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  • Generics vs Object performance

    - by Risho
    I'm doing practice problems from MCTS Exam 70-536 Microsft .Net Framework Application Dev Foundation, and one of the problems is to create two classes, one generic, one object type that both perform the same thing; in which a loop uses the class and iterated over thousand times. And using the timer, time the performance of both. There was another post at C# generics question that seeks the same questoion but nonone replied. Basically if in my code I run the generic class first it takes loger to process. If I run the object class first than the object class takes longer to process. The whole idea was to prove that generics perform faster. I used the original users code to save me some time. I didn't particularly see anything wrong with the code and was puzzled by the outcome. Can some one explain why the unusual results? Thanks, Risho Here is the code: class Program { class Object_Sample { public Object_Sample() { Console.WriteLine("Object_Sample Class"); } public long getTicks() { return DateTime.Now.Ticks; } public void display(Object a) { Console.WriteLine("{0}", a); } } class Generics_Samle<T> { public Generics_Samle() { Console.WriteLine("Generics_Sample Class"); } public long getTicks() { return DateTime.Now.Ticks; } public void display(T a) { Console.WriteLine("{0}", a); } } static void Main(string[] args) { long ticks_initial, ticks_final, diff_generics, diff_object; Object_Sample OS = new Object_Sample(); Generics_Samle<int> GS = new Generics_Samle<int>(); //Generic Sample ticks_initial = 0; ticks_final = 0; ticks_initial = GS.getTicks(); for (int i = 0; i < 50000; i++) { GS.display(i); } ticks_final = GS.getTicks(); diff_generics = ticks_final - ticks_initial; //Object Sample ticks_initial = 0; ticks_final = 0; ticks_initial = OS.getTicks(); for (int j = 0; j < 50000; j++) { OS.display(j); } ticks_final = OS.getTicks(); diff_object = ticks_final - ticks_initial; Console.WriteLine("\nPerformance of Generics {0}", diff_generics); Console.WriteLine("Performance of Object {0}", diff_object); Console.ReadKey(); } }

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  • C - How to use both aio_read() and aio_write().

    - by Slav
    I implement game server where I need to both read and write. So I accept incoming connection and start reading from it using aio_read() but when I need to send something, I stop reading using aio_cancel() and then use aio_write(). Within write's callback I resume reading. So, I do read all the time but when I need to send something - I pause reading. It works for ~20% of time - in other case call to aio_cancel() fails with "Operation now in progress" - and I cannot cancel it (even within permanent while cycle). So, my added write operation never happens. How to use these functions well? What did I missed? EDIT: Used under Linux 2.6.35. Ubuntu 10 - 32 bit. Example code: void handle_read(union sigval sigev_value) { /* handle data or disconnection */ } void handle_write(union sigval sigev_value) { /* free writing buffer memory */ } void start() { const int acceptorSocket = socket(AF_INET, SOCK_STREAM, 0); struct sockaddr_in addr; memset(&addr, 0, sizeof(struct sockaddr_in)); addr.sin_family = AF_INET; addr.sin_addr.s_addr = INADDR_ANY; addr.sin_port = htons(port); bind(acceptorSocket, (struct sockaddr*)&addr, sizeof(struct sockaddr_in)); listen(acceptorSocket, SOMAXCONN); struct sockaddr_in address; socklen_t addressLen = sizeof(struct sockaddr_in); for(;;) { const int incomingSocket = accept(acceptorSocket, (struct sockaddr*)&address, &addressLen); if(incomingSocket == -1) { /* handle error ... */} else { //say socket to append outcoming messages at writing: const int currentFlags = fcntl(incomingSocket, F_GETFL, 0); if(currentFlags < 0) { /* handle error ... */ } if(fcntl(incomingSocket, F_SETFL, currentFlags | O_APPEND) == -1) { /* handle another error ... */ } //start reading: struct aiocb* readingAiocb = new struct aiocb; memset(readingAiocb, 0, sizeof(struct aiocb)); readingAiocb->aio_nbytes = MY_SOME_BUFFER_SIZE; readingAiocb->aio_fildes = socketDesc; readingAiocb->aio_buf = mySomeReadBuffer; readingAiocb->aio_sigevent.sigev_notify = SIGEV_THREAD; readingAiocb->aio_sigevent.sigev_value.sival_ptr = (void*)mySomeData; readingAiocb->aio_sigevent.sigev_notify_function = handle_read; if(aio_read(readingAiocb) != 0) { /* handle error ... */ } } } } //called at any time from server side: send(void* data, const size_t dataLength) { //... some thread-safety precautions not needed here ... const int cancellingResult = aio_cancel(socketDesc, readingAiocb); if(cancellingResult != AIO_CANCELED) { //this one happens ~80% of the time - embracing previous call to permanent while cycle does not help: if(cancellingResult == AIO_NOTCANCELED) { puts(strerror(aio_return(readingAiocb))); // "Operation now in progress" /* don't know what to do... */ } } //otherwise it's okay to send: else { aio_write(...); } }

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  • Creating a binary file from an IntelHex in C#

    - by Allek
    I'm trying to create a binary file from a intelHex file. Iside the intelHex file I have data and address to which I should write the data inside the binary file. IntelHex file looks like that :10010000214601360121470136007EFE09D2190140 :100110002146017EB7C20001FF5F16002148011988 :10012000194E79234623965778239EDA3F01B2CAA7 :100130003F0156702B5E712B722B732146013421C7 :00000001FF So I have 4 lines here with data since the last one tells us thats the end of file. Here is what I'm doing to create the file while (!streamReader.EndOfStream) { string temp = String.Empty; int address = 0; line = streamReader.ReadLine(); // Get address for each data address = Convert.ToInt32(line.Substring(3, 4), 16); // Get data from each line temp = line.Substring(7, 2); if (temp == "01") break; else { temp = line.Substring(9, line.Length - 11); string[] array = new string[(temp.Length / 2)]; int j = 0; for (int i = 0; i < array.Length; ++i) { array[i] = temp[j].ToString() + temp[j + 1].ToString(); j = j + 2; } temp = String.Empty; for (int i = 0; i < array.Length; ++i) { temp = temp + Convert.ToChar(Convert.ToInt32(array[i], 16)); } } binaryWriter.Seek(address, SeekOrigin.Begin); binaryWriter.Write(temp); binaryWriter.Flush(); } Console.WriteLine("Done...\nPress any key to exit..."); The problem here is, that data in binary file in some places is not equal to data from the intelHex file. Looks like there is some random data added to the file and I do not know from where. First time I saw that there is an additional data before the data from the intelHex file. For instance first data line starts with 21, but in binary file I have a number 12 before the 21. I do not know what is wrong here. Hope someone can help me or guide me where I can find some usefull informations about creating binary files in C#

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  • Force close while calling mainactivity from widget (android)

    - by Shaji Thorn Blue
    Iam creating a simple widget, by this widget i want to open my mainactivity. Iam sending a unique key from my widget class to check whether my mainactivity is called via widget or not. But as soon as i clicked on my widget my mainactivity get force close. here is code of my widget class... @Override public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] widgets) { // TODO Auto-generated method stub int numofWidgets = widgets.length; for(int i=0;i<numofWidgets;i++){ int widget = widgets[i]; Intent in = new Intent(context, EmergencyButton.class); in.putExtra("uniquevalue", "widget"); PendingIntent pendingintent = PendingIntent.getActivity(context, 0, in, 0); RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widgetlayout); views.setOnClickPendingIntent(R.id.button, pendingintent); appWidgetManager.updateAppWidget(widget, views); } } And Here is my code of mainactivity where iam checking whether called came from widget or not @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.mainactivity); Intent intentwidget = this.getIntent(); if(intentwidget !=null) { String widgetdata = "nothing"; widgetdata = intentwidget.getExtras().getString("uniquevalue"); if(widgetdata.equals("widget")) { et1.setText(widgetdata); } } } And here is my logcat 11-04 14:57:14.361: E/AndroidRuntime(1701): FATAL EXCEPTION: main 11-04 14:57:14.361: E/AndroidRuntime(1701): java.lang.RuntimeException: Unable to start activityComponentInfo{com.appsionlabs.googlemapv2/com.appsionlabs.googlemapv2.EmergencyButton}: java.lang.NullPointerException 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.os.Handler.dispatchMessage(Handler.java:99) 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.os.Looper.loop(Looper.java:123) 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.app.ActivityThread.main(ActivityThread.java:3683) 11-04 14:57:14.361: E/AndroidRuntime(1701): at java.lang.reflect.Method.invokeNative(Native Method) 11-04 14:57:14.361: E/AndroidRuntime(1701): at java.lang.reflect.Method.invoke(Method.java:507) 11-04 14:57:14.361: E/AndroidRuntime(1701): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 11-04 14:57:14.361: E/AndroidRuntime(1701): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 11-04 14:57:14.361: E/AndroidRuntime(1701): at dalvik.system.NativeStart.main(Native Method) 11-04 14:57:14.361: E/AndroidRuntime(1701): Caused by: java.lang.NullPointerException 11-04 14:57:14.361: E/AndroidRuntime(1701): at com.appsionlabs.googlemapv2.EmergencyButton.onCreate(EmergencyButton.java:29) 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 11-04 14:57:14.361: E/AndroidRuntime(1701): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)

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  • Unable to decode hex values in javascript tooltip

    - by staudk27
    Hi all, I have quite the process that we go through in order to display some e-mail communications in our application. Trying to keep it as general as possible... -We make a request to a service via XML -Get the XML reply string, send the string to a method to encode any invalid characters as follows: public static String convertUTF8(String value) { char[] chars = value.toCharArray(); StringBuffer retVal = new StringBuffer(chars.length); for (int i = 0; i < chars.length; i++) { char c = chars[i]; int chVal = (int)c; if (chVal > Byte.MAX_VALUE) { retVal.append("&#x").append(Integer.toHexString(chVal)).append(";"); } else { retVal.append(c); } } return retVal.toString(); } We then send that result of a string to another method to remove any other invalid characters: public static String removeInvalidCharacters(String inString) { if (inString == null){ return null; } StringBuffer newString = new StringBuffer(); char ch; char c[] = inString.toCharArray(); for (int i = 0; i < c.length; i++) { ch = c[i]; // remove any characters outside the valid UTF-8 range as well as all control characters // except tabs and new lines if ((ch < 0x00FD && ch > 0x001F) || ch == '\t' || ch == '\n' || ch == '\r') { newString.append(ch); } } return newString.toString(); } This string is then "unmarshal'ed" via the SaxParser The object is then sent back to our Display action which generated the response to the calling jsp/javascript to create the page. The issue is some text can contain characters which can't be processed correctly. The following is eventually rendered on the JSP just fine: <PrvwCommTxt>This is a new test. Have a*&amp;#xc7;&amp;#xb4;)&amp;#xa1;.&amp;#xf1;&amp;#xc7;&amp;#xa1;.&amp;#xf1;*&amp;#xc7;&amp;#xb4;)...</PrvwCommTxt> Which shows up as "This is a new test. Have a*Ç´)¡.ñÇ¡." in the browser. -The following shows up in a tooltip while hovering over the above text: <CommDetails>This is a new test. Have a*Ç´)¡.ñÇ¡.ñ*Ç´)¡.ñ*´)(¡.ñÇ(¡.ñÇ* Wonderful Day!</CommDetails> This then shows up incorrectly when rendered in the tooltip javascript with all the HEX values and not being rendered correctly. Any suggestions on how to make the unknown characters show correctly in javascript?

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  • Output from OouraFFT correct sometimes but completely false other times. Why ?

    - by Yan
    Hi I am using Ooura FFT to compute the FFT of the accelerometer data in windows of 1024 samples. The code works fine, but then for some reason it produces very strange outputs, i.e. continuous spectrum with amplitudes of the order of 10^200. Here is the code: OouraFFT *myFFT=[[OouraFFT alloc] initForSignalsOfLength:1024 NumWindows:10]; // had to allocate it UIAcceleration *tempAccel = nil; double *input=(double *)malloc(1024 * sizeof(double)); double *frequency=(double *)malloc(1024*sizeof(double)); if (input) { //NSLog(@"%d",[array count]); for (int u=0; u<[array count]; u++) { tempAccel = (UIAcceleration *)[array objectAtIndex:u]; input[u]=tempAccel.z; //NSLog(@"%g",input[u]); } } myFFT.inputData=input; // specifies input data to myFFT [myFFT calculateWelchPeriodogramWithNewSignalSegment]; // calculates FFT for (int i=0;i<myFFT.dataLength;i++) // loop to copy output of myFFT, length of spectrumData is half of input data, so copy twice { if (i<myFFT.numFrequencies) { frequency[i]=myFFT.spectrumData[i]; // } else { frequency[i]=myFFT.spectrumData[myFFT.dataLength-i]; // copy twice } } for (int i=0;i<[array count];i++) { TransformedAcceleration *NewAcceleration=[[TransformedAcceleration alloc]init]; tempAccel=(UIAcceleration*)[array objectAtIndex:i]; NewAcceleration.timestamp=tempAccel.timestamp; NewAcceleration.x=tempAccel.x; NewAcceleration.y=tempAccel.z; NewAcceleration.z=frequency[i]; [newcurrentarray addObject:NewAcceleration]; // this does not work //[self replaceAcceleration:NewAcceleration]; //[NewAcceleration release]; [NewAcceleration release]; } TransformedAcceleration *a=nil;//[[TransformedAcceleration alloc]init]; // object containing fft of x,y,z accelerations for(int i=0; i<[newcurrentarray count]; i++) { a=(TransformedAcceleration *)[newcurrentarray objectAtIndex:i]; //NSLog(@"%d,%@",i,[a printAcceleration]); fprintf(fp,[[a printAcceleration] UTF8String]); //this is going wrong somewhow } fclose(fp); [array release]; [myFFT release]; //[array removeAllObjects]; [newcurrentarray release]; free(input); free(frequency);

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  • Can MySQL reasonably perform queries on billions of rows?

    - by haxney
    I am planning on storing scans from a mass spectrometer in a MySQL database and would like to know whether storing and analyzing this amount of data is remotely feasible. I know performance varies wildly depending on the environment, but I'm looking for the rough order of magnitude: will queries take 5 days or 5 milliseconds? Input format Each input file contains a single run of the spectrometer; each run is comprised of a set of scans, and each scan has an ordered array of datapoints. There is a bit of metadata, but the majority of the file is comprised of arrays 32- or 64-bit ints or floats. Host system |----------------+-------------------------------| | OS | Windows 2008 64-bit | | MySQL version | 5.5.24 (x86_64) | | CPU | 2x Xeon E5420 (8 cores total) | | RAM | 8GB | | SSD filesystem | 500 GiB | | HDD RAID | 12 TiB | |----------------+-------------------------------| There are some other services running on the server using negligible processor time. File statistics |------------------+--------------| | number of files | ~16,000 | | total size | 1.3 TiB | | min size | 0 bytes | | max size | 12 GiB | | mean | 800 MiB | | median | 500 MiB | | total datapoints | ~200 billion | |------------------+--------------| The total number of datapoints is a very rough estimate. Proposed schema I'm planning on doing things "right" (i.e. normalizing the data like crazy) and so would have a runs table, a spectra table with a foreign key to runs, and a datapoints table with a foreign key to spectra. The 200 Billion datapoint question I am going to be analyzing across multiple spectra and possibly even multiple runs, resulting in queries which could touch millions of rows. Assuming I index everything properly (which is a topic for another question) and am not trying to shuffle hundreds of MiB across the network, is it remotely plausible for MySQL to handle this? UPDATE: additional info The scan data will be coming from files in the XML-based mzML format. The meat of this format is in the <binaryDataArrayList> elements where the data is stored. Each scan produces = 2 <binaryDataArray> elements which, taken together, form a 2-dimensional (or more) array of the form [[123.456, 234.567, ...], ...]. These data are write-once, so update performance and transaction safety are not concerns. My naïve plan for a database schema is: runs table | column name | type | |-------------+-------------| | id | PRIMARY KEY | | start_time | TIMESTAMP | | name | VARCHAR | |-------------+-------------| spectra table | column name | type | |----------------+-------------| | id | PRIMARY KEY | | name | VARCHAR | | index | INT | | spectrum_type | INT | | representation | INT | | run_id | FOREIGN KEY | |----------------+-------------| datapoints table | column name | type | |-------------+-------------| | id | PRIMARY KEY | | spectrum_id | FOREIGN KEY | | mz | DOUBLE | | num_counts | DOUBLE | | index | INT | |-------------+-------------| Is this reasonable?

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  • Iphone newb Question - How to export information to a website?

    - by Rob
    I am a new iphone developer and was wondering if I could get some help with some code. I just want to know how to export basic character strings and variables to a website to be used by a third-party program. Basically, if I had something as basic as: int variableOne; int variableTwo; What code would I use to export these variables to a website?

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  • Help me with this java program

    - by aser
    The question : Input file: customer’s account number, account balance at beginning of month, transaction type (withdrawal, deposit, interest), transaction amount Output: account number, beginning balance, ending balance, total interest paid, total amount deposited, number of deposits, total amount withdrawn, number of withdrawals package sentinel; import java.io.*; import java.util.*; public class Ex7 { /** * @param args the command line arguments */ public static void main(String[] args) throws FileNotFoundException { int AccountNum; double BeginningBalance; double TransactionAmount; int TransactionType; double AmountDeposited=0; int NumberOfDeposits=0; double InterestPaid=0.0; double AmountWithdrawn=0.0; int NumberOfWithdrawals=0; boolean found= false; Scanner inFile = new Scanner(new FileReader("Account.in")); PrintWriter outFile = new PrintWriter("Account.out"); AccountNum = inFile.nextInt(); BeginningBalance= inFile.nextDouble(); while (inFile.hasNext()) { TransactionAmount=inFile.nextDouble(); TransactionType=inFile.nextInt(); outFile.printf("Account Number: %d%n", AccountNum); outFile.printf("Beginning Balance: $%.2f %n",BeginningBalance); outFile.printf("Ending Balance: $%.2f %n",BeginningBalance); outFile.println(); switch (TransactionType) { case '1': // case 1 if we have a Deposite BeginningBalance = BeginningBalance + TransactionAmount; AmountDeposited = AmountDeposited + TransactionAmount; NumberOfDeposits++; outFile.printf("Amount Deposited: $%.2f %n",AmountDeposited); outFile.printf("Number of Deposits: %d%n",NumberOfDeposits); outFile.println(); break; case '2':// case 2 if we have an Interest BeginningBalance = BeginningBalance + TransactionAmount; InterestPaid = InterestPaid + TransactionAmount; outFile.printf("Interest Paid: $%.2f %n",InterestPaid); outFile.println(); break; case '3':// case 3 if we have a Withdraw BeginningBalance = BeginningBalance - TransactionAmount; AmountWithdrawn = AmountWithdrawn + TransactionAmount; NumberOfWithdrawals++; outFile.printf("Amount Withdrawn: $%.2f %n",AmountWithdrawn); outFile.printf("Number of Withdrawals: %d%n",NumberOfWithdrawals); outFile.println(); break; default: System.out.println("Invalid transaction Tybe: " + TransactionType + TransactionAmount); } } inFile.close(); outFile.close(); } } But is gives me this : Exception in thread "main" java.util.InputMismatchException at java.util.Scanner.throwFor(Scanner.java:840) at java.util.Scanner.next(Scanner.java:1461) at java.util.Scanner.nextInt(Scanner.java:2091) at java.util.Scanner.nextInt(Scanner.java:2050) at sentinel.Ex7.main(Ex7.java:36) Java Result: 1

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  • LINQ transform Dictionary<key,value> to Dictionary<value,key>

    - by code4life
    I'm having a low-brainwave day... Does anyone know of a quick & elegant way to transform a Dictionary so that the key becomes the value and vice-versa? Example: var originalDictionary = new Dictionary<int, string>() { {1, "One"}, {2, "Two"}, {3, "Three"} }; becomes var newDictionary = new Dictionary<string, int>(); // contents: // { // {"One". 1}, {"Two". 2}, {"Three", 3} // };

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  • Active Directoy LDAP - Lock User Account

    - by Germ
    What is the prefered way to lock an Active Directory account? int val = (int)directoryentry.Properties["userAccountControl"].Value; directoryentry.Properties["userAccountControl"].Value = val | 0x0010; vs. directoryentry.InvokeSet("IsAccountLocked", true); Is there a better way?

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  • Change HttpContext.Request.InputStream

    - by user320478
    I am getting lot of errors for HttpRequestValidationException in my event log. Is it possible to HTMLEncode all the inputs from override of ProcessRequest on web page. I have tried this but it gives context.Request.InputStream.CanWrite == false always. Is there any way to HTMLEncode all the feilds when request is made? public override void ProcessRequest(HttpContext context) { if (context.Request.InputStream.CanRead) { IEnumerator en = HttpContext.Current.Request.Form.GetEnumerator(); while (en.MoveNext()) { //Response.Write(Server.HtmlEncode(en.Current + " = " + //HttpContext.Current.Request.Form[(string)en.Current])); } long nLen = context.Request.InputStream.Length; if (nLen > 0) { string strInputStream = string.Empty; context.Request.InputStream.Position = 0; byte[] bytes = new byte[nLen]; context.Request.InputStream.Read(bytes, 0, Convert.ToInt32(nLen)); strInputStream = Encoding.Default.GetString(bytes); if (!string.IsNullOrEmpty(strInputStream)) { List<string> stream = strInputStream.Split('&').ToList<string>(); Dictionary<int, string> data = new Dictionary<int, string>(); if (stream != null && stream.Count > 0) { int index = 0; foreach (string str in stream) { if (str.Length > 3 && str.Substring(0, 3) == "txt") { string textBoxData = str; string temp = Server.HtmlEncode(str); //stream[index] = temp; data.Add(index, temp); index++; } } if (data.Count > 0) { List<string> streamNew = stream; foreach (KeyValuePair<int, string> kvp in data) { streamNew[kvp.Key] = kvp.Value; } string newStream = string.Join("", streamNew.ToArray()); byte[] bytesNew = Encoding.Default.GetBytes(newStream); if (context.Request.InputStream.CanWrite) { context.Request.InputStream.Flush(); context.Request.InputStream.Position = 0; context.Request.InputStream.Write(bytesNew, 0, bytesNew.Length); //Request.InputStream.Close(); //Request.InputStream.Dispose(); } } } } } } base.ProcessRequest(context); }

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  • how to display numbers without garbage numbers?

    - by Medeti Naveen Kumar
    Hi friends, whenever i press the numbers in text filed upto 9 numbers my textfield has taken right values but i press 10 th number.i have found duplicate number. in my header file i declare a pressnumber is "long long int" -(IBAction)press:(id)sender{ pressNumber = pressNumber*10 + (int)[sender tag]; phonenumber.text = [NSString stringWithFormat:@"%d",currentNumber]; } i want to enter a phone number in my textfiled but it is not taken 10 right numbers. Thanking you,

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  • SQL query - choosing 'last updated' record in a group, better db design?

    - by Jimmy
    Hi, Let's say I have a MySQL database with 3 tables: table 1: Persons, with 1 column ID (int) table 2: Newsletters, with 1 column ID (int) table 3: Subscriptions, with columns Person_ID (int), Newsletter_ID (int), Subscribed (bool), Updated (Datetime) Subscriptions.Person_ID points to a Person, and Subscription.Newsletter_ID points to a Newsletter. Thus, each person may have 0 or more subscriptions to 0 or more magazines at once. The table Subscriptions will also store the entire history of each person's subscriptions to each newsletter. If a particular Person_ID-Newsletter_ID pair doesn't have a row in the Subscriptions table, then it's equivalent to that pair having a subscription status of 'false'. Here is a sample dataset Persons ID 1 2 3 Newsletters ID 4 5 6 Subscriptions Person_ID Newsletter_ID Subscribed Updated 2 4 true 2010-05-01 3 4 true 2010-05-01 3 5 true 2010-05-10 3 4 false 2010-05-15 Thus, as of 2010-05-16, Person 1 has no subscription, Person 2 has a subscription to Newsletter 4, and Person 3 has a subscription to Newsletter 5. Person 3 had a subscription to Newsletter 4 for a while, but not anymore. I'm trying to do 2 kinds of query. A query that shows everyone's active subscriptions as of query time (we can assume that updated will never be in the future -- thus, this means returning the record with the latest 'updated' value for each Person_ID-Newsletter_ID pair, as long as Subscribed is true (if the latest record for a Person_ID-Newsletter_ID pair has a Subscribed status of false, then I don't want that record returned)). A query that returns all active subscriptions for a specific newsletter - same qualification as in 1. regarding records with 'false' in the Subscribed column. I don't use SQL/databases often enough to tell if this design is good, or if the SQL queries needed would be slow on a database with, say, 1M records in the Subscriptions table. I was using the Visual query builder tool in Visual Studio 2010 but I can't even get the query to return the latest updated record for each Person_ID-Newsletter_ID pair. Is it possible to come up with SQL queries that don't involve using subqueries (presumably because they would become too slow with a larger data set)? If not, would it be a better design to have a separate Subscriptions_History table, and every time a subscription status for a Person_ID-Newsletter-ID pair is added to Subscriptions, any existing record for that pair is moved to Subscriptions_History (that way the Subscriptions table only ever contains the latest status update for any Person_ID-Newsletter_ID pair)? I'm using .net on Windows, so would it be easier (or the same, or harder) to do this kind of queries using Linq? Entity Framework? Thanks!

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  • JNA problem with char** (in dll)

    - by underline
    Hi, ok it is 'easy' to make jna wrapper solution for mapping exported functions within dll using jna: long f1(int x), just int long f2(char* y), just char[] but how to deal with long f3(char** z) ? I need f3's result(long) as well as z value on java side. Please don't say cpp code should be rewritten to avoid this:-)

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  • multi-thread access MySQL error

    - by user188916
    I have written a simple multi-threaded C program to access MySQL,it works fine except when i add usleep() or sleep() function in each thread function. i created two pthreads in the main method, int main(){ mysql_library_init(0,NULL,NULL); printf("Hello world!\n"); init_pool(&p,100); pthread_t producer; pthread_t consumer_1; pthread_t consumer_2; pthread_create(&producer,NULL,produce_fun,NULL); pthread_create(&consumer_1,NULL,consume_fun,NULL); pthread_create(&consumer_2,NULL,consume_fun,NULL); mysql_library_end(); } void * produce_fun(void *arg){ pthread_detach(pthread_self()); //procedure while(1){ usleep(500000); printf("producer...\n"); produce(&p,cnt++); } pthread_exit(NULL); } void * consume_fun(void *arg){ pthread_detach(pthread_self()); MYSQL db; MYSQL *ptr_db=mysql_init(&db); mysql_real_connect(); //procedure while(1){ usleep(1000000); printf("consumer..."); int item=consume(&p); addRecord_d(ptr_db,"test",item); } mysql_thread_end(); pthread_exit(NULL); } void addRecord_d(MYSQL *ptr_db,const char *t_name,int item){ char query_buffer[100]; sprintf(query_buffer,"insert into %s values(0,%d)",t_name,item); //pthread_mutex_lock(&db_t_lock); int ret=mysql_query(ptr_db,query_buffer); if(ret){ fprintf(stderr,"%s%s\n","cannot add record to ",t_name); return; } unsigned long long update_id=mysql_insert_id(ptr_db); // pthread_mutex_unlock(&db_t_lock); printf("add record (%llu,%d) ok.",update_id,item); } the program output errors like: [Thread debugging using libthread_db enabled] [New Thread 0xb7ae3b70 (LWP 7712)] Hello world! [New Thread 0xb72d6b70 (LWP 7713)] [New Thread 0xb6ad5b70 (LWP 7714)] [New Thread 0xb62d4b70 (LWP 7715)] [Thread 0xb7ae3b70 (LWP 7712) exited] producer... producer... consumer...consumer...add record (31441,0) ok.add record (31442,1) ok.producer... producer... consumer...consumer...add record (31443,2) ok.add record (31444,3) ok.producer... producer... consumer...consumer...add record (31445,4) ok.add record (31446,5) ok.producer... producer... consumer...consumer...add record (31447,6) ok.add record (31448,7) ok.producer... Error in my_thread_global_end(): 2 threads didn't exit [Thread 0xb72d6b70 (LWP 7713) exited] [Thread 0xb6ad5b70 (LWP 7714) exited] [Thread 0xb62d4b70 (LWP 7715) exited] Program exited normally. and when i add pthread_mutex_lock in function addRecord_d,the error still exists. So what exactly the problem is?

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  • How to store multiple variables from a File Input of unknown size in Java?

    - by AlphaOmegaStrife
    I'm a total beginner with my first programming assignment in Java. For our programming assignment, we will be given a .txt file of students like so: 3 345 Lisa Miller 890238 Y 2 <-(Number of classes) Mathematics MTH345 4 A Physics PHY357 3 B Bill Wilton 798324 N 2 English ENG378 3 B Philosophy PHL534 3 A Dandy Goat 746333 Y 1 History HIS101 3 A" The teacher will give us a .txt file on the day of turning it in with a list of unknown students. My problem is: I have a specific class for turning the data from the file into variables to be used for a different class in printing it to the screen. However, I do not know of a good way to get the variables from the input file for the course numbers, since that number is not predetermined. The only way I can think of to iterate over that unknown amount is using a loop, but that would just overwrite my variables every time. Also, the teacher has requested that we not use any JCL classes (I don't really know what this means.) Sorry if I have done a poor job of explaining this, but I can't think of a better way to conceptualize it. Let me know if I can clarify. Edit: public static void analyzeData() { Scanner inputStream = null; try { inputStream = new Scanner(new FileInputStream("Programming Assignment 1 Data.txt")); } catch (FileNotFoundException e) { System.out.println("File Programming Assignment 1 Data.txt could not be found or opened."); System.exit(0); } int numberOfStudents = inputStream.nextInt(); int tuitionPerHour = inputStream.nextInt(); String firstName = inputStream.next(); String lastname = inputStream.next(); String isTuitionPaid = inputStream.next(); int numberOfCourses = inputStream.nextInt(); String courseName = inputStream.next(); String courseNumber = inputStream.next(); int creditHours = inputStream.nextInt(); String grade = inputStream.next(); To show the methods I am using now, I am just using a Scanner to read from the file and for Scanner inputStream, I am using nextInt() or next() to get variables from the file. Obviously this will not work when I do not know exactly how many classes each student will have.

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  • C++ Stack Overflow

    - by PhilMAN
    Here is some code: void main() { GameEngine ge("phil", "anotherguy"); string response; do { ge.playGame(); cout << endl << "Do you want to (r)eplay the same battle, (s)tart a new battle, or (q)uit? "; cin >> response; } while(response == "r" || response == "R" || response == "s" || response == "S" ); } GameEngine::GameEngine(string name1, string name2) { p1Name = name1; p2Name = name2; } void GameEngine::playGame() { cout << "PLAY GAME" << endl; Army p1, p2; Battlefield testField; RuleSet rs; int xSize = 13; // Number of rows int ySize = 13; // Number of columns loadData(p1, p2, testField, rs, xSize, ySize); ... } void GameEngine::loadData(Army& p1, Army& p2, Battlefield& testField, RuleSet& rs, int& xSize, int& ySize) { string terrain = BattlefieldUtils::pickTerrain(); string armySplit[14];//id index 1 string ruleSplit[19];//in index 7 string armyP1, armyP2, ruleSet; Skill p1Skills[8]; Skill p2Skills[8]; CreatureStack p1Stacks[20]; CreatureStack p2Stacks[20]; ... } CreatureStack(){quantity = 0; isLive = false; id = -1;}; Army(){}; Battlefield(){}; RuleSet(){}; I have posted every line of code that executes until the program crashes. This code ran fine for a long time, I added some stuff that does not even execute until way after the code I have posted here, and bam stack overflow that occurs at GameEngine::loadData() line: CreatureStack p2Stacks[20]; will not go away. What am I doing wrong here? Is that all the stack can handle? I increased the stack size in Visual Studio and got the error to go away, but that slowed things down considerably, so I would rather just get to the source of the issue and fix that.

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  • Run-Time Check Failure #2 - Stack around the variable 'indices' was corrupted.

    - by numerical25
    well I think I know what the problem is. I am just having a hard time debugging it. I am working with the directx api and I am trying to generate a plane along the x and z axis according to a book I have. The problem is when I am creating my indices. I think I am setting values out of the bounds of the indices array. I am just having a hard time figuring out what I did wrong. I am unfamiliar with the this method of generating a plane. so its a little difficult for me. below is my code. Take emphasis on the indices loop. #include "MyGame.h" //#include "CubeVector.h" /* This code sets a projection and shows a turning cube. What has been added is the project, rotation and a rasterizer to change the rasterization of the cube. The issue that was going on was something with the effect file which was causing the vertices not to be rendered correctly.*/ typedef struct { ID3D10Effect* pEffect; ID3D10EffectTechnique* pTechnique; //vertex information ID3D10Buffer* pVertexBuffer; ID3D10Buffer* pIndicesBuffer; ID3D10InputLayout* pVertexLayout; UINT numVertices; UINT numIndices; }ModelObject; ModelObject modelObject; // World Matrix D3DXMATRIX WorldMatrix; // View Matrix D3DXMATRIX ViewMatrix; // Projection Matrix D3DXMATRIX ProjectionMatrix; ID3D10EffectMatrixVariable* pProjectionMatrixVariable = NULL; //grid information #define NUM_COLS 16 #define NUM_ROWS 16 #define CELL_WIDTH 32 #define CELL_HEIGHT 32 #define NUM_VERTSX (NUM_COLS + 1) #define NUM_VERTSY (NUM_ROWS + 1) bool MyGame::InitDirect3D() { if(!DX3dApp::InitDirect3D()) { return false; } D3D10_RASTERIZER_DESC rastDesc; rastDesc.FillMode = D3D10_FILL_WIREFRAME; rastDesc.CullMode = D3D10_CULL_FRONT; rastDesc.FrontCounterClockwise = true; rastDesc.DepthBias = false; rastDesc.DepthBiasClamp = 0; rastDesc.SlopeScaledDepthBias = 0; rastDesc.DepthClipEnable = false; rastDesc.ScissorEnable = false; rastDesc.MultisampleEnable = false; rastDesc.AntialiasedLineEnable = false; ID3D10RasterizerState *g_pRasterizerState; mpD3DDevice->CreateRasterizerState(&rastDesc, &g_pRasterizerState); mpD3DDevice->RSSetState(g_pRasterizerState); // Set up the World Matrix D3DXMatrixIdentity(&WorldMatrix); D3DXMatrixLookAtLH(&ViewMatrix, new D3DXVECTOR3(0.0f, 10.0f, -20.0f), new D3DXVECTOR3(0.0f, 0.0f, 0.0f), new D3DXVECTOR3(0.0f, 1.0f, 0.0f)); // Set up the projection matrix D3DXMatrixPerspectiveFovLH(&ProjectionMatrix, (float)D3DX_PI * 0.5f, (float)mWidth/(float)mHeight, 0.1f, 100.0f); if(!CreateObject()) { return false; } return true; } //These are actions that take place after the clearing of the buffer and before the present void MyGame::GameDraw() { static float rotationAngle = 0.0f; // create the rotation matrix using the rotation angle D3DXMatrixRotationY(&WorldMatrix, rotationAngle); rotationAngle += (float)D3DX_PI * 0.0f; // Set the input layout mpD3DDevice->IASetInputLayout(modelObject.pVertexLayout); // Set vertex buffer UINT stride = sizeof(VertexPos); UINT offset = 0; mpD3DDevice->IASetVertexBuffers(0, 1, &modelObject.pVertexBuffer, &stride, &offset); mpD3DDevice->IASetIndexBuffer(modelObject.pIndicesBuffer, DXGI_FORMAT_R32_UINT, 0); // Set primitive topology mpD3DDevice->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELIST); // Combine and send the final matrix to the shader D3DXMATRIX finalMatrix = (WorldMatrix * ViewMatrix * ProjectionMatrix); pProjectionMatrixVariable->SetMatrix((float*)&finalMatrix); // make sure modelObject is valid // Render a model object D3D10_TECHNIQUE_DESC techniqueDescription; modelObject.pTechnique->GetDesc(&techniqueDescription); // Loop through the technique passes for(UINT p=0; p < techniqueDescription.Passes; ++p) { modelObject.pTechnique->GetPassByIndex(p)->Apply(0); // draw the cube using all 36 vertices and 12 triangles mpD3DDevice->DrawIndexed(modelObject.numIndices,0,0); } } //Render actually incapsulates Gamedraw, so you can call data before you actually clear the buffer or after you //present data void MyGame::Render() { DX3dApp::Render(); } bool MyGame::CreateObject() { VertexPos vertices[NUM_VERTSX * NUM_VERTSY]; for(int z=0; z < NUM_VERTSY; ++z) { for(int x = 0; x < NUM_VERTSX; ++x) { vertices[x + z * NUM_VERTSX].pos.x = (float)x * CELL_WIDTH; vertices[x + z * NUM_VERTSX].pos.z = (float)z * CELL_HEIGHT; vertices[x + z * NUM_VERTSX].pos.y = 0.0f; vertices[x + z * NUM_VERTSX].color = D3DXVECTOR4(1.0, 0.0f, 0.0f, 0.0f); } } DWORD indices[NUM_VERTSX * NUM_VERTSY]; int curIndex = 0; for(int z=0; z < NUM_ROWS; ++z) { for(int x = 0; x < NUM_COLS; ++x) { int curVertex = x + (z * NUM_VERTSX); indices[curIndex] = curVertex; indices[curIndex + 1] = curVertex + NUM_VERTSX; indices[curIndex + 2] = curVertex + 1; indices[curIndex + 3] = curVertex + 1; indices[curIndex + 4] = curVertex + NUM_VERTSX; indices[curIndex + 5] = curVertex + NUM_VERTSX + 1; curIndex += 6; } } //Create Layout D3D10_INPUT_ELEMENT_DESC layout[] = { {"POSITION",0,DXGI_FORMAT_R32G32B32_FLOAT, 0 , 0, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"COLOR",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 12, D3D10_INPUT_PER_VERTEX_DATA, 0} }; UINT numElements = (sizeof(layout)/sizeof(layout[0])); modelObject.numVertices = sizeof(vertices)/sizeof(VertexPos); //Create buffer desc D3D10_BUFFER_DESC bufferDesc; bufferDesc.Usage = D3D10_USAGE_DEFAULT; bufferDesc.ByteWidth = sizeof(VertexPos) * modelObject.numVertices; bufferDesc.BindFlags = D3D10_BIND_VERTEX_BUFFER; bufferDesc.CPUAccessFlags = 0; bufferDesc.MiscFlags = 0; D3D10_SUBRESOURCE_DATA initData; initData.pSysMem = vertices; //Create the buffer HRESULT hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &modelObject.pVertexBuffer); if(FAILED(hr)) return false; modelObject.numIndices = sizeof(indices)/sizeof(DWORD); bufferDesc.ByteWidth = sizeof(DWORD) * modelObject.numIndices; bufferDesc.BindFlags = D3D10_BIND_INDEX_BUFFER; initData.pSysMem = indices; hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &modelObject.pIndicesBuffer); if(FAILED(hr)) return false; ///////////////////////////////////////////////////////////////////////////// //Set up fx files LPCWSTR effectFilename = L"effect.fx"; modelObject.pEffect = NULL; hr = D3DX10CreateEffectFromFile(effectFilename, NULL, NULL, "fx_4_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, mpD3DDevice, NULL, NULL, &modelObject.pEffect, NULL, NULL); if(FAILED(hr)) return false; pProjectionMatrixVariable = modelObject.pEffect->GetVariableByName("Projection")->AsMatrix(); //Dont sweat the technique. Get it! LPCSTR effectTechniqueName = "Render"; modelObject.pTechnique = modelObject.pEffect->GetTechniqueByName(effectTechniqueName); if(modelObject.pTechnique == NULL) return false; //Create Vertex layout D3D10_PASS_DESC passDesc; modelObject.pTechnique->GetPassByIndex(0)->GetDesc(&passDesc); hr = mpD3DDevice->CreateInputLayout(layout, numElements, passDesc.pIAInputSignature, passDesc.IAInputSignatureSize, &modelObject.pVertexLayout); if(FAILED(hr)) return false; return true; }

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  • Can you explicitly set a structure layout/alignment in C++ as you can in C#?

    - by Gary Willoughby
    In C# you have nice alignment attributes such as this: [StructLayout(LayoutKind.Explicit)] public struct Message { [FieldOffset(0)] public int a; [FieldOffset(4)] public short b; [FieldOffset(6)] public int c; [FieldOffset(22)] //Leave some empty space just for the heck of it. public DateTime dt; } Which gives you fine control on how you need your structure to be layed out in memory. Is there such a thing in standard C++?

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  • Poor performance / speed of regex with lookahead

    - by Hugo Zaragoza
    I have been observing extremely slow execution times with expressions with several lookaheads. I suppose that this is due to underlying data structures, but it seems pretty extreme and I wonder if I do something wrong or if there are known work-arounds. The problem is determining if a set of words are present in a string, in any order. For example we want to find out if two terms "term1" AND "term2" are somewhere in a string. I do this with the expresion: (?=.*\bterm1\b)(?=.*\bterm2\b) But what I observe is that this is an order of magnitude slower than checking first just \bterm1\b and just then \bterm2\b This seems to indicate that I should use an array of patterns instead of a single pattern with lookaheads... is this right? it seems wrong... Here is an example test code and resulting times: public static void speedLookAhead() { Matcher m, m1, m2; boolean find; int its = 1000000; // create long non-matching string char[] str = new char[2000]; for (int i = 0; i < str.length; i++) { str[i] = 'x'; } String test = str.toString(); // First method: use one expression with lookaheads m = Pattern.compile("(?=.*\\bterm1\\b)(?=.*\\bterm2\\b)").matcher(test); long time = System.currentTimeMillis(); ; for (int i = 0; i < its; i++) { m.reset(test); find = m.find(); } time = System.currentTimeMillis() - time; System.out.println(time); // Second method: use two expressions and AND the results m1 = Pattern.compile("\\bterm1\\b").matcher(test); m2 = Pattern.compile("\\bterm2\\b").matcher(test); time = System.currentTimeMillis(); ; for (int i = 0; i < its; i++) { m1.reset(test); m2.reset(test); find = m1.find() && m2.find(); } time = System.currentTimeMillis() - time; System.out.println(time); } This outputs in my computer: 1754 150

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