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  • RIM blackberry Record 3GP video

    - by pankaj_shukla
    Hi All, I am writing an application that can record a 3GP video. I have tried both MMAPI and Invoke API. But have following issues. Using MMAPI: 1. When I record to stream, It records video in RIMM streaming format. when I try to play this video player gives error "Unsupported media format.". 2. When I record to a file. It will create a file of size 0. Using Invoke API: 1. In MMS mode it does not allow to record a video more than 30 seconds. 2. In Normal mode size of the file is very large. 3. Once I invoke camera application I do not have any control on application. Here is my source code: _player = javax.microedition.media.Manager .createPlayer("capture://video?encoding=video/3gpp&mode=mms"); // I have tried every encoding returns from System.getProperty("video.encodings") method _player.realize(); _videoControl = (VideoControl) _player.getControl("VideoControl"); _recordControl = (RecordControl) _player.getControl("RecordControl"); _volumeControl = (VolumeControl) _player.getControl("VolumeControl"); String videoPath = System.getProperty("fileconn.dir.videos"); if (videoPath == null) { videoPath = "file:///store/home/user/videos/"; } _recordControl.setRecordLocation(videoPath + "RecordedVideo.3gp"); _player.addPlayerListener(this); Field videoField = (Field) _videoControl.initDisplayMode( VideoControl.USE_GUI_PRIMITIVE, "net.rim.device.api.ui.Field"); _videoControl.setVisible(true); add(videoField); _player.start(); ON start menu item Selection: try { _recordControl.startRecord(); } catch (Exception e) { _player.close(); showAlert(e.getClass() + " " + e.getMessage()); } On stop menuItem selection: try { _recordControl.commit(); } catch (Exception e) { _player.close(); showAlert(e.getClass() + " " + e.getMessage()); } Please let me if I am doing something wrong. Thanks, Pankaj

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  • Robust way to save/load objects with dependencies?

    - by mrteacup
    I'm writing an Android game in Java and I need a robust way to save and load application state quickly. The question seems to apply to most OO languages. To understand what I need to save: I'm using a Strategy pattern to control my game entities. The idea is I have a very general Entity class which e.g. stores the location of a bullet/player/enemy and I then attach a Behaviour class that tells the entity how to act: class Entiy { float x; float y; Behavior b; } abstract class Behavior { void update(Entity e); {} // Move about at a constant speed class MoveBehavior extends Behavior { float speed; void update ... } // Chase after another entity class ChaseBehavior extends Behavior { Entity target; void update ... } // Perform two behaviours in sequence class CombineBehavior extends Behavior { Behaviour a, b; void update ... } Essentially, Entity objects are easy to save but Behaviour objects can have a semi-complex graph of dependencies between other Entity objects and other Behaviour objects. I also have cases where a Behaviour object is shared between entities. I'm willing to change my design to make saving/loading state easier, but the above design works really well for structuring the game. Anyway, the options I've considered are: Use Java serialization. This is meant to be really slow in Android (I'll profile it sometime). I'm worried about robustness when changes are made between versions however. Use something like JSON or XML. I'm not sure how I would cope with storing the dependencies between objects however. Would I have to give each object a unique ID and then use these IDs on loading to link the right objects together? I thought I could e.g. change the ChaseBehaviour to store a ID to an entity, instead of a reference, that would be used to look up the Entity before performing the behaviour. I'd rather avoid having to write lots of loading/saving code myself as I find it really easy to make mistakes (e.g. forgetting to save something, reading things out in the wrong order). Can anyone give me any tips on good formats to save to or class designs that make saving state easier?

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  • Illegal Instruction When Programming C++ on Linux

    - by remagen
    Heyo, My program, which does exactly the same thing every time it runs (moves a point sprite into the distance) will randomly fail with the text on the terminal 'Illegal Instruction'. My googling has found people encountering this when writing assembly which makes sense because assembly throws those kinds of errors. But why would g++ be generating an illegal instruction like this? It's not like I'm compiling for Windows then running on Linux (which even then, as long as both are on x86 shouldn't AFAIK cause an Illegal Instruction). I'll post the main file below. I can't reliably reproduce the error. Although, if I make random changes (add a space here, change a constant there) that force a recompile I can get a binary which will fail with Illegal Instruction every time it is run, until I try setting a break point, which makes the illegal instruction 'dissapear'. :( #include <stdio.h> #include <stdlib.h> #include <GL/gl.h> #include <GL/glu.h> #include <SDL/SDL.h> #include "Screen.h" //Simple SDL wrapper #include "Textures.h" //Simple OpenGL texture wrapper #include "PointSprites.h" //Simple point sprites wrapper double counter = 0; /* Here goes our drawing code */ int drawGLScene() { /* These are to calculate our fps */ static GLint T0 = 0; static GLint Frames = 0; /* Move Left 1.5 Units And Into The Screen 6.0 */ glLoadIdentity(); glTranslatef(0.0f, 0.0f, -6); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); glEnable(GL_POINT_SPRITE_ARB); glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE); glBegin( GL_POINTS ); /* Drawing Using Triangles */ glVertex3d(0.0,0.0, 0); glVertex3d(1.0,0.0, 0); glVertex3d(1.0,1.0, counter); glVertex3d(0.0,1.0, 0); glEnd( ); /* Finished Drawing The Triangle */ /* Move Right 3 Units */ /* Draw it to the screen */ SDL_GL_SwapBuffers( ); /* Gather our frames per second */ Frames++; { GLint t = SDL_GetTicks(); if (t - T0 >= 50) { GLfloat seconds = (t - T0) / 1000.0; GLfloat fps = Frames / seconds; printf("%d frames in %g seconds = %g FPS\n", Frames, seconds, fps); T0 = t; Frames = 0; counter -= .1; } } return 1; } GLuint objectID; int main( int argc, char **argv ) { Screen screen; screen.init(); screen.resize(800,600); LoadBMP("./dist/Debug/GNU-Linux-x86/particle.bmp"); InitPointSprites(); while(true){drawGLScene();} }

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  • Twisted + SQLAlchemy and the best way to do it.

    - by Khorkrak
    So I'm writing yet another Twisted based daemon. It'll have an xmlrpc interface as usual so I can easily communicate with it and have other processes interchange data with it as needed. This daemon needs to access a database. We've been using SQL Alchemy in place of hard coding SQL strings for our latest projects - those mostly done for web apps in Pylons. We'd like to do the same for this app and re-use library code that makes use of SQL Alchemy. So what to do? Well of course since that library was written for use in a Pylons app it's all the straight-forward blocking style code that everyone is accustomed to and all of the non-blocking is magically handled by Pylons via threading, thread locals, scoped sessions and so on. So now for Twisted I guess I'm a bit stuck. I could: Just write the sql I need directly if it's minimal and use the dbapi pool in twisted to do runInteractions etc when I need to hit the db. Use the objects and inherently blocking methods in our library and block now and then in my Twisted daemon. Bah. Use sAsync which was last updated in 2008 and kind of reuse the models we have defined already but not really and it does address code that needs to work in Pylons either. Does that even work with the latest version SQL Alchemy? Who knows. That project looked great though - why was it apparently abandoned? Spawn a separate subprocess and have it deal with the library code and all it's blocking, the results being returned back to my daemon when ready as objects marshalled via YAML over xmlrpc. Use deferToThread and then expunge the objects returned having made sure to do eager loads so that I have all my stuff that I might need. Seems kind of ugha to me. I'm also stuck using Python 2.5.4 atm so no 2.6 yet and I don't think I can just do an import from future to get access to the cool new multiprocessing module stuff in there. That's OK though I guess as we've got dealing with interprocess communication down pretty well. So I'm leaning towards option 4 mostly as that would avoid the mortal sin of logic duplication with option 1 while also staying the heck away from threads. Any better ideas?

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  • Where are the function literals c++?

    - by academicRobot
    First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one.

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  • C: reading file and populating struct

    - by deostroll
    Hi, I have a structure with the following definition: typedef struct myStruct{ int a; char* c; int f; } OBJECT; I am able to populate this object and write it to a file. However I am not able to read the char* c value in it...while trying to read it, it gives me a segmentation fault error. Is there anything wrong with my code: //writensave.c #include "mystruct.h" #include <stdio.h> #include <string.h> #define p(x) printf(x) int main() { p("Creating file to write...\n"); FILE* file = fopen("struct.dat", "w"); if(file == NULL) { printf("Error opening file\n"); return -1; } p("creating structure\n"); OBJECT* myObj = (OBJECT*)malloc(sizeof(OBJECT)); myObj->a = 20; myObj->f = 45; myObj->c = (char*)calloc(30, sizeof(char)); strcpy(myObj->c, "This is a test"); p("Writing object to file...\n"); fwrite(myObj, sizeof(OBJECT), 1, file); p("Close file\n"); fclose(file); p("End of program\n"); return 0; } Here is how I am trying to read it: //readnprint.c #include "mystruct.h" #include <stdio.h> #define p(x) printf(x) int main() { FILE* file = fopen("struct.dat", "r"); char* buffer; buffer = (char*) malloc(sizeof(OBJECT)); if(file == NULL) { p("Error opening file"); return -1; } fread((void *)buffer, sizeof(OBJECT), 1, file); OBJECT* obj = (OBJECT*)buffer; printf("obj->a = %d\nobj->f = %d \nobj->c = %s", obj->a, obj->f, obj->c); fclose(file); return 0; }

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  • Replace text in XSL using wildcards

    - by JosephThomas
    This is similar to an earlier problem I was having which you guys solved in less than a day. I am working with XML files that are generated by a digital video camera. The camera allows the user to save all of the camera's settngs to an SD card so that the settings can be recalled or loaded into another camera. The XSL stylesheet I am writing will allow users to view the camera's settings, as saved to the SD card in a web browser. While most of the values in the XML file -- as formatted by my stylesheet -- make sense to humans, some do not. What I would like to do is have the stylesheet display text that is based on the value in the XML file but more easily understood by humans. A typical value that can be written to the XML file is "_23_970" which represents the camera's frame rate. This would be better displayed as 23.970 (or 023.970). The first underscore is a sort of place holder to make a space for values over 099.999. The second underscore, obviously represents the decimal. My previous (similar) question involved replacing predictable text, and the solution was matching templates. In this case, however, the camera can be set at any one of 119,999 frame rates (I think I did that math correctly). The approach, I would guess, is to pass a value to the displayed webpage that keeps the numeric values (each digit), replaces the second underscore with a decimal, and replaces the first underscore with either an nbsp or a zero (whichever is easier). If the first character in the string is a "1" (the camera can run at frame rates up to 120.000) then the one should be passed on to the page displayed by the stylesheet. I have read other posts here regarding wildcards, but couldn't find one that answered this question. EDIT: Sorry for leaving out important info. I fared better on my first try at asking a question! I guess I got complacent. Anyhow . . . I should have shown you the code that displays the text in the XSL file as is: <tr> <xsl:for-each select="Settings/Groups/Recording"> <tr><td class="title_column">Frame Rate</td><td><xsl:value-of select="RecOutLinkSpeed"/></td></tr> </xsl:for-each> </tr> I should also have given you the URL for the sample file I have been working with: http://josephthomas.info/Alexa/Setup_120511_140322.xml

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  • to write log files in two different files

    - by Sun
    my application run on customized client framework,the client framework used log4net to log their own log files. we are(our application) has to use the same log4net to log our log files in our own path(say our customized path). currently the our log files are created but log are not writing in that file.it is writting in the client framework log file. searched lot of sites the link http://stackoverflow.com/questions/308436/log4net-programmatcially-specify-multiple-loggers-with-multiple-file-appenders helped me to configure the log4net config programatically, still im log statemets are not written in my log file.the code used as below public class TraceLog { private string message = string.Empty; private static ILog ILogger = null; private static TraceLog instance = new TraceLog(); private TraceLog() { SetLevel("Log4net.MainForm", "ALL"); AddAppender("Log4net.MainForm", CreateFileAppender("FileAppender", "C:\\mylog.log")); } public static TraceLog Instance { get { return instance; } } public void Debug(string logMessage) { message = PrepareLog(logMessage); ILogger.Debug(message); } protected string PrepareLog(string logMessage) { string message = GetFileMethodLineNumberInfo(); message += logMessage; return message; } protected string GetFileMethodLineNumberInfo() { StackTrace stackTrace = new StackTrace(true); // The position 3 is relative to the index of the specified method StackFrame stackFrame = stackTrace.GetFrame(3); return (stackFrame.GetMethod().DeclaringType.Name + "/" + stackFrame.GetMethod().Name + "/" + stackFrame.GetFileLineNumber() + ":"); } private static void SetLevel(string loggerName, string levelName) { ILogger = LogManager.GetLogger(loggerName); log4net.Repository.Hierarchy.Logger l = (log4net.Repository.Hierarchy.Logger)ILogger.Logger; l.Level = l.Hierarchy.LevelMap[levelName]; } private static void AddAppender(string loggerName, IAppender appender) { ILogger = LogManager.GetLogger(loggerName); log4net.Repository.Hierarchy.Logger l = (log4net.Repository.Hierarchy.Logger)ILogger.Logger; l.AddAppender(appender); } private static IAppender CreateFileAppender(string name, string fileName) { FileAppender appender = new FileAppender(); appender.Name = name; appender.File = fileName; appender.AppendToFile = true; //PatternLayout layout = new PatternLayout(); //layout.ConversionPattern = "%d [%t] %-5p %c [%x] - %m%n"; //layout.ActivateOptions(); //appender.Layout = layout; appender.ActivateOptions(); return appender; } } } anyone pls help how to solve this

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  • Database Schema Versioning Strategies

    - by Jack Ryan
    I work on a project that uses a reasonably large database, the live version weighing in at somewhere around 60-80GB. The live database is the only real definitive source of our schema, and because of its size duplicating this database is too slow to be done often. This means we have ended up developing our database schema in a pretty ad hoc way, using sql compare to migrate changes from dev dbs to the live system, and only wiping our dev dbs every month or two. I am hoping to get some pointers on how to improve our database development work flow so that we have a little more control. Some things to think about: Currently nobody is really in charge of the database schema, all developers can change it if they need to, though generally these decisions are talked about before they are done. There are stored procedures, functions, and views in the database. These should probably be dumped to files so they can be reloaded on every build. Schema changes should probably be checked in as scripts. We have started to do this recently. However all our scripts must then be numbered (because there may be dependencies between them), and must be re runnable (because our build script currently runs them all in order). This makes them hard to read because they are full of conditionals that check whether tables or columns already exist. This is a step that is often forgotten by developers. Getting a new database should be quick and easy. This is currently a big problem, it takes several hours to get a copy of last nights backup and restore it onto a dev machine. Some mechanism needs to be in place to allow developers to update static data. We have tables that contain data that is never updated through the application, but does potentially need to be changed when we do a new release (often this drives dropdowns). The whole thing needs to be runnable as part of a build script. Are there any tools that can be used to help to do this? Eventually I would like to be at a point where a new DB can be built from scratch without copying any data from the live system. I don't mind writing some scripts to glue all the steps together but each part should be easily editable so that we continue to use it rather than make changes directly on DBs.

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  • Conceptual inheritance implementation

    - by TheSENDER
    Hi there, I'm writing a spatial data structure and I have a doubt about what's the best NODE implementation. According to my design I have an abstract node entity and three classes which inherit from it: EMPTYNODE, FULLNODE, INTERNALNODE. The first one has no particular data. The second one has 1 reference to a generic element. The third one has 2 references to other nodes. I have found several ways to implement this situation (that I have already coded) but I can't decide what's the best. The first solution that I have found is to use a single class Node that potentially performs all the operation in this way: private static class Node { private Elem elem = null; private Node left = null, right = null; public Elem getElem() { assert isFull(); return elem; } public boolean isEmpty() { return elem == null && left == null; } public boolean isFull() { return elem != null; } public boolean isInternal() { return elem == null && left != null; } } The second solution is to write an explicit division by classes where every class offers only its methods. Obviously in this way we are obliged to perform several casts to the node objects. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); } private static class FullNode extends Node{ private ITriangle elem; @Override public boolean isEmpty() { return false; } @Override public final boolean isFull() { return true; } @Override public final boolean isInternal() { return false; } public Elem getElem() { return elem; } } The third one solution is to use the inheritance allowing every classes to offer all the methods, but the object type should by check by "isEmpty()" and similar methods. In case of wrong call we'll throw an exception. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); public abstract Elem getElem(); } private static class Empty extends Node{ @Override public boolean isEmpty() { return true; } @Override public final boolean isFull() { return false; } @Override public final boolean isInternal() { return false; } @Override public Elem getElem() { throw new AssertionError(); } } What do you think about these three solutions? Which one would you use? Any other ideas? Thanks for your help. Every idea will be appreciated.

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  • Representation of a DateTime as the local to remote user

    - by TwoSecondsBefore
    Hello! I was confused in the problem of time zones. I am writing a web application that will contain some news with dates of publication, and I want the client to see the date of publication of the news in the form of corresponding local time. However, I do not know in which time zone the client is located. I have three questions. I have to ask just in case: does DateTimeOffset.UtcNow always returns the correct UTC date and time, regardless of whether the server is dependent on daylight savings time? For example, if the first time I get the value of this property for two minutes before daylight savings time (or before the transition from daylight saving time back) and the second time in 2 minutes after the transfer, whether the value of properties in all cases differ by only 4 minutes? Or here require any further logic? (Question #1) Please see the following example and tell me what you think. I posted the news on the site. I assume that DateTimeOffset.UtcNow takes into account the time zone of the server and the daylight savings time, and so I immediately get the correct UTC server time when pressing the button "Submit". I write this value to a MS SQL database in the field of type datetime2(0). Then the user opens a page with news and no matter how long after publication. This may occur even after many years. I did not ask him to enter his time zone. Instead, I get the offset of his current local time from UTC using the javascript function following way: function GetUserTimezoneOffset() { var offset = new Date().getTimezoneOffset(); return offset; } Next I make the calculation of the date and time of publication, which will show the user: public static DateTime Get_Publication_Date_In_User_Local_DateTime( DateTime Publication_Utc_Date_Time_From_DataBase, int User_Time_Zone_Offset_Returned_by_Javascript) { int userTimezoneOffset = User_Time_Zone_Offset_Returned_by_Javascript; // For // example Javascript returns a value equal to -300, which means the // current user's time differs from UTC to 300 minutes. Ie offset // is UTC +6. In this case, it may be the time zone UTC +5 which // currently operates summer time or UTC +6 which currently operates the // standard time. // Right? (Question #2) DateTimeOffset utcPublicationDateTime = new DateTimeOffset(Publication_Utc_Date_Time_From_DataBase, new TimeSpan(0)); // get an instance of type DateTimeOffset for the // date and time of publication for further calculations DateTimeOffset publication_DateTime_In_User_Local_DateTime = utcPublicationDateTime.ToOffset(new TimeSpan(0, - userTimezoneOffset, 0)); return publication_DateTime_In_User_Local_DateTime.DateTime;// return to user } Is the value obtained correct? Is this the right approach to solving this problem? (Question #3)

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  • C# 'could not found' existing method

    - by shybovycha
    Greetings! I've been fooling around (a bit) with C# and its assemblies. And so i've found such an interesting feature as dynamic loading assemblies and invoking its class members. A bit of google and here i am, writing some kind of 'assembly explorer'. (i've used some portions of code from here, here and here and none of 'em gave any of expected results). But i've found a small bug: when i tried to invoke class method from assembly i've loaded, application raised MissingMethod exception. I'm sure DLL i'm loading contains class and method i'm tryin' to invoke (my app ensures me as well as RedGate's .NET Reflector): The main application code seems to be okay and i start thinking if i was wrong with my DLL... Ah, and i've put both of projects into one solution, but i don't think it may cause any troubles. And yes, DLL project has 'class library' target while the main application one has 'console applcation' target. So, the question is: what's wrong with 'em? Here are some source code: DLL source: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ClassLibrary1 { public class Class1 { public void Main() { System.Console.WriteLine("Hello, World!"); } } } Main application source: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Reflection; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { Assembly asm = Assembly.LoadFrom(@"a\long\long\path\ClassLibrary1.dll"); try { foreach (Type t in asm.GetTypes()) { if (t.IsClass == true && t.FullName.EndsWith(".Class1")) { object obj = Activator.CreateInstance(t); object res = t.InvokeMember("Main", BindingFlags.Default | BindingFlags.InvokeMethod, null, obj, null); // Exception is risen from here } } } catch (Exception e) { System.Console.WriteLine("Error: {0}", e.Message); } System.Console.ReadKey(); } } } UPD: worked for one case - when DLL method takes no arguments: DLL class (also works if method is not static): public class Class1 { public static void Main() { System.Console.WriteLine("Hello, World!"); } } Method invoke code: object res = t.InvokeMember("Main", BindingFlags.Default | BindingFlags.InvokeMethod, null, null, null);

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  • When can Java produce a NaN (with specific code question)

    - by Brent
    I'm a bit perplexed by some code I'm currently writing. I am trying to preform a specific gradient descent (main loop included below) and depending on the initial conditions I will alternatively get good looking results (perhaps 20% of the time) or everything becomes NaN (the other 80% of the time). However it seems to me that none of the operations in my code could produce NaN's when given honest numbers! My main loop is: // calculate errors delta = m1 + m2 - M; eta = f1 + f2 - F; for (int i = 0; i < numChildren; i++) { epsilon[i] = p[i]*m1+(1-p[i])*m2+q[i]*f1+(1-q[i])*f2-C[i]; } // use errors in gradient descent // set aside differences for the p's and q's float mDiff = m1 - m2; float fDiff = f1 - f2; // first update m's and f's m1 -= rate*delta; m2 -= rate*delta; f1 -= rate*eta; f2 -= rate*eta; for (int i = 0; i < numChildren; i++) { m1 -= rate*epsilon[i]*p[i]; m2 -= rate*epsilon[i]*(1-p[i]); f1 -= rate*epsilon[i]*q[i]; f2 -= rate*epsilon[i]*(1-q[i]); } // now update the p's and q's for (int i = 0; i < numChildren; i++) { p[i] -= rate*epsilon[i]*mDiff; q[i] -= rate*epsilon[i]*fDiff; } This behavior can be seen when we have rate = 0.01; M = 30; F = 30; C = {15, 25, 35, 45}; with the p[i] and q[i] chosen randomly uniformly between 0 and 1, m1 and m2 chosen randomly uniformly to add to M, and f1 and f2 chosen randomly uniformly to add up to F. Does anyone see anything that could create these NaN's?

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  • j2me or android file upload to jsp

    - by user313613
    hi i new to mobile development i like to upload the file from blackberry and android how to develop the mobile side to this jsp page. please do reply me thanks here i mention the jsp file from roseindia.net. <%@ page import="java.io.*" % <% //to get the content type information from JSP Request Header String contentType = request.getContentType(); //here we are checking the content type is not equal to Null and as well as the passed data from mulitpart/form-data is greater than or equal to 0 if ((contentType != null) && (contentType.indexOf("multipart/form-data") = 0)) { DataInputStream in = new DataInputStream(request. getInputStream()); //we are taking the length of Content type data int formDataLength = request.getContentLength(); byte dataBytes[] = new byte[formDataLength]; int byteRead = 0; int totalBytesRead = 0; //this loop converting the uploaded file into byte code while (totalBytesRead < formDataLength) { byteRead = in.read(dataBytes, totalBytesRead, formDataLength); totalBytesRead += byteRead; } String file = new String(dataBytes); //for saving the file name String saveFile = file.substring(file.indexOf("filename=\"") + 10); saveFile = saveFile.substring(0, saveFile.indexOf("\n")); saveFile = saveFile.substring(saveFile.lastIndexOf("\\") + 1,saveFile.indexOf("\"")); int lastIndex = contentType.lastIndexOf("="); String boundary = contentType.substring(lastIndex + 1, contentType.length()); int pos; //extracting the index of file pos = file.indexOf("filename=\""); pos = file.indexOf("\n", pos) + 1; pos = file.indexOf("\n", pos) + 1; pos = file.indexOf("\n", pos) + 1; int boundaryLocation = file.indexOf(boundary, pos) - 4; int startPos = ((file.substring(0, pos)).getBytes()).length; int endPos = ((file.substring(0, boundaryLocation)) .getBytes()).length; // creating a new file with the same name and writing the content in new file FileOutputStream fileOut = new FileOutputStream(saveFile); fileOut.write(dataBytes, startPos, (endPos - startPos)); fileOut.flush(); fileOut.close(); %><Br><table border="2"><tr><td><b>You have successfully upload the file by the name of: <% out.println(saveFile); % <% } %

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  • Technical non-terminating condition in a loop

    - by Snarfblam
    Most of us know that a loop should not have a non-terminating condition. For example, this C# loop has a non-terminating condition: any even value of i. This is an obvious logic error. void CountByTwosStartingAt(byte i) { // If i is even, it never exceeds 254 for(; i < 255; i += 2) { Console.WriteLine(i); } } Sometimes there are edge cases that are extremely unlikeley, but technically constitute non-exiting conditions (stack overflows and out-of-memory errors aside). Suppose you have a function that counts the number of sequential zeros in a stream: int CountZeros(Stream s) { int total = 0; while(s.ReadByte() == 0) total++; return total; } Now, suppose you feed it this thing: class InfiniteEmptyStream:Stream { // ... Other members ... public override int Read(byte[] buffer, int offset, int count) { Array.Clear(buffer, offset, count); // Output zeros return count; // Never returns -1 (end of stream) } } Or more realistically, maybe a stream that returns data from external hardware, which in certain cases might return lots of zeros (such as a game controller sitting on your desk). Either way we have an infinite loop. This particular non-terminating condition stands out, but sometimes they don't. A completely real-world example as in an app I'm writing. An endless stream of zeros will be deserialized into infinite "empty" objects (until the collection class or GC throws an exception because I've exceeded two billion items). But this would be a completely unexpected circumstance (considering my data source). How important is it to have absolutely no non-terminating conditions? How much does this affect "robustness?" Does it matter if they are only "theoretically" non-terminating (is it okay if an exception represents an implicit terminating condition)? Does it matter whether the app is commercial? If it is publicly distributed? Does it matter if the problematic code is in no way accessible through a public interface/API? Edit: One of the primary concerns I have is unforseen logic errors that can create the non-terminating condition. If, as a rule, you ensure there are no non-terminating conditions, you can identify or handle these logic errors more gracefully, but is it worth it? And when? This is a concern orthogonal to trust.

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  • MySQL search for user and their roles

    - by Jenkz
    I am re-writing the SQL which lets a user search for any other user on our site and also shows their roles. An an example, roles can be "Writer", "Editor", "Publisher". Each role links a User to a Publication. Users can take multiple roles within multiple publications. Example table setup: "users" : user_id, firstname, lastname "publications" : publication_id, name "link_writers" : user_id, publication_id "link_editors" : user_id, publication_id Current psuedo SQL: SELECT * FROM ( (SELECT user_id FROM users WHERE firstname LIKE '%Jenkz%') UNION (SELECT user_id FROM users WHERE lastname LIKE '%Jenkz%') ) AS dt JOIN (ROLES STATEMENT) AS roles ON roles.user_id = dt.user_id At the moment my roles statement is: SELECT dt2.user_id, dt2.publication_id, dt.role FROM ( (SELECT 'writer' AS role, link_writers.user_id, link_writers.publication_id FROM link_writers) UNION (SELECT 'editor' AS role, link_editors.user_id, link_editors.publication_id FROM link_editors) ) AS dt2 The reason for wrapping the roles statement in UNION clauses is that some roles are more complex and require a table join to find the publication_id and user_id. As an example "publishers" might be linked accross two tables "link_publishers": user_id, publisher_group_id "link_publisher_groups": publisher_group_id, publication_id So in that instance, the query forming part of my UNION would be: SELECT 'publisher' AS role, link_publishers.user_id, link_publisher_groups.publication_id FROM link_publishers JOIN link_publisher_groups ON lpg.group_id = lp.group_id I'm pretty confident that my table setup is good (I was warned off the one-table-for-all system when researching the layout). My problem is that there are now 100,000 rows in the users table and upto 70,000 rows in each of the link tables. Initial lookup in the users table is fast, but the joining really slows things down. How can I only join on the relevant roles? -------------------------- EDIT ---------------------------------- Explain above (open in a new window to see full resolution). The bottom bit in red, is the "WHERE firstname LIKE '%Jenkz%'" the third row searches WHERE CONCAT(firstname, ' ', lastname) LIKE '%Jenkz%'. Hence the large row count, but I think this is unavoidable, unless there is a way to put an index accross concatenated fields? The green bit at the top just shows the total rows scanned from the ROLES STATEMENT. You can then see each individual UNION clause (#6 - #12) which all show a large number of rows. Some of the indexes are normal, some are unique. It seems that MySQL isn't optimizing to use the dt.user_id as a comparison for the internal of the UNION statements. Is there any way to force this behaviour? Please note that my real setup is not publications and writers but "webmasters", "players", "teams" etc.

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  • Derived template override return type of member function C++

    - by Ruud v A
    I am writing matrix classes. Take a look at this definition: template <typename T, unsigned int dimension_x, unsigned int dimension_y> class generic_matrix { ... generic_matrix<T, dimension_x - 1, dimension_y - 1> minor(unsigned int x, unsigned int y) const { ... } ... } template <typename T, unsigned int dimension> class generic_square_matrix : public generic_matrix<T, dimension, dimension> { ... generic_square_matrix(const generic_matrix<T, dimension, dimension>& other) { ... } ... void foo(); } The generic_square_matrix class provides additional functions like matrix multiplication. Doing this is no problem: generic_square_matrix<T, 4> m = generic_matrix<T, 4, 4>(); It is possible to assign any square matrix to M, even though the type is not generic_square_matrix, due to the constructor. This is possible because the data does not change across children, only the supported functions. This is also possible: generic_square_matrix<T, 4> m = generic_square_matrix<T, 5>().minor(1,1); Same conversion applies here. But now comes the problem: generic_square_matrix<T, 4>().minor(1,1).foo(); //problem, foo is not in generic_matrix<T, 3, 3> To solve this I would like generic_square_matrix::minor to return a generic_square_matrix instead of a generic_matrix. The only possible way to do this, I think is to use template specialisation. But since a specialisation is basically treated like a separate class, I have to redefine all functions. I cannot call the function of the non-specialised class as you would do with a derived class, so I have to copy the entire function. This is not a very nice generic-programming solution, and a lot of work. C++ almost has a solution for my problem: a virtual function of a derived class, can return a pointer or reference to a different class than the base class returns, if this class is derived from the class that the base class returns. generic_square_matrix is derived from generic_matrix, but the function does not return a pointer nor reference, so this doesn't apply here. Is there a solution to this problem (possibly involving an entirely other structure; my only requirements are that the dimensions are a template parameter and that square matrices can have additional functionality). Thanks in advance, Ruud

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  • Dynamic swappable Data Access Layer

    - by Andy
    I'm writing a data driven WPF client. The client will typically pull data from a WCF service, which queries a SQL db, but I'd like the option to pull the data directly from SQL or other arbitrary data sources. I've come up with this design and would like to hear your opinion on whether it is the best design. First, we have some data object we'd like to extract from SQL. // The Data Object with a single property public class Customer { private string m_Name = string.Empty; public string Name { get { return m_Name; } set { m_Name = value;} } } Then I plan on using an interface which all data access layers should implement. Suppose one could also use an abstract class. Thoughts? // The interface with a single method interface ICustomerFacade { List<Customer> GetAll(); } One can create a SQL implementation. // Sql Implementation public class SqlCustomrFacade : ICustomerFacade { public List<Customer> GetAll() { // Query SQL db and return something useful // ... return new List<Customer>(); } } We can also create a WCF implementation. The problem with WCF is is that it doesn't use the same data object. It creates its own local version, so we would have to copy the details over somehow. I suppose one could use reflection to copy the values of similar fields across. Thoughts? // Wcf Implementation public class WcfCustomrFacade : ICustomerFacade { public List<Customer> GetAll() { // Get date from the Wcf Service (not defined here) List<WcfService.Customer> wcfCustomers = wcfService.GetAllCustomers(); // The list we're going to return List<Customer> customers = new List<Customer>(); // This is horrible foreach(WcfService.Customer wcfCustomer in wcfCustomers) { Customer customer = new Customer(); customer.Name = wcfCustomer.Name; customers.Add(customer); } return customers; } } I also plan on using a factory to decide which facade to use. // Factory pattern public class FacadeFactory() { public static ICustomerFacade CreateCustomerFacade() { // Determine the facade to use if (ConfigurationManager.AppSettings["DAL"] == "Sql") return new SqlCustomrFacade(); else return new WcfCustomrFacade(); } } This is how the DAL would typically be used. // Test application public class MyApp { public static void Main() { ICustomerFacade cf = FacadeFactory.CreateCustomerFacade(); cf.GetAll(); } } I appreciate your thoughts and time.

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  • Ajax progress with PHP session

    - by FFish
    I have an app that processes images and use jQuery to display progress to the user. I done this with writing to a textfile each time and image is processed and than read this status with a setInterval. Because no images are actually written in the processing (I do it in PHP's memory) I thought a log.txt would be a solution, but I am not sure about all the fopen and fread's. Is this prone to issues? I tried also with PHP sessions, but can't seem to get it to work, I don't get why.. HTML: <a class="download" href="#">request download</a> <p class="message"></p> JS: $('a.download').click(function() { var queryData = {images : ["001.jpg", "002.jpg", "003.jpg"]}; $("p.message").html("initializing..."); var progressCheck = function() { $.get("dynamic-session-progress.php", function(data) { $("p.message").html(data); } ); }; $.post('dynamic-session-process.php', queryData, function(intvalId) { return function(data) { $("p.message").html(data); clearInterval(intvalId); } } (setInterval(progressCheck, 1000)) ); return false; }); process.php: // session_start(); $arr = $_POST['images']; $arr_cnt = count($arr); $filename = "log.txt"; for ($i = 1; $i <= $arr_cnt; $i++) { $content = "processing $val ($i/$arr_cnt)"; $handle = fopen($filename, 'w'); fwrite($handle, $content); fclose($handle); // $_SESSION['counter'] = $content; sleep(3); // to mimic image processing } echo "<a href='#'>download zip</a>"; progress.php: // session_start(); $filename = "log.txt"; $handle = fopen($filename, "r"); $contents = fread($handle, filesize($filename)); fclose($handle); echo $contents; // echo $_SESSION['counter'];

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  • How to pipe two CORE::system commands in a cross-platform way

    - by Pedro Silva
    I'm writing a System::Wrapper module to abstract away from CORE::system and the qx operator. I have a serial method that attempts to connect command1's output to command2's input. I've made some progress using named pipes, but POSIX::mkfifo is not cross-platform. Here's part of what I have so far (the run method at the bottom basically calls system): package main; my $obj1 = System::Wrapper->new( interpreter => 'perl', arguments => [-pe => q{''}], input => ['input.txt'], description => 'Concatenate input.txt to STDOUT', ); my $obj2 = System::Wrapper->new( interpreter => 'perl', arguments => [-pe => q{'$_ = reverse $_}'}], description => 'Reverse lines of input input', output => { '>' => 'output' }, ); $obj1->serial( $obj2 ); package System::Wrapper; #... sub serial { my ($self, @commands) = @_; eval { require POSIX; POSIX->import(); require threads; }; my $tmp_dir = File::Spec->tmpdir(); my $last = $self; my @threads; push @commands, $self; for my $command (@commands) { croak sprintf "%s::serial: type of args to serial must be '%s', not '%s'", ref $self, ref $self, ref $command || $command unless ref $command eq ref $self; my $named_pipe = File::Spec->catfile( $tmp_dir, int \$command ); POSIX::mkfifo( $named_pipe, 0777 ) or croak sprintf "%s::serial: couldn't create named pipe %s: %s", ref $self, $named_pipe, $!; $last->output( { '>' => $named_pipe } ); $command->input( $named_pipe ); push @threads, threads->new( sub{ $last->run } ); $last = $command; } $_->join for @threads; } #... My specific questions: Is there an alternative to POSIX::mkfifo that is cross-platform? Win32 named pipes don't work, as you can't open those as regular files, neither do sockets, for the same reasons. The above doesn't quite work; the two threads get spawned correctly, but nothing flows across the pipe. I suppose that might have something to do with pipe deadlocking or output buffering. What throws me off is that when I run those two commands in the actual shell, everything works as expected.

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  • Numpy/Python performing terribly vs. Matlab

    - by Nissl
    Novice programmer here. I'm writing a program that analyzes the relative spatial locations of points (cells). The program gets boundaries and cell type off an array with the x coordinate in column 1, y coordinate in column 2, and cell type in column 3. It then checks each cell for cell type and appropriate distance from the bounds. If it passes, it then calculates its distance from each other cell in the array and if the distance is within a specified analysis range it adds it to an output array at that distance. My cell marking program is in wxpython so I was hoping to develop this program in python as well and eventually stick it into the GUI. Unfortunately right now python takes ~20 seconds to run the core loop on my machine while MATLAB can do ~15 loops/second. Since I'm planning on doing 1000 loops (with a randomized comparison condition) on ~30 cases times several exploratory analysis types this is not a trivial difference. I tried running a profiler and array calls are 1/4 of the time, almost all of the rest is unspecified loop time. Here is the python code for the main loop: for basecell in range (0, cellnumber-1): if firstcelltype == np.array((cellrecord[basecell,2])): xloc=np.array((cellrecord[basecell,0])) yloc=np.array((cellrecord[basecell,1])) xedgedist=(xbound-xloc) yedgedist=(ybound-yloc) if xloc>excludedist and xedgedist>excludedist and yloc>excludedist and yedgedist>excludedist: for comparecell in range (0, cellnumber-1): if secondcelltype==np.array((cellrecord[comparecell,2])): xcomploc=np.array((cellrecord[comparecell,0])) ycomploc=np.array((cellrecord[comparecell,1])) dist=math.sqrt((xcomploc-xloc)**2+(ycomploc-yloc)**2) dist=round(dist) if dist>=1 and dist<=analysisdist: arraytarget=round(dist*analysisdist/intervalnumber) addone=np.array((spatialraw[arraytarget-1])) addone=addone+1 targetcell=arraytarget-1 np.put(spatialraw,[targetcell,targetcell],addone) Here is the matlab code for the main loop: for basecell = 1:cellnumber; if firstcelltype==cellrecord(basecell,3); xloc=cellrecord(basecell,1); yloc=cellrecord(basecell,2); xedgedist=(xbound-xloc); yedgedist=(ybound-yloc); if (xloc>excludedist) && (yloc>excludedist) && (xedgedist>excludedist) && (yedgedist>excludedist); for comparecell = 1:cellnumber; if secondcelltype==cellrecord(comparecell,3); xcomploc=cellrecord(comparecell,1); ycomploc=cellrecord(comparecell,2); dist=sqrt((xcomploc-xloc)^2+(ycomploc-yloc)^2); if (dist>=1) && (dist<=100.4999); arraytarget=round(dist*analysisdist/intervalnumber); spatialsum(1,arraytarget)=spatialsum(1,arraytarget)+1; end end end end end end Thanks!

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  • PHP Sockets Errors (connection refused and No such file or directory)

    - by Purefan
    Hello all, I am writing a server app (broadcaster) and a client (relayer). Several relayers can connect to the broadcaster at the same time, send information and the broadcaster will redirect the message to a matching relayer (for example relayer1 sends to broadcaster who sends to relayer43, relayer2 - broadcaster - relayer73...) The server part is working as I have tested it with a telnet client and although its at this point only an echo server it works. Both relayer and broadcaster sit on the same server so I am using AF_UNIX sockets, both files are in different folders though. I have tried two approaches for the relayer and both have failed, the first one is using socket_create: public function __construct() { // where is the socket server? $this->_sHost = 'tcp://127.0.0.1'; $this->_iPort = 11225; // open a client connection $this->_hSocket = socket_create(AF_UNIX, SOCK_STREAM, 0); echo 'Attempting to connect to '.$this->_sHost.' on port '.$this->_iPort .'...'; $result = socket_connect($this->_hSocket, $this->_sHost, $this->_iPort); if ($result === false) { echo "socket_connect() failed.\nReason: ($result) " . socket_strerror(socket_last_error($this->_hSocket)) . "\n"; } else { echo "OK.\n"; } This returns "Warning: socket_connect(): unable to connect [2]: No such file or directory in relayer.class.php on line 27" and (its running from command line) it often also returns a segmentation fault. The second approach is using pfsockopen: public function __construct() { // where is the socket server? $this->_sHost = 'tcp://127.0.0.1'; $this->_iPort = 11225; // open a client connection $fp = pfsockopen ($this->_sHost, $this->_iPort, $errno, $errstr); if (!$fp) { $result = "Error: could not open socket connection"; } else { // get the welcome message fgets ($fp, 1024); // write the user string to the socket fputs ($fp, 'Message ' . __LINE__); // get the result $result .= fgets ($fp, 1024); // close the connection fputs ($fp, "END"); fclose ($fp); // trim the result and remove the starting ? $result = trim($result); $result = substr($result, 2); // now print it to the browser } which only returns the error "Warning: pfsockopen(): unable to connect to tcp://127.0.0.1:11225 (Connection refused) in relayer.class.php on line 33 " In all tests I have tried with different host names, 127.0.0.1, localhost, tcp://127.0.0.1, 192.168.0.199, tcp://192.168.0.199, none of it has worked. Any ideas on this?

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  • Object oriented n-tier design. Am I abstracting too much? Or not enough?

    - by max
    Hi guys, I'm building my first enterprise grade solution (at least I'm attempting to make it enterprise grade). I'm trying to follow best practice design patterns but am starting to worry that I might be going too far with abstraction. I'm trying to build my asp.net webforms (in C#) app as an n-tier application. I've created a Data Access Layer using an XSD strongly-typed dataset that interfaces with a SQL server backend. I access the DAL through some Business Layer Objects that I've created on a 1:1 basis to the datatables in the dataset (eg, a UsersBLL class for the Users datatable in the dataset). I'm doing checks inside the BLL to make sure that data passed to DAL is following the business rules of the application. That's all well and good. Where I'm getting stuck though is the point at which I connect the BLL to the presentation layer. For example, my UsersBLL class deals mostly with whole datatables, as it's interfacing with the DAL. Should I now create a separate "User" (Singular) class that maps out the properties of a single user, rather than multiple users? This way I don't have to do any searching through datatables in the presentation layer, as I could use the properties created in the User class. Or would it be better to somehow try to handle this inside the UsersBLL? Sorry if this sounds a little complicated... Below is the code from the UsersBLL: using System; using System.Data; using PedChallenge.DAL.PedDataSetTableAdapters; [System.ComponentModel.DataObject] public class UsersBLL { private UsersTableAdapter _UsersAdapter = null; protected UsersTableAdapter Adapter { get { if (_UsersAdapter == null) _UsersAdapter = new UsersTableAdapter(); return _UsersAdapter; } } [System.ComponentModel.DataObjectMethodAttribute (System.ComponentModel.DataObjectMethodType.Select, true)] public PedChallenge.DAL.PedDataSet.UsersDataTable GetUsers() { return Adapter.GetUsers(); } [System.ComponentModel.DataObjectMethodAttribute (System.ComponentModel.DataObjectMethodType.Select, false)] public PedChallenge.DAL.PedDataSet.UsersDataTable GetUserByUserID(int userID) { return Adapter.GetUserByUserID(userID); } [System.ComponentModel.DataObjectMethodAttribute (System.ComponentModel.DataObjectMethodType.Select, false)] public PedChallenge.DAL.PedDataSet.UsersDataTable GetUsersByTeamID(int teamID) { return Adapter.GetUsersByTeamID(teamID); } [System.ComponentModel.DataObjectMethodAttribute (System.ComponentModel.DataObjectMethodType.Select, false)] public PedChallenge.DAL.PedDataSet.UsersDataTable GetUsersByEmail(string Email) { return Adapter.GetUserByEmail(Email); } [System.ComponentModel.DataObjectMethodAttribute (System.ComponentModel.DataObjectMethodType.Insert, true)] public bool AddUser(int? teamID, string FirstName, string LastName, string Email, string Role, int LocationID) { // Create a new UsersRow instance PedChallenge.DAL.PedDataSet.UsersDataTable Users = new PedChallenge.DAL.PedDataSet.UsersDataTable(); PedChallenge.DAL.PedDataSet.UsersRow user = Users.NewUsersRow(); if (UserExists(Users, Email) == true) return false; if (teamID == null) user.SetTeamIDNull(); else user.TeamID = teamID.Value; user.FirstName = FirstName; user.LastName = LastName; user.Email = Email; user.Role = Role; user.LocationID = LocationID; // Add the new user Users.AddUsersRow(user); int rowsAffected = Adapter.Update(Users); // Return true if precisely one row was inserted, // otherwise false return rowsAffected == 1; } [System.ComponentModel.DataObjectMethodAttribute (System.ComponentModel.DataObjectMethodType.Update, true)] public bool UpdateUser(int userID, int? teamID, string FirstName, string LastName, string Email, string Role, int LocationID) { PedChallenge.DAL.PedDataSet.UsersDataTable Users = Adapter.GetUserByUserID(userID); if (Users.Count == 0) // no matching record found, return false return false; PedChallenge.DAL.PedDataSet.UsersRow user = Users[0]; if (teamID == null) user.SetTeamIDNull(); else user.TeamID = teamID.Value; user.FirstName = FirstName; user.LastName = LastName; user.Email = Email; user.Role = Role; user.LocationID = LocationID; // Update the product record int rowsAffected = Adapter.Update(user); // Return true if precisely one row was updated, // otherwise false return rowsAffected == 1; } [System.ComponentModel.DataObjectMethodAttribute (System.ComponentModel.DataObjectMethodType.Delete, true)] public bool DeleteUser(int userID) { int rowsAffected = Adapter.Delete(userID); // Return true if precisely one row was deleted, // otherwise false return rowsAffected == 1; } private bool UserExists(PedChallenge.DAL.PedDataSet.UsersDataTable users, string email) { // Check if user email already exists foreach (PedChallenge.DAL.PedDataSet.UsersRow userRow in users) { if (userRow.Email == email) return true; } return false; } } Some guidance in the right direction would be greatly appreciated!! Thanks all! Max

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  • Can I use the [] operator in C++ to create virtual arrays

    - by Shane MacLaughlin
    I have a large code base, originally C ported to C++ many years ago, that is operating on a number of large arrays of spatial data. These arrays contain structs representing point and triangle entities that represent surface models. I need to refactor the code such that the specific way these entities are stored internally varies for specific scenarios. For example if the points lie on a regular flat grid, I don't need to store the X and Y coordinates, as they can be calculated on the fly, as can the triangles. Similarly, I want to take advantage of out of core tools such as STXXL for storage. The simplest way of doing this is replacing array access with put and get type functions, e.g. point[i].x = XV; becomes Point p = GetPoint(i); p.x = XV; PutPoint(i,p); As you can imagine, this is a very tedious refactor on a large code base, prone to all sorts of errors en route. What I'd like to do is write a class that mimics the array by overloading the [] operator. As the arrays already live on the heap, and move around with reallocs, the code already assumes that references into the array such as point *p = point + i; may not be used. Is this class feasible to write? For example writing the methods below in terms of the [] operator; void MyClass::PutPoint(int Index, Point p) { if (m_StorageStrategy == RegularGrid) { int xoffs,yoffs; ComputeGridFromIndex(Index,xoffs,yoffs); StoreGridPoint(xoffs,yoffs,p.z); } else m_PointArray[Index] = p; } } Point MyClass::GetPoint(int Index) { if (m_StorageStrategy == RegularGrid) { int xoffs,yoffs; ComputeGridFromIndex(Index,xoffs,yoffs); return GetGridPoint(xoffs,yoffs); // GetGridPoint returns Point } else return m_PointArray[Index]; } } My concern is that all the array classes I've seen tend to pass by reference, whereas I think I'll have to pass structs by value. I think it should work put other than performance, can anyone see any major pitfalls with this approach. n.b. the reason I have to pass by value is to get point[a].z = point[b].z + point[c].z to work correctly where the underlying storage type varies.

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  • GKSession sendDataToAllPeers getting invalid parameter

    - by cb4
    This is my first post and I wanted to start it by thanking the many stackoverflow contributors who will never know how much they helped me out these past several days as I worked to complete my first iOS app. I am indebted to them and to this site for giving them a place to post. To 'pay off' some of that debt, I hope this will help others as I have been helped... So, my app uses the GKPeerPickerController to make a connection to a 2nd device. Once connected, the devices can send text messages to each other. The receiving peer has the message displayed in a UIAlertView. Everything was working fine. Then I decided to experiment with locations and added code to get the current location. I convert it into latitude & longitude in degrees, minutes, and seconds and put them into one NSString. I added a button to my storyboard called 'Send Location' which, when tapped, sends the location to the connected peer. This is where I ran into the problem. Both the send text and send location methods call the sendPacket method with a NSString. sendPacket converts the string to NSData and calls sendDataToAllPeers. When I learned how to capture the error, it was "Invalid parameter for - sendDataToAllPeers:withDataMode:error:". [.....pause.....] Well, this was going to be a question but in writing all this to explain the problem, the answer just dawned on me. Did a few tests and verified it now works. The issue was not in sendDataToAllPeers, it was in the conversion of the NSString (strToSend) to NSData: packet = [strToSend dataUsingEncoding:NSASCIIStringEncoding]; Specifically, it was the degree sign character (little circle, ASCII 176). NSASCIIStringEncoding only includes ASCII characters up to 127 so don't use any above that. I'm sure there was a quicker way to find the problem, but I don't know Objective-C or Xcode's debugging facility well enough yet. Whew! Several hours to discover that little tidbit. I did learn a lot, though, and that's always a good thing!

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