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• Issue in achartengine jar file

  - by Anshuman

  Actually i have created an app in which i have used achartengine to contruct graph. It was running ok, but today i saw an update for android SDK to r17. Once i upadated the sdk the app i had build started crash. In the logcat i show the following error report. Why this happen, is it because the jar file i have used is deprecated. 03-27 14:44:26.320: E/AndroidRuntime(4360): java.lang.NoClassDefFoundError: [Lorg.achartengine.chart.PointStyle; 03-27 14:44:26.320: E/AndroidRuntime(4360): at in.com.example.ChartEngineActivity.onCreate(ChartEngineActivity.java:58) 03-27 14:44:26.320: E/AndroidRuntime(4360): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 03-27 14:44:26.320: E/AndroidRuntime(4360): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 03-27 14:44:26.320: E/AndroidRuntime(4360): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 03-27 14:44:26.320: E/AndroidRuntime(4360): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 03-27 14:44:26.320: E/AndroidRuntime(4360): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 03-27 14:44:26.320: E/AndroidRuntime(4360): at android.os.Handler.dispatchMessage(Handler.java:99) 03-27 14:44:26.320: E/AndroidRuntime(4360): at android.os.Looper.loop(Looper.java:130) 03-27 14:44:26.320: E/AndroidRuntime(4360): at android.app.ActivityThread.main(ActivityThread.java:3683) 03-27 14:44:26.320: E/AndroidRuntime(4360): at java.lang.reflect.Method.invokeNative(Native Method) 03-27 14:44:26.320: E/AndroidRuntime(4360): at java.lang.reflect.Method.invoke(Method.java:507) 03-27 14:44:26.320: E/AndroidRuntime(4360): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 03-27 14:44:26.320: E/AndroidRuntime(4360): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 03-27 14:44:26.320: E/AndroidRuntime(4360): at dalvik.system.NativeStart.main(Native Method)

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• Image Masking Problem

  - by Adnan Sohail

  Hi I am doing image masking. First I was using C*GImageMaskCreate()* function for masking but now I am using your solution which you had posted for masking. My problem is it works fine on simulator but on device it is not transparent and it gives rectangle of mask image at background. The following is my code. Now tell me what I have to do? Thanks. CGContextRef mainViewContentContext; CGColorSpaceRef colorSpace; UIImage *orgImage=[UIImage imageNamed:@"orgimage.png"]; CGImageRef img = [orgImage CGImage]; colorSpace = CGColorSpaceCreateDeviceRGB(); mainViewContentContext = CGBitmapContextCreate (NULL, width, height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast); CGColorSpaceRelease(colorSpace); if (mainViewContentContext==NULL) return NULL; CGRect subImageRect; CGImageRef tileImage; subImageRect = CGRectMake(xCord,yCord,width,height); tileImage = CGImageCreateWithImageInRect(img,subImageRect); CGImageRef maskImage = mask_image.CGImage; CGContextClipToMask(mainViewContentContext, CGRectMake(0, 0, width, height), maskImage); CGContextDrawImage(mainViewContentContext, CGRectMake(0, 0, width, height), tileImage); CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(mainViewContentContext); CGContextRelease(mainViewContentContext); UIImage *theImage = [UIImage imageWithCGImage:mainViewContentBitmapContext]; CGImageRelease(mainViewContentBitmapContext);

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• Make winform run away from the mouse.

  - by JACK IN THE CRACK

  Okay so I'm trying to make a little gag program that will "run away" from the mouse. So, to get the mouse coordinates for the whole screen and not just the form control I had to create a little helper: static class MouseHelper { [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] internal static extern bool GetCursorPos(ref Point pt); public static Point GetPosition() { Point w32Mouse = new Point(); GetCursorPos(ref w32Mouse); return w32Mouse; } } Now I thought I was going to use the MouseMove event... but that doesn't work for outside the form control either so I have an auto-enabled timer on a 10ms loop called timerMouseMove. public partial class Form1 : Form { public Form1() { InitializeComponent(); } private bool CollisionCheck() { Point win32Mouse = MouseHelper.GetPosition(); if (win32Mouse.X <= Location.X || win32Mouse.X >= (Location.X + Width)) return false; if (win32Mouse.Y <= Location.Y || win32Mouse.Y >= (Location.Y + Height)) return false; return true; } private void timerMouseMove_Tick(object sender, EventArgs e) { if (CollisionCheck()) Location = new Point(Location.X + 1, Location.Y + 1); } } So this works out nicely, at least I have the collision checking working and whatnot. But now, how should I go about figuring which side of the form the mouse has collided with, so that I can update its location to move in the opposite direction the mouse collides with it? And such halp

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• Xpath: Selecting all of an element type?

  - by Johannes

  I'm just starting to learn Xpath, I'm trying to write a line of code that will select all of the actors in EACH movie parent (through Java!). Below, I have an example of one movie, but there are multiple <Movie> elements, each with <Actor> elements. <Movie Genre = 'Other'> <Title>Requiem For A Dream</Title> <ReleaseYear>2000</ReleaseYear> <Director>Darren Aronofsky</Director> <Actor Character = 'Sara Goldfarb'>Ellen Burstyn</Actor> <Actor Character = 'Harry Goldfarb'>Jared Leto</Actor> <Actor Character = 'Marion Silver'>Jennifer Connelly</Actor> <Actor Character = 'Tyrone C. Love'>Marlon Wayans</Actor> </Movie> Currently, I can only select the first <Actor> element of each <Movie> element -- is it possible to select all of them without using a for loop? Here is my current line of code that displays the first <Actor> element of every <Movie> element: System.out.println("Starring: " + xpath.evaluate("Actor", movieNode) + " as " + xpath.evaluate("Actor/@Character", movieNode) + "\n"); Any and all help if much appreciated!

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• Treetop basic parsing and regular expression usage

  - by ucint

  I'm developing a script using the ruby Treetop library and having issues working with its syntax for regex's. First off, many regular expressions that work in other settings dont work the same in treetop. This is my grammar: (myline.treetop) grammar MyLine rule line string whitespace condition end rule string [\S]* end rule whitespace [\s]* end rule condition "new" / "old" / "used" end end This is my usage: (usage.rb) require 'rubygems' require 'treetop' require 'polyglot' require 'myline' parser = MyLineParser.new p parser.parse("randomstring new") This should find the word new for sure and it does! Now I wont to extend it so that it can find new if the input string becomes "randomstring anotherstring new yetanother andanother" and possibly have any number of strings followed by whitespace (tab included) before and after the regex for rule condition. In other words, if I pass it any sentence with the word "new" etc in it, it should be able to match it. So let's say I change my grammar to: rule line string whitespace condition whitespace string end Then, it should be able to find a match for: p parser.parse("randomstring new anotherstring") So, what do I have to do to allow the string whitespace to be repeated before and after condition? If I try to write this: rule line (string whitespace)* condition (whitespace string)* end , it goes in an infinite loop. If i replace the above () with [], it returns nil In general, regex's return a match when i use the above, but treetop regex's dont. Does anyone have any tips/points on how to go about this? Plus, since there isn't much documentation for treetop and the examples are either too trivial or too complex, is there anyone who knows a more thorough documentation/guide for treetop?

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• Does HttpListener work well on Mono?

  - by billpg

  Hi everyone. I'm looking to write a small web service to run on a small Linux box. I prefer to code in C#, so I'm looking to use Mono. I don't want the overhead of running a full web server or Mono's version of ASP.NET. I'm thinking of having a single process with a thread dealing with each client connection. Shared memory between threads instead of a database. I've read a little on Microsoft's version of HttpListener and how it works with the Http.sys driver. Alas, Mono's documentation on this class is just the automated class interface with no discussion of how it works under the hood. (Linux doesn't have Http.sys, so I imagine it's implemented substantially differently.) Could anyone point me towards some resources discussing this module please? Many thanks, Bill, billpg.com (A little background to my question for the interested.) Some time ago, I asked this question, interested in keeping a long conversation open with lots of back-and-forth. I had settled on designing my own ad-hoc protocol, but people I spoke to really wanted a REST interface, even at the cost of the "Okay, send your command now" signal. So, I wondered about running ASP.NET on a Linux/Mono server, but stumbled upon HttpListener. This seemed ideal, as each "conversation" could run in a separate thread. The thread that calls HttpListener in a loop can look for which thread each incomming connection is for and pass the reference to that thread. The alternative for an ASP.NET driven service, would be to have the ASPX code pick up the state from a database, and write back the new state when it finishes. Yes, it would work, but that's a lot of overhead.

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• Design Practice Retrieve Multiple Users - PHP

  - by pws5068

  Greetings all, I'm looking for a more efficient way to grab multiple users without too much code redundancy. I have a Users class, (here's a highly condensed representation) Class Users { function __construct() { ... ... } private static function getNew($id) { // This is all only example code $sql = "SELECT * FROM Users WHERE User_ID=?"; $user = new User(); $user->setID($id); .... return $user; } public static function getNewestUsers($count) { $sql = "SELECT * FROM Users ORDER BY Join_Date LIMIT ?"; $users = array(); // Prepared Statement Data Here while($stmt->fetch()) { $users[] = Users::getNew($id); ... } return $users; } // These have more sanity/security checks, demonstration only. function setID($id) { $this->id = $id; } function setName($name) { $this->name = $name; } ... } So clearly calling getNew() in a loop is inefficient, because it makes $count number of calls to the database each time. I would much rather select all users in a single SQL statement. The problem is that I have probably a dozen or so methods for getting arrays of users, so all of these would now need to know the names of the database columns which is repeating a lot of structure that could always change later. What are some other ways that I could approach this problem? My goals include efficiency, flexibility, scalability, and good design practice.

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• What is the best way to extend restful_authentication/AuthLogic to support lazy logins by an anonymo

  - by Kevin Elliott

  I'm building an iPhone application that talks to a Ruby on Rails backend. The Ruby on Rails application will also service web users. The restful_authentication plugin is an excellent way to provide quick and customizable user authentication. However, I would like users of the iPhone application to have an account created automatically by the phone's unique identifier ([[UIDevice device] uniqueIdentifier]) stored in a new column. Later, when users are ready to create a username/password, the account will be updated to contain the username and password, leaving the iPhone unique identifier intact. Users should not be able to access the website until they've setup their username/password. They can however, use the iPhone application, since the application can authenticate itself using it's identifier. What is the best way to modify restful_authentication to do this? Create a plugin? Or modify the generated code? What about alternative frameworks, such as AuthLogic. What is the best way to allow iPhones to get a generated auth token locked to their UUID's, but then let the user create a username/password later?

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• Throttling CPU/Memory usage of a Thread in Java?

  - by Nalandial

  I'm writing an application that will have multiple threads running, and want to throttle the CPU/memory usage of those threads. There is a similar question for C++, but I want to try and avoid using C++ and JNI if possible. I realize this might not be possible using a higher level language, but I'm curious to see if anyone has any ideas. EDIT: Added a bounty; I'd like some really good, well thought out ideas on this. EDIT 2: The situation I need this for is executing other people's code on my server. Basically it is completely arbitrary code, with the only guarantee being that there will be a main method on the class file. Currently, multiple completely disparate classes, which are loaded in at runtime, are executing concurrently as separate threads. I inherited this code (the original author is gone). The way it's written, it would be a pain to refactor to create separate processes for each class that gets executed. If that's the only good way to limit memory usage via the VM arguments, then so be it. But I'd like to know if there's a way to do it with threads. Even as a separate process, I'd like to be able to somehow limit its CPU usage, since as I mentioned earlier, several of these will be executing at once. I don't want an infinite loop to hog up all the resources. EDIT 3: An easy way to approximate object size is with java's Instrumentation classes; specifically, the getObjectSize method. Note that there is some special setup needed to use this tool.

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• About AMR audio file playing issue on different devices

  - by user352537

  I have got a quite strange problem here. I am developing an IM software and need to play audio files recorded by another client on Android. The same audio file I've got can be played with AVAudioPlayer on 3GS(IOS 4.2.1) device and simulator 4.2. But when I tried by play it on iPhone4(iOS 4.3.3), the function "play" always return NO. I also tried with two iPhone devices, the audio files recorded by iPhone client can be played on both 3GS and iPhone4. So I asked the Android developers about the record parameters they've used. They said that the "AudioEncoder" used by them was "DEFAULT". There are also some other parameters as following: **private AudioEncoder() {} public static final int DEFAULT = 0; /** AMR (Narrowband) audio codec */ public static final int AMR_NB = 1; /** @hide AMR (Wideband) audio codec */ public static final int AMR_WB = 2; /** @hide AAC audio codec */ public static final int AAC = 3; /** @hide enhanced AAC audio codec */ public static final int AAC_PLUS = 4; /** @hide enhanced AAC plus audio codec */ public static final int EAAC_PLUS = 5;** Does anybody know what's the matter?

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• Java Bucket Sort on Strings

  - by Michael

  I can't figure out what would be the best way to use Bucket Sort to sort a list of strings that will always be the same length. An algorithm would look like this: For the last character position down to the first: For each word in the list: Place the word into the appropriate bucket by current character For each of the 26 buckets(arraylists) Copy every word back to the list I'm writing in java and I'm using an arraylist for the main list that stores the unsorted strings. The strings will be five characters long each. This is what I started. It just abrubdly stops within the second for loop because I don't know what to do next or if I did the first part right. ArrayList<String> count = new ArrayList<String>(26); for (int i = wordlen; i > 0; i--) { for (int j = 0; i < myList.size(); i++) myList.get(j).charAt(i) } Thanks in advanced.

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• permutations gone wrong

  - by vbNewbie

  I have written code to implement an algorithm I found on string permutations. What I have is an arraylist of words ( up to 200) and I need to permutate the list in levels of 5. Basically group the string words in fives and permutated them. What I have takes the first 5 words generates the permutations and ignores the rest of the arraylist? Any ideas appreciated. Private Function permute(ByVal chunks As ArrayList, ByVal k As Long) As ArrayList ReDim ItemUsed(k) pno = 0 Permutate(k, 1) Return chunks End Function Private Shared Sub Permutate(ByVal K As Long, ByVal pLevel As Long) Dim i As Long, Perm As String Perm = pString ' Save the current Perm ' for each value currently available For i = 1 To K If Not ItemUsed(i) Then If pLevel = 1 Then pString = chunks.Item(i) 'pString = inChars(i) Else pString = pString & chunks.Item(i) 'pString += inChars(i) End If If pLevel = K Then 'got next Perm pno = pno + 1 SyncLock outfile outfile.WriteLine(pno & " = " & pString & vbCrLf) End SyncLock outfile.Flush() Exit Sub End If ' Mark this item unavailable ItemUsed(i) = True ' gen all Perms at next level Permutate(K, pLevel + 1) ' Mark this item free again ItemUsed(i) = False ' Restore the current Perm pString = Perm End If Next K above is = to 5 for the number of words in one permutation but when I change the for loop to the arraylist size I get an error of index out of bounds

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• Elegant Algorithm for Parsing Data Stream Into Record

  - by Matt Long

  I am interfacing with a hardware device that streams data to my app over Wifi. The data is streaming in just fine. The data contains a character header (DATA:) that indicates a new record has begun. The issues is that the data I receive doesn't necessarily fall on the header boundary, so I have to capture the data until what I've captured contains the header. Then, everything that precedes the header goes into the previous record and everything that comes after it goes into a new record. I have this working, but wondered if anyone has done this before and has a good computer-sciencey way to solve the problem. Here's what I do: Convert the NSData of the current read to an NSString Append the NSString to a placeholder string Check placeholder string for the header (DATA:). If the header is not there, just wait for the next read. If the header exists, append whatever precedes it to a previous record placeholder and hand that placeholder off to an array as a complete record that I can further parse into fields. Take whatever shows up after the header and place it in the record placeholder so that it can be appended to in the next read. Repeat steps 3 - 5. Let me know if you see any flaws with this or have a suggestion for a better way. Seems there should be some design pattern for this, but I can't think of one. Thanks.

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• twisted deferred/callbacks and asynchronous execution

  - by NetSkay

  hey guys, quick question about twisted and python... im trying to figure out how can i make my code more asynchronous using twisted and ive come to sort of a dead end, if a function of mine returns a deferred object, then i add a list of callbacks, the first callback will be called after the deferred function provides some result through deferred_obj.callback, then, in the chain of callbacks, the first callback will do something with the data and call the second callback and etc. however chained callbacks will not be considered asynchronous because they're chained and the event loop will keep firing each one of them concurrently until there is no more, right? however, if i have a deferred object, and i attach as its callback the deferred_obj.callback as in d.addCallback(deferred_obj.callback) then this will be considered asynchronous, because the deferred_obj is waiting for the data, and then the method that will pass the data is waiting on data as well, however once i d.callback 'd' object processes the data then it call deferred_obj.callback however since this object is deferred, unlike the case of chained callbacks, it will execute asynchronously... correct? meaning chained callbacks are NOT asynchronous while chained deferreds are, correct? thank you PS: assuming all of my code is non-blocking

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• Select * from 'many to many' SQL relationship

  - by Rampant Creative Group

  I'm still learning SQL and my brain is having a hard time with this one. Say I have 3 tables: teams players and teams_players as my link table All I want to do is run a query to get each team and the players on them. I tried this: SELECT * FROM teams INNER JOIN teams_players ON teams.id = teams_players.team_id INNER JOIN players ON teams_players.player_id = players.id But it returned a separate row for each player on each team. Is JOIN the right way to do it or should I be doing something else? ----------------------------------------- Edit Ok, so from what I'm hearing, this isn't necessarily a bad way to do it. I'll just have to group the data by team while I'm doing my loop. I have not yet tried the modified SQL statements provided, but I will today and get back to you. To answer the question about structure - I guess I wasn't thinking about the returned row structure which is part of what lead to my confusion. In this particular case, each team is limited to 4 players (or less) so I guess the structure that would be helpful to me is something like the following: teams.id, teams.name, players.id, players.name, players.id, players.name, players.id, players.name, players.id, players.name, 1 Team ABC 1 Jim 2 Bob 3 Ned 4 Roy 2 Team XYZ 2 Bob 3 Ned 5 Ralph 6 Tom

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• .NET Hashtable - "Same" key, different hashes

  - by Simon Lindgren

  Is it possible for two .net strings to have different hashes? I have a Hashtable with amongst others the key "path". When I loop through the elements in the table to print it, i can see that the key exists. When trying to looking it up however, there is no matching element. Debugging suggests that the string I'm looking for has a different hash than the one I'm supplying as the key. This code is in a Castle Monorail project, using brail as a view engine. The key I'm looking for is inserted by a brail line like this: UrlHelper.Link(node.CurrentPage.LinkText, {@params: {@path: "/Page1"}}) Then, in this method (in a custom IRoutingRule): public string CreateUrl(System.Collections.IDictionary parameters) { PrintDictionaryToLog(parameters); string url; if (parameters.Contains("path")) { url = (string)parameters["path"]; } else { return null; } } The key is printed to the log, but the function returns null. I didn't know this could even be a problem with .net strings, but I guess this is some kind of encoding issue? Oh, and this is running mono.

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• PHP alternating colors

  - by Jordan Pagaduan

  $dbc = mysql_connect('localhost','root','') or die (mysql_error()); mysql_select_db('payroll') or die (mysql_error()); $sql = "SELECT * FROM employee ORDER BY employee_id DESC"; $result = mysql_query($sql); while($row = mysql_fetch_array($result)) { echo " <tr> <td style=\"padding-left: 20px; border-bottom: 1px solid #999; border-right: 1px solid #999;\">".$row['first_name']." ".$row['last_name']."</td> <td style=\"text-align: center; border-bottom: 1px solid #999; border-right: 1px solid #999; padding-top: 2px ; padding-bottom: 3px ;\"><input type=\"button\" name=\"edit\" value=\"Edit\" class=\"selbtn\">&nbsp;<input type=\"button\" name=\"delete\" value=\"Delete\" class=\"selbtn\"></td> </tr> "; } I wanted to add an alternating color in the loop. what code should I add?

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• loops and conditionals inside triggers

  - by Ying

  I have this piece of logic I would like to implement as a trigger, but I have no idea how to do it! I want to create a trigger that, when a row is deleted, it checks to see if the value of one of its columns exists in another table, and if it does, it should also perform a delete on another table based on another column. So say we had a table Foo that has columns Bar, Baz. This is what id be doing if i did not use a trigger: function deleteFromFooTable(FooId) { SELECT (Bar,Baz) FROM FooTable WHERE id=FooId if not-empty(SELECT * FROM BazTable WHERE id=BazId) DELETE FROM BarTable WHERE id=BarId DELETE FROM FooTable WHERE id=FooId } I jumped some hoops in that pseudo code, but i hope you all get where im going. It seems what i would need is a way to do conditionals and to loop(in case of multiple row deletes?) in the trigger statement. So far, I haven't been able to find anything. Is this not possible, or is this bad practice? Thanks!

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• Can I ignore a SIGFPE resulting from division by zero?

  - by Mikeage

  I have a program which deliberately performs a divide by zero (and stores the result in a volatile variable) in order to halt in certain circumstances. However, I'd like to be able to disable this halting, without changing the macro that performs the division by zero. Is there any way to ignore it? I've tried using #include <signal.h> ... int main(void) { signal(SIGFPE, SIG_IGN); ... } but it still dies with the message "Floating point exception (core dumped)". I don't actually use the value, so I don't really care what's assigned to the variable; 0, random, undefined... EDIT: I know this is not the most portable, but it's intended for an embedded device which runs on many different OSes. The default halt action is to divide by zero; other platforms require different tricks to force a watchdog induced reboot (such as an infinite loop with interrupts disabled). For a PC (linux) test environment, I wanted to disable the halt on division by zero without relying on things like assert.

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• Getting identity from Ado.Net Update command

  - by rboarman

  My scenario is simple. I am trying to persist a DataSet and have the identity column filled in so I can add child records. Here's what I've got so far: using (SqlConnection connection = new SqlConnection(connStr)) { SqlDataAdapter adapter = new SqlDataAdapter("select * from assets where 0 = 1", connection); adapter.MissingMappingAction = MissingMappingAction.Passthrough; adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey; SqlCommandBuilder cb = new SqlCommandBuilder(adapter); var insertCmd = cb.GetInsertCommand(true); insertCmd.Connection = connection; connection.Open(); adapter.InsertCommand = insertCmd; adapter.InsertCommand.CommandText += "; set ? = SCOPE_IDENTITY()"; adapter.InsertCommand.UpdatedRowSource = UpdateRowSource.OutputParameters; var param = new SqlParameter("RowId", SqlDbType.Int); param.SourceColumn = "RowId"; param.Direction = ParameterDirection.Output; adapter.InsertCommand.Parameters.Add(param); SqlTransaction transaction = connection.BeginTransaction(); insertCmd.Transaction = transaction; try { assetsImported = adapter.Update(dataSet.Tables["Assets"]); transaction.Commit(); } catch (Exception ex) { transaction.Rollback(); // Log an error } connection.Close(); } The first thing that I noticed, besides the fact that the identity value is not making its way back into the DataSet, is that my change to add the scope_identity select statement to the insert command is not being executed. Looking at the query using Profiler, I do not see my addition to the insert command. Questions: 1) Why is my addition to the insert command not making its way to the sql being executed on the database? 2) Is there a simpler way to have my DataSet refreshed with the identity values of the inserted rows? 3) Should I use the OnRowUpdated callback to add my child records? My plan was to loop through the rows after the Update() call and add children as needed. Thank you in advance. Rick

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• How to distinguish between two different UDP clients on the same IP address?

  - by Ricket

  I'm writing a UDP server, which is a first for me; I've only done a bit of TCP communications. And I'm having trouble figuring out exactly how to distinguish which user is which, since UDP deals only with packets rather than connections and I therefore cannot tell exactly who I'm communicating with. Here is pseudocode of my current server loop: DatagramPacket p; socket.receive(p); // now p contains the user's IP and port, and the data int key = getKey(p); if(key == 0) { // connection request key = makeKey(p); clients.add(key, p.ip); send(p.ip, p.port, key); // give the user his key } else { // user has a key // verify key belongs to that IP address // lookup the user's session data based on the key // react to the packet in the context of the session } When designing this, I kept in mind these points: Multiple users may exist on the same IP address, due to the presence of routers, therefore users must have a separate identification key. Packets can be spoofed, so the key should be checked against its original IP address and ignored if a different IP tries to use the key. The outbound port on the client side might change among packets. Is that third assumption correct, or can I simply assume that one user = one IP+port combination? Is this commonly done, or should I continue to create a special key like I am currently doing? I'm not completely clear on how TCP negotiates a connection so if you think I should model it off of TCP then please link me to a good tutorial or something on TCP's SYN/SYNACK/ACK mess. Also note, I do have a provision to resend a key, if an IP sends a 0 and that IP already has a pending key; I omitted it to keep the snippet simple. I understand that UDP is not guaranteed to arrive, and I plan to add reliability to the main packet handling code later as well.

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• LinqKit stack overflow exception using predicate builder

  - by MLynn

  I am writing an application in C# using LINQ and LINQKit. I have a very large database table with company registration numbers in it. I want to do a LINQ query which will produce the equivalent SQL: select * from table1 where regno in('123','456') The 'in' clause may have thousands of terms. First I get the company registration numbers from a field such as Country. I then add all the company registration numbers to a predicate: var predicate = PredicateExtensions.False<table2>(); if (RegNos != null) { foreach (int searchTerm in RegNos) { int temp = searchTerm; predicate = predicate.Or(ec => ec.regno.Equals(temp)); } } On Windows Vista Professional a stack overflow exception occured after 4063 terms were added. On Windows Server 2003 a stack overflow exception occured after about 1000 terms were added. I had to solve this problem quickly for a demo. To solve the problem I used this notation: var predicate = PredicateExtensions.False<table2>(); if (RegNosDistinct != null) { predicate = predicate.Or(ec => RegNos.Contains(ec.regno)); } My questions are: Why does a stack overflow occur using the foreach loop? I take it Windows Server 2003 has a much smaller stack per process\thread than NT\2000\XP\Vista\Windows 7 workstation versions of Windows. Which is the fastest and most correct way to achieve this using LINQ and LINQKit? It was suggested I stop using LINQ and go back to dynamic SQL or ADO.NET but I think using LINQ and LINQKit is far better for maintainability.

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• continueTrackingWithTouch: withEvent: not being called continuously.

  - by Steven Noyes

  I have a very simply subclass of UIButton that will fire off a custom event when the button has been held for 2 seconds. To accomplish this, I overrode: // // Mouse tracking // - (BOOL)beginTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event { [super beginTrackingWithTouch:touch withEvent:event]; [self setTimeButtonPressed:[NSDate date]]; return (YES); } - (BOOL)continueTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event { [super continueTrackingWithTouch:touch withEvent:event]; if ([[self timeButtonPressed] timeIntervalSinceNow] > 2.0) { // // disable the button. This will eventually fire the event // but this is just stubbed to act as a break point area. // [self setEnabled:NO]; [self setSelected:NO]; } return (YES); } My problem is (this is in the simulator, can't do on device work quite yet) "continueTrackingWithTouch: withEvent:" is not being called unless the mouse is actually moved. It does not take much motion, but it does take some motion. By returning "YES" in both of these, I should be setup to receive continuous events. Is this an oddity of the simulator or am I doing something wrong? NOTE: userInteractionEnabled is set to YES. NOTE2: I could setup a timer in beginTrackingWithTouch: withEvent: but that seems like more effort for something that should be simple.

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• What's the relationship between the Intel Atom Developer Program and the MeeGo operating system?

  - by Arne Evertsson

  I'm trying to understand the relationship between the Intel Atom Developer Program (IADP) and the new OS called MeeGo. IADP let's me create applications that run on both MeeGo as well as Windows devices, as long as the device is based on the Atom processor. The IADP apps are published in an app store called AppUp, which is very much like the Apple App Store. The MeeGo operating system merges Intel's Moblin and Nokia's Maemo into one OS. The purpose seems to be to make it possible to develop software that will run on Intel powered devices, Nokia-made devices, as well devices from other companies. Nokia has its Ovi Store that will support MeeGo apps. With its OS independent runtime, the question is what an IADP app really is? Is an IADP app a beast of its own, or is it just a MeeGo app that has been restricted to run only on Atom powered devices? Will it be possible to recompile my IADP app to run on all MeeGo devices? Sold in Ovi Store? Intel and Nokia have me really confused. Where should I go as a developer?

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• C++ LPTSTR to int (but memory overwrite problem using atoi)

  - by Dexter

  I have the following code, m_edit is a MFC CEdit (I know I would never use MFC but project demanded it). It's a simple loop, that gets the text from a text edit, converts it to integer after getting the first line, then stores it in m_y vector. LPTSTR szTemp; vector<int> m_y; for(int i = 0; i < m_edit->GetLineCount(); i++){ szTemp = s_y.GetBuffer(0); m_edit->GetLine(i, szTemp); // get line text store in szTemp y = atoi(szTemp); m_y.push_back(y); szTemp = ""; y = 0; } IMPORTANT EXAMPLE: So let's say the CEdit has 6 numbers: 0 5 2 5 18 6 If you use Visual Studio's debugger you will notice an anomaly!! Here's what it shows: y = 0 y = 5 y = 2 y = 5 y = 18 y = 68 Do you see that? szTemp when inserted into atoi, it returns the number 6, but concatenates the 2nd digit of the last number!!! This is why I did szTemp = "";, but the problem persists. Also, let's say the last number was 17 (not 18), then this time debugger would say y = 67, so it is definitely this problem. However, Visual Studio debugger, when you hover over szTemp during this iteration, it says '6' <--- not '68' inside szTemp. So somehow atoi is ruining it. Am I suppose to concatenate a \0 into szTemp before putting it into atoi? How do I solve this easily?

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