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• Using C++ but not using the language's specific features, should switch to C?

  - by Petruza

  I'm developing a NES emulator as a hobby, in my free time. I use C++ because is the language I use mostly, know mostly and like mostly. But now that I made some advance into the project I realize I'm not using almost any specific features of C++, and could have done it in plain C and getting the same result. I don't use templates, operator overloading, polymorphism, inheritance. So what would you say? should I stay in C++ or rewrite it in C? I won't do this to gain in performance, it could come as a side effect, but the idea is why should I use C++ if I don't need it? The only features of C++ I'm using is classes to encapsulate data and methods, but that can be done as well with structs and functions, I'm using new and delete, but could as well use malloc and free, and I'm using inheritance just for callbacks, which could be achieved with pointers to functions. Remember, it's a hobby project, I have no deadlines, so the overhead time and work that would require a re-write are not a problem, might be fun as well. So, the question is C or C++?

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• Is the Entity Component System architecture object oriented by definition?

  - by tieTYT

  Is the Entity Component System architecture object oriented, by definition? It seems more procedural or functional to me. My opinion is that it doesn't prevent you from implementing it in an OO language, but it would not be idiomatic to do so in a staunchly OO way. It seems like ECS separates data (E & C) from behavior (S). As evidence: The idea is to have no game methods embedded in the entity. And: The component consists of a minimal set of data needed for a specific purpose Systems are single purpose functions that take a set of entities which have a specific component I think this is not object oriented because a big part of being object oriented is combining your data and behavior together. As evidence: In contrast, the object-oriented approach encourages the programmer to place data where it is not directly accessible by the rest of the program. Instead, the data is accessed by calling specially written functions, commonly called methods, which are bundled in with the data. ECS, on the other hand, seems to be all about separating your data from your behavior.

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• @staticmethod vs module-level function

  - by darkfeline

  This is not about @staticmethod and @classmethod! I know how staticmethod works. What I want to know is the proper use cases for @staticmethod vs. a module-level function. I've googled this question, and it seems there's some general agreement that module-level functions are preferred over static methods because it's more pythonic. Static methods have the advantage of being bound to its class, which may make sense if only that class uses it. However, in Python functionality is usually organized by module not class, so usually making it a module function makes sense too. Static methods can also be overridden by subclasses, which is an advantage or disadvantage depending on how you look at it. Although, static methods are usually "functionally pure" so overriding it may not be smart, but it may be convenient sometimes (though this may be one of those "convenient, but NEVER DO IT" kind of things only experience can teach you). Are there any general rule-of-thumbs for using either staticmethod or module-level functions? What concrete advantages or disadvantages do they have (e.g. future extension, external extension, readability)? If possible, also provide a case example.

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• When decomposing a large function, how can I avoid the complexity from the extra subfunctions?

  - by missingno

  Say I have a large function like the following: function do_lots_of_stuff(){ { //subpart 1 ... } ... { //subpart N ... } } a common pattern is to decompose it into subfunctions function do_lots_of_stuff(){ subpart_1(...) subpart_2(...) ... subpart_N(...) } I usually find that decomposition has two main advantages: The decomposed function becomes much smaller. This can help people read it without getting lost in the details. Parameters have to be explicitly passed to the underlying subfunctions, instead of being implicitly available by just being in scope. This can help readability and modularity in some situations. However, I also find that decomposition has some disadvantages: There are no guarantees that the subfunctions "belong" to do_lots_of_stuff so there is nothing stopping someone from accidentally calling them from a wrong place. A module's complexity grows quadratically with the number of functions we add to it. (There are more possible ways for things to call each other) Therefore: Are there useful convention or coding styles that help me balance the pros and cons of function decomposition or should I just use an editor with code folding and call it a day? EDIT: This problem also applies to functional code (although in a less pressing manner). For example, in a functional setting we would have the subparts be returning values that are combined in the end and the decomposition problem of having lots of subfunctions being able to use each other is still present. We can't always assume that the problem domain will be able to be modeled on just some small simple types with just a few highly orthogonal functions. There will always be complicated algorithms or long lists of business rules that we still want to correctly be able to deal with. function do_lots_of_stuff(){ p1 = subpart_1() p2 = subpart_2() pN = subpart_N() return assembleStuff(p1, p2, ..., pN) }

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• multi-thread in mmorpg server

  - by jean

  For MMORPG, there is a tick function to update every object's state in a map. The function was triggered by a timer in fixed interval. So each map's update can be dispatch to different thread. At other side, server handle player incoming package have its own threads also: I/O threads. Generally, the handler of the corresponding incoming package run in I/O threads. So there is a problem: thread synchronization. I have consider two methods: Synchronize with mutex. I/O thread lock a mutex before execute handler function and map thread lock same mutex before it execute map's update. Execute all handler functions in map's thread, I/O thread only queue the incoming handler and let map thread to pop the queue then call handler function. These two have a disadvantage: delay. For method 1, if the map's tick function is running, then all clients' request need to waiting the lock release. For method 2, if map's tick function is running, all clients' request need to waiting for next tick to be handle. Of course, there is another method: add lock to functions that use data which will be accessed both in I/O thread & map thread. But this is hard to maintain and easy to goes incorrect. It needs carefully check all variables whether or not accessed by both two kinds thread. My problem is: is there better way to do this? Notice that I said map is logic concept means no interactions can happen between two map except transport. I/O thread means thread in 3rd part network lib which used to handle client request.

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• Is there an alternative to the term "calling object"?

  - by ybakos

  Let's suppose you've got a class defined (in pseudocode): class Puppy { // ... string sound = "Rawr!"; void bark() { print(sound); } } And say, given a Puppy instance, you call it's bark() method: Puppy p; p.bark(); Notice how bark() uses the member variable sound. In many contexts, I've seen folks describe sound as the member variable of the "calling object." My question is, what's a better term to use than "calling object?" To me, the object is not doing any calling. We know that member functions are in a way just functions with an implicit this or self parameter. I've come up with "receiving object," or "message recipient," which makes sense if you're down with the "messaging" paradigm. Do any of you happy hackers have a term that you like to use? I feel it should mean "the object upon which a method is called" and TOUWAMIC just doesn't cut it.

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• Value my C++ knowledge

  - by PirateOwh

  I have only followed antiRTFM tutorials and read 2 books So, I'll list the things I know better : basic input output and all the variables : integers ( signed unsigned ), float, double, char arrays if, for, while, switch functions, and passing variables to functions and return type thing classes and the concept of oop with separating declaration and definition in the header and in the source pointers so this and some more i think is all i know of C++.. But, i need some exercises to test my knowledge because i want to move on to the library SDL, so I don't know if i should feel ready or not to move on to something totally different.. I feel I should know the basics for good at least. So the question is : How can i value my c++ knowledge? Is there any online tests? Is there any GDD ( Game Design Document ) for free to use and see if i can manage to do it so "i'd pass" ? ( I'm saying GDD since ill move on to SDL and try to make my own game ) When should I move to SDL? What are ALL the things I should "master" ( master is a big word to say.. but so you understand what i mean ) before moving on ? Please I'm really in need of expert advice. I think my question is detailed so i hope you understand what i mean and can give me a good reply. Thanks for the help!

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• Best setup/workflow for distributed team to integrated DSVC with fragmented huge .NET site?

  - by lazfish

  So we have a team with 2 developers one manager. The dev server sits in a home office and the live server sits in a rack somewhere handled by the larger part of my company. We have freedom to do as we please but I want to incorporate Kiln DSVC and FogBugz for us with some standard procedures to make sense of our decisions/designs/goals. Our main product is web-based training through our .NET site with many videos etc, and we also do mobile apps for multiple platforms. Our code-base is a 15 yr old fragmented mess. The approach has been rogue .asp/.aspx pages with some class management implemented in the last 6 years. We still mix our html/vb/js all on the same file when we add a feature/page to our site. We do not separate the business logic from the rest of the code. Wiring anything up in VS for Intelli-sense or testing or any other benefit is more frustrating than it is worth, because of having to manually rejigger everything back to one file. How do other teams approach this? I noticed when I did wire everything up for VS it wants to make a class for all functions. Do people normally compile DLLs for page-specific functions that won't be reusable? What approaches make sense for getting our practices under control while still being able to fix old anti-patterns and outdated code and still moving towards a logical structure for future devs to build on?

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• How are the conceptual pairs Abstract/Concrete, Generic/Specific, and Complex/Simple related to one another in software architecture?

  - by tjb1982

  (= 2 (+ 1 1)) take the above. The requirement of the '=' predicate is that its arguments be comparable. Any two structures are comparable in this case, and so the contract/requirement is pretty generic. The '+' predicate requires that its arguments be numbers. That's more specific. (socket domain type protocol) the arguments here are much more specific (even though the arguments are still just numbers and the function itself returns a file descriptor, which is itself an int), but the arguments are more abstract, and the implementation is built up from other functions whose abstractions are less abstract, which are themselves built from less and less abstract abstractions. To the point where the requirements are something like move from one location to another, observe whether the switch at that location is on or off, turn the switch on or off, or leave it the same, etc. But are functions also less and less complex the less abstract they are? And is there a relationship between the number and range of arguments of a function and the complexity of its implementation, as you go from more abstract to less abstract, and vice versa? (= 2 (+ 1 1) 2r10) the '=' predicate is more generic than the '+' predicate, and thus could be more complex in its implementation. The '+' predicate's contract is less generic, and so could be less complex in its implementation. Is this even a little correct? What about the 'socket' function? Each of those arguments is a number of some kind. What they represent, though, is something more elaborate. It also returns a number (just like the others do), which is also a representation of something conceptually much more elaborate than a number. To boil it down, I'm asking if there is a relationship between the following dimensions, and why: Abstract/Concrete Complex/Simple Generic/Specific And more specifically, do different configurations of these dimensions have a specific, measurable impact on the number and range of the arguments (i.e., the contract) of a function?

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• What's is the point of PImpl pattern while we can use interface for same purpose in C++?

  - by ZijingWu

  I see a lot of source code which using PIMPL idiom in C++. I assume Its purposes are hidden the private data/type/implementation, so it can resolve dependence, and then reduce compile time and header include issue. But interface class in C++ also have this capability, it can also used to hidden data/type and implementation. And to hidden let the caller just see the interface when create object, we can add an factory method in it declaration in interface header. The comparison is: Cost: The interface way cost is lower, because you doesn't even need to repeat the public wrapper function implementation void Bar::doWork() { return m_impl->doWork(); }, you just need to define the signature in the interface. Well understand: The interface technology is more well understand by every C++ developer. Performance: Interface way performance not worse than PIMPL idiom, both an extra memory access. I assume the performance is same. Following is the pseudocode code to illustrate my question: // Forward declaration can help you avoid include BarImpl header, and those included in BarImpl header. class BarImpl; class Bar { public: // public functions void doWork(); private: // You doesn't need to compile Bar.cpp after change the implementation in BarImpl.cpp BarImpl* m_impl; }; The same purpose can be implement using interface: // Bar.h class IBar { public: virtual ~IBar(){} // public functions virtual void doWork() = 0; }; // to only expose the interface instead of class name to caller IBar* createObject(); So what's the point of PIMPL?

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• help me being the next zuckerberg [closed]

  - by Kraken

  I really expect someone to help me with my problem as stated below. I started learning website making by having tutorials from w3schools.com but after doing taking the HTML tutorials I don't think I really can do anything with it. Maybe I don't know everything about HTML yet. I know the online tutorials are not enough but what I need you guys to tell me is that how can I learn making some nice websites. I have vacations for two months now and I think it would be the best time for me to learn making websites as I really love to be a website developer. Now I would like to start from the scratch. I know some C language (though I know it will not help me). So tell me from where shall I learn HTML and what all things shall I learn after that and in what order. If you can also help me with the material (let it be books or online tutorials). But I would like to know how can I gain confidence that I can make some websites as just learning online tutorials doesn't help me much. I also tried some video tutorials but in that too, they will just tell me some of the functions and not all. So what am I supposed to do.. just know a limited functions as they want me to know in video tutorials or do something else.

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• I've failed at PHP several times. Is Ruby the Cure? [closed]

  - by saltcod

  Extremely, extremely subjective question here, but its something I've been struggling with for quite a while. I've seriously tried to become a reasonable PHP coder for the past several years. But I've really failed every time. I hate to describe myself as a beginner, b/c I've been designing websites (using WordPress, Drupal, etc) for years, but still I just can't seem get better at programming. Could it be that I have some kind of allergy to PHP? I went through Chris Pine's awesome into to Ruby about a week ago (for about the fifth time), and though it did all all seem much clearer to me than PHP, I wondered if I was just switching languages to find an easy way out? The things I struggle with in PHP all seem elementary—when to use a function, how to return database queries in foreach/while statements, when to turn those queries into reusable functions, adding arguments to functions, etc, etc. And all the OOP stuff that I keep seeing these days just files over my head. I guess my question(s) are: Am I going about learning how to program in the wrong way? Do I have some aversion to PHP that's preventing me from catch on? If I keep pushing at Ruby/Rails, will it just eventually 'click'. Or, the one I fear, am I just unlikely to ever be a programmer? Honesty appreciated. Terry

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• Is it justified to use project-wide unique function and variable names to help future refactoring?

  - by kahoon

  Refactoring tools (like ReSharper) often can't be sure whether to rename a given identifier when, for example refactoring a JavaScript function. I guess this is a consequence of JavaScript's dynamic nature. ReSharper solves this problem by offering to rename reasonable lexical matches too. The developer can opt out of renaming certain functions, if he finds that the lexical match is purely accidental. This means that the developer has to approve every instance that will be affected by the renaming. For example let's consider we have two Backbone classes which are used completely independently from each other in our application: var Header = Backbone.View.extend({ close: function() {...} }) var Dialog = Backbone.View.extend({ close: function() {...} }) If you try to rename Dialog's close method to for example closeAndNotify, then ReSharper will offer to rename all occurences of Header's close method just because they are the same lexically prior to the renaming. To avoid this problem, please consider this: var Header = Backbone.View.extend({ closeHeader: function() {...} }) var Dialog = Backbone.View.extend({ closeDialog: function() {...} }) Now you can rename closeDialog unambiguously - given that you have no other classes having a method with the same name. Is it worth it to name my functions this way to help future refactoring?

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• How to fix legacy code that uses <string.h> unsafely?

  - by Snowbody

  We've got a bunch of legacy code, written in straight C (some of which is K&R!), which for many, many years has been compiled using Visual C 6.0 (circa 1998) on an XP machine. We realize this is unsustainable, and we're trying to move it to a modern compiler. Political issues have said that the most recent compiler allowed is VC++ 2005. When compiling the project, there are many warnings about the unsafe string manipulation functions used (sprintf(), strcpy(), etc). Reviewing some of these places shows that the code is indeed unsafe; it does not check for buffer overflows. The compiler warning recommends that we move to using sprintf_s(), strcpy_s(), etc. However, these are Microsoft-created (and proprietary) functions and aren't available on (say) gcc (although we're primarily a Windows shop we do have some clients on various flavors of *NIX) How ought we to proceed? I don't want to roll our own string libraries. I only want to go over the code once. I'd rather not switch to C++ if we can help it.

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• Python - Bitmap won't draw/display

  - by Wallter

  I have been working on this project for some time now - it was originally supposed to be a test to see if, using wxPython, I could build a button 'from scratch.' From scratch means: that i would have full control over all the aspects of the button (i.e. controlling the BMP's that are displayed... what the event handlers did... etc.) I have run into several problems (as this is my first major python project.) Now, when the all the code is working for the life of me I can't get an image to display. Basic code - not working dc = wx.BufferedPaintDC(self) dc.SetFont(self.GetFont()) dc.SetBackground(wx.Brush(self.GetBackgroundColour())) dc.Clear() dc.DrawBitmap(wx.Bitmap("/home/wallter/Desktop/Mouseover.bmp"), 100, 100) self.Refresh() self.Update() Full Main.py import wx from Custom_Button import Custom_Button from wxPython.wx import * ID_ABOUT = 101 ID_EXIT = 102 class MyFrame(wx.Frame): def __init__(self, parent, ID, title): wxFrame.__init__(self, parent, ID, title, wxDefaultPosition, wxSize(400, 400)) self.CreateStatusBar() self.SetStatusText("Program testing custom button overlays") menu = wxMenu() menu.Append(ID_ABOUT, "&About", "More information about this program") menu.AppendSeparator() menu.Append(ID_EXIT, "E&xit", "Terminate the program") menuBar = wxMenuBar() menuBar.Append(menu, "&File"); self.SetMenuBar(menuBar) # The call for the 'Experiential button' self.Button1 = Custom_Button(parent, -1, wx.Point(100, 100), wx.Bitmap("/home/wallter/Desktop/Mouseover.bmp"), wx.Bitmap("/home/wallter/Desktop/Normal.bmp"), wx.Bitmap("/home/wallter/Desktop/Click.bmp")) # The following three lines of code are in place to try to get the # Button1 to display (trying to trigger the Paint event (the _onPaint.) # Because that is where the 'draw' functions are. self.Button1.Show(true) self.Refresh() self.Update() # Because the Above three lines of code did not work, I added the # following four lines to trigger the 'draw' functions to test if the # '_onPaint' method actually worked. # These lines do not work. dc = wx.BufferedPaintDC(self) dc.SetFont(self.GetFont()) dc.SetBackground(wx.Brush(self.GetBackgroundColour())) dc.DrawBitmap(wx.Bitmap("/home/wallter/Desktop/Mouseover.bmp"), 100, 100) EVT_MENU(self, ID_ABOUT, self.OnAbout) EVT_MENU(self, ID_EXIT, self.TimeToQuit) def OnAbout(self, event): dlg = wxMessageDialog(self, "Testing the functions of custom " "buttons using pyDev and wxPython", "About", wxOK | wxICON_INFORMATION) dlg.ShowModal() dlg.Destroy() def TimeToQuit(self, event): self.Close(true) class MyApp(wx.App): def OnInit(self): frame = MyFrame(NULL, -1, "wxPython | Buttons") frame.Show(true) self.SetTopWindow(frame) return true app = MyApp(0) app.MainLoop() Full CustomButton.py import wx from wxPython.wx import * class Custom_Button(wx.PyControl): def __init__(self, parent, id, Pos, Over_BMP, Norm_BMP, Push_BMP, **kwargs): wx.PyControl.__init__(self,parent, id, **kwargs) self.Bind(wx.EVT_LEFT_DOWN, self._onMouseDown) self.Bind(wx.EVT_LEFT_UP, self._onMouseUp) self.Bind(wx.EVT_LEAVE_WINDOW, self._onMouseLeave) self.Bind(wx.EVT_ENTER_WINDOW, self._onMouseEnter) self.Bind(wx.EVT_ERASE_BACKGROUND,self._onEraseBackground) self.Bind(wx.EVT_PAINT,self._onPaint) self.pos = Pos self.Over_bmp = Over_BMP self.Norm_bmp = Norm_BMP self.Push_bmp = Push_BMP self._mouseIn = False self._mouseDown = False def _onMouseEnter(self, event): self._mouseIn = True def _onMouseLeave(self, event): self._mouseIn = False def _onMouseDown(self, event): self._mouseDown = True def _onMouseUp(self, event): self._mouseDown = False self.sendButtonEvent() def sendButtonEvent(self): event = wx.CommandEvent(wx.wxEVT_COMMAND_BUTTON_CLICKED, self.GetId()) event.SetInt(0) event.SetEventObject(self) self.GetEventHandler().ProcessEvent(event) def _onEraseBackground(self,event): # reduce flicker pass def Iz(self): dc = wx.BufferedPaintDC(self) dc.DrawBitmap(self.Norm_bmp, 100, 100) def _onPaint(self, event): # The printing functions, they should work... but don't. dc = wx.BufferedPaintDC(self) dc.SetFont(self.GetFont()) dc.SetBackground(wx.Brush(self.GetBackgroundColour())) dc.Clear() dc.DrawBitmap(self.Norm_bmp) # This never printed... I don't know if that means if the EVT # is triggering or what. print '_onPaint' # draw whatever you want to draw # draw glossy bitmaps e.g. dc.DrawBitmap if self._mouseIn: # If the Mouse is over the button dc.DrawBitmap(self.Over_bmp, self.pos) else: # Since the mouse isn't over it Print the normal one # This is adding on the above code to draw the bmp # in an attempt to get the bmp to display; to no avail. dc.DrawBitmap(self.Norm_bmp, self.pos) if self._mouseDown: # If the Mouse clicks the button dc.DrawBitmap(self.Push_bmp, self.pos) This code won't work? I get no BMP displayed why? How do i get one? I've gotten the staticBitmap(...) to display one, but it won't move, resize, or anything for that matter... - it's only in the top left corner of the frame? Note: the frame is 400pxl X 400pxl - and the "/home/wallter/Desktop/Mouseover.bmp"

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• Fatal error on a non-object

  - by Chris Leah

  Hey, so I have created a function to check the DB for unique entries, but when I call the function it doesn't seem to work and gives me a fatal error any ideas ? Thanks :) //Check for unique entries function checkUnique($table, $field, $compared) { $query = $mysqli->query('SELECT '.$mysqli->real_escape_string($field).' FROM '.$mysqli->real_escape_string($table).' WHERE "'.$mysqli->real_escape_string($field).'" = "'.$mysqli->real_escape_string($compared).'"'); if(!$query){ return TRUE; } else { return FALSE; } } The page calling it..... //Start session session_start(); //Check if the session is already set, if so re-direct to the game if(isset($_SESSION['id'], $_SESSION['logged_in'])){ Header('Location: ../main/index.php'); }; //Require database connection require_once('../global/includes/db.php'); require_once('../global/functions/functions.php'); //Check if the form has been submitted if (isset($_POST['signup'])){ //Validate input if (!empty($_POST['username']) && !empty($_POST['password']) && $_POST['password']==$_POST['password_confirm'] && !empty($_POST['email']) && validateEmail($_POST['email']) == TRUE && checkUnique('users', 'email', $_POST['email']) == TRUE && checkUnique('users', 'username', $_POST['username']) == TRUE) { //Insert user to the database $insert_user = $mysqli->query('INSERT INTO (`username, `password`, `email`, `verification_key`) VALUES ("'.$mysqli->real_escape_string($_POST['username']).'", "'.$mysqli-real_escape_string(md5($_POST['password'])).'", "'.$mysqli->real_escape_string($_POST['email']).'", "'.randomString('alnum', 32). '"') or die($mysqli->error()); //Get user information $getUser = $mysqli->query('SELECT id, username, email, verification_key FROM users WHERE username = "'.$mysqli->real_escape_string($_POST['username']).'"' or die($mysqli->error())); //Check if the $getUser returns true if ($getUser->num_rows == 1) { //Fetch associated fields to this user $row = $getUser->fetch_assoc(); //Set mail() variables $headers = 'From: [email protected]'."\r\n". 'Reply-To: [email protected]'."\r\n". 'X-Mailer: PHP/'.phpversion(); $subject = 'Activate your account (Music Battles.net)'; //Set verification email message $message = 'Dear '.$row['username'].', I would like to welcome you to Music Battles. Although in order to enjoy the gmae you must first activate your account. \n\n Click the following link: http://www.musicbattles.net/home/confirm.php?id='.$row['id'].'key='.$row['verification_key'].'\n Thanks for signing up, enjoy the game! \n Music Battles Team'; //Attempts to send the email if (mail($row['email'], $subject, $message, $headers)) { $msg = '<p class="success">Accound has been created, please go activate it from your email.</p>'; } else { $error = '<p class="error">The account was created but your email was not sent.</p>'; } } else { $error = '<p class="error">Your account was not created.</p>'; } } else { $error = '<p class="error">One or more fields contain non or invalid data.</p>'; } } Erorr.... Fatal error: Call to a member function query() on a non-object in /home/mbattles/public_html/global/functions/functions.php on line 5

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• Where do I start ?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be learning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• Where are the function address literals in c++?

  - by academicRobot

  First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). <UPDATE> After some reading with help from answer by Chris Dodd, what I'm looking for is literal function addresses as template parameters. Chris' answer indicates how to do this for standard functions, but how can the addresses of member functions be used as template parameters? Since the standard prohibits non-static member function addresses as template parameters (c++03 14.3.2.3), I suspect the work around is quite complicated. Any ideas for a workaround? Below the original form of the question is left as is for context. </UPDATE> The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one. Edit The intent of this question is not to implement delegates, rather to identify a pattern that will embed a conventional function call, (in immediate mode) directly into third party code, possibly a template.

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• How do I learn algorithms?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be lear ning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• C++ pimpl idiom wastes an instruction vs. C style?

  - by Rob

  (Yes, I know that one machine instruction usually doesn't matter. I'm asking this question because I want to understand the pimpl idiom, and use it in the best possible way; and because sometimes I do care about one machine instruction.) In the sample code below, there are two classes, Thing and OtherThing. Users would include "thing.hh". Thing uses the pimpl idiom to hide it's implementation. OtherThing uses a C style – non-member functions that return and take pointers. This style produces slightly better machine code. I'm wondering: is there a way to use C++ style – ie, make the functions into member functions – and yet still save the machine instruction. I like this style because it doesn't pollute the namespace outside the class. Note: I'm only looking at calling member functions (in this case, calc). I'm not looking at object allocation. Below are the files, commands, and the machine code, on my Mac. thing.hh: class ThingImpl; class Thing { ThingImpl *impl; public: Thing(); int calc(); }; class OtherThing; OtherThing *make_other(); int calc(OtherThing *); thing.cc: #include "thing.hh" struct ThingImpl { int x; }; Thing::Thing() { impl = new ThingImpl; impl->x = 5; } int Thing::calc() { return impl->x + 1; } struct OtherThing { int x; }; OtherThing *make_other() { OtherThing *t = new OtherThing; t->x = 5; } int calc(OtherThing *t) { return t->x + 1; } main.cc (just to test the code actually works...) #include "thing.hh" #include <cstdio> int main() { Thing *t = new Thing; printf("calc: %d\n", t->calc()); OtherThing *t2 = make_other(); printf("calc: %d\n", calc(t2)); } Makefile: all: main thing.o : thing.cc thing.hh g++ -fomit-frame-pointer -O2 -c thing.cc main.o : main.cc thing.hh g++ -fomit-frame-pointer -O2 -c main.cc main: main.o thing.o g++ -O2 -o $@ $^ clean: rm *.o rm main Run make and then look at the machine code. On the mac I use otool -tv thing.o | c++filt. On linux I think it's objdump -d thing.o. Here is the relevant output: Thing::calc(): 0000000000000000 movq (%rdi),%rax 0000000000000003 movl (%rax),%eax 0000000000000005 incl %eax 0000000000000007 ret calc(OtherThing*): 0000000000000010 movl (%rdi),%eax 0000000000000012 incl %eax 0000000000000014 ret Notice the extra instruction because of the pointer indirection. The first function looks up two fields (impl, then x), while the second only needs to get x. What can be done?

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• I never really understood: what is Application Binary Interface (ABI)?

  - by claws

  I never clearly understood what is an ABI. I'm sorry for such a lengthy question. I just want to clearly understand things. Please don't point me to wiki article, If could understand it, I wouldn't be here posting such a lengthy post. This is my mindset about different interfaces: TV remote is an interface between user and TV. It is an existing entity but useless (doesn't provide any functionality) by itself. All the functionality for each of those buttons on the remote is implemented in the Television set. Interface: It is a "existing entity" layer between the functionality and consumer of that functionality. An, interface by itself is doesn't do anything. It just invokes the functionality lying behind. Now depending on who the user is there are different type of interfaces. Command Line Interface(CLI) commands are the existing entities, consumer is the user and functionality lies behind. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: commands consumer: user Graphical User Interface(GUI) window,buttons etc.. are the existing entities, again consumer is the user and functionality lies behind. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: window,buttons etc.. consumer: user Application Programming Interface(API) functions or to be more correct, interfaces (in interfaced based programming) are the existing entities, consumer here is another program not a user. and again functionality lies behind this layer. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: functions, Interfaces(array of functions). consumer: another program/application. Application Binary Interface (ABI) Here is my problem starts. functionality: ??? existing entities: ??? consumer: ??? I've wrote few softwares in different languages and provided different kind of interfaces (CLI, GUI, API) but I'm not sure, if I ever, provided any ABI. http://en.wikipedia.org/wiki/Application_binary_interface says: ABIs cover details such as data type, size, and alignment; the calling convention, which controls how functions' arguments are passed and return values retrieved; the system call numbers and how an application should make system calls to the operating system; Other ABIs standardize details such as the C++ name mangling,[2] . exception propagation,[3] and calling convention between compilers on the same platform, but do not require cross-platform compatibility. Who needs these details? Please don't say, OS. I know assembly programming. I know how linking & loading works. I know what exactly happens inside. Where did C++ name mangling come in between? I thought we are talking at the binary level. Where did languages come in between? anyway, I've downloaded the [PDF] System V Application Binary Interface Edition 4.1 (1997-03-18) to see what exactly it contains. Well, most of it didn't make any sense. Why does it contain 2 chapters (4th & 5th) which describe the ELF file format.Infact, these are the only 2 significant chapters that specification. Rest of all the chapters "Processor Specific". Anyway, I thought that it is completely different topic. Please don't say that ELF file format specs are the ABI. It doesn't qualify to be Interface according to the definition. I know, since we are talking at such low level it must be very specific. But I'm not sure how is it "Instruction Set Architecture(ISA)" specific? Where can I find MS Window's ABI? So, these are the major queries that are bugging me.

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• (PHP) Validation, Security and Speed - Does my app have these?

  - by Devner

  Hi all, I am currently working on a building community website in PHP. This contains forms that a user can fill right from registration to lot of other functionality. I am not an Object-oriented guy, so I am using functions most of the time to handle my application. I know I have to learn OOPS, but currently need to develop this website and get it running soon. Anyway, here's a sample of what I let my app. do: Consider a page (register.php) that has a form where a user has 3 fields to fill up, say: First Name, Last Name and Email. Upon submission of this form, I want to validate the form and show the corresponding errors to the users: <form id="form1" name="form1" method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>"> <label for="name">Name:</label> <input type="text" name="name" id="name" /><br /> <label for="lname">Last Name:</label> <input type="text" name="lname" id="lname" /><br /> <label for="email">Email:</label> <input type="text" name="email" id="email" /><br /> <input type="submit" name="submit" id="submit" value="Submit" /> </form> This form will POST the info to the same page. So here's the code that will process the POST'ed info: <?php require("functions.php"); if( isset($_POST['submit']) ) { $errors = fn_register(); if( count($errors) ) { //Show error messages } else { //Send welcome mail to the user or do database stuff... } } ?> <?php //functions.php page: function sql_quote( $value ) { if( get_magic_quotes_gpc() ) { $value = stripslashes( $value ); } else { $value = addslashes( $value ); } if( function_exists( "mysql_real_escape_string" ) ) { $value = mysql_real_escape_string( $value ); } return $value; } function clean($str) { $str = strip_tags($str, '<br>,<br />'); $str = trim($str); $str = sql_quote($str); return $str; } foreach ($_POST as &$value) { if (!is_array($value)) { $value = clean($value); } else { clean($value); } } foreach ($_GET as &$value) { if (!is_array($value)) { $value = clean($value); } else { clean($value); } } function validate_name( $fld, $min, $max, $rule, $label ) { if( $rule == 'required' ) { if ( trim($fld) == '' ) { $str = "$label: Cannot be left blank."; return $str; } } if ( isset($fld) && trim($fld) != '' ) { if ( isset($fld) && $fld != '' && !preg_match("/^[a-zA-Z\ ]+$/", $fld)) { $str = "$label: Invalid characters used! Only Lowercase, Uppercase alphabets and Spaces are allowed"; } else if ( strlen($fld) < $min or strlen($fld) > $max ) { $curr_char = strlen($fld); $str = "$label: Must be atleast $min character &amp; less than $max char. Entered characters: $curr_char"; } else { $str = 0; } } else { $str = 0; } return $str; } function validate_email( $fld, $min, $max, $rule, $label ) { if( $rule == 'required' ) { if ( trim($fld) == '' ) { $str = "$label: Cannot be left blank."; return $str; } } if ( isset($fld) && trim($fld) != '' ) { if ( !eregi('^[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\.([a-zA-Z]{2,4})$', $fld) ) { $str = "$label: Invalid format. Please check."; } else if ( strlen($fld) < $min or strlen($fld) > $max ) { $curr_char = strlen($fld); $str = "$label: Must be atleast $min character &amp; less than $max char. Entered characters: $curr_char"; } else { $str = 0; } } else { $str = 0; } return $str; } function val_rules( $str, $val_type, $rule='required' ){ switch ($val_type) { case 'name': $val = validate_name( $str, 3, 20, $rule, 'First Name'); break; case 'lname': $val = validate_name( $str, 10, 20, $rule, 'Last Name'); break; case 'email': $val = validate_email( $str, 10, 60, $rule, 'Email'); break; } return $val; } function fn_register() { $errors = array(); $val_name = val_rules( $_POST['name'], 'name' ); $val_lname = val_rules( $_POST['lname'], 'lname', 'optional' ); $val_email = val_rules( $_POST['email'], 'email' ); if ( $val_name != '0' ) { $errors['name'] = $val_name; } if ( $val_lname != '0' ) { $errors['lname'] = $val_lname; } if ( $val_email != '0' ) { $errors['email'] = $val_email; } return $errors; } //END of functions.php page ?> OK, now it might look like there's a lot, but lemme break it down target wise: 1. I wanted the foreach ($_POST as &$value) and foreach ($_GET as &$value) loops to loop through the received info from the user submission and strip/remove all malicious input. I am calling a function called clean on the input first to achieve the objective as stated above. This function will process each of the input, whether individual field values or even arrays and allow only tags and remove everything else. The rest of it is obvious. Once this happens, the new/cleaned values will be processed by the fn_register() function and based on the values returned after the validation, we get the corresponding errors or NULL values (as applicable). So here's my questions: 1. This pretty much makes me feel secure as I am forcing the user to correct malicious data and won't process the final data unless the errors are corrected. Am I correct? Does the method that I follow guarantee the speed (as I am using lots of functions and their corresponding calls)? The fields of a form differ and the minimum number of fields I may have at any given point of time in any form may be 3 and can go upto as high as 100 (or even more, I am not sure as the website is still being developed). Will having 100's of fields and their validation in the above way, reduce the speed of application (say upto half a million users are accessing the website at the same time?). What can I do to improve the speed and reduce function calls (if possible)? 3, Can I do something to improve the current ways of validation? I am holding off object oriented approach and using FILTERS in PHP for the later. So please, I request you all to suggest me way to improve/tweak the current ways and suggest me if the script is vulnerable or safe enough to be used in a Live production environment. If not, what I can do to be able to use it live? Thank you all in advance.

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• I am having a problem of class cast exception. Can anyone please help me out?

  - by Piyush

  This is my code: package com.example.userpage; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; public class UserPage extends Activity { String tv,tv1; EditText name,pass; TextView x,y; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button button = (Button) findViewById(R.id.widget44); button.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { name.setText(" "); pass.setText(" "); } }); x = (TextView) findViewById(R.id.widget46); y = (TextView) findViewById(R.id.widget47); name = (EditText)findViewById(R.id.widget41); pass = (EditText)findViewById(R.id.widget42); Button button1 = (Button) findViewById(R.id.widget45); button1.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { tv= name.getText().toString(); tv1 = pass.getText().toString(); x.setText(tv); y.setText(tv1); } }); } } And this is my log cat: 02-16 12:24:30.488: DEBUG/AndroidRuntime(973): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<< 02-16 12:24:30.488: DEBUG/AndroidRuntime(973): CheckJNI is ON 02-16 12:24:31.208: DEBUG/AndroidRuntime(973): --- registering native functions --- 02-16 12:24:33.498: DEBUG/AndroidRuntime(973): Shutting down VM 02-16 12:24:33.537: DEBUG/dalvikvm(973): Debugger has detached; object registry had 1 entries 02-16 12:24:33.537: INFO/AndroidRuntime(973): NOTE: attach of thread 'Binder Thread #3' failed 02-16 12:24:34.917: DEBUG/AndroidRuntime(981): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<< 02-16 12:24:34.927: DEBUG/AndroidRuntime(981): CheckJNI is ON 02-16 12:24:35.617: DEBUG/AndroidRuntime(981): --- registering native functions --- 02-16 12:24:38.029: INFO/ActivityManager(67): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.userpage/.UserPage } 02-16 12:24:38.129: DEBUG/AndroidRuntime(981): Shutting down VM 02-16 12:24:38.160: DEBUG/dalvikvm(981): Debugger has detached; object registry had 1 entries 02-16 12:24:38.168: INFO/AndroidRuntime(981): NOTE: attach of thread 'Binder Thread #3' failed 02-16 12:25:12.028: DEBUG/AndroidRuntime(990): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<< 02-16 12:25:12.038: DEBUG/AndroidRuntime(990): CheckJNI is ON 02-16 12:25:12.708: DEBUG/AndroidRuntime(990): --- registering native functions --- 02-16 12:25:15.178: DEBUG/dalvikvm(176): GC_EXPLICIT freed 114 objects / 5880 bytes in 115ms 02-16 12:25:15.318: DEBUG/PackageParser(67): Scanning package: /data/app/vmdl25170.tmp 02-16 12:25:15.588: INFO/PackageManager(67): Removing non-system package:com.example.userpage 02-16 12:25:15.597: INFO/ActivityManager(67): Force stopping package com.example.userpage uid=10036 02-16 12:25:15.648: INFO/Process(67): Sending signal. PID: 916 SIG: 9 02-16 12:25:15.877: INFO/UsageStats(67): Unexpected resume of com.android.launcher while already resumed in com.example.userpage 02-16 12:25:17.028: WARN/InputManagerService(67): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@4400ecf8 02-16 12:25:17.928: DEBUG/PackageManager(67): Scanning package com.example.userpage 02-16 12:25:17.949: INFO/PackageManager(67): Package com.example.userpage codePath changed from /data/app/com.example.userpage-1.apk to /data/app/com.example.userpage-2.apk; Retaining data and using new 02-16 12:25:17.987: INFO/PackageManager(67): /data/app/com.example.userpage-2.apk changed; unpacking 02-16 12:25:18.037: DEBUG/installd(35): DexInv: --- BEGIN '/data/app/com.example.userpage-2.apk' --- 02-16 12:25:18.737: DEBUG/dalvikvm(997): DexOpt: load 81ms, verify 112ms, opt 6ms 02-16 12:25:18.768: DEBUG/installd(35): DexInv: --- END '/data/app/com.example.userpage-2.apk' (success) --- 02-16 12:25:18.799: INFO/ActivityManager(67): Force stopping package com.example.userpage uid=10036 02-16 12:25:18.808: WARN/PackageManager(67): Code path for pkg : com.example.userpage changing from /data/app/com.example.userpage-1.apk to /data/app/com.example.userpage-2.apk 02-16 12:25:18.839: WARN/PackageManager(67): Resource path for pkg : com.example.userpage changing from /data/app/com.example.userpage-1.apk to /data/app/com.example.userpage-2.apk 02-16 12:25:18.868: DEBUG/PackageManager(67): Activities: com.example.userpage.UserPage 02-16 12:25:19.297: INFO/installd(35): move /data/dalvik-cache/data@[email protected]@classes.dex -> /data/dalvik-cache/data@[email protected]@classes.dex 02-16 12:25:19.297: DEBUG/PackageManager(67): New package installed in /data/app/com.example.userpage-2.apk 02-16 12:25:19.598: DEBUG/dalvikvm(67): GC_FOR_MALLOC freed 7979 objects / 516856 bytes in 246ms 02-16 12:25:20.498: INFO/ActivityManager(67): Force stopping package com.example.userpage uid=10036 02-16 12:25:20.708: DEBUG/dalvikvm(129): GC_EXPLICIT freed 124 objects / 5672 bytes in 157ms 02-16 12:25:21.838: DEBUG/dalvikvm(67): GC_EXPLICIT freed 4208 objects / 236264 bytes in 419ms 02-16 12:25:21.918: WARN/RecognitionManagerService(67): no available voice recognition services found 02-16 12:25:22.127: INFO/installd(35): unlink /data/dalvik-cache/data@[email protected]@classes.dex 02-16 12:25:22.478: DEBUG/AndroidRuntime(990): Shutting down VM 02-16 12:25:22.488: DEBUG/dalvikvm(990): Debugger has detached; object registry had 1 entries 02-16 12:25:22.588: INFO/AndroidRuntime(990): NOTE: attach of thread 'Binder Thread #3' failed 02-16 12:25:24.137: DEBUG/AndroidRuntime(1003): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<< 02-16 12:25:24.147: DEBUG/AndroidRuntime(1003): CheckJNI is ON 02-16 12:25:24.817: DEBUG/AndroidRuntime(1003): --- registering native functions --- 02-16 12:25:27.450: INFO/ActivityManager(67): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.userpage/.UserPage } 02-16 12:25:27.628: DEBUG/AndroidRuntime(1003): Shutting down VM 02-16 12:25:27.780: INFO/AndroidRuntime(1003): NOTE: attach of thread 'Binder Thread #3' failed 02-16 12:25:28.018: DEBUG/dalvikvm(1003): Debugger has detached; object registry had 1 entries 02-16 12:25:28.148: INFO/ActivityManager(67): Start proc com.example.userpage for activity com.example.userpage/.UserPage: pid=1010 uid=10036 gids={} 02-16 12:25:30.308: DEBUG/AndroidRuntime(1010): Shutting down VM 02-16 12:25:30.308: WARN/dalvikvm(1010): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): FATAL EXCEPTION: main 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.userpage/com.example.userpage.UserPage}: java.lang.ClassCastException: android.widget.TextView 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.os.Handler.dispatchMessage(Handler.java:99) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.os.Looper.loop(Looper.java:123) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.app.ActivityThread.main(ActivityThread.java:4627) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at java.lang.reflect.Method.invokeNative(Native Method) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at java.lang.reflect.Method.invoke(Method.java:521) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at dalvik.system.NativeStart.main(Native Method) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): Caused by: java.lang.ClassCastException: android.widget.TextView 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at com.example.userpage.UserPage.onCreate(UserPage.java:35) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 02-16 12:25:30.388: ERROR/AndroidRuntime(1010): ... 11 more 02-16 12:25:30.438: WARN/ActivityManager(67): Force finishing activity com.example.userpage/.UserPage 02-16 12:25:31.088: WARN/ActivityManager(67): Activity pause timeout for HistoryRecord{43f164f8 com.example.userpage/.UserPage} 02-16 12:25:32.588: DEBUG/dalvikvm(292): GC_EXPLICIT freed 46 objects / 2240 bytes in 6282ms 02-16 12:25:35.267: INFO/Process(1010): Sending signal. PID: 1010 SIG: 9 02-16 12:25:35.468: WARN/InputManagerService(67): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@43e60a90 02-16 12:25:35.900: INFO/ActivityManager(67): Process com.example.userpage (pid 1010) has died. 02-16 12:25:38.278: DEBUG/dalvikvm(176): GC_EXPLICIT freed 172 objects / 12280 bytes in 127ms 02-16 12:25:43.011: WARN/ActivityManager(67): Activity destroy timeout for HistoryRecord{43f164f8 com.example.userpage/.UserPage} 02-16 12:28:12.698: DEBUG/AndroidRuntime(1019): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<< 02-16 12:28:12.711: DEBUG/AndroidRuntime(1019): CheckJNI is ON 02-16 12:28:13.367: DEBUG/AndroidRuntime(1019): --- registering native functions --- 02-16 12:28:15.998: DEBUG/dalvikvm(176): GC_EXPLICIT freed 114 objects / 5888 bytes in 183ms 02-16 12:28:16.539: DEBUG/PackageParser(67): Scanning package: /data/app/vmdl25171.tmp 02-16 12:28:16.867: INFO/PackageManager(67): Removing non-system package:com.example.userpage 02-16 12:28:16.867: INFO/ActivityManager(67): Force stopping package com.example.userpage uid=10036 02-16 12:28:17.277: DEBUG/PackageManager(67): Scanning package com.example.userpage 02-16 12:28:17.308: INFO/PackageManager(67): Package com.example.userpage codePath changed from /data/app/com.example.userpage-2.apk to /data/app/com.example.userpage-1.apk; Retaining data and using new 02-16 12:28:17.328: INFO/PackageManager(67): /data/app/com.example.userpage-1.apk changed; unpacking 02-16 12:28:17.367: DEBUG/installd(35): DexInv: --- BEGIN '/data/app/com.example.userpage-1.apk' --- 02-16 12:28:18.357: DEBUG/dalvikvm(1026): DexOpt: load 85ms, verify 114ms, opt 6ms 02-16 12:28:18.398: DEBUG/installd(35): DexInv: --- END '/data/app/com.example.userpage-1.apk' (success) --- 02-16 12:28:18.428: INFO/ActivityManager(67): Force stopping package com.example.userpage uid=10036 02-16 12:28:18.438: WARN/PackageManager(67): Code path for pkg : com.example.userpage changing from /data/app/com.example.userpage-2.apk to /data/app/com.example.userpage-1.apk 02-16 12:28:18.477: WARN/PackageManager(67): Resource path for pkg : com.example.userpage changing from /data/app/com.example.userpage-2.apk to /data/app/com.example.userpage-1.apk 02-16 12:28:18.477: DEBUG/PackageManager(67): Activities: com.example.userpage.UserPage 02-16 12:28:18.977: INFO/installd(35): move /data/dalvik-cache/data@[email protected]@classes.dex -> /data/dalvik-cache/data@[email protected]@classes.dex 02-16 12:28:18.988: DEBUG/PackageManager(67): New package installed in /data/app/com.example.userpage-1.apk 02-16 12:28:19.528: DEBUG/dalvikvm(67): GC_FOR_MALLOC freed 6733 objects / 459728 bytes in 211ms 02-16 12:28:20.138: INFO/ActivityManager(67): Force stopping package com.example.userpage uid=10036 02-16 12:28:20.368: DEBUG/dalvikvm(129): GC_EXPLICIT freed 892 objects / 48744 bytes in 175ms 02-16 12:28:21.317: WARN/RecognitionManagerService(67): no available voice recognition services found 02-16 12:28:22.827: DEBUG/dalvikvm(67): GC_EXPLICIT freed 3877 objects / 241128 bytes in 452ms 02-16 12:28:22.979: INFO/installd(35): unlink /data/dalvik-cache/data@[email protected]@classes.dex 02-16 12:28:23.277: DEBUG/AndroidRuntime(1019): Shutting down VM 02-16 12:28:23.307: DEBUG/dalvikvm(1019): Debugger has detached; object registry had 1 entries 02-16 12:28:23.328: INFO/AndroidRuntime(1019): NOTE: attach of thread 'Binder Thread #3' failed 02-16 12:28:24.989: DEBUG/AndroidRuntime(1032): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<< 02-16 12:28:24.989: DEBUG/AndroidRuntime(1032): CheckJNI is ON 02-16 12:28:25.888: DEBUG/AndroidRuntime(1032): --- registering native functions --- 02-16 12:28:28.588: INFO/ActivityManager(67): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.userpage/.UserPage } 02-16 12:28:28.888: DEBUG/AndroidRuntime(1032): Shutting down VM 02-16 12:28:28.997: DEBUG/dalvikvm(1032): Debugger has detached; object registry had 1 entries 02-16 12:28:29.038: INFO/AndroidRuntime(1032): NOTE: attach of thread 'Binder Thread #3' failed 02-16 12:28:30.417: INFO/ActivityManager(67): Start proc com.example.userpage for activity com.example.userpage/.UserPage: pid=1039 uid=10036 gids={} 02-16 12:28:32.588: DEBUG/AndroidRuntime(1039): Shutting down VM 02-16 12:28:32.598: WARN/dalvikvm(1039): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): FATAL EXCEPTION: main 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.userpage/com.example.userpage.UserPage}: java.lang.ClassCastException: android.widget.TextView 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.os.Handler.dispatchMessage(Handler.java:99) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.os.Looper.loop(Looper.java:123) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.app.ActivityThread.main(ActivityThread.java:4627) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at java.lang.reflect.Method.invokeNative(Native Method) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at java.lang.reflect.Method.invoke(Method.java:521) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at dalvik.system.NativeStart.main(Native Method) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): Caused by: java.lang.ClassCastException: android.widget.TextView 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at com.example.userpage.UserPage.onCreate(UserPage.java:34) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 02-16 12:28:32.648: ERROR/AndroidRuntime(1039): ... 11 more 02-16 12:28:32.698: WARN/ActivityManager(67): Force finishing activity com.example.userpage/.UserPage 02-16 12:28:32.967: DEBUG/dalvikvm(292): GC_EXPLICIT freed 46 objects / 2240 bytes in 6840ms 02-16 12:28:33.247: WARN/ActivityManager(67): Activity pause timeout for HistoryRecord{43ee7b70 com.example.userpage/.UserPage} 02-16 12:28:36.947: INFO/Process(1039): Sending signal. PID: 1039 SIG: 9 02-16 12:28:37.017: INFO/ActivityManager(67): Process com.example.userpage (pid 1039) has died. 02-16 12:28:37.128: WARN/InputManagerService(67): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@43e872f8 02-16 12:28:42.087: DEBUG/dalvikvm(176): GC_EXPLICIT freed 156 objects / 11488 bytes in 145ms 02-16 12:28:45.391: WARN/ActivityManager(67): Activity destroy timeout for HistoryRecord{43ee7b70 com.example.userpage/.UserPage} 02-16 12:28:47.177: DEBUG/SntpClient(67): request time failed: java.net.SocketException: Address family not supported by protocol

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• C++: Can a macro expand "abc" into 'a', 'b', 'c'?

  - by Peter Alexander

  I've written a variadic template that accepts a variable number of char parameters, i.e. template <char... Chars> struct Foo; I was just wondering if there were any macro tricks that would allow me to instantiate this with syntax similar to the following: Foo<"abc"> or Foo<SOME_MACRO("abc")> or Foo<SOME_MACRO(abc)> etc. Basically, anything that stops you from having to write the characters individually, like so Foo<'a', 'b', 'c'> This isn't a big issue for me as it's just for a toy program, but I thought I'd ask anyway.

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• argument promotions in C function calls

  - by HaoCheng

  I learned from ----As to when default promotions kick in: default argument promotions are used exactly when the expected type of the argument is unknown, which is to say when there's no prototype or when the argument is variadic. But an example confusing me is: void func(char a, char b) { printf("a=%p,b=%p\n",&a,&b); } int main(void) { char a=0x11,b=0x22; func(a,b); return 0; } It is cleard in the above example: when calling func in main, there is no need to promote the arguments a and b, but the output shows &a = &b +4 not &a = &b+1. If no promotion occured, why 4 bytes between two CHAR argument?

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