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  • Decimal To Octal Converter, last digit issue

    - by Srishan Supertramp
    I tried making a C program to convert a user entered decimal number to octal. I wrote the C code with my own logic without any research of how other users try to do it. It works fine for the number 601 and some other numbers but for most numbers it returns the octal equivalent with the last digit being 1 less than it should be. For 75 it returns 112 instead of 113. I realize using printf with %o gets the job done but it's kind of defeating the purpose of learning to program. Here's my code: #include <stdio.h> #include <math.h> /* converting decimal to octal */ int main() { int n,x,y,p,s; printf("Enter a decimal number "); scanf("%d",&x); s=0;p=0; while (x!=0) { y=x%8; s=s+y*pow(10,p); x=(x-y)/8; p=p+1; } printf("the octal equivalent is: %d\n",s); getch(); return 0; }

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  • Efficiency of manually written loops vs operator overloads (C++)

    - by Sagekilla
    Hi all, in the program I'm working on I have 3-element arrays, which I use as mathematical vectors for all intents and purposes. Through the course of writing my code, I was tempted to just roll my own Vector class with simple +, -, *, /, etc overloads so I can simplify statements like: for (int i = 0; i < 3; i++) r[i] = r1[i] - r2[i]; // becomes: r = r1 - r2; Which should be more or less identical in generated code. But when it comes to more complicated things, could this really impact my performance heavily? One example that I have in my code is this: Manually written version: for (int j = 0; j < 3; j++) { p.vel[j] = p.oldVel[j] + (p.oldAcc[j] + p.acc[j]) * dt2 + (p.oldJerk[j] - p.jerk[j]) * dt12; p.pos[j] = p.oldPos[j] + (p.oldVel[j] + p.vel[j]) * dt2 + (p.oldAcc[j] - p.acc[j]) * dt12; } Using a Vector class with operator overloads: p.vel = p.oldVel + (p.oldAcc + p.acc) * dt2 + (p.oldJerk - p.jerk) * dt12; p.pos = p.oldPos + (p.oldVel + p.vel) * dt2 + (p.oldAcc - p.acc) * dt12; I am compiling my code for maximum possible speed, as it's extremely important that this code runs quickly and calculates accurately. So will me relying on my Vector's for these sorts of things really affect me? For those curious, this is part of some numerical integration code which is not trivial to run in my program. Any insight would be appreciated, as would any idioms or tricks I'm unaware of.

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  • Easily measure elapsed time

    - by hap497
    I am trying to use time() to measure various points of my program. What I don't understand is why the values in the before and after are the same? I understand this is not the best way to profile my program, I just want to see how long something take. printf("**MyProgram::before time= %ld\n", time(NULL)); doSomthing(); doSomthingLong(); printf("**MyProgram::after time= %ld\n", time(NULL)); I have tried: struct timeval diff, startTV, endTV; gettimeofday(&startTV, NULL); doSomething(); doSomethingLong(); gettimeofday(&endTV, NULL); timersub(&endTV, &startTV, &diff); printf("**time taken = %ld %ld\n", diff.tv_sec, diff.tv_usec); How do I read a result of **time taken = 0 26339? Does that mean 26,339 nanoseconds = 26.3 msec? What about **time taken = 4 45025, does that mean 4 seconds and 25 msec?

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  • user enter data to different arrays

    - by user2900469
    This is fragment of my code (arrays as you can see): double[] Price; String[] names; int[] Quantity; Price = new double[5]; names = new String[5]; Quantity = new int[5]; Price[1] = 3.10; Price[2] = 7.80; Price[3] = 0.20; names[1] = "Ballpen"; names[2] = "Notebook"; names[3] = "Envelope"; Quantity[1] = 20; Quantity[2] = 5; Quantity[3] = 140; I enter data to arrays by myself in this case. Now i want to change my code so that my program asks user for names, price and quantity (using the Scanner class). After user enter data, program keep this in three different arrays. I dont know how to transfer data from user to arrays. I would be grateful for some example code or any help.

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  • DMProcessConfigXML fails while loading dlls on the windows mobile 6.5.

    - by jieun
    What I want to do is uninstall my program on the device Programmatically. So I trying to use DMProcessConfigXML() as this site It seems to work well on the emulator, but it didn't work on my device. Application goes exit after calling DMProcessConfigXML() without return result code. This is a part of code. after line 2, program is terminated. const wchar_t *_deleteUninstallOFficeLiteXML = L"<wap-provisioningdoc>" L" <characteristic type=\"UnInstall\">" L" <characteristic type=\"myApp\">" L" <parm name=\"uninstall\" value=\"1\"/>" L" </characteristic>" L" </characteristic>" L"</wap-provisioningdoc>"; 1. HRESULT hr = E_FAIL; 2. hr = DMProcessConfigXML(_deleteUninstallXML, CFGFLAG_PROCESS, &out); 3. if (FAILED(hr)) 4. { ... Does anyone know why this happen and how to fix?

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  • c++ exercise question

    - by Djecua
    in need of help on a C++ program that will help a deli owner help her customers.Prompt the user for the number of bagels.if then calculate the customers payment two ways. first it finds the price of the smallest multiple of 13 bagels that is closet to the customer's order. it then calculates the price of the customer's order so that the customer's payment is the smallest amount possible with the customer getting the exact number of bagels ordered. if the first method is the smallest amount the program outputs the number of bagels the customer will receive along with the dollar amount owed and the dollar amount saved. otherwise just print the number of bagels received the dollar amount owed $ 3.80 for a dozen bagels (13 bagels) half a dozen(6 bagels) sing bagel cost $.50 owner of the deli is a honest merchant, customers always get the best price on an order, even if they get more bagels than ordered, for example a customer that orders 10 bagels would pay $ 4.60 (2.60 for a half dozen bagels plus $2.00 for 4 single bagels.merchant gives her customer 13 bagels saving the customer $0.80 If someone can example to me how would i design to give customer extra bagels and how to calculate cost.

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  • Segmentation Fault?

    - by user336808
    Hello, when I run this program while inputting a number greater than 46348, I get a segmentation fault. For any values below it, the program works perfectly. I am using CodeBlocks 8.02 on Ubuntu 10.04 64-bit. The code is as follows: int main() { int number = 46348; vector<bool> sieve(number+1,false); vector<int> primes; sieve[0] = true; sieve[1] = true; for(int i = 2; i <= number; i++) { if(sieve[i]==false) { primes.push_back(i); int temp = i*i; while(temp <= number) { sieve[temp] = true; temp = temp + i; } } } for(int i = 0; i < primes.size(); i++) cout << primes[i] << " "; return 0; }

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  • Threads are blocked in malloc and free, virtual size

    - by Albert Wang
    Hi, I'm running a 64-bit multi-threaded program on the windows server 2003 server (X64), It run into a case that some of the threads seem to be blocked in the malloc or free function forever. The stack trace is like follows: ntdll.dll!NtWaitForSingleObject() + 0xa bytes ntdll.dll!RtlpWaitOnCriticalSection() - 0x1aa bytes ntdll.dll!RtlEnterCriticalSection() + 0xb040 bytes ntdll.dll!RtlpDebugPageHeapAllocate() + 0x2f6 bytes ntdll.dll!RtlDebugAllocateHeap() + 0x40 bytes ntdll.dll!RtlAllocateHeapSlowly() + 0x5e898 bytes ntdll.dll!RtlAllocateHeap() - 0x1711a bytes MyProg.exe!malloc(unsigned __int64 size=0) Line 168 C MyProg.exe!operator new(unsigned __int64 size=1) Line 59 + 0x5 bytes C++ ntdll.dll!NtWaitForSingleObject() ntdll.dll!RtlpWaitOnCriticalSection() ntdll.dll!RtlEnterCriticalSection() ntdll.dll!RtlpDebugPageHeapFree() ntdll.dll!RtlDebugFreeHeap() ntdll.dll!RtlFreeHeapSlowly() ntdll.dll!RtlFreeHeap() MyProg.exe!free(void * pBlock=0x000000007e8e4fe0) C BTW, the param values passed to the new operator is not correct here maybe due to optimization. Also, at the same time, I found in the process Explorer, the virtual size of this program is 10GB, but the private bytes and working set is very small (<2GB). We did have some threads using virtualalloc but in a way that commit the memory in the call, and these threads are not blocked. m_pBuf = VirtualAlloc(NULL, m_size, MEM_COMMIT, PAGE_READWRITE); ...... VirtualFree(m_pBuf, 0, MEM_RELEASE); This looks strange to me, seems a lot of virtual space is reserved but not committed, and malloc/free is blocked by lock. I'm guessing if there's any corruptions in the memory/object, so plan to turn on gflag with pageheap to troubleshoot this. Does anyone has similar experience on this before? Could you share with me so I may get more hints? Thanks a lot!

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  • loop is cut one element of the array

    - by Walaa
    The problem is : Write a program that reads a number n and then declares an array of n elements. The program then fills the array with the first n numbers, where each number is two to the power of the previous. Finally, display array’s contents. My code : import java.util.*; public class Q1 { static Scanner scan = new Scanner (System.in); public static void main(String args [] ) { int num; int i = 0; System.out.println("Enter a number :"); num = scan.nextInt(); double [] a=new double[num]; a[0]= num ; for ( ;i<=a.length-1 ; i++) { a[i+1] = Math.pow(2,a[i]); System.out.println((int)(a[i]) ); } } } The error is : ----jGRASP exec: java Q1 Enter a number : 4 4 16 65536 Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4 at Q1.main(Q1.java:16) ----jGRASP wedge2: exit code for process is 1. why it says that? And the number by user printed twice!

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  • deserializing multiple types from a stream

    - by clanier9
    I have a card game program, and so far, the chat works great back and forth over the TCPClient streams between host and client. I want to make it do this with serializing and deserializing so that I can also pass cards between host and client. I tried to create a separate TCPClient stream for the passing of cards but it didn't work and figured it may be easier to keep one TCPClient stream that gets the text messages as well as cards. So I created a class, called cereal, which has the properties for the cards that will help me rebuild the card from an embedded database of cards on the other end. Is there a way to make my program figure out whether a card has been put in the stream or if it's just text in the stream so I can properly deserialize it to a string or to a cereal? Or should I add a string property to my cereal class and when that property is filled in after deserializing to the cereal, i'll know it's just text (if that field is empty after deserializing i'll know it's a card)? I'm thinking a try catch, where it tries to deserialize to a string, and if it fails it will catch and cast as a cereal. Or am I just way off base with this and should choose another route? I'm using visual studio 2011, am using a binaryformatter, and am new to serializing/deserializing.

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  • C# Homework - control structures (for, if)

    - by Freakingout
    I got a homework assignment today: "Create a program that calculates out how many ways you can add three numbers so that they equal 1000." I think this code should work, but it doesn't write out anything. using System; namespace ConsoleApp02 { class Program { public static void Main(string[] args) { for(int a = 0; a < 1000; a++) { for(int b = 0; b < 1000; b++) { for(int c = 0; c < 1000; c++) { for(int puls = a + b + c; puls < 1000; puls++) { if(puls == 1000) { Console.WriteLine("{0} + {1} + {2} = 1000", a, b, c); } } } } } Console.ReadKey(true); } } } What am I doing wrong? Any tips or solution?

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  • Implementing a scrabble trainer (cheater)

    - by bstullkid
    Hello, I've recently been playing alot of online scrabble so I decided to make a program that quickly searches through a dictionary of 200,000+ words with an input of up to any 26 letters. My first attempt was fail as it took a while when you input 8 or more letters (just a basic look through dictionary and cancel out a letter if its found kind of thing), so I made a tree like structure containing only an array of 26 of the same structure and a flag to indicate the end of a word, doing that It can output all possible words in under a second even with an input of 26 characters. But it seems that when I input 12 or more letters with some of the same characters repeated i get duplicates; can anyone see why I would be getting duplicates with this code? (ill post my program at the bottom) Also, the next step once the duplicates are weeded out is to actually be able to input the letters on the game board and then have it calculate the best word you can make on a given board. I am having trouble trying to figure out a good algorithm that can analyze a scrabble board and an input of letters and output a result; the possible words that could be made I have no problem with but actually checking a board efficiently (ie can this word fit here, or here etc... without creating a non dictionary word in the process on some other string of letters) Anyone have a idea for an approach at that? (given a scrabble board, and an input of 7 letters, find all possible valid words or word sets that you can make) lol crap i forgot to email myself the code from my other computer thats in another state... ill post it on monday when I get back there! btw the dictionary im using is sowpods (http://www.calvin.edu/~rpruim/scrabble/ospd3.txt)

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  • Creating collaborative whiteboard drawing application

    - by Steven Sproat
    I have my own drawing program in place, with a variety of "drawing tools" such as Pen, Eraser, Rectangle, Circle, Select, Text etc. It's made with Python and wxPython. Each tool mentioned above is a class, which all have polymorphic methods, such as left_down(), mouse_motion(), hit_test() etc. The program manages a list of all drawn shapes -- when a user has drawn a shape, it's added to the list. This is used to manage undo/redo operations too. So, I have a decent codebase that I can hook collaborative drawing into. Each shape could be changed to know its owner -- the user who drew it, and to only allow delete/move/rescale operations to be performed on shapes owned by one person. I'm just wondering the best way to develop this. One person in the "session" will have to act as the server, I have no money to offer free central servers. Somehow users will need a way to connect to servers, meaning some kind of "discover servers" browser...or something. How do I broadcast changes made to the application? Drawing in realtime and broadcasting a message on each mouse motion event would be costly in terms of performance and things get worse the more users there are at a given time. Any ideas are welcome, I'm not too sure where to begin with developing this (or even how to test it)

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  • error: expected ',' or '...' before numeric constant

    - by goldfrapp04
    Just a Qt Gui Application with QDialog as the Base Class, the simplest type you can expect. I've programmed on Qt for several times but this is the first time I meet this problem... I've added minimal code to the program, and here's the code in dialog.h (which is mostly automatically generated) #ifndef DIALOG_H #define DIALOG_H #include <QDialog> #include <QPixmap> #include "bmp.h" namespace Ui { class Dialog; } class Dialog : public QDialog { Q_OBJECT public: explicit Dialog(QWidget *parent = 0); ~Dialog(); private slots: void on_openButton_clicked(); private: Ui::Dialog *ui; BMP srcImage; QImage compressedImage[3]; }; #endif // DIALOG_H While I edit, the "public:" is underlined and says "unexpected token '('". When I try to build the program, it says in the line "Q_OBJECT", "error: expected ',' or '...' before numeric constant". I'm sure I've defined nothing related to it (to be exact, I defined an N and an n in file bmp.h, both are int). Any idea of what's wrong here? Thanks.

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  • Request for advice about class design, inheritance/aggregation

    - by Lasse V. Karlsen
    I have started writing my own WebDAV server class in .NET, and the first class I'm starting with is a WebDAVListener class, modelled after how the HttpListener class works. Since I don't want to reimplement the core http protocol handling, I will use HttpListener for all its worth, and thus I have a question. What would the suggested way be to handle this: Implement all the methods and properties found inside HttpListener, just changing the class types where it matters (ie. the GetContext + EndGetContext methods would return a different class for WebDAV contexts), and storing and using a HttpListener object internally Construct WebDAVListener by passing it a HttpListener class to use? Create a wrapper for HttpListener with an interface, and constrct WebDAVListener by passing it an object implementing this interface? If going the route of passing a HttpListener (disguised or otherwise) to the WebDAVListener, would you expose the underlying listener object through a property, or would you expect the program that used the class to keep a reference to the underlying HttpListener? Also, in this case, would you expose some of the methods of HttpListener through the WebDAVListener, like Start and Stop, or would you again expect the program that used it to keep the HttpListener reference around for all those things? My initial reaction tells me that I want a combination. For one thing, I would like my WebDAVListener class to look like a complete implementation, hiding the fact that there is a HttpListener object beneath it. On the other hand, I would like to build unit-tests without actually spinning up a networked server, so some kind of mocking ability would be nice to have as well, which suggests I would like the interface-wrapper way. One way I could solve this would be this: public WebDAVListener() : WebDAVListener(new HttpListenerWrapper()) { } public WebDAVListener(IHttpListenerWrapper listener) { } And then I would implement all the methods of HttpListener (at least all those that makes sense) in my own class, by mostly just chaining the call to the underlying HttpListener object. What do you think? Final question: If I go the way of the interface, assuming the interface maps 1-to-1 onto the HttpListener class, and written just to add support for mocking, is such an interface called a wrapper or an adapter?

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  • Is glDisableClientState required?

    - by Shawn
    Every example I've come across for rendering array data is similar to the following code, in which in your drawing loop you first call glEnableClientState for what you will be using and when you are done you call glDisableClientState: void drawScene(void) { glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glBindTexture(GL_TEXTURE_2D, texturePointerA); glTexCoordPointer(2, GL_FLOAT, 0,textureCoordA); glVertexPointer(3, GL_FLOAT, 0, verticesA); glDrawElements(GL_QUADS, numPointsDrawnA, GL_UNSIGNED_BYTE, drawIndicesA); glBindTexture(GL_TEXTURE_2D, texturePointerB); glTexCoordPointer(2, GL_FLOAT, 0,textureCoordB); glVertexPointer(3, GL_FLOAT, 0, verticesB); glDrawElements(GL_QUADS, numPointsDrawnB, GL_UNSIGNED_BYTE, drawIndicesB); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glDisableClientState(GL_VERTEX_ARRAY); } In my program I am always using texture coordinates and vertex arrays, so I thought it was pointless to keep enabling and disabling them every frame. I moved the glEnableClientState outside of the loop like so: bool initGL(void) { //... glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); } void drawScene(void) { glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glBindTexture(GL_TEXTURE_2D, texturePointerA); glTexCoordPointer(2, GL_FLOAT, 0,textureCoordA); glVertexPointer(3, GL_FLOAT, 0, verticesA); glDrawElements(GL_QUADS, numPointsDrawnA, GL_UNSIGNED_BYTE, drawIndicesA); glBindTexture(GL_TEXTURE_2D, texturePointerB); glTexCoordPointer(2, GL_FLOAT, 0,textureCoordB); glVertexPointer(3, GL_FLOAT, 0, verticesB); glDrawElements(GL_QUADS, numPointsDrawnB, GL_UNSIGNED_BYTE, drawIndicesB); } It seems to work fine. My question is: Do I need to call glDisableClientState somewhere; perhaps when the program is closed?. Also, is it ok to do it like this? Is there something I'm missing since everyone else enables and disables each frame?

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  • Cannot Find Symbol Method?

    - by Aaron
    In my driver program, This line gives me cannot find symbol error and I don't know why, the method is clearly defined in the SavingsAccount class, and I can refer to all other methods in my driver program but just not that one, I tried changing the type to double, and etc but still not working. Refer to ** Account acct2 = new SavingsAccount (name); acct2.calculateBalance(); SavingsAccount Class Inherited from Account Class: public class SavingsAccount extends Account { private final short minBalance = 0; private double overdraftFee; private double yearlyInterestRate = 0.02; private double interestAmount; public SavingsAccount (String name) { super(name); } public double withdraw (double amount) { if (accountBalance - amount >= minBalance) { accountBalance -= amount; System.out.print ("Withdraw Successful"); } else { accountBalance -= amount; overdraftFee = accountBalance * (0.10); accountBalance += overdraftFee; System.out.print ("Withdraw Succesful, however overdraft fee of 10% has been applied to your account"); } return accountBalance; } **public void calculateBalance () { interestAmount = (accountBalance * yearlyInterestRate); accountBalance += interestAmount; }** public String toString() { return super.toString() + " Interest Received: " + interestAmount; } } Account class, if needed import java.util.Random; import java.text.NumberFormat; public abstract class Account { protected double accountBalance; protected long accountNumber; protected String accountHolder; public Account (String name) { accountHolder = name; accountBalance = 0; Random accountNo = new Random(); accountNumber = accountNo.nextInt(100000); } public double deposit (double amount) { accountBalance += amount; return accountBalance; } public String toString() { NumberFormat accountBal = NumberFormat.getCurrencyInstance(); return "Account Balance: " + accountBal.format(accountBalance) + "\nAccount Number: " + accountNumber; } public String getAccountHolder() { return accountHolder; } public double getAccountBalance() { return accountBalance; } public abstract double withdraw (double amount); }

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  • How to compare two structure strings in C++

    - by Arvandor
    Ok, so this week in class we're working with arrays. I've got an assignment that wanted me to create a structure for an employee containing an employee ID, first name, last name, and wages. Then it has me ask users for input for 5 different employees all stored in an array of this structure, then ask them for a search field type, then a search value. Lastly, display all the information for all positive search results. I'm still new, so I'm sure it isn't a terribly elegant program, but what I'm trying to do now is figure out how to compare a user entered string with the string stored in the structure... I'll try to give all the pertinent code below. struct employee { int empid, string firstname, string lastname, float wage }; employee emparray[] = {}; employee value[] = {}; //Code for populating emparray and structure, then determine search field etc. cout << "Enter a search value: "; cin >> value.lastname; for(i = 0; i < 5; i++) { if(strcmp(value.lastname.c_str, emparray[i].lastname.c_str) == 0) { output(); } } Which... I thought would work, but it's giving me the following error.. Error 1 error C3867: 'std::basic_string<_Elem,_Traits,_Alloc>::c_str': function call missing argument list; use '&std::basic_string<_Elem,_Traits,_Alloc>::c_str' to create a pointer to member d:\myfile Any thoughts on what's going on? Is there a way to compare two .name notated strings without totally revamping the program? IF you want to drill me on best practices, please feel free, but also please try to solve my particular problem.

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  • Is the C++ compiler optimizer allowed to break my destructor ability to be called multiple times?

    - by sharptooth
    We once had an interview with a very experienced C++ developer who couldn't answer the following question: is it necessary to call the base class destructor from the derived class destructor in C++? Obviously the answer is no, C++ will call the base class destructor automagically anyway. But what if we attempt to do the call? As I see it the result will depend on whether the base class destructor can be called twice without invoking erroneous behavior. For example in this case: class BaseSafe { public: ~BaseSafe() { } private: int data; }; class DerivedSafe { public: ~DerivedSafe() { BaseSafe::~BaseSafe(); } }; everything will be fine - the BaseSafe destructor can be called twice safely and the program will run allright. But in this case: class BaseUnsafe { public: BaseUnsafe() { buffer = new char[100]; } ~BaseUnsafe () { delete[] buffer; } private: char* buffer; }; class DerivedUnsafe { public: ~DerivedUnsafe () { BaseUnsafe::~BaseUnsafe(); } }; the explicic call will run fine, but then the implicit (automagic) call to the destructor will trigger double-delete and undefined behavior. Looks like it is easy to avoid the UB in the second case. Just set buffer to null pointer after delete[]. But will this help? I mean the destructor is expected to only be run once on a fully constructed object, so the optimizer could decide that setting buffer to null pointer makes no sense and eliminate that code exposing the program to double-delete. Is the compiler allowed to do that?

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  • Measuring how "heavily linked" a node is in a graph

    - by Eduardo León
    I have posted this question at MathOverflow.com as well. I am no mathematician and English is not my first language, so please excuse me if my question is too stupid, it is poorly phrased, or both. I am developing a program that creates timetables. My timetable-creating algorithm, besides creating the timetable, also creates a graph whose nodes represent each class I have already programmed, and whose arcs represent which pairs of classes should not be programmed at the same time, even if they have to be reprogrammed. The more "heavily linked" a node is, the more inflexible its associated class is with respect to being reprogrammed. Sometimes, in the middle of the process, there will be no option but to reprogram a class that has already been programmed. I want my program to be able to choose a class that, if reprogrammed, affects the least possible number of other already-programmed classes. That would mean choosing a node in the graph that is "not very heavily linked", subject to some constraints with respect to which nodes can be chosen. EDIT: The question was... Do you know any algorithm that measures how "heavily linked" a node is?

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  • The way cores, processes, and threads work exactly?

    - by unknownthreat
    I need a bit of an advice for understanding how this whole procedure work exactly. If I am incorrect in any part described below, please correct me. In a single core CPU, it runs each process in the OS, jumping around from one process to another to utilize the best of itself. A process can also have many threads, in which the CPU core runs through these threads when it is running on the respective process. Now, on a multiple core CPU, Do the cores run in every process together, or can the cores run separately in different processes at one particular point of time? For instance, you have program A running two threads, can a duo core CPU run both threads of this program? I think the answer should be yes if we are using something like OpenMP. But while the cores are running in this OpenMP-embedded process, can one of the core simply switch to other process? For programs that are created for single core, when running at 100%, why the CPU utilization of each core are distributed? (ex. A duo core CPU of 80% and 20%. The utilization percentage of all cores always add up to 100% for this case.) Do the cores try help each other run each thread of each process in some ways? Frankly, I'm not sure how this works exactly. Any advice is appreciated.

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  • Inline function v. Macro in C -- What's the Overhead (Memory/Speed)?

    - by Jason R. Mick
    I searched Stack Overflow for the pros/cons of function-like macros v. inline functions. I found the following discussion: Pros and Cons of Different macro function / inline methods in C ...but it didn't answer my primary burning question. Namely, what is the overhead in c of using a macro function (with variables, possibly other function calls) v. an inline function, in terms of memory usage and execution speed? Are there any compiler-dependent differences in overhead? I have both icc and gcc at my disposal. My code snippet I'm modularizing is: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = AttractiveTerm * AttractiveTerm; EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); My reason for turning it into an inline function/macro is so I can drop it into a c file and then conditionally compile other similar, but slightly different functions/macros. e.g.: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = pow(SigmaSquared/RadialDistanceSquared,9); EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); (note the difference in the second line...) This function is a central one to my code and gets called thousands of times per step in my program and my program performs millions of steps. Thus I want to have the LEAST overhead possible, hence why I'm wasting time worrying about the overhead of inlining v. transforming the code into a macro. Based on the prior discussion I already realize other pros/cons (type independence and resulting errors from that) of macros... but what I want to know most, and don't currently know is the PERFORMANCE. I know some of you C veterans will have some great insight for me!!

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  • iPhone inputting NSUserDefaults into a UITextField

    - by Rob
    I am writing a program where I where the first time a user runs it - they will have to fill out about 10 different UITextFields. I am trying to save the fields so that on subsequent runs of the program that whatever they previously put will already be displayed in those UITextFields so the wont have to re-input it in - unless they want to edit something in which case they still have that option. I think that I have figured out a good way to save the strings using NSUserDefaults but now I am trying to figure out how to have those fields populate a UITextField - it doesnt seem as easy as if they were UILabels. This is the route I am attempting: // in the viewDidLoad portion. NSUserDefaults *userData = [NSUserDefaults standardUserDefaults]; //Hooks. NSString *placeHolderName = [userData stringForKey:@"name"]; txtName.text = @"%@", placeHolderName; When I do this, it simply displays the '%@' in the textfields. I want whatever variable being held by placeHolderName to be automatically put into that UITextField. Is this possible?

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  • Designing a chain of states

    - by devoured elysium
    I want to model a kind of FSM(Finite State Machine). I have a sequence of states (let's say, from StateA to StateZ). This sequence is called a Chain and is implemented internally as a List. I will add states by the order I want them to run. My purpose is to be able to make a sequence of actions in my computer (for example, mouse clicks). (I know this has been done a zillion times). So a state is defined as a: boolean Precondition() <- Checks to see if for this state, some condition is true. For example, if I want to click in the Record button of a program, in this method I would check if the program's process is running or not. If it is, go to the next state in the chain list, otherwise, go to what was defined as the fail state (generally is the first state of them all). IState GetNextState() <- Returns the next state to evaluate. If Precondition() was sucessful, it should yield the next state in the chain otherwise it should yield the fail state. Run() Simply checks the Precondition() and sets the internal data so GetNextState() works as expected. So, a naive approach to this would be something like this: Chain chain = new Chain(); //chain.AddState(new State(Precondition, FailState, NextState) <- Method structure chain.AddState(new State(new WinampIsOpenCondition(), null, new <problem here, I want to referr to a state that still wasn't defined!>); The big problem is that I want to make a reference to a State that at this point still wasn't defined. I could circumvent the problem by using strings when refrering to states and using an internal hashtable, but isn't there a clearer alternative? I could just pass only the pre-condition and failure states in the constructor, having the chain just before execution put in each state the correct next state in a public property but that seems kind of awkward.

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  • Import CSV to class structure as the user defines

    - by Assimilater
    I have a contact manager program and I would like to offer the feature to import csv files. The problem is that different data sources order the fields in different ways. I thought of programming an interface for the user to tell it the field order and how to handle exceptions. Here is an example line in one of many possible field orders: "ID#","Name","Rank","Address1","Address2","City","State","Country","Zip","Phone#","Email","Join Date","Sponsor ID","Sponsor Name" "Z1234","Call, Anson","STU","1234 E. 6578 S.","","Somecity","TX","United States","012345","000-000-0000","[email protected]","5/24/2010","z12343","Quantum Independence" Notice that in one data field "Name" there is a comma to separate last name and first name and in another there is not. My plan is to have a line for each field (ie ID, Name, City etc.) and a statement "import to" and list box with options like: Don't Import, BusinessJoin Date, First Name, Zip and the program recognizes those as properties of an object... I'd also like the user to be able to record preset field orders so they can re-use them for csv files from the same download source. Then I also need it to check if a record all ready exists (is there a record for Anson Call all ready?) and allow the user to tell it what to do if there is a record (ie mailing address may have changes, so if that field is filled overwrite it, or this mailing address is invalid, leave the current data untouched for this person, overwrite the rest). While I'm capable of coding this...i'm not very excited about it and I'm wondering if there's a tool or set of tools out there to all ready perform most of this functionality... I hope this makes sense...

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