9]{13}$"); //REGEX ENTRY HERE if(cardProtocol.test(document.forms[0].cardNumber.value)) document.forms[0].ccResult.value = "Valid credit card number"; } The above code doesn't work in firefox. I've tried modifying it with 2 alerts to make sure the number is good and the boolean is good...and still no luck: if(document.forms[0].cardName.value == "American Express") { var cardProtocol = new RegExp("^3[47][0-9]{13}$"); //REGEX ENTRY HERE <------ alert(document.forms[0].cardNumber.value) alert(cardProtocol.test(document.forms[0].cardNumber.value)) if((cardProtocol.test(document.forms[0].cardNumber.value)) == true ) // <--Problem { document.forms[0].ccResult.value = "Valid credit card number"; } else { document.forms[0].ccResult.value = "Invalid credit card number"; } } Any ideas? the if loop is the culprit but I'm not figuring out why it is not working. Please throw up the code for the if loop! Thanks for the help!

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