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  • Overloading stream insertion without violating information hiding?

    - by Chris
    I'm using yaml-cpp for a project. I want to overload the << and >> operators for some classes, but I'm having an issue grappling with how to "properly" do this. Take the Note class, for example. It's fairly boring: class Note { public: // constructors Note( void ); ~Note( void ); // public accessor methods void number( const unsigned long& number ) { _number = number; } unsigned long number( void ) const { return _number; } void author( const unsigned long& author ) { _author = author; } unsigned long author( void ) const { return _author; } void subject( const std::string& subject ) { _subject = subject; } std::string subject( void ) const { return _subject; } void body( const std::string& body ) { _body = body; } std::string body( void ) const { return _body; } private: unsigned long _number; unsigned long _author; std::string _subject; std::string _body; }; The << operator is easy sauce. In the .h: YAML::Emitter& operator << ( YAML::Emitter& out, const Note& v ); And in the .cpp: YAML::Emitter& operator << ( YAML::Emitter& out, const Note& v ) { out << v.number() << v.author() << v.subject() << v.body(); return out; } No sweat. Then I go to declare the >> operator. In the .h: void operator >> ( const YAML::Node& node, Note& note ); But in the .cpp I get: void operator >> ( const YAML::Node& node, Note& note ) { node[0] >> ? node[1] >> ? node[2] >> ? node[3] >> ? return; } If I write things like node[0] >> v._number; then I would need to change the CV-qualifier to make all of the Note fields public (which defeats everything I was taught (by professors, books, and experience))) about data hiding. I feel like doing node[0] >> temp0; v.number( temp0 ); all over the place is not only tedious, error-prone, and ugly, but rather wasteful (what with the extra copies). Then I got wise: I attempted to move these two operators into the Note class itself, and declare them as friends, but the compiler (GCC 4.4) didn't like that: src/note.h:44: error: ‘YAML::Emitter& Note::operator<<(YAML::Emitter&, const Note&)’ must take exactly one argument src/note.h:45: error: ‘void Note::operator(const YAML::Node&, Note&)’ must take exactly one argument Question: How do I "properly" overload the >> operator for a class Without violating the information hiding principle? Without excessive copying?

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  • lwjgl applets 101: How can I write them?

    - by Vuntic
    I have a working app in lwjgl. It doesn't do much yet; I've just started, but it does compile and run like it's supposed to. I want to make it into an applet. I've followed the guide here, and I have an applet that runs nicely and displays text and such in the applet area and can access the functions of lwjgl (like Sys.alert), but I can't figure out how to get opengl to actually render. I've tried extending an AWTGLCanvas and calling this.add(myAWTGLCanvas), where this is the Applet that I'm using, but... nothing. The initGL() and paintGL() methods never get called. I wonder if I'm supposed to be doing something with Display, but that's not for applets, right? Help? Also: This counts as a "beginner" question, right?

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  • Integrate Cppcheck with Emacs

    - by N.N.
    Is it possible to integrate Cppcheck with Emacs in a more sophisticated way than simply calling the shell command on the current buffer? I would like Emacs to be able to parse Cppcheck's messages and treat them as messages from a compiler (similar to how compile works), such as using C-x ` to visit the targets of Cppcheck's messages. Here is some example output Cppcheck: $ cppcheck --enable=all test.cpp Checking test.cpp... [test.cpp:4]: (error) Possible null pointer dereference: p - otherwise it is redundant to check if p is null at line 5 [test.cpp:38]: (style) The scope of the variable 'i' can be reduced [test.cpp:38]: (style) Variable 'i' is assigned a value that is never used [test.cpp:23]: (error) Possible null pointer dereference: p [test.cpp:33]: (error) Possible null pointer dereference: p Checking usage of global functions.. [test.cpp:36]: (style) The function 'f' is never used [test.cpp:1]: (style) The function 'f1' is never used [test.cpp:9]: (style) The function 'f2' is never used [test.cpp:26]: (style) The function 'f3' is never used

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  • How to make it easy for users to install my software? Does the programming language matter?

    - by lala
    I'm a beginner to intermediate programmer and I've learned some java and C#. I want to start thinking about making some simple programs that I can release to the world. Just some basic stuff like calendar software that will probably be free. Users want the install process to be quick and easy. To install a java program, I have to tell them to have java installed. To install a C# program, I have to tell them to have .NET installed. I'm worried this might put off some potential users who just want to double click an exe file, choose a directory and be pretty much done. So, I guess this is an either/or two part question: 1) Is there a programming language that makes it easier to set up an installer without requiring users to have other stuff installed? or: 2) Is there some way to set up an installer that checks the system to see if it has java/.NET/whatever, and then includes java/.Net/whatever in the installation if it's not already there?

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  • jQuery - cycle help

    - by MrTunes
    I'm looking to get some help on using the cycle library for jQuery. I'm in the beginner demos, and I got the absolute first one completed. This is the second one on the page. <script src="jquery-1.2.6.min.js" type="text/javascript"></script> <script src="jquery.cycle.all.min.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function() { $('.pics').cycle({ fx: 'scrollDown', speed: 300, timeout: 2000 }); </script> My CSS is identical to the one on the page, that's why I put .pics in the quotes.

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  • Can I import sql with php?

    - by shin
    Please bear with me(beginner). I am planning to set up an application where visitors can login and play/mess around with my application. So I want to refresh my php application once a day with a cron job. But I never wrote a cron job script before. I understand that I have to truncate all the tables/data and add the initial data. With phpmyadmin, I can import data. Is there any way I can import sql file after truncate the tables? What is the best way? Do I have to create table and insert all data? Help and resources will be appreciated. Thanks in advance.

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  • Continuing education with Visual Basic 9

    - by TSSH
    I am completely new to programming and starting my education with visual basic 9 and SQL. I have read Visual Basic, in easy steps, 2nd edition by Mike Mcgrath. Although it was very easy to understand, it only gave me an introduction to learning VB. I'm looking for something more in depth, albeit for a beginner. I've read through the questions with a VB and book tag. Unfortunately, most of what I've found here references VB 6 and VB 8. Any recommendations? I cannot afford to create a library or college at the moment. So, I need to make sure that what I do buy counts. Thanks for any suggestions!

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  • How can I rewrite this code to improve its clarity?

    - by eric
    Could you write this 'cleaner' ? Just a simple question from a beginner:) if(isset($_GET['tid']) && trim($_GET['tid'])!==""){ $act = 'tid'; $tid = trim($_GET['tid']); }elseif(isset($_GET['fid']) && trim($_GET['fid'])!==""){ $act = 'fid'; $fid = trim($_GET['fid']); }elseif(isset($_GET['mid']) && trim($_GET['mid'])!==""){ $act = 'mid'; }elseif(isset($_GET['act']) && trim($_GET['act'])!==""){ $act = trim($_GET['act']); }else{ $act = ""; }

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  • lwjgl 101: How can I write applets?

    - by Vuntic
    I have a working app in lwjgl. It doesn't do much yet; I've just started, but it does compile and run like it's supposed to. I want to make it into an applet. I've followed the guide here, and I have an applet that runs nicely and displays text and such in the applet area and can access the functions of lwjgl (like Sys.alert), but I can't figure out how to get opengl to actually render. I've tried extending an AWTGLCanvas and calling this.add(myAWTGLCanvas), where this is the Applet that I'm using, but... nothing. The initGL() and paintGL() methods never get called. I wonder if I'm supposed to be doing something with Display, but that's not for applets, right? Help? Also: This counts as a "beginner" question, right? Edit: Here's a simplified version of what I have.

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  • Some unclear PHP syntax

    - by serhio
    I am a PHP beginner and saw on the forum this PHP expression: $regex = <<<'END' / ( [\x00-\x7F] # single-byte sequences 0xxxxxxx | [\xC0-\xDF][\x80-\xBF] # double-byte sequences 110xxxxx 10xxxxxx | [\xE0-\xEF][\x80-\xBF]{2} # triple-byte sequences 1110xxxx 10xxxxxx * 2 | [\xF0-\xF7][\x80-\xBF]{3} # quadruple-byte sequence 11110xxx 10xxxxxx * 3 ) | ( [\x80-\xBF] ) # invalid byte in range 10000000 - 10111111 | ( [\xC0-\xFF] ) # invalid byte in range 11000000 - 11111111 /x END; Is this code correct? What do these strange (for me) constructions like <<<, 'END', /, /x, and END; mean? I recieve: Parse error: syntax error, unexpected T_SL in /home/vhosts/mysite.com/public_html/mypage.php on line X Thanks

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  • How to create a new File in Qt

    - by GG
    Hello friends, I am a Qt beginner and just got stuck with the problem. I am looking for a file SomePath/NewDirectoryA/NewFile.kml ( NewFile.kml will be the only file in NewDirectoryA, having this directory just to maintain semantics in the project ). If SomePath/NewDirectoryA/NewFile.kml exists then I will use it in my code and If it doesn't exist then I have to create it. If this File doesn't exist then this directory also doesn't exist in SomePath. So If only I have to create a file I can use QFile and open it in ReadWrite or WriteOnly mode. But the problem is I have to create the file with the directory itself. I tried with QFile with file name SomePath/NewDirectoryA/NewFile.kml but it didn't worked. Please suggest me a way in which I can create a new file( NewFile.kml ) in a new directory( NewDirectorA ) at a given location( SomePath ).

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  • How to provide Input to Dialogs designed by Qt Designer

    - by GG
    Hello, I am a Qt beginner and working with Qt Designer to develop some small UI elements. I read http://doc.trolltech.com/4.5/designer-using-a-ui-file.html to use these GUI elements in my code and using multiple inheritance approach. I am introducing bookmark feature which somewhat look like http://img293.imageshack.us/img293/3041/screenshotyb.png. Now the problem I am facing is How can I show all existing bookmark folders in the drop down(say folders are in a QVector). So my main problem is how can I pass some inputs to the UI element. I think I'm clear, please let me know if further explanation is required. Sorry for adding links directly, rich formatting in my browser is not working. Thanks in advance,

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  • Visual c++ opencv 2.1 contains()

    - by kaushalyjain
    how to check whether a given point is contained in a rectangle using the contains() function in Rect_ construct... Please give me the exact function and its parameters.Like when i type this Point b(2,2); Rect a(10,10,50,50); cout<< Rect_::contains(b); There is a compile error saying 1c:\users\kaushal\documents\visual studio 2008\projects\test1\test1.cpp(23) : error C2352: 'cv::Rect_<Tp::contains' : illegal call of non-static member function 1c:\opencv2.1\include\opencv\cxcore.hpp(385) : see declaration of 'cv::Rect<_Tp::contains'

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  • Plural to Singular conversion trouble in Rails Migrations?

    - by Earlz
    Hi, I'm a beginner at Ruby On Rails and am trying to get a migration to work with the name Priorities So, here is the code I use in my migration: class Priorities < ActiveRecord::Migration def self.up create_table :priorities do |t| t.column :name, :string, :null => false, :limit => 32 end Priority.create :name => "Critical" Priority.create :name => "Major" Priority.create :name => "Minor" end def self.down drop_table :priorities end end This results in the following error though: NOTICE: CREATE TABLE will create implicit sequence "priorities_id_seq" for serial column "priorities.id" NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "priorities_pkey" for table "priorities" rake aborted! An error has occurred, this and all later migrations canceled: uninitialized constant Priorities::Priority Is this some problem with turning ies to y for converting something plural to singular?

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  • Trouble creating a makefile

    - by catia
    Hi everyone! I'm having some trouble making a Makefile. Write now I just compile everything every time. Although, the professor is ok with that, I do want to get it working faster and to avoid unnecessary compiling. Here's what I have. FILES= p6.cpp SetIter.cpp Node.cpp Set.cpp CFLAGS= -ansi -pendantic -Wall -Wextra CC= g++ MakePg6: p6.cpp SetIter.cpp Node.cpp Set.cpp $(CC) $(CFLAGS) $(FILES) -o pg6 Node.cpp - node class Set.cpp - uses nodes. Friend of Node. SetIter.cpp - gets a set and uses a pointer to iterator through I'm confused with some of the depencies arising from the friends thing and the point of lib.o being included in the Makefile as some sites have. Any help is greatly appreciated. Thanks in advance.

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  • C++ - Where to code a member function for an inherited object.

    - by Francisco P.
    Hello! I have a few classes (heat, gas, contact, pressure) inheriting from a main one (sensor). I have a need to store them in a vector<Sensor *> (part of the specification). At some point in time, I need to call a function that indiscriminately stores those Sensor *. (also part of the specification, not open for discussion) Something like this: for(size_t i = 0; i < Sensors.size(); ++i) Sensors[i]->storeSensor(os) //os is an ofstream kind of object, passed onwards by reference Where and how shall storeSensor be defined? Is there any simple way to do this or will I need to disregard the specification? Mind you, I'm a beginner! Thanks for your time!

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  • output all data from db to a php page

    - by Sarit
    Hi, I'm a real beginner with PHP & mysql. Just for studying and for a simple example at school I would like to work this simple query and possibly output all the rows (or maybe even one) to a very basic output on a php page: <?php $user= "root"; $host="localhost"; $password=""; $database = "PetCatalog"; $cxn = mysqli_connect($host,$user,$password,$database) or die ("couldn’t connect to server"); $query = "SELECT * FROM Pet"; $result = mysql_query($cxn,$query) or die ("Couldn’t execute query."); $row = mysqli_fetch_assoc($result); echo "$result"; ?> this is the error message i've been getting: Warning: mysql_query() expects parameter 1 to be string, object given in C:\xampplite\htdocs\myblog\query.php on line 18 Couldn’t execute query. What should I do? Thanks!

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  • How do I convert a single char in string to an int

    - by Guest
    Keep in mind, if you choose to answer the question, I am a beginner in the field of programming and may need a bit more explanation than others as to how the solutions work. Thank you for your help. My problem is that I am trying to do computations with parts of a string (consisting only of numbers), but I do not know how to convert an individual char to an int. The string is named "message". for (int place = 0; place < message.size(); place++) { if (secondPlace == 0) { cout << (message[place]) * 100 << endl; } } Thank you.

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  • simple modification results in error

    - by lgwest
    When I tried to do a simple modification of the "hello android" program that eclipse adt plugin generates I get error and can't get the program to run again even if I restore the file to its original contents. The modification was that I changed a string in strings.xml. the line was: <string name="app_name">Todo List</string> and the app was runnable, then I changed it to <string name="app_name">Todo List1</string> and it was an error: [2010-04-21 23:18:03 - Todo_list] Error in an XML file: aborting build. And a new empty file also showed up called: strings.out.xml And then I can't get the prrogram back into runnable state even if I delete the empyt file and restore the original line, I'm a confused beginner of java, android and eclipse.

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  • C++ - How to call a member function for an inherited object.

    - by Francisco P.
    Hello! I have a few classes (heat, gas, contact, pressure) inheriting from a main one (sensor). I have a need to store them in a vector<Sensor *> (part of the specification). At some point in time, I need to call a function that indiscriminately stores those Sensor *. (also part of the specification, not open for discussion) Something like this: for(size_t i = 0; i < Sensors.size(); ++i) Sensors[i]->storeSensor(os) //os is an ofstream kind of object, passed onwards by reference Where and how shall storeSensor be defined? Is there any simple way to do this or will I need to disregard the specification? Mind you, I'm a beginner! Thanks for your time!

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  • Beginning Programmer Interested in Android - Should I Start with Java?

    - by Hudey
    I'm a beginner in programming. My experience so far is only in Actionscript 2 and 3. So I have a basic understanding of declaring variables, loops, arrays, if/then, do/while... I'm wanting to move to developing for Android phones so I'm wondering what suggestions people have for where to go next. Should I jump right to Android? Start with a 'beginning Java' approach? Or should I go some other route to beef up my knowledge of OOP concepts before launching into Android? I have my Dev environment set up and completed the Hello Android tutorial and I'm just wondering if I am going to be in over my head quickly?

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  • C++ for small, individual projects (i.e. hobby programming)

    - by Ygam
    I recently started C++. I am using PHP right now and decided to take a look at C++. Web programming had me working with a couple of languages, with a couple of people. I wanted to do programming where I only had to bother with one language and create small utility apps (mostly not web-based). I wanted a compiled, strongly-type language without memorizing a tome of classes. Basically I wanted to learn C++ for the following: mobile programming (I don't ever want to go touching Java, and I don't have a Mac for Objective C or IPhone SDK) small desktop apps like DTRs, POSs creating small desktop-based games creating small Air-like applications that can access the web for additional content I heard that C++ is not beginner-friendly and is mostly used for huge projects with lots of calculations and fine details (like 3D games). Is it practical or even possible for me to use C++ for the above cases? (Sorry, I haven't delved on C++ that much yet, so aside from "huge, monolithic project", I don't know any other uses for it)

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  • How can I get `find` to ignore .svn directories?

    - by John Kugelman
    I often use the find command to search through source code, delete files, whatever. Annoyingly, because Subversion stores duplicates of each file in its .svn/text-base/ directories my simple searches end up getting lots of duplicate results. For example, I want to recursively search for uint in multiple messages.h and messages.cpp files: # find -name 'messages.*' -exec grep -Iw uint {} + ./messages.cpp: Log::verbose << "Discarding out of date message: id " << uint(olderMessage.id) ./messages.cpp: Log::verbose << "Added to send queue: " << *message << ": id " << uint(preparedMessage->id) ./messages.cpp: Log::error << "Received message with invalid SHA-1 hash: id " << uint(incomingMessage.id) ./messages.cpp: Log::verbose << "Received " << *message << ": id " << uint(incomingMessage.id) ./messages.cpp: Log::verbose << "Sent message: id " << uint(preparedMessage->id) ./messages.cpp: Log::verbose << "Discarding unsent message: id " << uint(preparedMessage->id) ./messages.cpp: for (uint i = 0; i < 10 && !_stopThreads; ++i) { ./.svn/text-base/messages.cpp.svn-base: Log::verbose << "Discarding out of date message: id " << uint(olderMessage.id) ./.svn/text-base/messages.cpp.svn-base: Log::verbose << "Added to send queue: " << *message << ": id " << uint(preparedMessage->id) ./.svn/text-base/messages.cpp.svn-base: Log::error << "Received message with invalid SHA-1 hash: id " << uint(incomingMessage.id) ./.svn/text-base/messages.cpp.svn-base: Log::verbose << "Received " << *message << ": id " << uint(incomingMessage.id) ./.svn/text-base/messages.cpp.svn-base: Log::verbose << "Sent message: id " << uint(preparedMessage->id) ./.svn/text-base/messages.cpp.svn-base: Log::verbose << "Discarding unsent message: id " << uint(preparedMessage->id) ./.svn/text-base/messages.cpp.svn-base: for (uint i = 0; i < 10 && !_stopThreads; ++i) { ./virus/messages.cpp:void VsMessageProcessor::_progress(const string &fileName, uint scanCount) ./virus/messages.cpp:ProgressMessage::ProgressMessage(const string &fileName, uint scanCount) ./virus/messages.h: void _progress(const std::string &fileName, uint scanCount); ./virus/messages.h: ProgressMessage(const std::string &fileName, uint scanCount); ./virus/messages.h: uint _scanCount; ./virus/.svn/text-base/messages.cpp.svn-base:void VsMessageProcessor::_progress(const string &fileName, uint scanCount) ./virus/.svn/text-base/messages.cpp.svn-base:ProgressMessage::ProgressMessage(const string &fileName, uint scanCount) ./virus/.svn/text-base/messages.h.svn-base: void _progress(const std::string &fileName, uint scanCount); ./virus/.svn/text-base/messages.h.svn-base: ProgressMessage(const std::string &fileName, uint scanCount); ./virus/.svn/text-base/messages.h.svn-base: uint _scanCount; How can I tell find to ignore the .svn directories?

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