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  • C++ standard: dereferencing NULL pointer to get a reference?

    - by shoosh
    I'm wondering about what the C++ standard says about code like this: int* ptr = NULL; int& ref = *ptr; int* ptr2 = &ref; In practice the result is that ptr2 is NULL but I'm wondering, is this just an implementation detail or is this well defined in the standard? Under different circumstances a dereferencing of a NULL pointer should result in a crash but here I'm dereferencing it to get a reference which is implemented by the compiler as a pointer so there's really no actual dereferencing of NULL.

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  • How to tell if there is an available thread in a thread pool in java

    - by Gormcito
    I am trying to proccess a queue of tasks from a database table as fast as possible while also limiting the number of threads to process the tasks. I am using a fixed sized thread pool with Executors.newFixedThreadPool(N); I want to know if there is a way of knowing if the thread pool is full, by that I mean are there currently 50 threads running, if so then I'll wait for a thread to be available before starting a new one instead of sleeping the main thread. Code of what I would like to do: ExecutorService executor = Executors.newFixedThreadPool(N); ResultSet results; while( true ) { results = getWaitingTasksStmt.executeQuery(); while( results.next() && executor.notFull() ) { executor.submit( new thread( new runnableInheritedClass(results) ) ); } }

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  • What is the best place to store globals in Rails app?

    - by Nick Gorbikoff
    Hello. I was wondering if there is the best practice on where to store global settings in a rails app. What I mean by that is i.e: I have a few globals defined that may change, but not likely and it seems inappropriate to store them in DB since they are used so much. For instance I have SYSTEM_EMAIL & SYSTEM_EMAIL_SIGNATURE & SYSTEM_STORAGE_ROOT. Right now I keep them in environment.rb, but I'm not sure if this is the right palce to store them. Thank you

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  • Twin edges - Half edge data structure

    - by Pradeep Kumar
    I have implemented a Half-edge data structure for loading 3d objects. I find that the part of assigning twin/pair edges takes the longest computation time (especially for objects which have hundreds of thousands half edges). The reason is that I use nested loops to accomplish this. Is there a simpler and efficient way of doing this? Below is the code which I've written. HE is the half-edge data structure. hearr is a vector containing all the half edges. vert is the starting vertex and end is the ending vertex. Thanks!! HE *e1,*e2; for(size_t i=0;i<hearr.size();i++){ e1=hearr[i]; for(size_t j=1;j<hearr.size();j++){ e2=hearr[j]; if((e1->vert==e2->end)&&(e2->vert==e1->end)){ e1->twin=e2; e2->twin=e1; } } }

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  • Segfaults with singletons

    - by Ockonal
    Hello, I have such code: // Non singleton class MyLogManager { void write(message) {Ogre::LogManager::getSingletonPtr()->logMessage(message);} } class Utils : public singleton<Utils> { MyLogManager *handle; MyLogManager& getHandle { return *handle; } }; namespace someNamespace { MyLogManager &Log() { return Utils::get_mutable_instance().getHandle(); } } int main() { someNamespace::Log().write("Starting game initializating..."); } In this code I'm using boost's singleton (from serialization) and calling Ogre's log manager (it's singleton-type too). The program fails at any trying to do something with Ogre::LogManager::getSingletonPtr() object with code User program stopped by signal (SIGSEGV) I checked that getSingletonPtr() returns address 0x000 But using code Utils::get_mutable_instance().getHandle().write("foo") works good in another part of program. What's wrong could be there with calling singletons?

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  • how to take input for uint32_t variable

    - by sksingh73
    i have declared a variable as uint32_t num; when i take input for this variable i.e cinnum; cout< when i run this program, i gives num value as 12345678, it works fine & give cout. but when i give input as 1234abcd. it creates problem & displays only 1234. please suggest solution to resolve this problem.

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  • && (AND) and || (OR) in Java IF statements

    - by Azimuth
    My question might be very basic but still I think it worths to ask. I have the following code: if(!partialHits.get(req_nr).containsKey(z) || partialHits.get(req_nr).get(z) < tmpmap.get(z)){ partialHits.get(z).put(z, tmpmap.get(z)); } where partialHits is a HashMap. What will happen if the first statement is true? Will Java still check the second statement? Because in order the first statement to be true, the HashMap should not contain the given key, so if the second statement is checked, I will get NullPointerException. So in simple words, if we have the following code if(a && b) if(a || b) would Java check b if a is false in the first case and if a is true in the second case?

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  • How to implement fluent interface with a base class, in C++

    - by Vincenzo
    How can I implement this fluent interface in C++: class Base { public: Base& add(int x) { return *this; } } class Derived : public Base { public: Derived& minus(int x) { return *this; } } Derived d; d.add(1).minus(2).add(3).minus(4); Current code doesn't work since Base class doesn't know anything about Derived class, etc. I would be very thankful for a hint/suggestion.

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  • Android liveWallpaper background

    - by Beginer Developer
    How do I scroll the background image on an ACTION_MOVE event? Here is my code used to draw the background image: void drawFrame() { final SurfaceHolder holder = getSurfaceHolder(); Canvas c = null; try { c = holder.lockCanvas(); if (c != null) { c.drawBitmap(myBg, 0, 0, mPaint); } } finally { if (c != null) holder.unlockCanvasAndPost(c); } // Reschedule the next redraw mHandler.removeCallbacks(mDrawAnim); if (mVisible && mAnime) { mHandler.postDelayed(mDrawAnim, 50 ); } }

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  • Twitter URL encoding

    - by Rich
    Hi, We're about to launch a little twitter Christmas competition, and I've run into a little snag. To enter, people will need to post a tweet in the following format: @user blah, blah, blah #hashtag Currently, I have a form where they enter their answer (the blah, blah, blah) and a PHP script which encodes the entire statement and adds on the twitter url: http://www.twitter.com/home?status=%40user%20blah%2Cblah%2Cblah%20%23hashtag Then takes the user to twitter and puts the status in the update field. However, whilst the spaces (%20) are decoded fine the @ and # characters remain as %40 & %23 respectively, even when the tweet is posted. I cannot put the actual characters in the url as twitter mistakes this for a search. Is there any way to solve this? I'd like to do it without requiring username & password etc if possible. Any help will be greatly appreciated.

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  • pass by const reference of class

    - by small_potato
    void foo(const ClassName &name) { ... } How can I access the method of class instance name? name.method() didn't work. then I tried: void foo(const ClassName &name) { ClassName temp = name; ... .... } I can use temp.method, but after foo was executed, the original name screwed up, any idea? BTW, the member variable of name didn't screwed up, but it was the member variable of subclass of class screwed up.

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  • putting values from database into a drop down list

    - by sushant
    hi. my tool is in asp. i am using this code for a query in sql dim req_id req_id=Request.Form("Req_id") if req_id<>"" then Set conn=server.CreateObject("adodb.connection") conn.Open session("Psrconnect") Set rs=CreateObject("Adodb.Recordset") rs.Open "select * from passwords where REQ_ID='"&req_id&"'", conn i want to put the results of this query into a drop down list. how do i do it? any help is very much appreciated.

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  • Get current location using CLLocationCoordinate2D

    - by Mobility
    I am trying to get current location of user using CLLocationCoordinate2D. I want the values in the format like CLLocationCoordinate2D start = {-28.078694,153.382844 }; So that I can use them like following: NSString *urlAddress = [NSString stringWithFormat:@"http://maps.google.com/?saddr=%1.6f,%1.6f&daddr=%1.6f,%1.6f", start.latitude, start.longitude, destination.latitude, destination.longitude]; I used CLLocation *location = [[CLLocation alloc]init ]; CLLocationDegrees currentLatitude = location.coordinate.latitude; CLLocationDegrees currentLongitude = location.coordinate.longitude; to get current lat & long. But I am getting 0.000 for both when I try to test. I am testing on iPhone 4s. If there is any sample code, it will be great.

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  • C++ Regarding cin.ignore()

    - by user1578897
    i would hope someone can modify my code as its so buggy. sometime its work, sometime it dont.. so let me explain more.. Text file data is as below Line3D, [70, -120, -3], [-29, 1, 268] Line3D, [25, -69, -33], [-2, -41, 58] To read the above line.. i use the following char buffer[30]; cout << "Please enter filename: "; cin.ignore(); getline(cin,filename); readFile.open(filename.c_str()); //if successfully open if(readFile.is_open()) { //record counter set to 0 numberOfRecords = 0; while(readFile.good()) { //input stream get line by line readFile.getline(buffer,20,','); if(strstr(buffer,"Point3D")) { Point3D point3d_tmp; readFile>>point3d_tmp; // and so on... Then i did a overload on the ifstream for Line3d ifstream& operator>>(ifstream &input,Line3D &line3d) { int x1,y1,z1,x2,y2,z2; //get x1 input.ignore(2); input>>x1; //get y1 input.ignore(); input>>y1; //get z1 input.ignore(); input>>z1; //get x2 input.ignore(4); input>>x2; //get y2 input.ignore(); input>>y2; //get z2 input.ignore(); input>>z2; input.ignore(2); Point3D pt1(x1,y1,z1); Point3D pt2(x2,y2,z2); line3d.setPt1(pt1); line3d.setPt2(pt2); line3d.setLength(); } But the issue is the record work sometime and sometime it dont.. what i mean is if at this point //i add a cout cout << x1 << y1 << z1; cout << x2 << y2 << z2; //its works! Point3D pt1(x1,y1,z1); Point3D pt2(x2,y2,z2); line3d.setPt1(pt1); line3d.setPt2(pt2); line3d.setLength(); but if i take away the cout it dont work. how do i change my cin.ignore() so the data can be handle properly , consider number range is -999 to 999

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  • Remove alert from a javascript

    - by albastar
    I've the below code from a tutorial,i want the action but i just want to remove the alert, here is the code: <script type="text/javascript"> setTimeout('read()', 10000); function read() { FB.api('/me/news.reads' + '?article=<?php echo $fbrdurl ?>&access_token=<?php echo $access_token ?>','post', function(response) { var msg = 'Error occured'; if (!response || response.error) { if (response.error) { msg += "\n\nType: "+response.error.type+"\n\nMessage: "+response.error.message; } alert(msg); } else { alert('Post was successful! Action ID: ' + response.id); } }); } </script> I've tried this: <script type="text/javascript"> setTimeout('read()', 10000); function read() { FB.api('/me/news.reads' + '?article=<?php echo $fbrdurl ?>&access_token=<?php echo $access_token ?>','post'; } </script> but not worked, thanks

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  • Conversion of Single to two UInt16 values in .net

    - by Gio
    In the good old days of C. I could cast a float to an int (assuming 32 bit system), do some bit manipluation ( bitwise and, right shift, ect ), and get the upper and lower 16 bit hex representations of the floating point number, which I could then store in two short values. I'm not seeing an easy way of doing this in C#. System.Convert.ToUInt16 just does a float to int convert (even after I shift right), which leaves a vlaue of 0 if the float is less than 0, which is not the desired effect. //useless leaves me witg a value 0f 0 UIN16 s1 = (UInt16)((System.Convert.ToUInt32(d2) & 0xffff0000) >> 16); //capture the high word UInt16 s2 = (UInt16)(System.Convert.ToUInt32(d2) & 0xffff); //capture the low word A basic cast (UInt32) doesn't work either.

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  • PHP cURL loading delay

    - by lasquarte
    Hello. My problem is, I need to cURL-load a page that uses Ajax-based search, to get results of that search. And I need to organize a delay between curl_exec() and value returning. In other words, I need to execute curl_exec() for no less than 5 seconds. sleep() seems to stop curl execution and does not work. Will greatly appreciate any hint or clue UPD I don't know how, but on this page http://vkontakte.ru/gsearch.php?section=video&q=sample&name=1, but it requires an account to access curl DOES capture the search made by ajax. But if page tooks too long to load, Ajax returns "action was too fast" error. So I just need to prolong curl execution. Sorry if being unclear.

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  • How do I add on multiple $_POST['row'] and variables?

    - by Ralph The Mouf
    I am struggling to find out the syntactically correct way in which to add on more variables and rows to these statements: /* WANT TO ADD ON FIVE MORE $_POST[''] */ if(isset($_POST['check_prof']) && $_POST['check_prof'] == 'checked') { $check_prof = "checked"; }else{ $check_prof = "unchecked"; } /* SAME HERE, WANT TO ADD THE OTHER FIVE IN HERE AS WELL */ $query = "UPDATE `Users` SET `check_prof` = '" . $check_prof . "' WHERE `id` = '" . $auth->id . "' LIMIT 1"; mysql_query($query,$connection); $auth->refresh(); }

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  • Prevent keypress whilst shift key is held

    - by deifwud
    I'm trying to prevent certain keys from being entered into an input box, but only if that particular key is pressed whilst the shift key is held: $('selector').keydown(function(e) { console.log(e.shiftKey); if (e.shiftKey && e.which == 51) { e.preventDefault(); alert('Disallowed'); } }); The alert fires but the character still appears in the text box. If I remove e.shiftKey from the if statement and press the key (without shift held), the alert fires and the character does not appear in the text box. I've tried searching around for an explanation as to why this happens but to no avail, any help would be greatly appreciated! edit Removing the alert seems to fix the problem (which seems bizarre), I'd really love to know why it behaves in this way though, it doesn't seem to make any sense. Thanks

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  • OpenGL ES perspective projection

    - by TimeManx
    I'm having a hard time understanding how glFrustum & gluPerspective work. I understand the concept of perspective projection but the functions aren't behaving how I expect them to. For example, if I set the frustum this way glFrustumf(0, 10, 0, 10, 1, 100) and have a rectangle at points 0, 0, 1, 0, 10, 1, 10, 10, 1, 10, 0, 1 then the rectangle is drawn with its left edge at -5 & right edge at 5, so the left half of the rectangle isn't visible. And if x is translated, I'd expect y to be too. But that doesn't happen either. In whatever examples I've seen, the coordinates for the projection matrix are taken as glFrustumf(-10, 10, -10, 10, 1, 100) but either way, whatever part is shown should be dependent on the rectangle's coordinates, right?

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  • "And" condition in C#/LINQ Query

    - by user1213055
    partial void PrintDocLetter1_CanExecute(ref bool result) { if (this.PatientsMasterItem.DoctorsMasterItem != null) { var Doctor = PatientsMasterItem.DoctorsMasterItem; var PatientList = Doctor.PatientsMasterItem; var Letters = PatientsMasterItem.LettersSentItem; if ((PatientList.Count() > 1) && (Letters.Any(i => i.LetterType == "DoctorLetter1"))) { result = false; } else { result = true; } } } I think something is wrong with my second condition. I'm trying to find two things. 1) Doctors with more than 1 patient. 2) Among those patients whether a lettertype called "DoctorLetter1" has been sent or not. The above code is working good for that particular record but not working other patients with same doctors where patient1 has already been sent with DoctorLetter1.

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  • Need help in translating code from C or C++ to Java.

    - by Vuntic
    From this article. Here's the code: float InvSqrt(float x){ // line 0 float xhalf = 0.5f * x; int i = *(int*)&x; // store floating-point bits in integer i = 0x5f3759d5 - (i >> 1); // initial guess for Newton's method x = *(float*)&i; // convert new bits into float x = x*(1.5f - xhalf*x*x); // One round of Newton's method return x; } ...I can't even tell if that's C or C++. Could someone translate it to Java for me, please? It's (only, I hope) lines 2 and 4 that are confusing me. I'll edit out the confusion about C/C++ from the tags once somebody tells me which it is.

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  • IIS7 URL Redirect with Regex

    - by andyjv
    I'm preparing for a major overhaul of our shopping cart, which is going to completely change how the urls are structured. For what its worth, this is for Magento 1.7. An example URL would be: {domain}/item/sub-domain/sub-sub-domain-5-16-7-16-/8083770?plpver=98&categid=1027&prodid=8090&origin=keyword and redirect it to {domain}/catalogsearch/result/?q=8083710 My web.config is: <?xml version="1.0" encoding="UTF-8"?> <configuration> <system.webServer> <rewrite> <rules> <rule name="Magento Required" stopProcessing="false"> <match url=".*" ignoreCase="false" /> <conditions> <add input="{URL}" pattern="^/(media|skin|js)/" ignoreCase="false" negate="true" /> <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" /> <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" /> </conditions> <action type="Rewrite" url="index.php" /> </rule> <rule name="Item Redirect" stopProcessing="true"> <match url="^item/([_\-a-zA-Z0-9]+)/([_\-a-zA-Z0-9]+)/([_\-a-zA-Z0-9]+)(\?.*)" /> <action type="Redirect" url="catalogsearch/result/?q={R:3}" appendQueryString="true" redirectType="Permanent" /> <conditions trackAllCaptures="true"> </conditions> </rule> </rules> </rewrite> <httpProtocol allowKeepAlive="false" /> <caching enabled="false" /> <urlCompression doDynamicCompression="true" /> </system.webServer> </configuration> Right now it seems the redirect is completely ignored, even though in the IIS GUI the sample url passes the regex test. Is there a better way to redirect or is there something wrong with my web.config?

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  • Problem Making C++ script

    - by Abs
    Hello all, I am not sure if I can post this sort of question (apologies in advance) but I am trying to build something from this blog post. # mkdir wkthumb # cat > wkthumb.cpp # qmake -project # qmake && make # ./wkthumb I have no experience with this, but I download all the files needed in the directory wkthumb using git. I have gone inside this directory and tried to execute cat > wkthumb.cpp - this just hangs for me. In addition, I thought cat was supposed to be used like this: cat file1.txt file2.txt > file3.txt? The above is blank with the first arguments? I am using Fedora Core 10.

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