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  • Why is 'using namespace std;' considered a bad practice in C++?

    - by Mana
    Okay, sorry for the simplistic question, but this has been bugging me ever since I finished high school C++ last year. I've been told by others on numerous occasions that my teacher was wrong in saying that we should have "using namespace std;" in our programs, and that std::cout and std::cin are more proper. However, they would always be vague as to why this is a bad practice. So, I'm asking now: Why is "using namespace std;" considered bad? Is it really that inefficient, or risk declaring ambiguous vars(variables that share the same name as a function in std namespace) that much? Or does this impact program performance noticeably as you get into writing larger applications? I'm sorry if this is something I should have googled to solve; I figured it would be nice to have this question on here regardless in case anyone else was wondering.

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  • on .bind('click') it is not deleting the first div

    - by Jean
    Hello, When I click on a particular div, that div should fade out, simple, but when I click on one of the divs it deletes the div on top of the stack. ie., when I click #sel6 it removes sel5 html code <div id="selc" class="selc" style="position:absolute; left:15px; top:200px; width:260px;"> <div id="sel5" class="sel">something</div> <div id="sel6" class="sel">something</div> <div id="sel7" class="sel">something</div> </div jquery code sel_id, sel_1 are variables $('.selc').bind('click',function(){ var sel_id = $('.sel').attr('id'); alert(sel_id); $('#'+sel_id).fadeOut('slow'); $('#'+sel_id).remove(); $('.search_box').append(sel_1); }); Thanks Jean

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  • bash tools for parsing arguments

    - by BCS
    I have a bash script that uses a few variables (call them $foo and $bar). Right now the script defines them at the top with hard coded values like this: foo=fooDefault bar=barDefault .... # use $foo and $bar What I want is to be able to use the script like any of these: myscript # use all defaults myscript -foo=altFoo # use default bar myscript -bar=altBar # use default foo myscript -bar=altBar -foo=altFoo An ideal solution would allow me to just list the variable that I want to check for flags for. Is there a reasonably nice way to do this? I've seen getopt and I think it might do about 70% of what I'm looking for but I'm wondering if there is a tool or indium that builds on it or the like that gets the rest.

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  • Handling a binary operation that makes sense only for part of a hierarchy.

    - by usersmarvin_
    I have a hierarchy, which I'll simplify greatly, of implementations of interface Value. Assume that I have two implementations, NumberValue, and StringValue. There is an average operation which only makes sense for NumberValue, with the signature NumberValue average(NumberValue numberValue){ ... } At some point after creating such variables and using them in various collections, I need to average a collection which I know is only of type NumberValue, there are three possible ways of doing this I think: Very complicated generic signatures which preserve the type info in compile time (what I'm doing now, and results in hard to maintain code) Moving the operation to the Value level, and: throwing an unsupportedOperationException for StringValue, and casting for NumberValue. Casting at the point where I know for sure that I have a NumberValue, using slightly less complicated generics to insure this. Does anybody have any better ideas, or a recommendation on oop best practices?

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  • How to check if Google Street View available and display message?

    - by Vafello
    I am passing lat and lng variables and display google sreet view in a div. The problem is that when the StreetView is unavilable then nothing is displayed. I would like to check if there is a streetview for a given lat and lng and display a message. Here is my code: var myPano = new GStreetviewPanorama(document.getElementById("street2"), panoOpts); var location = new GLatLng(lat,lng) myPano.setLocationAndPOV(location); Maybe I should use something like: Event.addListener(myPano, "error", errorMessage()); Any ideas?

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  • Converting time period strings to value/unit pair

    - by randomtoor
    I need to parse the contents of a string that represents a time period. The format of the string is value/unit, e.g.: 1s, 60min, 24h. I would separate the actual value (an int) and unit (a str) to separated variables. At the moment I do it like this: def validate_time(time): binsize = time.strip() unit = re.sub('[0-9]','',binsize) if unit not in ['s','m','min','h','l']: print "Error: unit {0} is not valid".format(unit) sys.exit(2) tmp = re.sub('[^0-9]','',binsize) try: value = int(tmp) except ValueError: print "Error: {0} is not valid".format(time) sys.exit(2) return value,unit However, it is not ideal as things like 1m0 are also (wrongly) validated (value=10,unit=m). What is the best way to validate/parse this input?

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  • Data not entering the table

    - by Luke
    //loop through usernames to add to league table for ($i = 0; $i < count($user); $i++) { //set some new variables in an array $username = $user[$i]; $squad = $team[$i]; //add details to league table if ( $username != "Ghost") { $database->addUsersToLeagueTable($username, $squad); } } I use this code to add to the league table, the following is more code: function addUsersToLeagueTable($username, $squad) { $q = "INSERT INTO `$_SESSION[comp_name]` ( `user` , `team` , `home_games_played` , `home_wins` , `home_draws` , `home_losses` ,`home_points, `home_goals_for` , `home_goals_against` , `away_games_played` , `away_wins` , `away_draws` , `away_losses` , `away_points` , `away_goals_for` , `away_goals_against` ) VALUES ( '$username', '$squad', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0')"; return mysql_query($q, $this->connection); } Can you see any obvious reason why this isn't happening? Thanks

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  • How to setup custom CSS based on account settings in a Django site?

    - by sdolan
    So I'm writing a Django based website that allows users select a color scheme through an administration interface. I already have middleware/context processors that links the current request (based on domain) to the account. My question is how to dynamically serve the CSS with the account's custom color scheme. I see two options: Add a CSS block to the base template that overrides the styles w/variables passed in through a context processors. Use a custom URL (e.g. "/static/dynamic/css//styles.css") that gets routed to a view that grabs all the necessary values and creates the css file. I'm content with either option, but was wondering if anyone else out there has dealt with similar problems and could give some insight as to "Best Practices".

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  • Can I add a custom method to Core Data-generated classes?

    - by Andy
    I've got a couple of Core Data-generated class files that I'd like to add custom methods to. I don't need to add any instance variables. How can I do this? I tried adding a category of methods: // ContactMethods.h (my category on Core Data-generated "Contact" class) #import "Contact.h" @interface Contact (ContactMethods) -(NSString*)displayName; @end ... // ContactMethods.m #import "ContactMethods.h" @implementation Contact (ContactMethods) -(NSString*)displayName { return @"Some Name"; // this is test code } @end This doesn't work, though. I get a compiler message that "-NSManagedObject may not respond to 'displayName' " and sure enough, when I run the app, I don't get "Some Name" where I should be seeing it.

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  • session expires to soon in php

    - by user1669425
    I want to extend a session time so that a session variable does not expire until after 12 hours. Problem is that after 24 minutes (default time for a session until it expires) of inactivity it still expires the session and hence gives me undefined indexes for those SESSION variables. What else do I need to do in the code below in order to be able to extend the sessions so that it does not expire on its own until 12 hours has passed: <?php ini_set('session.gc_maxlifetime',12*60*60); ini_set('session.cookie_lifetime',12*60*60); phpinfo(); session_start(); ....//rest of code below ?> in phpinfo() it states this below for gc_maxlifetime: Local Value Master Value session.gc_maxlifetime 43200 1440 session.cookie_lifetime 43200 0

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  • looping and arrays

    - by user1838418
    Hi I'm trying to construct a loop to execute 16 states of the 8 4 2 1 code in (C++) while( condition) { double Bubble[16], Bubble1[16]; Bubble[0] = ( a-2 - (b-2) ) + ( c-2 - (d-2)); // represents 0000 Bubble[1] = ( a-2 - (b-2) ) + ( c-2 - (d+2)); // represents 0001 Bubble[2] = ( a-2 - (b-2) ) + ( c+2 - (d-2)); // represents 0010 Bubble[3] = ( a-2 - (b-2) ) + ( c+2 - (d+2)); //represents 0011 ....... Bubble[15] =(a+2 - (b+2) ) + ( c+2 - (d+2)); //represents 1111 } Is there an easy way of coding using for loops? instead of writing bubble[] every time? 0 stands for -2 and 1 stands for +2. So I have 4 variables and each one need to be incremented and/or decremented. Can this be done using for loop? Appreciate your help

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  • Is it bad practice to use Reflection in Unit testing?

    - by Sebi
    During the last years I always thought that in Java, Reflection is widely used during Unit testing. Since some of the variables/methods which have to be checked are private, it is somehow necessary to read the values of them. I always thought that the Reflection API is also used for this purpose. Last week i had to test some packages and therefore write some JUnit tests. As always i used Reflection to access private fields and methods. But my supervisor who checked the code wasn't really happy with that and told me that the Reflection API wasn't meant to use for such "hacking". Instead he suggested to modifiy the visibility in the production code. Is it really bad practice to use Reflection? I can't really believe that

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  • Another thread safe queue implementation

    - by jensph
    I have a class, Queue, that I tried to make thread safe. It has these three member variables: std::queue<T> m_queue; pthread_mutex_t m_mutex; pthread_cond_t m_condition; and a push and pop implemented as: template<class T> void Queue<T>::push(T value) { pthread_mutex_lock( &m_mutex ); m_queue.push(value); if( !m_queue.empty() ) { pthread_cond_signal( &m_condition ); } pthread_mutex_unlock( &m_mutex ); } template<class T> bool Queue<T>::pop(T& value, bool block) { bool rtn = false; pthread_mutex_lock( &m_mutex ); if( block ) { while( m_queue.empty() ) { pthread_cond_wait( &m_condition, &m_mutex ); } } if( !m_queue.empty() ) { value = m_queue.front(); m_queue.pop(); rtn = true; } pthread_mutex_unlock( &m_mutex ); return rtn; } Unfortunately there are occasional issues that may be the fault of this code. That is, there are two threads and sometimes thread 1 never comes out of push() and at other times thread 2 never comes out of pop() (the block parameter is true) though the queue isn't empty. I understand there are other implementations available, but I'd like to try to fix this code, if needed. Anyone see any issues? The constructor has the appropriate initializations: Queue() { pthread_mutex_init( &mMutex, NULL ); pthread_cond_init( &mCondition, NULL ); } and the destructor, the corresponding 'destroy' calls.

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  • Iterating through a range of dates in Python

    - by ShawnMilo
    This is working fine, but I'm looking for any feedback on how to do it better. Right now I think it's better than nested loops, but it starts to get Perl-one-linerish when you have a generator in a list comprehension. Any suggestions are welcome. day_count = (end_date - start_date).days + 1 for single_date in [d for d in (start_date + timedelta(n) for n in range(day_count)) if d <= end_date]: print strftime("%Y-%m-%d", single_date.timetuple()) Notes: I'm not actually using this to print; that's just for demo purposes. The variables start_date and end_date are datetime.date objects, because I don't need the timestamps (they're going to be used to generate a report). I checked the StackOverflow questions which were similar before posting this, but none were exactly the same. Sample Output (for a start date of 2009-05-30 and an end date of 2009-06-09): 2009-05-30 2009-05-31 2009-06-01 2009-06-02 2009-06-03 2009-06-04 2009-06-05 2009-06-06 2009-06-07 2009-06-08 2009-06-09

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  • reload a form with the same parameter of the previous

    - by kawtousse
    Hi every one, I have really a problem that I don't know how to deal with it. I am using JSP and Servlet with the Eclipse IDE. First of all, the user fill an html table with the values that he has selected and written in the form. after that he will find his parameters displayed in the html table. the problem now is : the table contains in each row an edit button when clicking on it; the user should have the form automatically filled with values"previously selected" of the row. so it's how to reload the form with variables from html table. Note : I construct the table with a servlet. Please help.

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  • Error messages in ASP.NET with jQuery UI

    - by eugeneK
    I've been using my own Error reporting module which was combination of simple c# and jQueryUI Dialog. Problem is that once error or success occurs i do write it's value to session. It does work pretty good on pages with Responce.Redirect on error but not on pages where i catch an error and then return to same form. My question is why does session which added pre-postback fails to load in pages where i have return statement on some condition. And if there another way to save errors and success message except in session ? Maybe global variables or something like that ...

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  • JSP::Confused with the session objects

    - by Legend
    I just started exploring Java Servlets and JSP and am a little confused about the sessions object. Inside a servlet I have this: public class SampleServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException { HttpSession session = request.getSession(true); session.setAttribute("_session", "_value"); response.sendRedirect("page2.jsp"); } } Now, inside page2.jsp, there is a session object as well, but when I do this <% out.print(session.getAttribute("_session")) %> it gives me an error. Can someone tell me the right way of doing this? As to what I am trying to do, I want to share some session variables.

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  • Declared Properties and assigning values with self

    - by Shaun Budhram
    I understand how declared properties work - I just need a clarification on when Objective C is using the accessor method vs. when it is not. Say I have a property declared using retain: @property (nonatomic, retain) NSDate *date; ... and later... @synthesize date If I say: date = x Is that calling the accessor method? Or is it just setting the variable? self.date = x This seems to call the accessor method (I think but I'm not sure, since it seems like the retain count is increasing). Can anyone clarify this issue? I'm curious because i have some variables that seem to become invalid before I need them (and I have to specifically call retain), and I suspect this is why.

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  • from JS to iphone dev - what's the best language to start with?

    - by Enkai
    I am a total beginner and would like to eventually learn to develop for the iphone. I have just done a beginner's CS course where the language we learned was JavaScript. We studied basic concepts like: variables, arrays, loops (for,while,if,if..else..), properties and functions. I'm wondering if I am starting in the right/wrong place by following this book: Learn C on the Mac by Dave Mark? I have read a few chapters and am finding it a bit hard to get my head around the way that C works, for example the way that Strings are printed seems overly complicated as compared to JS. Do you think that JS was the wrong language to start off with and would I be better to go from JS straight to Objective-C rather than to C? I have tried to read up on previous threads on the merits/demerits of learning C first but haven't found any that relate JS to learning C/Obj C/ Cocoa. Any advice appreciated as I am very new to this. Thanks

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  • Problems reading text file data in Java

    - by user1828401
    I have this code: BufferedReader br =new BufferedReader(new FileReader("userdetails.txt")); String str; ArrayList<String> stringList = new ArrayList<String>(); while ((str=br.readLine())!=null){ String datavalue [] = str.split(","); String category = datavalue[0]; String value = datavalue[1]; stringList.add(category); stringList.add(value); } br.close(); it works when the variables category and value do not have a comma(,),however the values in the variable value does contain commas.Is there a way that I can split the index of the without using comma?

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  • 16 millisecond quantization when sending/receivingtcp packets

    - by MKZ
    Hi, I have a C++ application running on windows xp 32 system sending and receiving short tcp/ip packets. Measuring (accurately) the arrival time I see a quantization of the arrival time to 16 millisecond time units. (Meaning all packets arriving are at (16 )xN milliseconds separated from each other) To avoid packet aggregation I tried to disable the NAGLE algorithm by setting the IPPROTO_TCP option to TCP_NODELAY in the socket variables but it did not help I suspect that the problem is related to the windows schedular which also have a 16 millisecond clock.. Any idea of a solution to this problem ? Thanks

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  • Possible to exclude or reorder a column from `*` ?

    - by Earlz
    Is it possible to exclude a column from a select * from table statement with SQL Server? I have a need for this and this is my only option other than parsing a raw SQL string to get out the required field names (I really don't want to do that). Just to be bold. When the query is made I do not have access to the list of fields needed from the table but I do know which field I do not need. This is part of a complex multi-part query. Surely there must be some way even if it's "hackish" such as using table variables or views My other option is to reorder the columns. My problem is with ExecuteScalar SQL functions which get the first row and first column.

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  • PHP preg_match Math Function

    - by Matt
    I'm writing a script that will allow a user to input a string that is a math statement, to then be evaluated. I however have hit a roadblock. I cannot figure out how, using preg_match, to dissallow statements that have variables in them. Using this, $calc = create_function("", "return (" . $string . ");" ); $calc();, allows users to input a string that will be evaluated, but it crashes whenever something like echo 'foo'; is put in place of the variable $string.

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  • Seeking assistance with Escaping Data for MySQL queries

    - by JM4
    Please don't send me a link to php.net referencing mysql_real_escape_string as the only response. I have read through the page and while I understand the general concepts, I am having some trouble based on how my INSERT statement is currently built. Today, I am using the following: $sql = "INSERT INTO tablename VALUES ('', '$_SESSION['Member1FirstName'], '$_SESSION['Member1LastName'], '$_SESSION['Member1ID'], '$_SESSION['Member2FirstName'], '$_SESSION['Member2LastName'], '$_SESSION['Member2ID'] .... and the list goes on for 20+ members with some other values entered. It seems most people in the examples already have all their data stored in an array. On my site, I accept form inputs, action="" is set to self, php validation takes place and if validation passes, data is stored into SESSION variables on page 2 then redirected to the next page in the process (page 3) (approximately 8-10 pages in the whole process). thanks!

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  • echoing our parts of an Array?

    - by Wes
    I have the following array that I get as an output from facebook: http://www.paste.to/v/1jntlnml With the following code: $stream = $facebook->api_client->stream_get('',128342905144,'0','0',30,'','','',''); foreach($stream as $wallpost) { echo '<pre>'; print_r($wallpost); echo '</pre>'; } So I get the data that I need, but I want to call the individual variables within this array. For example, echo out the [message] for each post. Since it only loops once, I cant echo $wallpost['message'] or anything similar. any idea?

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