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  • Why in Objective-C, we use self = [super init] instead of just [super init]?

    - by ????
    In a book, I saw that if a subclass is overriding a superclass's method, we may have self = [super init]; First, is this supposed to be done in the subclass's init method? Second, I wonder why the call is not just [super init]; ? I mean, at the time of calling init, the memory is allocated by alloc already (I think by [Foobar alloc] where Foobar is the subclass's name. So can't we just call [super init] to initialize the member variables? Why do we have to get the return value of init and assign to self? I mean, before calling [super init], self should be pointing to a valid memory allocation chuck... so why assigning something to self again? (if assigning, won't [super init] just return self's existing value?)

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  • How to pass a value between Silverlight pages for WP7?

    - by Sebastian Gray
    I've got a MainPage.xaml page a Detail.xaml page. I've passed variables to the Detail.xaml from MainPage.xaml by using a static variable and referencing it in Detail.xaml (the detail page is acting like a dialog). However once I've updated the content of another object, I want to call a method in MainPage.xaml to refresh the content of that page using the updated object from the Detail.xaml page. I assume I am not using the correct paradigm for this and should probably be using MVVM or something but I'm not familiar with the implementation and was hoping there was a simple way to do this?

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  • How do I call a method when all threads (backgroundWorkers) are done with their jobs in .NET

    - by claws
    Hello, I'm using C# .NET. Its a GUI application. When user clicks a button work is assigned to 4 different background workers. Each take different amount of time and the end result is they populate some variables. I need to call a method which operates on these end results of each bgwoeker and gives the final output. How to accomplish this? Problem here is to be sure that all bgworkers are done with their job.

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  • Build a Sitemap but webpages don't use links

    - by THX1138.6
    Folks I am trying to build a sitemap (we need one badly) for a huge multi-page web app. Technically its not much more than a collection of php/MySQL web forms that use javascript instead of traditional linkage to access the many pages. >td width="100" align="center" ONMOUSEOVER="this.className='bgover'" ONMOUSEOUT="this.className='bgout'" onclick="location.href='../main.php'">Main Page</td> Above is code sample of how the links are currently managed. I know I can search through the various pages, nearly a 1000, and find these "location.href" variables and that will help me a sitemap for each section. But maybe there is an easier way? WE use Trac and SVN so perhaps I am going about this the wrong way? Any advice would be appreciated.

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  • Breaking from for loop in MATLAB GUI

    - by Nick
    I have a for loop in the opening function of a GUI in MATLAB and I'm trying to use a callback button to break the loop. I'm new to MATLAB. Here's the code I have: %In the opening function of the GUI handles.stop_now = 0; for i=1:inf if handles.stop_now==1 break; end end % Executes on button press function pushbutton_Callback(hObject, eventdata, handles) % hObject handle to end_segmenting_button (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) handles.stop_now=1; guidata(hObject, handles); For some reason, despite defining the variables with handles, the loop doesn't break upon pressing the button. Anyone know what's going on? Thanks.

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  • Time difference in seconds (as a floating point)

    - by pocoa
    >>> from datetime import datetime >>> t1 = datetime.now() >>> t2 = datetime.now() >>> delta = t2 - t1 >>> delta.seconds 7 >>> delta.microseconds 631000 Is there any way to get that as 7.631000 ? I can use time module, but I also need that t1 and t2 variables as DateTime objects. So if there is a way to do it with datettime, that would be great.

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  • How to use the variable declared in one class in another class in Obj C.

    - by srikanth rongali
    I have a NSDate *date1 in class1 implementation file(I initialized it as Global variable). I have NSDate *date2 in class 2 implementation file (initialized it as Global variable). I need to calculate the NSTimeInterval between the two dates in class 2. But I could not do it. I could not access date1 in this class. It is giving error as (date2 undeclared). Please give me help in how to call other class variables in this class. Thank you.

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  • Keeping Computer Science Writing Accessible and Eloquent

    - by Federer
    This question is particularly aimed at descriptions and explanations of what is happening in a computer program, as well as any general advice or approaches for undertaking technical reports in Computer Science at both undergraduate and graduate levels. You see, I am having particular difficulty in the best way to explain what is happening. As in, given any given program from a multi-agent system to a standard webservice, the best and most eloquent way to say exactly what is going on, the logic behind it and it's respective justifications. Should I avoid saying class names? Avoid specifying methods? Keep referring to class variables and any particular references? I'm banging my head against the wall at trying to keep a solid technical foundation and making it accessible to people of all backgrounds. Apologies for the rather vague question. Cheers.

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  • From Fraction to Decimal and Back?

    - by CC
    Hi folks... Is it possible to store a fraction like 3/6 in a variable of some sort? When I try this it only stores the numbers before the /. I know that I can use 2 variables and divide them, but the input is from a single text field. Is this at all possible? I want to do this because I need to calculate the fractions to decimal odds. A bonus question ;) - Is there an easy way to calculate a decimal value to a fraction? Thanks..

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  • C++ associative array with arbitrary types for values

    - by Gerald Kaszuba
    What is the best way to have an associative array with arbitrary value types for each key in C++? Currently my plan is to create a "value" class with member variables of the types I will be expecting. For example: class Value { int iValue; Value(int v) { iValue = v; } std::string sValue; Value(std::string v) { sValue = v; } SomeClass *cValue; Value(SomeClass *v) { cValue = c; } }; std::map<std::string, Value> table; A downside with this is you have to know the type when accessing the "Value". i.e.: table["something"] = Value(5); SomeClass *s = table["something"].cValue; // broken pointer Also the more types that are put in Value, the more bloated the array will be. Any better suggestions?

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  • Casting Class into String and Vice Versa in JAVA

    - by topgun_ivard
    I have a program in which I need to store a Class object into memory by casting it into String. Is it possible to convert the String back into the original Class so that I can use that class variables? I am doing this in JAVA. Example: test.java class hello{ public String h1; public String h2; } public class test { public static void main(String[] args) { hello h = new hello(); h.h1 = "hello"; h.h2 = "world"; String s = h.toString(); System.out.println("Print s : "+s); // Now I need to convert String s into type hello so that // I can do this: // (hello)s.h1; // (hello)s.h2; } } NOTE: this is not a homework, this is a personal project and I would be grateful if anyone can help! Thanks! Ivar

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  • C string program

    - by mrblippy
    Hi, i have been given a task to do ar school that must read three strings in, store the third string in dynamically allocated memory and print out the last 4 letters of the first word alphabetically. Here is the program i have so far but the strings are all stored in different variables, making them hard to sort. if anyone could give me a hand and help me finish this program i would be very grateful. thanks #include <stdio.h> #include <stdlib.h> #include <string.h> int main() { char word1[101]; char word2[101]; char* word3; char buffer[101]; scanf("%s", word1); scanf("%s", word2); scanf("%s", buffer); word3 = (char *) malloc(strlen(buffer)+1); strcpy(word3, buffer); return 0; }

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  • Objective C memory leaking

    - by Jakub Lédl
    Hi everyone, I'm creating one Cocoa application for myself and I found a problem. I have two NSTextFields and they're connected to each other as nextKeyViews. When I run this app with memory leaks detection tool and tab through those 2 textboxes for a while, enter some text etc., I start to leak memory. It shows me that the AppKit library is responsible, the leaked objects are NSCFStrings and the responsible frames are [NSEvent charactersIgnoringModifiers] and [NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:]. I know this is quite a brief and incomplete description, but does anyone have any ideas what could be the problem? Also, I don't use GC, so I release my instance variables in the controllers dealloc. What about the outlets? Since IBOutlet is just a mark for Interface Builder and doesn't actually mean anything, should I release them too?

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  • how to hack this php class for parse ZIP file in random or specific order

    - by Jesse
    My English is poor so I will make it short. Right now, I have imzip.zip which has three txt files: a.txt b.txt c.txt When I try to load imzip.zip using: http://pastebin.com/m1d974990 It loads the files alphabetically. In this case: a.txt b.txt c.txt However, I would like to be able to have the class load on different variables such as by size, date or simply random. The problem is I have no idea how I would go about modifying the class to fit my needs. I would really appreciate your help! :D

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  • MS VC++ 6 class wizard

    - by Shane MacLaughlin
    Ok, I'm developing an application that has been in pretty much continous development over the last 16 years, from C in DOS, through various flavours of C++ and now is largely based around C++ with MFC and StingRay GUIs and various other SDKs. While I use VS 2005 for the release builds, I still use MSVC 6 for much of the GUI building, simply because ClassWizard is so much quicker in this environment than the weak equivalent tools that followed. Note that I am using ClassWizard to automatically generate code for my own user defined types (see Custom DDXs) and I like to add a lot of member variables and methods in one go. Creating them one at a time as per later versions of Visual Studio for me is a big backward step. At the same time, working with multiple IDEs is also a pain. My question is in two parts; Is there any way of getting ClassWizard to work is VS 2005 or VS 2008? Is there any drop in replacement, or alternative IDE, that provides similar levels of productivty for old C++ hacks such as myself?

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  • Classic asp paging and session state

    - by flavour404
    Hi, Working on a classic asp page that uses paging. The error I am having a problem with is this: Lets say that you have 5 pages returned in your record set and you are on page 2. You leave and come back, you then press the link for page 3, the trouble is your session has timed out. I don't know why this happens but the page is reloaded, but the session check is bypassed and of course when the page attempts to retrieve the record set the session variables are now empty so I am getting a message stating: error near ',' line 1, because now the query is defunct. How do I get around this? Thanks, Ron.

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  • update value of a variable outside a class in VB.NET

    - by dpp
    I have a class derived from a Form, it has textbox for username and password and an OK button. I want it to behave like an InputBox so I can use it like this: Dim Username As String = "" Dim Password As String = "" Dim authorization As New Authorization(Username, Password) authorization.ShowDialog() 'The user will click OK and I will expect the Username and Password to change based on the user input MsgBox(Username & " " & Password) The Authorization class: Public Class Authorization Dim RefUsername As String Dim RefPassword As String Public Sub New(ByRef Username As String, ByRef Password As String) InitializeComponent() RefUsername = Username 'I'm trying to pass reference instead of value RefPassword = Password 'I'm trying to pass reference instead of value End Sub Private Sub OKButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AuthorizeButton.Click RefUsername = Username.Text 'I'm trying to change value of variable outside the class RefPassword = Password.Text 'I'm trying to change value of variable outside the class Me.Close() End Sub End Class In short, I want to change the value of variables outside the class when the user clicks the OK, how am I going to accomplish that?

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  • How to convert dates to numbers in Matlab

    - by user1297712
    I have some variables like these: a(1)=00:26:00 a(2)=744:32:00 a(3)=8040:33:00 I want to convert them to numbers, so I use the datenum command. The biggest number should be 8040:33:00, but look what happens. datenum(a([1 2 3])) ans = 1.0e+005 * 7.3487 7.3485 7.3486 But if I don´t calculate a(1): datenum(a([2 3],51)) ans = 1.0e+005 * 7.3490 7.3520 That´s the results that I want to get. I think that the problem is that a(2) and a(3) have more than 24hours but I haven´t found any way to solve this problem. Thanks.

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  • Reference Parameters in C++: VERY basic example please.

    - by Sagistic
    I am trying to understand how to use reference parameters. There are several examples in my text, however they are too complicated for me to understand why and how to use them. Could anyone give me the MOST basic example of how/why to use one, and perhaps the difference with or without it (what would happen if you didn't attach the '&'). for example, if I've created a function: int doSomething(int& a, int& b), what would be the consequences of not putting in that '&.' I understand that reference variables are used in order to change a formal-reference, which then allows a two-way exchange of parameters. However, that is the extent of my knowledge, and a more concrete example would be of much help. Thank you.

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  • Does C++ require a destructor call for each placement new?

    - by Josh Haberman
    I understand that placement new calls are usually matched with explicit calls to the destructor. My question is: if I have no need for a destructor (no code to put there, and no member variables that have destructors) can I safely skip the explicit destructor call? Here is my use case: I want to write C++ bindings for a C API. In the C API many objects are accessible only by pointer. Instead of creating a wrapper object that contains a single pointer (which is wasteful and semantically confusing). I want to use placement new to construct an object at the address of the C object. The C++ object will do nothing in its constructor or destructor, and its methods will do nothing but delegate to the C methods. The C++ object will contain no virtual methods. I have two parts to this question. Is there any reason why this idea will not work in practice on any production compiler? Does this technically violate the C++ language spec?

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  • C++: is it safe to read an integer variable that's being concurrently modified without locking?

    - by Hongli
    Suppose that I have an integer variable in a class, and this variable may be concurrently modified by other threads. Writes are protected by a mutex. Do I need to protect reads too? I've heard that there are some hardware architectures on which, if one thread modifies a variable, and another thread reads it, then the read result will be garbage; in this case I do need to protect reads. I've never seen such architectures though. This question assumes that a single transaction only consists of updating a single integer variable so I'm not worried about the states of any other variables that might also be involved in a transaction.

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  • What is linux equivalent of running a .bat file on windows from PHP using system()

    - by undefined
    I have a PHP script that runs a .bat file on my windows machine using $result = system("cmd /C nameOfBatchFile.bat"); This sets some environmental variables and is used to call Amazon EC2 API from the command line. How do I do the same from a Linux server? I have renamed my .bat file to a shell (.sh) and changed the script to use 'export' when setting env vars. I have tested by running the code from a putty terminal and it does what it should. So I know the commands in the script are good. How do I run this from PHP? I have tried running the same command as above with the new filename and I don't get any errors, or file not found etc but it doesn't appear to work. Where do I start trying to solve this?

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  • Is there a name for a pure-data Objective-C class?

    - by BrianEnigma
    This is less of a code-specific question and more of an Objective-C nomenclature question. In C you have struct for pure data. In Enterprise Java, you have "bean" classes that are purely member variables with getters and setters, but no business logic. In Adobe FLEX, you have "Value Objects". In Objective-C, is there a proper name for an object (descended from NSObject, of course) that simply has ivars and getters/setters (or @property/@synthesize, if you want to get fancy) and no real business logic? A more concrete example might be a simple class with getters and setters for filename, file size, description, and assorted other metadata. You could then take a bunch of these and easily throw them into a container (NSDictionary, NSArray) without the need for messy NSValue wrapping of a C struct. It is also a little more structure than putting, say, a bunch of loosely-typed child NSDictionaries into a parent container object.

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  • Writing Strings to files in python

    - by Leif Andersen
    I'm getting the following error when trying to write a string to a file in pythion: Traceback (most recent call last): File "export_off.py", line 264, in execute save_off(self.properties.path, context) File "export_off.py", line 244, in save_off primary.write(file) File "export_off.py", line 181, in write variable.write(file) File "export_off.py", line 118, in write file.write(self.value) TypeError: must be bytes or buffer, not str I basically have a string class, which contains a string: class _off_str(object): __slots__ = 'value' def __init__(self, val=""): self.value=val def get_size(self): return SZ_SHORT def write(self,file): file.write(self.value) def __str__(self): return str(self.value) Furthermore, I'm calling that class like this: def write(self, file): for variable in self.variables: variable.write(file) I have no idea what is going on. I've seen other python programs writing strings to files, so why can't this one? Thank you very much for your help.

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  • Where does static variable work in C# page. At Application level or Page Level

    - by Shantanu Gupta
    I had an interview today and every thing was going very good, but then an interviewer asked me a question Where Does Static Variable Work in C#- At Application Level or At Page Level. I was not very much clear about this answer as I only knew that static variables are stored on heap and I didn't knew anything about web related thing about it. Then tried to make me more clear by giving an example that in a page I am using static variable and three users are accessing the page one of the user updates the value of static variable, What value will be visible to remaining two users an old copy or the update will be reflected.

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