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  • Reduce function calls

    - by Curious2learn
    Hello, I profiled my python program and found that the following function was taking too long to run. Perhaps, I can use a different algorithm and make it run faster. However, I have read that I can also possibly increase the speed by reducing function calls, especially when it gets called repeatedly within a loop. I am a python newbie and would like to learn how to do this and see how much faster it can get. Currently, the function is: def potentialActualBuyers(setOfPeople,theCar,price): count=0 for person in setOfPeople: if person.getUtility(theCar) >= price and person.periodCarPurchased==None: count += 1 return count where setOfPeople is a list of person objects. I tried the following: def potentialActualBuyers(setOfPeople,theCar,price): count=0 Utility=person.getUtility for person in setOfPeople: if Utility(theCar) >= price and person.periodCarPurchased==None: count += 1 return count This, however, gives me an error saying local variable 'person' referenced before assignment Any suggestions, how I can reduce function calls or any other changes that can make the code faster. Again, I am a python newbie and even though I may possibly be able to use a better algorithm, it is still worthwhile learning the answer to the above question. Thanks very much.

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  • Short names versus long names in Windows

    - by normski
    I have some code which gets the short name from a file path, using GetShortNameW(), and then later retrieves the long name view GetLongNameA(). The original file is of the form "C:/ProgramData/My Folder/File.ext" However, following conversion to short, then back to long, the filename becomes "C:/Program Files/My Folder/Filename.ext". The short name is of the form "C:/PROGRA~2/MY_FOL~1/FIL~1.EXT" The short name is being incorrectly resolved. The code compiles using VS 2005 on Windows 7 (I cannot upgrade the project to VS2008) Does anybody have any idea why this might be happening? DWORD pathLengthNeeded = ::GetShortPathNameW(aRef->GetFilePath().c_str(), NULL, 0); if(pathLengthNeeded != 0) { WCHAR* shortPath = new WCHAR[pathLengthNeeded]; DWORD newPathNameLength = ::GetShortPathNameW(aRef->GetFilePath().c_str(), shortPath, pathLengthNeeded); if(newPathNameLength != 0) { UI_STRING unicodePath(shortPath); std::string asciiPath = StringFromUserString(unicodePath); pathLengthNeeded = ::GetLongPathNameA(asciiPath.c_str(),NULL, 0); if(pathLengthNeeded != 0) {// convert it back to a long path if possible. For goodness sake can't we use Unicode throughout?F char* longPath = new char[pathLengthNeeded]; DWORD newPathNameLength = ::GetLongPathNameA(asciiPath.c_str(), longPath, pathLengthNeeded); if(newPathNameLength != 0) { std::string longPathString(longPath, newPathNameLength); asciiPath = longPathString; } delete [] longPath; } SetFullPathName(asciiPath); } delete [] shortPath; }

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  • UDP sockets in ad hoc network (Ubuntu 9.10)

    - by Ekhiotz
    Hi! I am using BSD sockets in Ubuntu 9.10 to send UDP packets in broadcast with the following code: sock_fd = socket(PF_INET,SOCK_DGRAM,IPPROTO_UDP); //sock_fd=socket(AF_INET,SOCK_DGRAM,0); receiver_addr.sin_family = PF_INET; //does not send with broadcast in ad hoc receiver_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST); inet_aton("169.254.255.255",&receiver_addr.sin_addr); receiver_addr.sin_port = htons(port); int broadcast = 1; // this call is what allows broadcast packets to be sent: if (setsockopt(sock_fd, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof broadcast) == -1) { perror("setsockopt (SO_BROADCAST)"); exit(1); } ret=sendto(sock_fd, packet, size, 0,(struct sockaddr*)&receiver_addr,sizeof(receiver_addr)); Note that is not all the code, it is only to have an idea. The program sends all the data with INADDR_BROADCAST if I am connected to an infrastructure wireless network. However, if my laptop is connected to an ad-hoc network, it is able to receive all the data, but not to send it. I have solved the problem using the 169.254.255.255 broadcast address, but I would like to know what is going on. Thank you in advance!

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  • little java help....

    - by jona
    Hi I am doing some practice problems and trying to print a diagonal line like the example below. I have writen the program you see below and I honestly dont understand what I am doing wrong. I m a java beginner and I cant see how to find the error. Example ( If you only see a straight line of stars...then imagine it diagonally....from top left to bottom right) * * * * * code: class Diagonal{ public static void main(String args[]) { int row, col; for(row = 1; row < 6; row++) { for(col = 1; col <= row; col++) { if(col==row){ System.out.print("*"); } else{ System.out.print(""); } System.out.println(); } } } } I am trying to learn for loops because they really confuse me. Another practice is to print a similar diagonal line but this time from right to left. I cant do that without getting this right however :( I believe they will be pretty similar? Above my reasining is this: As long as the column # is the same as the row number the print the line or otherwise leave a blank....what's wrong with how i did it? THANK YOU!

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  • Looking to reimplement build toolchain from bash/grep/sed/awk/(auto)make/configure to something more

    - by wash
    I currently maintain a few boxes that house a loosely related cornucopia of coding projects, databases and repositories (ranging from a homebrew *nix distro to my class notes), maintained by myself and a few equally pasty-skinned nerdy friends (all of said cornucopia is stored in SVN). The vast majority of our code is in C/C++/assembly (a few utilities are in python/perl/php, we're not big java fans), compiled in gcc. Our build toolchain typically consists of a hodgepodge of make, bash, grep, sed and awk. Recent discovery of a Makefile nearly as long as the program it builds (as well as everyone's general anxiety with my cryptic sed and awking) has motivated me to seek a less painful build system. Currently, the strongest candidate I've come across is Boost Build/Bjam as a replacement for GNU make and python as a replacement for our build-related bash scripts. Are there any other C/C++/asm build systems out there worth looking into? I've browsed through a number of make alternatives, but I haven't found any that are developed by names I know aside from Boost's. (I should note that an ability to easily extract information from svn commandline tools such as svnversion is important, as well as enough flexibility to configure for builds of asm projects as easily as c/c++ projects)

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  • Mapping an instance of IList in NHibernate

    - by Martin Kirsche
    I'm trying to map a parent-child relationship using NHibernate (2.1.2), MySql.Data (6.2.2) and MySQL Server (5.1). I figured out that this must be done using a <bag> in the mapping file. I build a test app which is running without yielding any errors and is doing an insert for each entry but somehow the foreign key inside the children table (ParentId) is always empty (null). Here are the important parts of my code... Parent public class Parent { public virtual int Id { get; set; } public virtual IList<Child> Children { get; set; } } <class name="Parent"> <id name="Id"> <generator class="native"/> </id> <bag name="Children" cascade="all"> <key column="ParentId"/> <one-to-many class="Child"/> </bag> </class> Child public class Child { public virtual int Id { get; set; } } <class name="Child"> <id name="Id"> <generator class="native"/> </id> </class> Program using (ISession session = sessionFactory.OpenSession()) { session.Save( new Parent() { Children = new List<Child>() { new Child(), new Child() } }); } Any ideas what I did wrong?

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  • Visualising a 'Smarties' lid using XAML (WPF/Silverlight, Visual Studio/Blend)

    - by Mr. Disappointment
    Hi folks, First off, to clarify something in the title which could well be ambiguous/misleading, I'd like to inform you of my definition of 'Smarties', as I know often products are available all over - only under a different alias. Smarties are a candy product in the UK, little chocolate drops covered in a crispy shell which are distributed in a card tube, this tube used to have a plastic lid/top with an individual letter on the underside (they've taken a more economical approach as of late), the lid/top of the old-style tube is the main element of this question. Familiarisation Link Lid View Link Okay, now with the seller-type pitch out of the way (no, I don't work for Nestlé ;)), hopefully the question is becoming rather clear. Essentially, I'd like to recreate one of these lids using XAML, ultimately to be utilised in a Silverlight web application. That is, I'd like to result in a reusable control, of which the following is true: It looks like a Smarties lid. The colour can be specified. The letter can be specified. The control can be rotated to display either side. The second two seem trivial, but we must bare in mind that the background colour specified will almost, if not always, be the same as the foreground, leaving a visibility issue where the character content is concerned; as for the rotation, I'm hoping this kind of functionality is reasonably available, and acceptable to implement. So, to put this out there, consider a control named SmartiesLid which derives from ToggleButton (appropriate?) and further plotted out using a style in a resource dictionary which applies to it, as follows: <Style TargetType="local:SmartiesLid"> <Setter Property="Background" Value="Red"/> <Setter Property="Foreground" Value="Red"/> <Setter Property="VerticalContentAlignment" Value="Center"/> <Setter Property="HorizontalContentAlignment" Value="Center"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="local:SmartiesLid"> <Grid x:Name="LayoutRoot"> <Grid.ColumnDefinitions> <ColumnDefinition Width=".05*"/> <ColumnDefinition/> <ColumnDefinition/> <ColumnDefinition Width=".05*"/> </Grid.ColumnDefinitions> <Grid.RowDefinitions> <RowDefinition Height=".05*"/> <RowDefinition/> <RowDefinition/> <RowDefinition Height=".05*"/> <RowDefinition Height=".1*"/> </Grid.RowDefinitions> <Ellipse Grid.RowSpan="4" Grid.ColumnSpan="4" Fill="{TemplateBinding Background}" Stroke="Transparent"/> <Ellipse Grid.RowSpan="2" Grid.ColumnSpan="2" Grid.Column="1" Grid.Row="1" Fill="{TemplateBinding Background}" Stroke="Transparent"> <Ellipse.Effect> <DropShadowEffect Direction="280" ShadowDepth="6" BlurRadius="6"/> </Ellipse.Effect> </Ellipse> <TextBlock Grid.RowSpan="2" Grid.ColumnSpan="2" Grid.Column="1" Grid.Row="1" Name="LetterTextBlock" Text="{TemplateBinding Content}" Foreground="{TemplateBinding Foreground}" FontSize="190" HorizontalAlignment="Center" VerticalAlignment="Center"> </TextBlock> <!-- <Path Stretch="Fill" Grid.Row="3" Grid.RowSpan="2" Grid.Column="1" Grid.ColumnSpan="2" Fill="Black" Data="..."> How to craw the lid 'tab'? </Path> --> </Grid> <ControlTemplate.Resources> <TranslateTransform x:Key="IndentTransform" X="10" /> <RotateTransform x:Key="RotateTransform" Angle="0" /> <Storyboard x:Key="MouseOver"> </Storyboard> <Storyboard x:Key="MouseLeave"> </Storyboard> </ControlTemplate.Resources> <ControlTemplate.Triggers> <Trigger Property="IsMouseOver" Value="true"> <Trigger.EnterActions> <BeginStoryboard Storyboard="{StaticResource MouseOver}"/> </Trigger.EnterActions> <Trigger.ExitActions> <BeginStoryboard Storyboard="{StaticResource MouseLeave}"/> </Trigger.ExitActions> </Trigger> <Trigger Property="IsPressed" Value="true"> <Setter TargetName="LayoutRoot" Property="RenderTransform" Value="{StaticResource IndentTransform}"/> </Trigger> <Trigger Property="IsChecked" Value="true"> <Setter TargetName="LayoutRoot" Property="RenderTransform" Value="{StaticResource RotateTransform}"/> </Trigger> <Trigger Property="IsEnabled" Value="False"> <Setter Property="Foreground" Value="Gray"/> <Setter Property="Opacity" Value="0.5"/> </Trigger> </ControlTemplate.Triggers> </ControlTemplate> </Setter.Value> </Setter> </Style> With this in mind, can anyone give input on, in decreasing order of my incompetence in an area: Designing the overall look and feel of the damn thing (I'm no designer, and while I could hack away at this single control for days and potentially get something relatively useful, it's always a gamble). The particular barrier for me here is 'pathing' the tab of the lid, as you will see in the XAML as an element commented out. Should Path be used, or would it be more appropriate to transform a rectangle with rounded corners, or any specific suggestions? Bevelling the individually displayed letter; as detailed above, when the colour of both the foreground and background are the same then this will be invisible if no effects are applied, also for a decent level of realism I'd like to be able to apply such an effect/s. So far use of DropShadow and Balder3DEngine have fulfilled my requirements for graphics in XAML, how achievable is a bevel effect? Rotating the control on mouse-click, that is, showing the opposing face. Is this going to be possible using a style and XAML only for the design? Or is it that ugliness may rear it's head in the form of code-behind to show/hide embedded controls? Should the faces be separate controls and later somehow combined? Allowing the control to size dynamically. I'm supposing I will be able to convert a solid, absolute layout to a nice generic one when I actually have the former in place. Obviously this entails sizing the centralised letter and the lid 'tab', but that's it really, other than keeping the aspect ratio equal (since the ellipses grow nicely with the grid). Any suggestions to approaching this would be greatly appreciated, particularly with a dynamically growing font - I've done that before in a web-imaging scenario using code and System.Drawing, and wouldn't like to approach it in even a similar way. By the way, the reason I specify both WPF and Silverlight is that, from my current knowledge, the inputs being written targeting either of these will be fairly transferable for similar output by the other, albeit not without alterations in either scenario. The resulting application is in fact destined to be written in Silverlight, however, so I don't fancy inviting anything from WPF which will guarantee my only being able to convert 90% of it. I'll go give this little project a start, maybe in Blend(?), hopefully can catch up with some advice shortly. Thanks, Mr. D EDIT: Next question, ought this to be broken up into separate questions? :/

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  • C# Minimize all running windows when application runs

    - by Derek
    I am working on a C# windows form application. How can i edit my code in a way that when more than 2 faces is being detected by my webcam. More information: When "FaceDetectedLabel.Text = "Faces Detected : " + cam.facesdetected.ToString();" becomes Face Detected: 2 or more... How can i do the following: Minimize all program running except my application. Log out of my computer Here is my code: namespace PBD { public partial class MainPage : Form { //declaring global variables private Capture capture; //takes images from camera as image frames public MainPage() { InitializeComponent(); } private void ProcessFrame(object sender, EventArgs arg) { Wrapper cam = new Wrapper(); //show the image in the EmguCV ImageBox WebcamPictureBox.Image = cam.start_cam(capture).Resize(390, 243, Emgu.CV.CvEnum.INTER.CV_INTER_CUBIC).ToBitmap(); FaceDetectedLabel.Text = "Faces Detected : " + cam.facesdetected.ToString(); } private void MainPage_Load(object sender, EventArgs e) { #region if capture is not created, create it now if (capture == null) { try { capture = new Capture(); } catch (NullReferenceException excpt) { MessageBox.Show(excpt.Message); } } #endregion Application.Idle += ProcessFrame; }

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  • Flex : providing data with a PHP Class

    - by Tristan
    Hello, i'm a very new user to flex (never use flex, nor flashbuilder, nor action script before), but i want to learn this langage because of the beautiful RIA and chart it can do. I watched the video on adobe : 1 hour to build your first program but i'm stuck : On the video it says that we have to provide a PHP class for accessing data and i used the example that flash builder gave (with zend framework and mysqli). I never used those ones and it makes a lot to learn if i count zen + mysqli. My question is : can i use a PHP class like this one ? What does flash builder except in return ? i hear that was automatic. example it may be wrong, i'm not very familiar with classes when acessing to database : <?php class DBConnection { protected $server = "localhost"; protected $username = "root"; protected $password = "root"; protected $dbname = "something"; protected $connection; function __construct() { $this->connection = mysql_connect($this->server, $this->username, $this->password); mysql_select_db($this->dbname,$this->connection); mysql_query("SET NAMES 'utf8'", $this->connection); } function query($query) { $result = mysql_query($query, $this->connection); if (!$result) { echo 'request error ' . mysql_error($this->connection); exit; } return $result; } function getAll() { $req = "select * from servers"; $result = query($req) return $result } function num_rows() { return mysql_num_rows($result); } function end() { mysql_close($this->connection); } } ?> Thank you,

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  • Using an SHA1 with Microsoft CAPI

    - by Erik Jõgi
    I have an SHA1 hash and I need to sign it. The CryptSignHash() method requires a HCRYPTHASH handle for signing. I create it and as I have the actual hash value already then set it: CryptCreateHash(cryptoProvider, CALG_SHA1, 0, 0, &hash); CryptSetHashParam(hash, HP_HASHVAL, hashBytes, 0); The hashBytes is an array of 20 bytes. However the problem is that the signature produced from this HCRYPTHASH handle is incorrect. I traced the problem down to the fact that CAPI actually doesn't use all 20 bytes from my hashBytes array. For some reason it thinks that SHA1 is only 4 bytes. To verify this I wrote this small program: HCRYPTPROV cryptoProvider; CryptAcquireContext(&cryptoProvider, NULL, NULL, PROV_RSA_FULL, 0); HCRYPTHASH hash; HCRYPTKEY keyForHash; CryptCreateHash(cryptoProvider, CALG_SHA1, keyForHash, 0, &hash); DWORD hashLength; CryptGetHashParam(hash, HP_HASHSIZE, NULL, &hashLength, 0); printf("hashLength: %d\n", hashLength); And this prints out hashLength: 4 ! Can anyone explain what I am doing wrong or why Microsoft CAPI thinks that SHA1 is 4 bytes (32 bits) instead of 20 bytes (160 bits).

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  • about option buttons in User form

    - by Mars
    I have a question: I need to create a user form that contain that usual OK and Cancel Buttons. It also should contain two sets of Options buttons, each set placed inside a frame. The captions on the first set should be basketball, baseball, football, the captions on the second set should be watch on TV and Go to games. I need to write the event handlers and code in a module so that when the program runs, the user sees the form. If the user makes a couple of choices and clicks OK, he should see a message like "Your favorite sport is basketball, and you usually watch on TV." If the user clicks Cancel, the message "Sorry you don't want to play" should appear. I think I almost have it working, but I don't know why I cannot successfully execute the Macro. My Code is : Option Explicit Private Sub CommandButton2_Click() MsgBox ("sorry if you don't want to play") End Sub Private Sub commandbuttons_Click() Dim optbasket As String, optbaseball As String, optfootball As String Dim optwog As String, optgtg As String Select Case True Case optbasket optbasket = True Case optbaseball optbaseball = True Case optfootball optfootball = True End Select If optwog Then optwog = True Else optgtg = True End If btnok = MsgBox("you favorite sport is " & Frame1.Value & "you usually " & Frame2.Value & ",") End Sub Private Sub OptionButton1_Click() End Sub Private Sub btmcancel_Click() End Sub Private Sub btnok_Click() End Sub Private Sub Frame1_Click() End Sub Private Sub Frame2_Click() End Sub Private Sub optbaseball_Click() End Sub Private Sub optbasketball_Click() End Sub Private Sub optfootball_Click() End Sub Thank you very much!!!

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  • architecture and tools for a remote control application?

    - by slothbear
    I'm working on the design of a remote control application. From my iPhone or a web browser, I'll send a few commands. Soon my home computer will perform the commands and send back results. I know there are remote desktop apps, but I want something programmable, something simpler, and something that I wrote. My current direction is to use Amazon Simple Queue Service (SQS) as the message bus. The iPhone places some messages in a queue. My local Java/JRuby program notices the messages on the queue, performs the work and sends back status via a different queue. This will be a very low-volume application. At $1.00 for a million requests (plus a handful of data transfer charges), Amazon SQS looks a lot more affordable than having my own server of any type. And super reliable, that's important for me too. Are there better/standard toolkits or architectures for this kind of remote control? Cost is not a big issue, but I prefer the tons I learn by doing it myself. I'm moderately concerned about security, but doubt it will be a problem. The list of commands recognized will be very short, and only recognized in specific contexts. No "erase hard drive" stuff. update: I'll probably distribute these programs to some other people who want the same function, but who don't have Amazon SQS accounts. For now, they'll use anonymous access to my queues, with random 80-character queue names.

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  • How to find an embedded platform?

    - by gmagana
    I am new to the locating hardware side of embedded programming and so after being completely overwhelmed with all the choices out there (pc104, custom boards, a zillion option for each board, volume discounts, devel kits, ahhh!!) I am asking here for some direction. Basically, I must find a new motherboard and (most likely) re-implement the program logic. Rewriting this in C/C++/Java/C#/Pascal/BASIC is not a problem for me. so my real problem is finding the hardware. This motherboard will have several other devices attached to it. Here is a summary of what I need to do: Required: 2 RS232 serial ports (one used all the time for primary UI, the second one not continuous) 1 modem (9600+ baud ok) [Modem will be in simultaneous use with only one of the serial port devices, so interrupt sharing with one serial port is OK, but not both] Minimum permanent/long term storage: Whatever O/S requires + 1 MB (executable) + 512 KB (Data files) RAM: Minimal, whatever the O/S requires plus maybe 1MB for executable. Nice to have: USB port(s) Ethernet network port Wireless network Implementation languages (any O/S I will adapt to): First choice Java/C# (Mono ok) Second choice is C/Pascal Third is BASIC Ok, given all this, I am having a lot of trouble finding hardware that will support this that is low in cost. Every manufacturer site I visit has a lot of options, and it's difficult to see if their offering will even satisfy my must-have requirements (for example they sometimes list 3 "serial ports", but it appears that only one of the three is RS232, for example, and don't mention what the other two are). The #1 constraint is cost, #2 is size. Can anyone help me with this? This little task has left me thinking I should have gone for EE and not CS :-). EDIT: A bit of background: This is a system currently in production, but the original programmer passed away, and the current hardware manufacturer cannot find hardware to run the (currently) DOS system, so I need to reimplement this in a modern platform. I can only change the programming and the motherboard hardware.

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  • how to fix my error saying expected expression before 'else'

    - by user292489
    this program intended to read a .txt, a set of numbers, file and wwrite to another two .txt files called even amd odd as follows: #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { int i=0,even,odd; int number[i]; // check to make sure that all the file names are entered if (argc != 3) { printf("Usage: executable in_file output_file\n"); exit(0); } FILE *dog = fopen(argv[1], "r"); FILE *feven= fopen(argv[2], "w"); FILE *fodd= fopen (argv[3], "w"); // check whether the file has been opened successfully if (dog == NULL) { printf("File %s cannot open!\n", argv[1]); exit(0); } //odd = fopen(argv[2], "w"); { if (i%2!=1) i++;} fprintf(feven, "%d", even); fscanf(dog, "%d", &number[i]); else { i%2==1; i++;} fprintf(fodd, "%d", odd); fscanf(dog, "%d", &number[i]); fclose(feven); fclose(fodd);

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  • Hashing the state of a complex object in .NET

    - by Jan
    Some background information: I am working on a C#/WPF application, which basically is about creating, editing, saving and loading some data model. The data model contains of a hierarchy of various objects. There is a "root" object of class A, which has a list of objects of class B, which each has a list of objects of class C, etc. Around 30 classes involved in total. Now my problem is that I want to prompt the user with the usual "you have unsaved changes, save?" dialog, if he tries to exit the program. But how do I know if the data in current loaded model is actually changed? There is of course ways to solve this, like e.g. reloading the model from file and compare against the one in memory value by value or make every UI control set a flag indicating the model has been changed. Now instead, I want to create a hash value based on the model state on load and generate a new value when the user tries to exit, and compare those two. Now the question: So inspired of that, I was wondering if there exist some way to generate a hash value from the (value)state of some arbitrary complex object? Preferably in a generic way, e.g. no need to apply attributes to each involved class/field. One idea could be to use some of .NET's serialization functionality (assuming it will work out-of-the-box in this case) and apply a hash function to the content of the resulting file. However, I guess there exist some more suitable approach. Thanks in advance.

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  • Declaration, allocation and assignment of an array of pointers to function pointers

    - by manneorama
    Hello Stack Overflow! This is my first post, so please be gentle. I've been playing around with C from time to time in the past. Now I've gotten to the point where I've started a real project (a 2D graphics engine using SDL, but that's irrelevant for the question), to be able to say that I have some real C experience. Yesterday, while working on the event system, I ran into a problem which I couldn't solve. There's this typedef, //the void parameter is really an SDL_Event*. //but that is irrelevant for this question. typedef void (*event_callback)(void); which specifies the signature of a function to be called on engine events. I want to be able to support multiple event_callbacks, so an array of these callbacks would be an idea, but do not want to limit the amount of callbacks, so I need some sort of dynamic allocation. This is where the problem arose. My first attempt went like this: //initial size of callback vector static const int initial_vecsize = 32; //our event callback vector static event_callback* vec = 0; //size static unsigned int vecsize = 0; void register_event_callback(event_callback func) { if (!vec) __engine_allocate_vec(vec); vec[vecsize++] = func; //error here! } static void __engine_allocate_vec(engine_callback* vec) { vec = (engine_callback*) malloc(sizeof(engine_callback*) * initial_vecsize); } First of all, I have omitted some error checking as well as the code that reallocates the callback vector when the number of callbacks exceed the vector size. However, when I run this code, the program crashes as described in the code. I'm guessing segmentation fault but I can't be sure since no output is given. I'm also guessing that the error comes from a somewhat flawed understanding on how to declare and allocate an array of pointers to function pointers. Please Stack Overflow, guide me.

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  • Application design question, best approach?

    - by Jamie Keeling
    Hello, I am in the process of designing an application that will allow you to find pictures (screen shots) made from certain programs. I will provide the locations of a few of the program in the application itself to get the user started. I was wondering how I should go about adding new locations as the time goes on, my first thought was simply hard coding it into the application but this will mean the user has to reinstall it to make the changes take affect. My second idea was to use an XML file to contain all the locations as well as other data, such as the name of the application. This also means the user can add their own locations if they wish as well as sharing them over the internet. The second option seemed the best approach but then I had to think how would it be managed on the users computer. Ideally I'd like just a single .exe without the reliance on any external files such as the XML but this would bring me back to point one. Would it be best to simply use the ClickOnce deployment to create an entry in the start menu and create a folder containing the .exe and the file names? Thanks for the feedback, I don't want to start implementing the application until the design is nailed.

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  • SCJP Book, IO section: Is this a typo or is there a reason it would look like this?

    - by iamchuckb
    My question is about line 4, where the new PrintWriter is created with the constructor taking the FileWriter fw as a parameter. I don't understand the use of chaining the BufferedWriter bw to FileWriter if it isn't used later on in the actual writing. Can Java apply chaining in a way that bw still somehow affects the rest of the program? 16. try { 17. FileWriter fw = new FileWriter(test); 18. BufferedWriter bw = new BufferedWriter(fw, 1024); 19. PrintWriter out = new PrintWriter(fw); 20. out.println("<html><body><h1>"); 21. out.println(args[0]); 22. out.println("</h1></body></html>"); 23. out.close(); 24. bw.close(); 25. fw.close(); 26. }catch(IOException e) { 27. e.printStackTrace(); 28. } I think it is probably a typo and they meant to use bw as the parameter for PrintWriter out but like the title says, I'm new to this. Thanks to all in advance.

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  • c++ use of winmain()

    - by Jack
    Hi, I just started learning programming for windows in c++. I had this crazy image, that win32 programming is based on calling windows functions and sending parameters to and from them. Like, when you want to create window, you call some win32 function that handles windows GUI and say "Hi, please, create me new window, 100 x 100 px, with two buttons", and that GUI function says "Hi, no problem, when something happends, like user clicks one button, I will change this variable xy located in this location". So, I thought that it will be very similiar to console programming. But the very first instruction surprised me. I always thought that every program executes main() function first. So, when I launch app, windows stores some parameters on top of stack and run that application. So I assumed that initializing main() is just a c++ way to tell the compiler where the first instruction should be. But in win32 programming, there is function called winmain() which starts first. So I am little confused. I thought it´s rule that compiler must have main() to start with, that main just defines where ti start, like some start point identifier. So, please, why is there winmain() function instead of main()? When I thought that C++ programming is as logical as assembler, it confuses me once again.

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  • c++ use of winmain()

    - by Jack
    Hi, I just started learning programming for windows in c++. I had this crazy image, that win32 programming is based on calling windows functions and sending parameters to and from them. Like, when you want to create window, you call some win32 function that handles windows GUI and say "Hi, please, create me new window, 100 x 100 px, with two buttons", and that GUI function says "Hi, no problem, when something happends, like user clicks one button, I will change this variable xy located in this location". So, I thought that it will be very similiar to console programming. But the very first instruction surprised me. I always thought that every program executes main() function first. So, when I launch app, windows stores some parameters on top of stack and run that application. So I assumed that initializing main() is just a c++ way to tell the compiler where the first instruction should be. But in win32 programming, there is function called winmain() which starts first. So I am little confused. I thought it´s rule that compiler must have main() to start with, that main just defines where ti start, like some start point identifier. So, please, why is there winmain() function instead of main()? When I thought that C++ programming is as logical as assembler, it confuses me once again.

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  • Producer consumer with qualifications

    - by tgguy
    I am new to clojure and am trying to understand how to properly use its concurrency features, so any critique/suggestions is appreciated. So I am trying to write a small test program in clojure that works as follows: there 5 producers and 2 consumers a producer waits for a random time and then pushes a number onto a shared queue. a consumer should pull a number off the queue as soon as the queue is nonempty and then sleep for a short time to simulate doing work the consumers should block when the queue is empty producers should block when the queue has more than 4 items in it to prevent it from growing huge Here is my plan for each step above: the producers and consumers will be agents that don't really care for their state (just nil values or something); i just use the agents to send-off a "consumer" or "producer" function to do at some time. Then the shared queue will be (def queue (ref [])). Perhaps this should be an atom though? in the "producer" agent function, simply (Thread/sleep (rand-int 1000)) and then (dosync (alter queue conj (rand-int 100))) to push onto the queue. I am thinking to make the consumer agents watch the queue for changes with add-watcher. Not sure about this though..it will wake up the consumers on any change, even if the change came from a consumer pulling something off (possibly making it empty) . Perhaps checking for this in the watcher function is sufficient. Another problem I see is that if all consumers are busy, then what happens when a producer adds something new to the queue? Does the watched event get queued up on some consumer agent or does it disappear? see above I really don't know how to do this. I heard that clojure's seque may be useful, but I couldn't find enough doc on how to use it and my initial testing didn't seem to work (sorry don't have the code on me anymore)

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  • C++ data member initializer is not allowed

    - by user1435915
    I totally new to C++ so bear with me. I want to make a class with a static array, and access to this array from the main. Here is what i want to do in C#. namespace ConsoleApplication1 { class Program { static void Main(string[] args) { Class a = new Class(); Console.WriteLine(a.arr[1]); } } } ===================== namespace ConsoleApplication1 { class Class { public static string[] s_strHands = new string[]{"one","two","three"}; } } Here is what i have tried: // justfoolin.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <string> #include <iostream> using namespace std; class Class { public: static string arr[3] = {"one", "two", "three"}; }; int _tmain(int argc, _TCHAR* argv[]) { Class x; cout << x.arr[2] << endl; return 0; } But i got: IntelliSense: data member initializer is not allowed

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  • Disposing ActiveX resources owned by another thread

    - by Stefan Teitge
    I've got a problem problem with threading and disposing resources. I've got a C# Windows Forms application which runs expensive operation in a thread. This thread instantiates an ActiveX control (AxControl). This control must be disposed as it uses a high amount of memory. So I implemented a Dispose() method and even a destructor. After the thread ends the destructor is called. This is sadly called by the UI thread. So invoking activexControl.Dispose(); fails with the message "COM object that has been separated from its underlying RCW", as the object belongs to another thread. How to do this correctly or is it just a bad design I use? (I stripped the code down to the minimum including removing any safety concerns.) class Program { [STAThread] static void Main() { // do stuff here, e.g. open a form new Thread(new ThreadStart(RunStuff); // do more stuff } private void RunStuff() { DoStuff stuff = new DoStuff(); stuff.PerformStuff(); } } class DoStuff : IDisposable { private AxControl activexControl; DoStuff() { activexControl = new AxControl(); activexControl.CreateControl(); // force instance } ~DoStuff() { Dispose(); } public void Dispose() { activexControl.Dispose(); } public void PerformStuff() { // invent perpetuum mobile here, takes time } }

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  • Best way to catch a WCF exception in Silverlight?

    - by wahrhaft
    I have a Silverlight 2 application that is consuming a WCF service. As such, it uses asynchronous callbacks for all the calls to the methods of the service. If the service is not running, or it crashes, or the network goes down, etc before or during one of these calls, an exception is generated as you would expect. The problem is, I don't know how to catch this exception. Because it is an asynchronous call, I can't wrap my begin call with a try/catch block and have it pick up an exception that happens after the program has moved on from that point. Because the service proxy is automatically generated, I can't put a try/catch block on each and every generated function that calls EndInvoke (where the exception actually shows up). These generated functions are also surrounded by External Code in the call stack, so there's nowhere else in the stack to put a try/catch either. I can't put the try/catch in my callback functions, because the exception occurs before they would get called. There is an Application_UnhandledException function in my App.xaml.cs, which captures all unhandled exceptions. I could use this, but it seems like a messy way to do it. I'd rather reserve this function for the truly unexpected errors (aka bugs) and not end up with code in this function for every circumstance I'd like to deal with in a specific way. Am I missing an obvious solution? Or am I stuck using Application_UnhandledException? [Edit] As mentioned below, the Error property is exactly what I was looking for. What is throwing me for a loop is that the fact that the exception is thrown and appears to be uncaught, yet execution is able to continue. It triggers the Application_UnhandledException event and causes VS2008 to break execution, but continuing in the debugger allows execution to continue. It's not really a problem, it just seems odd.

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  • Using mod-rewrite to conditionally select existing file in a subdirectory based on Host header?

    - by Kevin Hakanson
    I'm working through a problem where I want to select a different static content file based on the incoming Host header. The simple example is a mapping from URLs to files like this: www.example.com/images/logo.gif - \images\logo.gif skin2.example.com/images/logo.gif - \images\skin2\logo.gif skin3.example.com/images/logo.gif - \images\skin3logo.gif I have this working with the following RewriteRules, but I don't like how I have to repeat myself so much. Each host has the same set of rules, and each RewriteCond and RewriteRule has the same path. I'd like to use the RewriteMap, but I don't know how to use it to map the %{HTTP_HOST} to the path. <VirtualHost *:80> DocumentRoot "C:/Program Files/Apache Software Foundation/Apache2.2/htdocs" ServerName www.example.com ServerAlias skin2.example.com ServerAlias skin3.example.com RewriteEngine On RewriteCond %{HTTP_HOST} skin2.example.com RewriteCond %{DOCUMENT_ROOT}$1/skin2/$2 -f RewriteRule ^(.*)/(.*) $1/skin2/$2 [L] RewriteCond %{HTTP_HOST} skin3.example.com RewriteCond %{DOCUMENT_ROOT}$1/skin3/$2 -f RewriteRule ^(.*)/(.*) $1/skin3/$2 [L] </VirtualHost> The concept behind the rules is if the same filename exists in a subdirectory for that host, use it instead of the direct targeted file. This uses host based subdirectories at the lowest level, and not a top level subdirectory to separate content.

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