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• Why Switch/Case and not If/Else If?

  - by OB OB

  This question in mainly pointed at C/C++, but I guess other languages are relevant as well. I can't understand why is switch/case still being used instead of if/else if. It seems to me much like using goto's, and results in the same sort of messy code, while the same results could be acheived with if/else if's in a much more organized manner. Still, I see these blocks around quite often. A common place to find them is near a message-loop (WndProc...), whereas these are among the places when they raise the heaviest havoc: variables are shared along the entire block, even when not propriate (and can't be initialized inside it). Extra attention has to be put on not dropping break's, and so on... Personally, I avoid using them, and I wonder wether I'm missing something? Are they more efficient than if/else's? Are they carried on by tradition?

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• Does MATLAB perform tail call optimization?

  - by Shea Levy

  I've recently learned Haskell, and am trying to carry the pure functional style over to my other code when possible. An important aspect of this is treating all variables as immutable, i.e. constants. In order to do so, many computations that would be implemented using loops in an imperative style have to be performed using recursion, which typically incurs a memory penalty due to the allocation a new stack frame for each function call. In the special case of a tail call (where the return value of a called function is immediately returned to the callee's caller), however, this penalty can be bypassed by a process called tail call optimization (in one method, this can be done by essentially replacing a call with a jmp after setting up the stack properly). Does MATLAB perform TCO by default, or is there a way to tell it to?

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• Difference of two 'uint'

  - by vanslly

  When you attempt to declare an unsigned variable in C#.NET with a value outside its value range it is flagged as a compiler error, but if you produce a negative value at runtime and assign it to that variable at runtime the value wraps. uint z = -1; // Will not compile uint a = 5; uint b = 6; uint c = a - b; // Will result in uint.MaxValue Is there a good reason why unsigned variables wrap in such a situation instead of throwing an exception? Thanks.

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• Currency Math in JavaScript

  - by Jared

  Can someone please help me out with a JavaScript/jQuery solution for this arithmetic problem: I need to subtract one number from the other. The problem is that the numbers have a dollar sign (because its money), therefore jQuery is treating them as strings instead of numbers. I have created two variables - toalAssets and totalLiabilites. I would like to subtract the latter from the former and place the result into another variable called netWorth. Perhaps i need to use parseFloat()? But I'm not sure how - This is all a little over my head!

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• Declare two classes from eachother.

  - by tumba25

  I'm writing a app in NetBeans. I have two classes MyApp_View and MyApp_Functions. The MyApp_View class starts like this public class MyApp_View extends FrameView { MyApp_Functions My_functions = new MyApp_Functions(); public MyApp_View(SingleFrameApplication app) { super(app); In MyApp_Functions I have MyApp_View my_view = new MyApp_View(null); I want to access the public variables in MyApp_View from MyApp_Functions and the public methods in functions from view, but have no success with this. Is this doable? And how?

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• GWT removeHandler on first event notification

  - by Keith

  I want to remove a GWT event handler the first time I receive an event. I also want to avoid polluting my class with tracking registration objects that aren't really necessary. I currently have it coded as: final HandlerRegistration[] registrationRef = new HandlerRegistration[1]; registrationRef[0] = dialog.addFooHandler(new FooHandler() { public void onFoo(FooEvent event) { HandlerRegistration removeMe = registrationRef[0]; if(removeMe != null) { removeMe.removeHandler(); } // do stuff here } }); but the use of registrationRef makes the code less readable. Is there a better way to do this without adding variables to my class?

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• Load a controller into an other controller in cakephp

  - by john

  im developing a web application, using multiple pages, each with their own controller. The problem now is that there are some variables in a controller, created for one page, that are required for an other page ( with a different controller). Therefor i need to load one controller into the other one. I did this by adding App::import('Controller', 'sections'); $sections= new sectionsController; $sections-constructClasses(); to the controller, but this doens't seem to work.. Maybe u guys have some ideas? Thnx in advance!

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• optional search parameters in sql query and rows with null values

  - by glenn.danthi

  Ok here is my problem : Before i start the description, let me to tell you that I have googled up a lot and I am posting this question for a good optimal solution :) i am building a rest service on WCF to get userProfiles... the user can filter userProfiles by giving something like userProfiles?location=London now i have the following method GetUserProfiles(string firstname, string lastname, string age, string location) the sql query string i built is: select firstname, lastname, .... from profiles where (firstName like '%{firstname}%') AND (lastName like '%{lastName}%') ....and so on with all variables being replaced by string formatter. Problem with this is that it filters any row having firstname, lastname, age or location having a null value.... doing something like (firstName like '%{firstName}%' OR firstName IS NULL) would be tedious and the statement would become unmaintanable! (in this example there are only 4 arguments, but in my actual method there are 10) What would be the best solution for this?....How is this situation usually handled? Database used : MySql

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• How come checkbox state is not always passed along to PHP script?

  - by George Edison

  I have an HTML form: <form action='process.php' method='post'> <input type='checkbox' name='check_box_1' /> Check me!<br> </form> Here is a section from the PHP script process.php: echo (isset($_POST['check_box_1']))?'Set':'Not set'; The output of the script when the checkbox is set is Set But when the checkbox is not set, the output is: Not set Why is this? This seems like a very poor design because my PHP script checks a number of $_POST variables to make sure they were passed along to the script. When the $_POST['check_box_1'] value is not set, then how do I know whether the script failed to pass along the value or the checkbox was just not set?

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• what's an option strict and explicit?

  - by Ygam

  I saw this post: "Typos… Just use option strict and explicit please.. during one software development project, which I was on as a consultant, they were getting ridiculous amounts of errors everywhere… turned out the developer couldn’t spell and would declare variables with incorrect spelling.. no big deal, until you use the correct spelling when you’re assigning a value to it… and you had option explicit off. Ouch to them…" what is an option strict and explicit anyway? I have googled it up but can't get the idea (because mostly it's Visual Basic, I'm doing PHP)

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• How to convert JavaScript dictionary into Python syntax

  - by Sputnix

  Writing out javascript dictionary from inside of JavaScript- enabled application (such as Adobe) into external .jsx file (or any other .txt file) the context of resulted file dictionary looks like: ({one:"1", two:"2"}) (Please note that each dictionary keys are written as they are the variables name (which is not true). A next step is to read this .jsx file with Python. I need to find a way to convert ({one:"1", two:"2"}) into Python dictionary syntax such as: {'one':"1", 'two':"2"} It has been already suggested that instead of using JavaScript's built-in dict.toSource() it would make more sense to use JSON which would write a dictionary content in similar to Python syntax. But unfortunately using JSON is not an option for me. I need to find a way to convert ({one:"1", two:"2"}) into {'one':"1", 'two':"2"} using Python alone. Any suggestions on how to achieve it? Once again, the problem mostly in dictionary keys syntax which inside of Python look like variable names instead of strings-like dictionary keys names: one vs "one"

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• Using the "naked" attribute for functions in GCC

  - by Art Spasky

  GCC documentation (http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html) states in 6.29 Declaring Attributes of Functions "naked Use this attribute on the ARM, AVR, IP2K, RX and SPU ports to indicate that the specified function does not need prologue/epilogue sequences generated by the compiler. It is up to the programmer to provide these sequences. The only statements that can be safely included in naked functions are asm statements that do not have operands. All other statements, including declarations of local variables, if statements, and so forth, should be avoided. Naked functions should be used to implement the body of an assembly function, while allowing the compiler to construct the requisite function declaration for the assembler." Can I safely call functions using C syntax from naked functions, or only by using asm?

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• [C++]Advantage of using a static member function instead of an equivalent non-static member function

  - by jonathanasdf

  I was wondering whether there's any advantages to using a static member function when there is a non-static equivalent. Will it result in faster execution (because of not having to care about all of the member variables), or maybe less use of memory (because of not being included in all instances)? Basically, the function I'm looking at is an utility function to rotate an integer array representing pixel colours an arbitrary number of degrees around an arbitrary centre point. It is placed in my abstract Bullet base class, since only the bullets will be using it and I didn't want the overhead of calling it in some utility class. It's a bit too long and used in every single derived bullet class, making it probably not a good idea to inline. How would you suggest I define this function? As a static member function of Bullet, of a non-static member function of Bullet, or maybe not as a member of Bullet but defined outside of the class in Bullet.h? What are the advantages and disadvantages of each?

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• C++ - dynamic pointer of array

  - by Eagle

  Hi to all, first i would like to say i am Newbie in C++. As part of my master thesis i am writing a program in C++ which also get as parameters the variables m and d (both integers). Were d is the power of 2 (this means 2^d elements). Parameter m define the number of possible interactions between one element and the total group (2^d elements). The number of possible interactions is computed as following: \kappa = \sum_{i=0}^m\binom{d}{i} (at present i generate vector of vectors for 2^d x \kappa, but my Prof. would like me to create different statistics to different m's. My first though was to to generate a dynamic array of m arrays of different sizes... Then i though of defining a 3-dim array with the biggest needed 2d array, but also program speed is important (e.g d = 20). i would like to ask for your advice how to define such kind of dynamic array that will also be fast. Regards

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• RoR function help

  - by Aviatrix

  Can someone write a function for me on RoR , i simply don't have the time to study Ruby and RoR for just one time use. The function should do the following things : 1) have an array with variables 2) for each variable in the array execute 4-5 other functions get the results and insert them in another table in the same DB table name - refined CityName varchar Subdomain varchar = the varriable in the array Nearby text State varchar ZipCodes text AreaCodes text Some of the functions return arrays. i will really apreciate the help ! Thanks in advance.

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• Start thread with two parameters

  - by Matt

  I've got a method that gets called on an event, which presents me with two variables varA, varB (both strings). This method gets called with new information quite frequently, thus I have created a separate method that takes in the two parameters. I want to run this method in a thread, however have struck the issue that Thread.Start will not accept parameters. I've tried a few supposed methods, but have so far had no luck.. I think my best bet is to create a separate class, and handle it there.. However I have a List which I am inserting data into, and hit a dead end when the separate class tried to access that list, since it was in a different class. Can someone help me out here please?

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• Generic WithEvents

  - by serhio

  Error: 'WithEvents' variables can only be typed as classes, interfaces or type parameters with class constraints Background: Public Class Tadpole(Of T As IVisibleChanged, P As IVisibleChanged) Private WithEvents _Tad As T ' ERROR ' Private WithEvents _Pole As P ' ERROR ' Public Property Tad() As T ... Public Property Pole() As P ... End Class ''' IVisibleChanged ''' Public Interface IVisibleChanged Property Visible() As Boolean Event VisibleChanged As EventHandler End Interface Workaround: a. Use AddHandler to handle events defined in a structure. EDIT b. use Private WithEvents _Tad AsIVisibleChanged (M.A. Hanin) c. ?

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• facebook iframe application gives null GET/POST

  - by misterjinx

  hey everybody, I came up to something really strange with a facebook iframe application. I don't know why but my global supervariables $_GET and $_POST are empty (nulls actually)! As far as i know, when using iframe for doing applications all the specific facebook variables are kept inside the $_GET variable. But for some reason now I don't have anything. I don't know what might be the problem. And as this wouldn't be enough, when i submit a form using POST as method, my $_POST variable is also null! What you guys think might be the problem? I've spent half a day trying to figure this out, but i didn't get any result.

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• Is there an easy way to make `boost::ptr_vector` more debugger friendly in Visual Studio?

  - by Billy ONeal

  I'm considering using boost::ptr_container as a result of the responses from this question. My biggest problem with the library is that I cannot view the contents of the collection in the debugger, because the MSVC debugger doesn't recognize it, and therefore I cannot see the contents of the containers. (All the data gets stored as void * internally) I've heard MSVC has a feature called "debugger visualizers" which would allow the user to make the debugger smarter about these kinds of things, but I've never written anything like this, and I'm not hugely firmiliar with such things. For example, compare the behavior of boost::shared_ptr with MSVC's own std::tr1::shared_ptr. In the debugger (i.e. in the Watch window), the boost version shows up as a big mess of internal variables used for implementing the shared pointer, but the MSVC version shows up as a plain pointer to the object (and the shared_ptr's innards are hidden). How can I get started either using or implementing such a thing?

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• What's the right way to use idlestartup on python 2.6.5?

  - by user210481

  Idlestartup is analogous to pythonstartup variable, but for IDLE, instead of command line. But it seems not to work properly. I'm using python 2.6.5 on Windows. I have the following script assigned to it: from pprint import pprint import sys newPath = 'C:\\Python26\test') sys.path.append(newPath) print "initial config loaded" Both variables Idlestartup and pythonstartup are assigned to the same file (script above). When running IDLE, pprint and sys are NOT available, the final message is NOT printed, but newPath was added to sys.path. Running the command line, pprint and sys are available, the final message is printed and newPath was added to sys.path. Is it a bug? Am I doing something wrong? Thanks

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• How to pass an array in AS3 to an array in php?

  - by luiz

  Hello friends, I have the following array as3 example: var arrayDefinitionsargsAmfPhp:Array = new Array(); arrayDefinitionsargsAmfPhp['tabela'] = "controls"; arrayDefinitionsargsAmfPhp['width'] = "100"; sending him to the remote object for php, example: async = bridge.getOperation(amfphpFunction).send(arrayDefinitionsargsAmfPhp); In php I try to get the array like this: function retornamenu($tableInBd) { $arr = array($tableInBd); $tableInBdname = $arr['tabela']; $widthInBdname = $arr['width']; But unfortunately these variables $tableInBdname and $widthInBdname not come to php, can someone help me with an example? Thank already

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• Why the "mutable default argument fix" syntax is so ugly, asks python newbie

  - by Cawas

  Now following my series of "python newbie questions" and based on another question. Go to http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html#other-languages-have-variables and scroll down to "Default Parameter Values". There you can find the following: def bad_append(new_item, a_list=[]): a_list.append(new_item) return a_list def good_append(new_item, a_list=None): if a_list is None: a_list = [] a_list.append(new_item) return a_list So, question here is: why is the "good" syntax over a known issue ugly like that in a programming language that promotes "elegant syntax" and "easy-to-use"? Why not just something in the definition itself, that the "argument" name is attached to a "localized" mutable object like: def better_append(new_item, a_list=[].local): a_list.append(new_item) return a_list I'm sure there would be a better way to do this syntax, but I'm also almost positive there's a good reason to why it hasn't been done. So, anyone happens to know why?

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• R counting the occurrences of similar rows of data frame

  - by Matt

  I have data in the following format called DF (this is just a made up simplified sample): eval.num, eval.count, fitness, fitness.mean, green.h.0, green.v.0, offset.0 random 1 1 1500 1500 100 120 40 232342 2 2 1000 1250 100 120 40 11843 3 3 1250 1250 100 120 40 981340234 4 4 1000 1187.5 100 120 40 4363453 5 1 2000 2000 200 100 40 345902 6 1 3000 3000 150 90 10 943 7 1 2000 2000 90 90 100 9304358 8 2 1800 1900 90 90 100 284333 However, the eval.count column is incorrect and I need to fix it. It should report the number of rows with the same values for (green.h.0, green.v.0, and offset.0) by only looking at the previous rows. The example above uses the expected values, but assume they are incorrect. How can I add a new column (say "count") which will count all previous rows which have the same values of the specified variables? I have gotten help on a similar problem of just selecting all rows with the same values for specified columns, so I supposed I could just write a loop around that, but it seems inefficient to me.

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• Effective methods for reading and writing large files in C

  - by Bertholt Stutley Johnson

  I'm writing an application that deals with very large user-generated input files. The program will copy about 95 percent of the file, effectively duplicating it and switching a few words and values in the copy, and then appending the copy (in chunks) to the original file, such that each block (consisting of between 10 and 50 lines) in the original is followed by the copied and modified block, and then the next original block, and so on. The user-generated input conforms to a certain format, and it is highly unlikely that any line in the original file is longer than 100 characters long. Which would be the better approach? a) To use one file pointer and use variables that hold the current position of how much has been read and where to write to, seeking the file pointer back and forth to read and write; or b) To use multiple file pointers, one for reading and one for writing. I am mostly concerned with the efficiency of the program, as the input files will reach up to 25,000 lines, each about 50 characters long. Thanks!

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• recursive function's summation in MATLAB

  - by lucky

  B=[1 1 1 1 1 1....1] % vector of length N elements Xk= sin(2*pi/16) i need to find function alpha(l,k) which is having two variables l and k and a condition given that alpha(l,0)=alpha(l,-1)=alpha(l,-2)......=alpha(l,-(N-1))=0 i.e no matter what value of l ,alpha = 0 for past values A= input('no of iterations'); % no. of iterations user want N=input('N values of alpha:') alpha1=[]; for k=0:A-1 l=0:N-1 % need 10 separate alpha values for every k, which goes from 0 to A-1 alpha(l,k)= Xk + summation( B(j)*alpha(l,k-j)) % as summation goes from j=1 to N alpha1=[alpha1 alpha] end; could anyone please help me to solve this recursive function, i am new to matlab. alpha

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