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• How to implement a grapher in C#

  - by iansinke

  So I'm writing a graphing calculator. So far I have a semi-functional grapher, however, I'm having a hard time getting a good balance between accurate graphs and smooth looking curves. The current implementation (semi-pseudo-code) looks something like this: for (float i = GraphXMin; i <= GraphXMax; i++) { PointF P = new PointF(i, EvaluateFunction(Function, i) ListOfPoints.Add(P) } Graphics.DrawCurve(ListOfPoints) The problem with this is since it only adds a point at every integer value, graphs end up distorted when their turning points don't fall on integers (e.g. sin(x)^2). I tried incrementing i by something smaller (like 0.1), which works, but the graph looks very rough. I am using C# and GDI+. I have SmoothingMethod set to AntiAlias, so that's not the problem, as you can see from the first graph. Is there some sort of issue with drawing curves with a lot of points? Should the points perhaps be positioned exactly on pixels? I'm sure some of you have worked on something very similar before, so any suggestions? While you're at it, do you have any suggestions for graphing functions with asymptotes? e.g. 1/x^2 P.S. I'm not looking for a library that does all this - I want to write it myself.

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• Thread mutex behaviour

  - by Alberteddu

  Hi there, I'm learning C. I'm writing an application with multiple threads; I know that when a variable is shared between two or more threads, it is better to lock/unlock using a mutex to avoid deadlock and inconsistency of variables. This is very clear when I want to change or view one variable. int i = 0; /** Global */ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; /** Thread 1. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); /** Thread 2. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); This is correct, I think. The variable i, at the end of the executions, contains the integer 2. Anyway, there are some situations in which I don't know exactly where to put the two function calls. For example, suppose you have a function obtain(), which returns a global variable. I need to call that function from within the two threads. I have also two other threads that call the function set(), defined with a few arguments; this function will set the same global variable. The two functions are necessary when you need to do something before getting/setting the var. /** (0) */ /** Thread 1, or 2, or 3... */ if(obtain() == something) { if(obtain() == somethingElse) { // Do this, sometimes obtain() and sometimes set(random number) (1) } else { // Do that, just obtain(). (2) } } else { // Do this and do that (3) // If # of thread * 3 > 10, then set(3*10) For example. (4) } /** (5) */ Where I have to lock, and where I have to unlock? The situation can be, I think, even more complex. I will appreciate an exhaustive answer. Thank you in advance. —Alberto

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• Friends, templates, overloading <<

  - by Crystal

  I'm trying to use friend functions to overload << and templates to get familiar with templates. I do not know what these compile errors are: Point.cpp:11: error: shadows template parm 'class T' Point.cpp:12: error: declaration of 'const Point<T>& T' for this file #include "Point.h" template <class T> Point<T>::Point() : xCoordinate(0), yCoordinate(0) {} template <class T> Point<T>::Point(T xCoordinate, T yCoordinate) : xCoordinate(xCoordinate), yCoordinate(yCoordinate) {} template <class T> std::ostream &operator<<(std::ostream &out, const Point<T> &T) { std::cout << "(" << T.xCoordinate << ", " << T.yCoordinate << ")"; return out; } My header looks like: #ifndef POINT_H #define POINT_H #include <iostream> template <class T> class Point { public: Point(); Point(T xCoordinate, T yCoordinate); friend std::ostream &operator<<(std::ostream &out, const Point<T> &T); private: T xCoordinate; T yCoordinate; }; #endif My header also gives the warning: Point.h:12: warning: friend declaration 'std::ostream& operator<<(std::ostream&, const Point<T>&)' declares a non-template function Which I was also unsure why. Any thoughts? Thanks.

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• Modal QMessageBox does not behave like native Windows dialogs

  - by Philip Daubmeier

  My application has a dialog that asks the user via a QMessageBox whether he wants to discard all changes he made or wants to keep editing. I want this dialog to be modal to the whole application. I read somewhere that this is the standard behavior for a QMessageBox, so I dont have to set it explicitly with something like: mbox.setWindowModality(Qt::ApplicationModal); I wonder why it behaves differently from other modal dialogs in the OS (Windows 7 in my case). On the one hand it functions like it should, i.e. all other input methods in the application are blocked until the user answeres the dialog. However, it doesn't 'blink'* if the user clicks any other window of the application. Is there any way to get Qt to behave like a native Windows dialog? Thanks in advance! *If you don't know what I mean with this 'blinking': Just open notepad on a Windows OS, type some text and try to close it. A dialog pops up that asks to save, discard or keep editing. Now click somewhere on the editor window - the border and titlebar of the dialog flashes/blinks a few times.

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• What are the drawbacks of this Classing format?

  - by Keysle

  This is a 3 layer example of my classing format function __(_){return _.constructor} //class var _ = ( CLASS = function(){ this.variable = 0; this.sub = new CLASS.SUBCLASS(); }).prototype; _.func = function(){ alert('lvl'+this.variable); this.sub.func(); } _.divePeak = function(){ alert('lvl'+this.variable); this.sub.variable += 5; } //sub class _ = ( __(_).SUBCLASS = function(){ this.variable = 1; this.sub = new CLASS.SUBCLASS.DEEPCLASS(); }).prototype; _.func = function(){ alert('lvl'+this.variable); this.sub.func(); } //deep class _ = ( __(_).DEEPCLASS = function(){ this.variable = 2; }).prototype; _.func = function(){ alert('lvl'+this.variable); } Before you blow a gasket, let me explain myself. The purpose behind the underscores is to accelerate the time needed to specify functions for a class and also specify sub classes of a class. To me it's easier to read. I KNOW, this does interfere with underscore.js if you intend to use it in your classes. I'm sure _.js can be easily switched over to another $ymbol though ... oh wait, But I digress. Why have classes within a class? because solar.system() and social.system() mean two totally different things but it's convenient to use the same name. Why user underscores to manage the definition of the class? because "Solar.System.prototype" took me about 2 seconds to type out and 2 typos to correct. It also keeps all function names for all classes in the same column of texts, which is nice for legibility. All I'm doing is presenting my reasoning behind this method and why I came up with it. I'm 3 days into learning OO JS and I am very willing to accept that I might have messed up.

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• PHP / Zend custom date input formats

  - by mld

  Hi, I'm creating a library component for other developers on my team using PHP and Zend. This component needs to be able to take as input a date (string) and another string telling it the format of that date. Looking through the Zend documentation and examples, I thought I found the solution - $dateObject = Zend_Date('13.04.2006', array('date_format' => 'dd.MM.yyyy')); this line, however, throws an error - call to undefined function. So instead I tried this - $dt = Zend_Locale_Format::getDate('13.04.2006', array('date_format' => 'dd.MM.yyyy')); This gets the job done, but throws an error if a date that is entered isn't valid. The docs make it look like you can use the isDate() function to check validity - Zend_Date::isDate('13.04.2006', array('date_format' => 'dd.MM.yyyy')) but this line always returns false. So my questions - Am I going about this the right way? If not, is there a better way to handle this via Zend or straight PHP? If I do use Zend_Locale_Format::getDate(), do I need to worry about a locale being set elsewhere and changing the results of the call? I'm locked into PHP 5.2.6 on windows, btw... so 5.3+ functions & strptime() are out.

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• Show div based on getDay and getHours + getMinutes

  - by Peta Reardon

  I am building a website for a radio station and want to show which presenter is currently on air. I have built a web app that contains data on the presenter: name, photo, bio and start/end times for each weekday. <div id="presenter1"> <div class="slot"> <div id="sunday-off"> - </div> <div id="monday-afternoon">12:00 - 15:59</div> <div id="tuesday-afternoon">12:00 - 15:59</div> <div id="wednesday-afternoon">12:00 - 15:59</div> <div id="thursday-afternoon">12:00 - 15:59</div> <div id="friday-afternoon">12:00 - 15:59</div> <div id="saturday-morning">06:00 - 08:59</div> </div> </div> What I would like to do is use Javascript functions getDay() and getHours() + getMinutes() to show only the presenter that is scheduled to be on air based on the times specified in the app. The main part I am having difficulty with is with determining whether this presenter falls within the current time and then showing/hiding the div as necessary. Any help or guidance on how I can acheive this would be greatly appreciated.

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• iPhone OpenGLES: Textures are consuming too much memory and the program crashes with signal "0"

  - by CustomAppsMan

  I am not sure what the problem is. My app is running fine on the simulator but when I try to run it on the iPhone it crashes during debugging or without debugging with signal "0". I am using the Texture2D.m and OpenGLES2DView.m from the examples provided by Apple. I profiled the app on the iPhone with Instruments using the Memory tracer from the Library and when the app died the final memory consumed was about 60Mb real and 90+Mb virtual. Is there some other problem or is the iPhone just killing the application because it has consumed too much memory? If you need any information please state it and I will try to provide it. I am creating thousands of textures at load time which is why the memory consumption is so high. Really cant do anything about reducing the number of pics being loaded. I was running before on just UIImage but it was giving me really low frame rates. I read on this site that I should use OpenGLES for higher frame rates. Also sub question is there any way not to use UIImage to load the png file and then use the Texture class provided to create the texture for OpenGLES functions to use it for drawing? Is there some function in OpenGLES which will create a texture straight from a png file?

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• making query from different related tables using codeigniter

  - by fatemeh karam

  I'm using codeigniter as i mentioned this is a part of my view code foreach($projects_query as $row)// $row indicates the projects { ?> <tr><td><h3><button type="submit" class="button red-gradient glossy" name = "project_click" > <?php echo $row->txtTaskName; ?></button></h3></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr> <?php foreach($tasks_query as $row2) { // if( $row->txtTaskName == "TestProject") if($row->intTaskID == $row2->intInside)// intInside indicades that the current task($row2) is the subset of which task (system , subsystem or project) { if($row2->intSummary == 0)//if the task(the system) is an executable task & doesn't have any subtask: { $query_team_user_id = $this->admin_in_out_model->get_user_team_task_query($row2->intTaskID);//runs the function and generates a query from tbl_userteamtask where intTaskID equals to the selected row's intTaskID foreach($query_team_user_id as $row_teamid) { $query_teamname = $this->admin_in_out_model->get_team_name($row_teamid->intTeamID); $query_fn_ln = $this->admin_in_out_model->get_fn_ln_from_userid($row_teamid->intUserID); foreach($query_teamname as $row_teamname) {?> <tr><td></td><td></td><td><h4> <?php echo $row2->txtTaskName;?></h4></td> <td><b><font color='#F33558'><?php echo $row_teamname->txtTeamName;?></font></b></td> <?php } foreach($query_fn_ln as $row_f_l_name) {?> <td> <?php echo $row_f_l_name->txtFirstname." ".$row_f_l_name->txtLastname;?></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td> <?php }?> </tr> <?php } } else{ ?> <tr><td></td><td></td><td><h4> <?php echo $row2->txtTaskName;?></h4></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><?php } foreach($tasks_query as $row_subsystems) { if($row_subsystems->intInside == $row2->intTaskID )//if the task is the subtask of a system(it means the task is a subsystem) { if($row_subsystems->intSummary == 0)//if the task is an executable task & doesn't have any subtask: { $query_team_user_id = $this->admin_in_out_model->get_user_team_task_query($row_subsystems->intTaskID); foreach($query_team_user_id as $row_teamid) {?> <tr><?php $query_teamname = $this->admin_in_out_model->get_team_name($row_teamid->intTeamID); $query_fn_ln = $this->admin_in_out_model->get_fn_ln_from_userid($row_teamid->intUserID); foreach($query_teamname as $row_teamname) {?> <td></td><td></td><td><h5><?php echo $row_subsystems->txtTaskName?></h5><br/></td> <td><b><font color='#F33558'><?php echo $row_teamname->txtTeamName;?></font></b></td><?php } foreach($query_fn_ln as $row_f_l_name) {?> <td><?php echo $row_f_l_name->txtFirstname." ".$row_f_l_name->txtLastname;?></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><?php }?> </tr><?php } } else{ ?><tr><td></td><td></td><td><h5><?php echo $row_subsystems->txtTaskName?></h5></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><?php } foreach($tasks_query as $row_tasks) { if($row_tasks->intInside == $row_subsystems->intTaskID )//if the task is the subtask of a subsystem { if($row_tasks->intSummary == 0)//if the task is an executable task & doesn't have any subtask: { $query_team_user_id = $this->admin_in_out_model->get_user_team_task_query($row_tasks->intTaskID); foreach($query_team_user_id as $row_teamid) {?> <tr><?php $query_teamname = $this->admin_in_out_model->get_team_name($row_teamid->intTeamID); $query_fn_ln = $this->admin_in_out_model->get_fn_ln_from_userid($row_teamid->intUserID); foreach($query_teamname as $row_teamname) {?> <td></td><td></td><td><b><?php echo $row_tasks->txtTaskName;?></b></td> <td><b><font color='#F33558'><?php echo $row_teamname->txtTeamName;?></font></b></td><?php } foreach($query_fn_ln as $row_f_l_name) {?> <td><?php echo $row_f_l_name->txtFirstname." ".$row_f_l_name->txtLastname;?></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><?php }?> </tr><?php } } } } } } } } }?> and in controller i have $projects_query = $this->admin_in_out_model->get_projects(); $tasks_query = $this->admin_in_out_model->get_systems(); $userteamtask = $this->admin_in_out_model->get_user_team_task(); $data['tasks_query'] = $tasks_query; $data['projects_query'] = $projects_query; $this->load->view('project_view',$data); but as you see I'm calling my model functions within the view how can i do something else to do this i mean not calling my model function in my view I have to add that, my model function have parameters these are the model functions: function get_projects() { $this -> db -> select('*'); $this -> db -> from('tbl_task'); $this -> db -> where('intInside','0'); $query = $this->db->get(); return $query->result(); } function get_systems() { $this -> db -> select('*'); $this -> db -> from('tbl_task '); $this -> db -> where('intInside <> ','0'); $query = $this->db->get(); return $query->result(); } function get_user_team_task_query($task_id)//gets information from tbl_userteamtask where the field intTaskID is equal to $task_id { $this -> db -> select('*'); $this -> db -> from('tbl_userteamtask'); $this -> db -> where('intTaskID',$task_id); $query_teamid = $this->db->get(); return $query_teamid->result(); } function get_user_team_task()//gets information from tbl_userteamtask where the field intTaskID is equal to $task_id { $this -> db -> select('*'); $this -> db -> from('tbl_userteamtask'); // $this -> db -> where('intTaskID',$task_id); $query_teamid = $this->db->get(); return $query_teamid->result(); } function get_team_name($query_teamid) { $this -> db -> select('*'); $this -> db -> from('tbl_team'); $this -> db -> where('intTeamID',$query_teamid); $query_teamname = $this->db->get(); return $query_teamname->result(); } function get_user_name($query_userid) { $this -> db -> select('*'); $this -> db -> from('tbl_user'); $this -> db -> where('intUserID',$query_userid); $query_username = $this->db->get(); return $query_username->result(); } function get_fn_ln_from_userid($selected_id) { $this -> db -> select('tbl_user.intUserID, tbl_user.intPersonID,tbl_person.intPersonID,tbl_person.txtFirstname, tbl_person.txtLastname'); $this -> db -> from('tbl_user , tbl_person'); $where = "tbl_user.intPersonID = tbl_person.intPersonID "; $this -> db -> where($where); $this -> db -> where('tbl_user.intUserID', $selected_id); $query = $this -> db -> get();//makes query from DB return $query->result(); } do I have to use subquery ? is this true? i mean can i do this? foreach( $data as $key => $each ) { $data[$key]['team_id'] = $this->get_user_team_task_query( $each['intTaskID'] ); foreach($data[$key]['team_id'] as $key_teamname => $each) { $data[$key_teamname]['team_name'] = $this->get_team_name( $each['intTeamID'] ); } } the model code: foreach( $data as $key => $each ) { $data[$key]['intTaskID'] = $each['intTaskID']; $data[$key]['team_id'] = $this->get_user_team_task_query( $each['intTaskID'] ); foreach($data[$key]['team_id'] as $key => $each) { $data[$key]['team_name'] = $this->get_team_name( $each['intTeamID'] ); #fetching of the teamname and saving in the array $data[$key]['user_name'] = $this->get_fn_ln_from_userid( $each['intUserID'] ); foreach($data[$key]['user_name'] as $key => $each) { $data[$key]['first_name'] = $each['txtFirstname'] ; $data[$key]['last_name'] = $each['txtLastname'] ; } $data[$key]['first_name'] = $data[$key]['first_name']; $data[$key]['last_name'] = $data[$key]['last_name']; } }

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• Proper Memory Management for Objective-C Method

  - by Justin

  Hi, I'm programming an iPhone app and I had a question about memory management in one of my methods. I'm still a little new to managing memory manually, so I'm sorry if this question seems elementary. Below is a method designed to allow a number pad to place buttons in a label based on their tag, this way I don't need to make a method for each button. The method works fine, I'm just wondering if I'm responsible for releasing any of the variables I make in the function. The application crashes if I try to release any of the variables, so I'm a little confused about my responsibility regarding memory. Here's the method: FYI the variable firstValue is my label, it's the only variable not declared in the method. -(IBAction)inputNumbersFromButtons:(id)sender { UIButton *placeHolderButton = [[UIButton alloc] init]; placeHolderButton = sender; NSString *placeHolderString = [[NSString alloc] init]; placeHolderString = [placeHolderString stringByAppendingString:firstValue.text]; NSString *addThisNumber = [[NSString alloc] init]; int i = placeHolderButton.tag; addThisNumber = [NSString stringWithFormat:@"%i", i]; NSString *newLabelText = [[NSString alloc] init]; newLabelText = [placeHolderString stringByAppendingString:addThisNumber]; [firstValue setText:newLabelText]; //[placeHolderButton release]; //[placeHolderString release]; //[addThisNumber release]; //[newLabelText release]; } The application works fine with those last four lines commented out, but it seems to me like I should be releasing these variables here. If I'm wrong about that I'd welcome a quick explanation about when it's necessary to release variables declared in functions and when it's not. Thanks.

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• PHP: Extract direct sub directory from path string

  - by Nebs

  I need to extract the name of the direct sub directory from a full path string. For example, say we have: $str = "dir1/dir2/dir3/dir4/filename.ext"; $dir = "dir1/dir2"; Then the name of the sub-directory in the $str path relative to $dir would be "dir3". Note that $dir never has '/' at the ends. So the function should be: $subdir = getsubdir($str,$dir); echo $subdir; // Outputs "dir3" If $dir="dir1" then the output would be "dir2". If $dir="dir1/dir2/dir3/dir4" then the output would be "" (empty). If $dir="" then the output would be "dir1". Etc.. Currently this is what I have, and it works (as far as I've tested it). I'm just wondering if there's a simpler way since I find I'm using a lot of string functions. Maybe there's some magic regexp to do this in one line? (I'm not too good with regexp unfortunately). function getsubdir($str,$dir) { // Remove the filename $str = dirname($str); // Remove the $dir if(!empty($dir)){ $str = str_replace($dir,"",$str); } // Remove the leading '/' if there is one $si = stripos($str,"/"); if($si == 0){ $str = substr($str,1); } // Remove everything after the subdir (if there is anything) $lastpart = strchr($str,"/"); $str = str_replace($lastpart,"",$str); return $str; } As you can see, it's a little hacky in order to handle some odd cases (no '/' in input, empty input, etc). I hope all that made sense. Any help/suggestions are welcome.

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• C++ - Basic WinAPI question

  - by HardCoder1986

  Hello! I am now working on a some sort of a game engine and I had an idea to put everything engine-related into a static library and then link it to my actual problem. Right now I achieved it and actually link that library and every functions seem to work fine, except those, which are windows-related. I have a chunk of code in my library that looks like this: hWnd = CreateWindow(className, "Name", WS_OVERLAPPED | WS_CAPTION | WS_EX_TOPMOST, 0, 0, 800, 600, NULL, NULL, GetModuleHandle(NULL), this); if (hWnd) { ShowWindow(hWnd, SW_NORMAL); UpdateWindow(hWnd); } else { MessageBox(NULL, "Internal program error", "Error", MB_OK | MB_ICONERROR); return; } When this code was not in the library, but in the actual project, it worked fine, created the window and everything was ok. Right now (when I'm linking to my library that contains this code) CreateWindow(...) call returns NULL and GetLastError() returns "Operation succesfully completed" (wtf?). Could anybody help me with this? Is it possible to create a window and display it using a static library call and why could my code fail? Thank you.

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• How to write a "thread safe" function in C ?

  - by Andrei Ciobanu

  Hello I am writing some data structures in C, and I've realized that their associated functions aren't thread safe. The i am writing code uses only standard C, and I want to achieve some sort of 'synchronization'. I was thinking to do something like this: enum sync_e { TRUE, FALSE }; typedef enum sync_e sync; struct list_s { //Other stuff struct list_node_s *head; struct list_node_s *tail; enum sync_e locked; }; typedef struct list_s list; , to include a "boolean" field in the list structure that indicates the structures state: locked, unlocked. For example an insertion function will be rewritten this way: int list_insert_next(list* l, list_node *e, int x){ while(l->locked == TRUE){ /* Wait */ } l->locked = TRUE; /* Insert element */ /* -------------- */ l->locked = FALSE; return (0); } While operating on the list the 'locked' field will be set to TRUE, not allowing any other alterations. After operation completes the 'locked' field will be again set to 'TRUE'. Is this approach good ? Do you know other approaches (using only standard C).

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• In Emacs, how can I use imenu more sensibly with C#?

  - by Cheeso

  I've used emacs for a long time, but I haven't been keeping up with a bunch of features. One of these is speedbar, which I just briefly investigated now. Another is imenu. Both of these were mentioned in in-emacs-how-can-i-jump-between-functions-in-the-current-file? Using imenu, I can jump to particular methods in the module I'm working in. But there is a parse hierarchy that I have to negotiate before I get the option to choose (with autocomplete) the method name. It goes like this. I type M-x imenu and then I get to choose Using or Types. The Using choice allows me to jump to any of the using statements at the top level of the C# file (something like imports statements in a Java module, for those of you who don't know C#). Not super helpful. I choose Types. Then I have to choose a namespace and a class, even though there is just one of each in the source module. At that point I can choose between variables, types, and methods. If I choose methods I finally get the list of methods to choose from. The hierarchy I traverse looks like this; Using Types Namespace Class Types Variables Methods method names Only after I get to the 5th level do I get to select the thing I really want to jump to: a particular method. Imenu seems intelligent about the source module, but kind of hard to use. Am I doing it wrong?

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• System Calls in windows & Native API?

  - by claws

  Recently I've been using lot of Assembly language in *NIX operating systems. I was wondering about the windows domain. Calling convention in linux: mov $SYS_Call_NUM, %eax mov $param1 , %ebx mov $param2 , %ecx int $0x80 Thats it. That is how we should make a system call in linux. Reference of all system calls in linux: Regarding which $SYS_Call_NUM & which parameters we can use this reference : http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.html OFFICIAL Reference : http://kernel.org/doc/man-pages/online/dir_section_2.html Calling convention in Windows: ??? Reference of all system calls in Windows: ??? Unofficial : http://www.metasploit.com/users/opcode/syscalls.html , but how do I use these in assembly unless I know the calling convention. OFFICIAL : ??? If you say, they didn't documented it. Then how is one going to write libc for windows without knowing system calls? How is one gonna do Windows Assembly programming? Atleast in the driver programming one needs to know these. right? Now, whats up with the so called Native API? Is Native API & System calls for windows both are different terms referring to same thing? In order to confirm I compared these from two UNOFFICIAL Sources System Calls: http://www.metasploit.com/users/opcode/syscalls.html Native API: http://undocumented.ntinternals.net/aindex.html My observations: All system calls are beginning with letters Nt where as Native API is consisting of lot of functions which are not beginning with letters Nt. System Call of windows are subset of Native API. System calls are just part of Native API. Can any one confirm this and explain.

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• Combine Arbitrary number of polygons together

  - by Jakobud

  I have an arbitrary number of polygons (hexes in this case) that are arranged randomly, but they are all touching another hex. Each individual hex has 6 x,y vertices. The vertex's are known for all the hexes. Can anyone point me in the direction of an algorithm that will combine all the hexes into a single polygon? Essentially I'm just looking for a function that spits out an array of vertex locations that are ordered in a way that when drawing lines from one to the next, it forms the polygon. This is my method so far: Create array of all the vertices for all the hexes. Determine the number of times a vertex occurs in the array If vertex is in the array 3+ times, delete the vertices from the array. If vertex is in the array 2 times, delete one of them. The next step is tricky though. I'm using canvas to draw out these polygons, which essentially involves drawing a line from one vertex to the next. So the order of the vertices in the final array is important. It can't be sorted arbitrarily. Also, I'm not looking for a "convex hull" algorithm, as that would not draw the polygon correctly. Are there any functions out there that do something like this? Am I on the right track or is there a better more efficient way?

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• Passing functor and function pointers interchangeably using a templated method in C++

  - by metroxylon

  I currently have a templated class, with a templated method. Works great with functors, but having trouble compiling for functions. Foo.h template <typename T> class Foo { public: // Constructor, destructor, etc... template <typename Func> void bar(T x, Func f); }; template <typename T> template <typename Func> Foo::bar(T x, Func f) { /* some code here */ } Main.cpp #include "Foo.h" template <typename T> class Functor { public: Functor() {} void operator()(T x) { /* ... */ } private: /* some attributes here */ }; void Function(T x) { /* ... */ } int main() { Foo<int> foo; foo.bar(2, Functor); // No problem foo.bar(2, Function); // <unresolved overloaded function type> return 0; }

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• Binary serialization and deserialization without creating files (via strings)

  - by the_V

  Hi, I'm trying to create a class that will contain functions for serializing/deserializing objects to/from string. That's what it looks like now: public class BinarySerialization { public static string SerializeObject(object o) { string result = ""; if ((o.GetType().Attributes & TypeAttributes.Serializable) == TypeAttributes.Serializable) { BinaryFormatter f = new BinaryFormatter(); using (MemoryStream str = new MemoryStream()) { f.Serialize(str, o); str.Position = 0; StreamReader reader = new StreamReader(str); result = reader.ReadToEnd(); } } return result; } public static object DeserializeObject(string str) { object result = null; byte[] bytes = System.Text.Encoding.ASCII.GetBytes(str); using (MemoryStream stream = new MemoryStream(bytes)) { BinaryFormatter bf = new BinaryFormatter(); result = bf.Deserialize(stream); } return result; } } SerializeObject method works well, but DeserializeObject does not. I always get an exception with message "End of Stream encountered before parsing was completed". What may be wrong here?

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• Calling a WPF Appliaction and modify exposed properties?

  - by Justin

  I have a WPF Keyboard Application, it is developed in such a way that an application could call it and modify its properties to adapt the Keyboard to do what it needs to. Right now I have a file *.Keys.Set which tells the appliaction (on open) to style itself according to that new style. I know this file could be passed as a command line argument into the appliaction. That would not be a problem. My concern is, is thier a way via a managed environment to change the properties of the executable as long as they are exposed properly, an example: 'Creates a new instance of the Keyboard Appliaction Dim e_key as new WpfAppliaction("C:\egt\components\keyboard.exe") 'Sets the style path e_key.SetStylePath("c:\users\joe\apps\me\default.keys.set") e_key.Refresh() 'Applies the style e_key.HideMenu() 'Hides the menu e_key.ShowDeck("PIN") 'Shows the custom "deck" of keyboard keys the developer 'Created in the style appliaction. ''work with events and resposne 'Clear the instance from memory e_key.close e_key.dispose e_key = nothing This would allow my application to become easily accessible to other Touch Screen Application Developers, allowing them to use my key_board and keep the functionality they need. It seems like it might be possible because (name of executable).application shows all the exposed functions, properties, and values. I just have never done this before. Any help would be appreciated, thank you in advance.

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• C++ variable to const expression

  - by user1344784

  template <typename Real> class A{ }; template <typename Real> class B{ }; //... a few dozen more similar template classes class Computer{ public slots: void setFrom(int from){ from_ = from; } void setTo(int to){ to_ = to; } private: template <int F, int T> void compute(){ using boost::fusion::vector; using boost::fusion::at_c; vector<A<float>, B<float>, ...> v; at_c<from_>(v).operator()(at_c<to_>(v)); //error; needs to be const-expression. }; This question isn't about Qt, but there is a line of Qt code in my example. The setFrom() and setTo() are functions that are called based on user selection via the GUI widget. The root of my problem is that 'from' and 'to' are variables. In my compute member function I need to pick a type (A, B, etc.) based on the values of 'from' and 'to'. The only way I know how to do what I need to do is to use switch statements, but that's extremely tedious in my case and I would like to avoid. Is there anyway to convert the error line to a constant-expression?

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• Loop elements with Jquery and call Omniture s.tl() function to track

  - by ilovewebdev

  Hi, i have a page with a list of items. Each item has a print now link (a.printMe) to print each item. At the end of the list, there's a print all link (a.printAll) to print all items. I want to track number of times an item was printed. If a.printAll link is clicked, then i will send all the item's tracking value to Omniture. I added tracking string into individual item's a.printMe href attribute and track with the following functions: $('a.printMe').click(function() { var value = $(this).attr('href'); track(value); }); $('a.printAll').click(function() { $('a.printMe').each(function() { this.click(); }); // works in IE only. IE 6-8 }); function track(value) { var s = s_gi('account'); s.prop10 = value; s.linkTrackVars = 'prop10'; s.tl(true, 'o'); } The problem is only the last item (in the list) has its value sent to Omniture when i clicked on a.printAll. I finally got the above to work in IE but not Firefox. Anyone encounter this before?

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• Proper API Design for Version Independence?

  - by Justavian

  I've inherited an enormous .NET solution of about 200 projects. There are now some developers who wish to start adding their own components into our application, which will require that we begin exposing functionality via an API. The major problem with that, of course, is that the solution we've got on our hands contains such a spider web of dependencies that we have to be careful to avoid sabotaging the API every time there's a minor change somewhere in the app. We'd also like to be able to incrementally expose new functionality without destroying any previous third party apps. I have a way to solve this problem, but i'm not sure it's the ideal way - i was looking for other ideas. My plan would be to essentially have three dlls. APIServer_1_0.dll - this would be the dll with all of the dependencies. APIClient_1_0.dll - this would be the dll our developers would actual refer to. No references to any of the mess in our solution. APISupport_1_0.dll - this would contain the interfaces which would allow the client piece to dynamically load the "server" component and perform whatever functions are required. Both of the above dlls would depend upon this. It would be the only dll that the "client" piece refers to. I initially arrived at this design, because the way in which we do inter process communication between windows services is sort of similar (except that the client talks to the server via named pipes, rather than dynamically loading dlls). While i'm fairly certain i can make this work, i'm curious to know if there are better ways to accomplish the same task.

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• which is better: a lying copy constructor or a non-standard one?

  - by PaulH

  I have a C++ class that contains a non-copyable handle. The class, however, must have a copy constructor. So, I've implemented one that transfers ownership of the handle to the new object (as below) class Foo { public: Foo() : h_( INVALID_HANDLE_VALUE ) { }; // transfer the handle to the new instance Foo( const Foo& other ) : h_( other.Detach() ) { }; ~Foo() { if( INVALID_HANDLE_VALUE != h_ ) CloseHandle( h_ ); }; // other interesting functions... private: /// disallow assignment const Foo& operator=( const Foo& ); HANDLE Detach() const { HANDLE h = h_; h_ = INVALID_HANDLE_VALUE; return h; }; /// a non-copyable handle mutable HANDLE h_; }; // class Foo My problem is that the standard copy constructor takes a const-reference and I'm modifying that reference. So, I'd like to know which is better (and why): a non-standard copy constructor: Foo( Foo& other ); a copy-constructor that 'lies': Foo( const Foo& other ); Thanks, PaulH

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• C# Timer -- measuring time slower

  - by Fassenkugel

  I'm writing a code where: I.) The user adds "events" during run-time. (To a flowlayoutpanel) These events are turning some LEDs on/off, after "x" time has elapsed and the LED-turning functions are written in a Led-function.cs class. i.e: 1) Turn left led on After 3500ms 2) Turn right led on After 4000ms II.) When the user hits start a timer starts. // Create timer. System.Timers.Timer _timer; _timer = new System.Timers.Timer(); _timer.Interval = (1); _timer.Elapsed += (sender, e) => { HandleTimerElapsed(LedObject, device, _timer); }; _timer.Start(); III.) The timer's tick event is raised every millisecond and checks if the user definied time has ellapsed. Im measuring the elapsed time with adding +1 to an integer at every tick event. (NumberOfTicks++;) //Timer Handle private void HandleTimerElapsed(Led_Functions LedObject, string device, System.Timers.Timer _timer) { NumberOfTicks++; if (NumberOfTicks >= Start_time[0]) { LedObject.LeftLED_ONnobutton(device); } } IV.) What I noticed was that when the tick was set to 1. (So the tick event is raised every millisecond) Even if I set 3000ms to the evet the LED actually flashed around 6 seconds. When the tick was set to 100. (So every 0,1s) then the flash was more accurate (3,5sec or so). Any Ideas why im having this delay in time? Or do you have any ideas how could I implement it better? Thank you!

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• Why should I abstract my data layer?

  - by Gazillion

  OOP principles were difficult for me to grasp because for some reason I could never apply them to web development. As I developed more and more projects I started understanding how some parts of my code could use certain design patterns to make them easier to read, reuse, and maintain so I started to use it more and more. The one thing I still can't quite comprehend is why I should abstract my data layer. Basically if I need to print a list of items stored in my DB to the browser I do something along the lines of: $sql = 'SELECT * FROM table WHERE type = "type1"';' $result = mysql_query($sql); while($row = mysql_fetch_assoc($result)) { echo '<li>'.$row['name'].'</li>'; } I'm reading all these How-Tos or articles preaching about the greatness of PDO but I don't understand why. I don't seem to be saving any LoCs and I don't see how it would be more reusable because all the functions that I call above just seem to be encapsulated in a class but do the exact same thing. The only advantage I'm seeing to PDO are prepared statements. I'm not saying data abstraction is a bad thing, I'm asking these questions because I'm trying to design my current classes correctly and they need to connect to a DB so I figured I'd do this the right way. Maybe I'm just reading bad articles on the subject :) I would really appreciate any advice, links, or concrete real-life examples on the subject!

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