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  • Why subtract null pointer in offsetof()?

    - by Bruce Christensen
    Linux's stddef.h defines offsetof() as: #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) whereas the Wikipedia article on offsetof() (http://en.wikipedia.org/wiki/Offsetof) defines it as: #define offsetof(st, m) \ ((size_t) ( (char *)&((st *)(0))->m - (char *)0 )) Why subtract (char *)0 in the Wikipedia version? Is there any case where that would actually make a difference?

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  • Use super class's address/pointer in initialization list

    - by JQ
    context 1: class D : public B1, public B2{}; context 2: B2 takes B1 to initialize: B2( B1 * ) //B2's constructor my question is in D's initialization list: D::D() : B1(), B2( ? )... What should be in ? I don't want to put " (B1*)this " in the ? place, because it's no good to use "this" in initialization list. And since B1 part has been initialized, it makes sense to use it. What should I do ?

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  • How to store a function pointer in C#

    - by Joshua
    Let's say I want to store a group of function pointers in a List<(*func), and then later call them, perhaps even with parameters... Like if I stored in a Dict<(*func), object[] params could I call the func with the parameters? How would I do this?

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  • C++ vector pointer/reference problem

    - by sub
    Please take a look at this example: #include <iostream> #include <vector> #include <string> using namespace std; class mySubContainer { public: string val; }; class myMainContainer { public: mySubContainer sub; }; void doSomethingWith( myMainContainer &container ) { container.sub.val = "I was modified"; } int main( ) { vector<myMainContainer> vec; /** * Add test data */ myMainContainer tempInst; tempInst.sub.val = "foo"; vec.push_back( tempInst ); tempInst.sub.val = "bar"; vec.push_back( tempInst ); // 1000 lines of random code here int i; int size = vec.size( ); myMainContainer current; for( i = 0; i < size; i ++ ) { cout << i << ": Value before='" << vec.at( i ).sub.val << "'" << endl; current = vec.at( i ); doSomethingWith( current ); cout << i << ": Value after='" << vec.at( i ).sub.val << "'" << endl; } system("pause");//i suck } A hell lot of code for an example, I know. Now so you don't have to spend years thinking about what this [should] do[es]: I have a class myMainContainer which has as its only member an instance of mySubContainer. mySubContainer only has a string val as member. So I create a vector and fill it with some sample data. Now, what I want to do is: Iterate through the vector and make a separate function able to modify the current myMainContainer in the vector. However, the vector remains unchanged as the output tells: 0: Value before='foo' 0: Value after='foo' 1: Value before='bar' 1: Value after='bar' What am I doing wrong? doSomethingWith has to return void, I can't let it return the modified myMainContainer and then just overwrite it in the vector, that's why I tried to pass it by reference as seen in the doSomethingWith definition above.

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  • How to check if a pointer is null in C++ Visual 2010

    - by mariomario
    I am having problems here if I want to check if eerste points to nothing i get Blockquote Unhandled exception at 0x003921c6 in Bank.exe: 0xC0000005: Access violation reading location 0xccccccd0. and i am kinda wondering why he justs skips the if statement or doens't stop when the object eerste points to nothing Bank::Bank() { LijstElement *eerste = NULL; LijstElement *laatste = NULL; } Rekening * Bank::getRekening(int rekNr) { if(NULL != eerste) { LijstElement *nummer = eerste; while(nummer->volgende!= NULL) { Rekening *een = nummer->getRekening(); if(een->getRekNr()==rekNr) { return een; } else { nummer = nummer->volgende; } } } return NULL; }

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  • Allocating memory for a array to char pointer

    - by nunos
    The following piece of code gives a segmentation fault when allocating memory for the last arg. What am I doing wrong? Thanks. int n_args = 0, i = 0; while (line[i] != '\0') { if (isspace(line[i++])) n_args++; } for (i = 0; i < n_args; i++) command = malloc (n_args * sizeof(char*)); char* arg = NULL; arg = strtok(line, " \n"); while (arg != NULL) { arg = strtok(NULL, " \n"); command[i] = malloc ( (strlen(arg)+1) * sizeof(char) ); strcpy(command[i], arg); i++; } Thanks.

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  • C++ pointer to different array

    - by begun
    Assume I have an array a and an array b. Both have the same type and size but different values. Now I create 3 or so pointers that point to different elements in a, you could say a[ 0 ], a[ 4 ] and a[ 13 ]. Now if I overwrite a with b via a=b - Where will the pointers point? Do the pointers still point to their original positions in a but the values they point to are now those of b?

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  • C++: Copying to dereferenced pointer...

    - by bbb
    Hi. I currently have a weird problem with a program segfaulting but im not able to spot the error. I think the problem boils down to this. struct S {int a; vector<sometype> b;} S s1; // fill stuff into a and b S* s2 = new S(); *s2 = s1; Could it be that the final copying is illegal in some way? Im really confused right now... Thanks

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  • Pointer-like behavior in Java

    - by Shmoo
    I got the following: class A{ int foo; } class B extends A{ public void bar(); } I got a instance of A and want to convert it to an instance of B without losing the reference to the variable foo. For example: A a = new A(); a.foo = 2; B b = a; <-- what I want to do. //use b b.foo = 3; //a.foo should now be 3 Thanks for any help!

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  • game speed problem

    - by Meko
    HI..I made a little game.But this game works on every computer with different speed.I think it is about resolution.I used every thing in paintcomponent.and If I change screen size the game goes slower or faster.And if i run this game on another computer wich has different resolution it also works different. This is my game http://rapidshare.com/files/364597095/ShooterGame.2.6.0.jar and here code public class Shooter extends JFrame implements KeyListener, Runnable { JFrame frame = new JFrame(); String player; Font startFont, startSubFont, timerFont,healthFont; Image img; Image backGround; Graphics dbi; URL url1 = this.getClass().getResource("Images/p2.gif"); URL url2 = this.getClass().getResource("Images/p3.gif"); URL url3 = this.getClass().getResource("Images/p1.gif"); URL url4 = this.getClass().getResource("Images/p4.gif"); URL urlMap = this.getClass().getResource("Images/zemin.jpg"); Player p1 = new Player(5, 150, 10, 40, Color.GREEN, url3); Computer p2 = new Computer(750, 150, 10, 40, Color.BLUE, url1); Computer p3 = new Computer(0, 0, 10, 40, Color.BLUE, url2); Computer p4 = new Computer(0, 0, 10, 40, Color.BLUE, url4); ArrayList<Bullets> b = new ArrayList<Bullets>(); ArrayList<CBullets> cb = new ArrayList<CBullets>(); Thread sheap; boolean a, d, w, s; boolean toUp, toDown; boolean GameOver; boolean Level2; boolean newGame, resart, pause; int S, E; int random; int cbSpeed = 0; long timeStart, timeEnd; int timeElapsed; long GameStart, GameEnd; int GameScore; int Timer = 0; int timerStart, timerEnd; public Shooter() { sheap = new Thread(this); sheap.start(); startFont = new Font("Tiresias PCFont Z", Font.BOLD + Font.ITALIC, 32); startSubFont = new Font("Tiresias PCFont Z", Font.BOLD + Font.ITALIC, 25); timerFont = new Font("Tiresias PCFont Z", Font.BOLD + Font.ITALIC, 16); healthFont = new Font("Tiresias PCFont Z", Font.BOLD + Font.ITALIC, 16); setTitle("Shooter 2.5.1"); setBounds(350, 250, 800, 600); // setResizable(false); setBackground(Color.black); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); addKeyListener(this); a = d = w = s = false; toUp = toDown = true; GameOver = true; newGame = true; Level2 = false; S = E = 0; setVisible(true); } public void paint(Graphics g) { img = createImage(getWidth(), getHeight()); dbi = img.getGraphics(); paintComponent(dbi); g.drawImage(img, 0, 0, this); } public void paintComponent(Graphics g) { repaint(); timeStart = System.currentTimeMillis(); backGround = Toolkit.getDefaultToolkit().getImage(urlMap); g.drawImage(backGround, 0, 0, null); g.setColor(Color.red); g.setFont(healthFont); g.drawString("" + player + " Health : " + p1.health, 30, 50); g.setColor(Color.red); g.drawString("Computer Health : " + (p2.health + p3.health + p4.health), 600, 50); g.setColor(Color.BLUE); g.setFont(timerFont); g.drawString("Time : " + Timer, 330, 50); if (newGame) { g.setColor(Color.LIGHT_GRAY); g.setFont(startFont); g.drawString("Well Come To Shoot Game", 200, 190); g.drawString("Press ENTER To Start", 250, 220); g.setColor(Color.LIGHT_GRAY); g.setFont(startSubFont); g.drawString("Use W,A,S,D and Space For Fire", 200, 250); g.drawString("GOOD LUCK", 250, 280); newGame(); } if (!GameOver) { for (Bullets b1 : b) { b1.draw(g); } for (CBullets b2 : cb) { b2.draw(g); } update(); // Here MOvements for Player and For Fires } if (p1.health <= 0) { g.setColor(p2.col); g.setFont(startFont); g.drawString("Computer Wins ", 200, 190); g.drawString("Press Key R to Restart ", 200, 220); GameOver = true; } else if (p2.health <= 0 && p3.health <= 0 && p4.health <= 0) { g.setColor(p1.col); g.setFont(startFont); g.drawString(""+player+" Wins ", 200, 190); g.drawString("Press Key R to Resart ", 200, 220); GameOver = true; g.setColor(Color.MAGENTA); g.drawString(""+player+"`s Score is " + Timer, 200, 120); } if (Level2) { if (p3.health >= 0) { p3.draw(g); for (CBullets b3 : cb) { b3.draw(g); } } else { p3.x = 1000; } if (p4.health >= 0) { p4.draw(g); for (CBullets b4 : cb) { b4.draw(g); } } else { p4.x = 1000; } } if (p1.health >= 0) { p1.draw(g); } if (p2.health >= 0) { p2.draw(g); } else { p2.x = 1000; } } public void update() { if (w && p1.y > 54) { p1.moveUp(); } if (s && p1.y < 547) { p1.moveDown(); } if (a && p1.x > 0) { p1.moveLeft(); } if (d && p1.x < 200) { p1.moveRight(); } random = 1 * (int) (Math.random() * 100); if (random > 96) { if (p2.health >= 0) { CBullets bo = p2.getCBull(); bo.xVel =-1-cbSpeed; cb.add(bo); } if (Level2) { if (p3.health >= 0) { CBullets bo1 = p3.getCBull(); bo1.xVel = -2-cbSpeed; cb.add(bo1); } if (p4.health >= 0) { CBullets bo2 = p4.getCBull(); bo2.xVel = -4-cbSpeed; cb.add(bo2); } } } if (S == 1) { if (p1.health >= 0) { Bullets bu = p1.getBull(); bu.xVel = 5; b.add(bu); S += 1; } } //Here Also Problem .. When COmputer have More fire then it gaves Array Exeption . Or Player have More Fire for (int i = cb.size() -1; i = 0 ; i--) { boolean bremoved = false; for (int j = b.size() -1 ; j =0 ; j--) { if (b.get(j).rect.intersects(cb.get(i).rect) || cb.get(i).rect.intersects(b.get(j).rect)) { bremoved = true; b.remove(j); } } if(bremoved) cb.remove(i); } for (int i = 0; i < b.size(); i++) { b.get(i).move(); if (b.get(i).rect.intersects(p2.rect)) { if (p2.health >= 0) { p2.health--; b.remove(i); // System.out.println("Hited P2"); i--; continue; } } if (b.get(i).rect.intersects(p3.rect)) { if (p3.health >= 0) { p3.health--; b.remove(i); // System.out.println("Hited P3"); i--; continue; } } if (b.get(i).rect.intersects(p4.rect)) { if (p4.health >= 0) { p4.health--; b.remove(i); // System.out.println("Hited P4"); i--; continue; } } if (b.get(i).rect.x > 790) { b.remove(i); } } for (int j = 0; j < cb.size(); j++) { cb.get(j).move(); if (cb.get(j).rect.intersects(p1.rect) && cb.get(j).xVel < 0) { p1.health--; cb.remove(j); j--; continue; } } timeEnd = System.currentTimeMillis(); timeElapsed = (int) (timeEnd - timeStart); } public void level2() { if (p2.health <= 10) { Level2 = true; cbSpeed = 4; p3.x = 750; p4.x = 750; p2.speed = 10; p3.speed = 20; p4.speed = 30; } } public void keyTyped(KeyEvent e) { } public void keyPressed(KeyEvent e) { switch (e.getKeyCode()) { case KeyEvent.VK_ENTER: newGame = false; break; case KeyEvent.VK_P: pause = true; break; case KeyEvent.VK_R: resart = true; break; case KeyEvent.VK_A: a = true; break; case KeyEvent.VK_D: d = true; break; case KeyEvent.VK_W: w = true; break; case KeyEvent.VK_S: s = true; break; case KeyEvent.VK_SPACE: S += 1; break; } } public void keyReleased(KeyEvent e) { switch (e.getKeyCode()) { case KeyEvent.VK_A: a = false; break; case KeyEvent.VK_D: d = false; break; case KeyEvent.VK_W: w = false; break; case KeyEvent.VK_S: s = false; break; case KeyEvent.VK_SPACE: S = 0; break; } } public void newGame() { p1.health = 20; p2.health = 20; p3.health = 20; p4.health = 20; p3.x = 0; p4.x = 0; p2.x = 750; Level2 = false; cbSpeed = 0; p2.speed = 9; b.removeAll(b); cb.removeAll(cb); timerStart = (int) System.currentTimeMillis(); GameOver = false; } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { KeyListener k = new Shooter(); } }); } @Override public void run() { player = JOptionPane.showInputDialog(frame, "Enter Player Name", "New Player", JOptionPane.DEFAULT_OPTION); while (true) { timerEnd = (int) System.currentTimeMillis(); if (resart) { newGame(); resart = false; } if (pause) { Thread.currentThread().notify(); } try { if (!GameOver) { Timer = timerEnd - timerStart; level2(); if (p1.y < p2.y && p2.y60) { p2.moveUp(); } if (p1.y < p3.y && p3.y43) { p3.moveUp(); } if (p1.y < p4.y && p4.y43) { p4.moveUp(); } if (p1.y > p2.y && p2.y<535) { p2.moveDown(); } if (p1.y > p3.y && p3.y<535) { p3.moveDown(); } if (p1.y > p4.y && p4.y<530) { p4.moveDown(); } } if (timeElapsed < 125) { Thread.currentThread().sleep(125); } } catch (InterruptedException ex) { System.out.print("FInished"); } } } }

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  • Increasing speed of python code

    - by Curious2learn
    Hi, I have some python code that has many classes. I used cProfile to find that the total time to run the program is 68 seconds. I found that the following function in a class called Buyers takes about 60 seconds of those 68 seconds. I have to run the program about 100 times, so any increase in speed will help. Can you suggest ways to increase the speed by modifying the code? If you need more information that will help, please let me know. def qtyDemanded(self, timePd, priceVector): '''Returns quantity demanded in period timePd. In addition, also updates the list of customers and non-customers. Inputs: timePd and priceVector Output: count of people for whom priceVector[-1] < utility ''' ## Initialize count of customers to zero ## Set self.customers and self.nonCustomers to empty lists price = priceVector[-1] count = 0 self.customers = [] self.nonCustomers = [] for person in self.people: if person.utility >= price: person.customer = 1 self.customers.append(person) else: person.customer = 0 self.nonCustomers.append(person) return len(self.customers) self.people is a list of person objects. Each person has customer and utility as its attributes. EDIT - responsed added ------------------------------------- Thanks so much for the suggestions. Here is the response to some questions and suggestions people have kindly made. I have not tried them all, but will try others and write back later. (1) @amber - the function is accessed 80,000 times. (2) @gnibbler and others - self.people is a list of Person objects in memory. Not connected to a database. (3) @Hugh Bothwell cumtime taken by the original function - 60.8 s (accessed 80000 times) cumtime taken by the new function with local function aliases as suggested - 56.4 s (accessed 80000 times) (4) @rotoglup and @Martin Thomas I have not tried your solutions yet. I need to check the rest of the code to see the places where I use self.customers before I can make the change of not appending the customers to self.customers list. But I will try this and write back. (5) @TryPyPy - thanks for your kind offer to check the code. Let me first read a little on the suggestions you have made to see if those will be feasible to use. EDIT 2 Some suggested that since I am flagging the customers and noncustomers in the self.people, I should try without creating separate lists of self.customers and self.noncustomers using append. Instead, I should loop over the self.people to find the number of customers. I tried the following code and timed both functions below f_w_append and f_wo_append. I did find that the latter takes less time, but it is still 96% of the time taken by the former. That is, it is a very small increase in the speed. @TryPyPy - The following piece of code is complete enough to check the bottleneck function, in case your offer is still there to check it with other compilers. Thanks again to everyone who replied. import numpy class person(object): def __init__(self, util): self.utility = util self.customer = 0 class population(object): def __init__(self, numpeople): self.people = [] self.cus = [] self.noncus = [] numpy.random.seed(1) utils = numpy.random.uniform(0, 300, numpeople) for u in utils: per = person(u) self.people.append(per) popn = population(300) def f_w_append(): '''Function with append''' P = 75 cus = [] noncus = [] for per in popn.people: if per.utility >= P: per.customer = 1 cus.append(per) else: per.customer = 0 noncus.append(per) return len(cus) def f_wo_append(): '''Function without append''' P = 75 for per in popn.people: if per.utility >= P: per.customer = 1 else: per.customer = 0 numcustomers = 0 for per in popn.people: if per.customer == 1: numcustomers += 1 return numcustomers

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  • speed string search in PHP

    - by Marc
    Hi! I have a 1.2GB file that contains a one line string. What I need is to search the entire file to find the position of an another string (currently I have a list of strings to search). The way what I'm doing it now is opening the big file and move a pointer throught 4Kb blocks, then moving the pointer X positions back in the file and get 4Kb more. My problem is that a bigger string to search, a bigger time he take to got it. Can you give me some ideas to optimize the script to get better search times? this is my implementation: function busca($inici){ $limit = 4096; $big_one = fopen('big_one.txt','r'); $options = fopen('options.txt','r'); while(!feof($options)){ $search = trim(fgets($options)); $retro = strlen($search);//maybe setting this position absolute? (like 12 or 15) $punter = 0; while(!feof($big_one)){ $ara = fgets($big_one,$limit); $pos = strpos($ara,$search); $ok_pos = $pos + $punter; if($pos !== false){ echo "$pos - $punter - $search : $ok_pos <br>"; break; } $punter += $limit - $retro; fseek($big_one,$punter); } fseek($big_one,0); } } Thanks in advance!

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  • which factors determines the speed of a processor? [closed]

    - by Deb
    I think that clock rate of processor determines the speed of core, in my case it is 1.86GHz. But If I am not wrong, it also determines that how much energy it will consume. If you have more frequency then more power it will consume. I choose Power Saver scheme to increase my battery life, however it reduces my core speed to half of the actual speed. I understand this happens because of SpeedStep, but I don't see any slowdown of my computer. So my problem is why we have such high frequency cores as it uses too much power. We can use low frequency cores. Actually I get confused between the two terms Speed of the processor and its frequency. So how much important is the frequency of core in case of any processor.

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  • How to get an ARM CPU clock speed in Linux?

    - by MiKy
    I have an ARM-based embedded machine based on S3C2416 board. According to the specifications I have available there should be a 533 MHz ARM9 (ARM926EJ-S according to /proc/cpuinfo), however the software running on it "feels" slow, compared to the same software on my Android phone with a 528MHz ARM CPU. /proc/cpuinfo tells me that BogoMIPS is 266.24. I know that I should not trust BogoMIPS regarding performance ("Bogo" = bogus), however I would like to get a measurement on the actual CPU speed. On x86, I could use the rdtsc instruction to get the time stamp counter, wait a second (sleep(1)), read the counter again to get an approximation on the CPU speed, and according to my experience, this value was close enough to the real CPU speed. How can I find the actual CPU speed of given ARM processor? Update I found this simple Pi calculator, which I compiled both for my Android phone and the ARM board. The results are as follows: S3C2416 # cat /proc/cpuinfo Processor : ARM926EJ-S rev 5 (v5l) BogoMIPS : 266.24 Features : swp half fastmult edsp java ... #./pi_arm 10000 Calculation of PI using FFT and AGM, ver. LG1.1.2-MP1.5.2a.memsave ... 8.50 sec. (real time) Android # cat /proc/cpuinfo Processor : ARMv6-compatible processor rev 2 (v6l) BogoMIPS : 527.56 Features : swp half thumb fastmult edsp java # ./pi_android 10000 Calculation of PI using FFT and AGM, ver. LG1.1.2-MP1.5.2a.memsave ... 5.95 sec. (real time) So it seems that the ARM926EJ-S is slower than my Android phone, but not twice slower as I would expect by the BogoMIPS figures. I am still unsure about the clock speed of the ARM9 CPU.

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  • How much the distance and ms can affect on the download speed ?

    - by Prix
    Let's consider A (client) and B (server) where A makes download from B. How much can a bad routing from A to B affect the download speed ? For example A does a tracert to B and get a response of 10 steps where the avg ms is around 300 with 10% packet loss at the 4 step and when the connection is normal the avg from A to B is 10 ~ 30 ms. Could this sort of impact reduce A download speed drasticaly or as long as both side and routes have enough link for the full speed of A from B and vice-versa it should maintain the same speed ? Besides tracert and the ping analyse of A to B what else is used to identify the problem ? If you need extra information please let me know.

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  • how to increase speed of my execution

    - by ratty
    i am creating project in c#.net. my execution process is very slow. i also found the reason for that.in one method i copied the values from one list to another.that list consists more 3000values for every row . how can i speed up this process.any body help me

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  • Python vs. Java performance (runtime speed)

    - by Bijan
    Ignoring all the characteristics of each languages and focusing SOLELY on speed, which language is better performance-wise? You'd think this would be a rather simple question to answer, but I haven't found a decent one. I'm aware that some types of operations may be faster with python, and vice-versa, but I cannot find any detailed information on this. Can anyone shed some light on the performance differences?

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  • Speed of NSScanner vs NSXMLParser?

    - by Chris
    I have an iPhone App that reads in an XML file, then pulls out the necessary data by looping through an NSScanner. The XML is not particularly long. I am wondering if it would be worth the work to implement NSXMLParser in place of using NSScanner, if I will see any real improvement in speed?

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  • Speed test (open source)

    - by Nimbuz
    Are there any good (preferably PHP) open source scripts that I use to measure download/upload speeds? Something like speedtest.net but without Flash. Basically, I want to put up a 'broadband speed test' website. I found this but is there anything better already available? Thanks!

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  • Mouse pointer size inconsistent

    - by charon00
    Since installing Ubuntu 12.04, I've been having a problem with the mouse pointer size. On the desktop, it is quite a bit larger than it should be (24), though the different cursors (editing text, hyperlink hand, etc) are correct. The size changes to the correct size when the pointer is over some application windows (GVim, Netbeans, Firefox), but then changes back once it is moved out of the window. There was a similar question here, but the Xdefaults solution did not work for me, and I didn't want to try the one requiring editing the icon image. In addition, I've tried changing the cursor theme using sudo update-alternatives --config x-cursor-theme as well as using the dconf-editor, but though I can change the theme, the size issue remains. In case it's relevant, I'm running on a dual-screen setup with monitor sizes of 2560x1600 and 1920x1080, using the NVidia video driver. Is there another way to control pointer size, or a setting that might be messing it up? EDIT: These are the values/options I have for update-alternatives and in dconf-editor. I'm now wondering if Netbeans and Firefox are making the mouse pointer smaller than it should be, but I'm not sure how big 24 should be... update-alternatives: Selection Path Priority Status ------------------------------------------------------------ 0 /usr/share/icons/DMZ-White/cursor.theme 90 auto mode 1 /etc/X11/cursors/core.theme 30 manual mode 2 /etc/X11/cursors/handhelds.theme 20 manual mode 3 /etc/X11/cursors/redglass.theme 20 manual mode 4 /etc/X11/cursors/whiteglass.theme 20 manual mode * 5 /usr/share/icons/DMZ-Black/cursor.theme 30 manual mode 6 /usr/share/icons/DMZ-White/cursor.theme 90 manual mode dconf-editor: I can't post the image since I'm a new user but the cursor-size is set to 24 and the cursor-theme is DMZ-Black.

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  • weighted RNG speed problem in C++

    - by supert
    I have a (fast) bit of C++ code that samples cards from a 52 card deck: void sample_allcards(int table[5], int holes[], int players) { int temp[5 + 2 * players]; bool try_again; int c, n, i; for (i = 0; i < 5 + 2 * players; i++) { try_again = true; while (try_again == true) { try_again = false; c = fast_rand52(); // reject collisions for (n = 0; n < i + 1; n++) { try_again = (temp[n] == c) || try_again; } temp[i] = c; } } copy_cards(table, temp, 5); copy_cards(holes, temp + 5, 2 * players); } I am implementing code to sample the hole cards according to a known distribution (stored as a 2d table). My code for this looks like: void sample_allcards_weighted(double weights[][HOLE_CARDS], int table[5], int holes[], int players) { // weights are distribution over hole cards int temp[5 + 2 * players]; int n, i; // table cards for (i = 0; i < 5; i++) { bool try_again = true; while (try_again == true) { try_again = false; int c = fast_rand52(); // reject collisions for (n = 0; n < i + 1; n++) { try_again = (temp[n] == c) || try_again; } temp[i] = c; } } for (int player = 0; player < players; player++) { // hole cards according to distribution i = 5 + 2 * player; bool try_again = true; while (try_again == true) { try_again = false; // weighted-sample c1 and c2 at once double w[1326]; memcpy(w, weights[player], sizeof(w)); // h is a number < 1325 int h = weighted_randi(w, HOLE_CARDS); // i2h uses h and sets temp[i] to the 2 cards implied by h i2h(&temp[i], h); // reject collisions for (n = 0; n < i; n++) { try_again = (temp[n] == temp[i]) || (temp[n] == temp[i+1]) || try_again; } } } copy_cards(table, temp, 5); copy_cards(holes, temp + 5, 2 * players); } My problem? The weighted sampling algorithm is a factor of 10 slower. Speed is very important for my application. Is there a way to improve the speed of my algorithm to something more reasonable? Am I doing something wrong in my implementation? Thanks.

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