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• Question about effective logging in C#

  - by MartyIX

  I've written a simple class for debugging and I call the method Debugger.WriteLine(...) in my code like this: Debugger.WriteLine("[Draw]", "InProgress", "[x,y] = " + x.ToString("0.00") + ", " + y.ToString("0.00") + "; pos = " + lastPosX.ToString() + "x" + lastPosY.ToString() + " -> " + posX.ToString() + "x" + posY.ToString() + "; SS = " + squareSize.ToString() + "; MST = " + startTime.ToString("0.000") + "; Time = " + time.ToString() + phase.ToString(".0000") + "; progress = " + progress.ToString("0.000") + "; step = " + step.ToString() + "; TimeMovementEnd = " + UI.MovementEndTime.ToString()); The body of the procedure Debugger.WriteLine is compiled only in Debug mode (directives #if, #endif). What makes me worry is that I often need ToString() in Debugger.WriteLine call which is costly because it creates still new strings (for changing number for example). How to solve this problem? A few points/questions about debugging/tracing: I don't want to wrap every Debugger.WriteLine in an IF statement or to use preprocessor directives in order to leave out debugging methods because it would inevitable lead to a not very readable code and it requires too much typing. I don't want to use any framework for tracing/debugging. I want to try to program it myself. Are Trace methods (http://msdn.microsoft.com/en-us/library/system.diagnostics.trace.aspx) left out if compiling in release mode? If it is so is it possible that my methods would behave similarly? http://msdn.microsoft.com/en-us/library/fht0f5be.aspx output = String.Format("You are now {0} years old.", years); Which seems nice. Is it a solution for my problem with ToString()?

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• Qt/MFC Migration Framework tool: properly exiting DLL?

  - by User

  I'm using the Qt/MFC Migration Framework tool following this example: http://doc.qt.nokia.com/solutions/4/qtwinmigrate/winmigrate-qt-dll-example.html The dll I build is loaded by a 3rd party MFC-based application. The 3rd party app basically calls one of my exported DLL functions to startup my plugin and another function to shutdown my application. Currently I'm doing nothing in my shutdown function. When I load my DLL in the 3rd party app the startup function is called and my DLL starts successfully and I can see my message box. However if I shutdown my plugin and then try to start it again I get the following error: Debug Error! Program: <my 3rd party app> Module: 4.7.1 File: global\qglobal.cpp Line: 2262 ASSERT failure in QWidget: "Widgets must be created in the GUI thread.", file kernel\qwidget.cpp line 1233 (Press Retry to debug the application) Abort Retry Ignore This makes me think I'm not doing something to properly shutdown my plugin. What do I need to do to shut it down properly? UPDATE: http://doc.qt.nokia.com/solutions/4/qtwinmigrate/winmigrate-walkthrough.html says: The DLL also has to make sure that it can be loaded together with other Qt based DLLs in the same process (in which case a QApplication object will probably exist already), and that the DLL that creates the QApplication object remains loaded in memory to avoid other DLLs using memory that is no longer available to the process. So I wonder if there is some problem where I need to somehow keep the original DLL loaded no matter what?

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• How to use reflection to call a method and pass parameters whose types are unknown at compile time?

  - by MandoMando

  I'd like to call methods of a class dynamically with parameter values that are "parsed" from a string input. For example: I'd like to call the following program with these commands: c:myprog.exe MethodA System.Int32 777 c:myprog.exe MethodA System.float 23.17 c:myprog.exe MethodB System.Int32& 777 c:myprog.exe MethodC System.Int32 777 System.String ThisCanBeDone static void Main(string[] args) { ClassA aa = new ClassA(); System.Type[] types = new Type[args.Length / 2]; object[] ParamArray = new object[types.Length]; for (int i=0; i < types.Length; i++) { types[i] = System.Type.GetType(args[i*2 + 1]); // LINE_X: this will obviously cause runtime error invalid type/casting ParamArray[i] = args[i*2 + 2]; MethodInfo callInfo = aa.GetType().GetMethod(args[0],types); callInfo.Invoke(aa, ParamArray); } // In a non-changeable classlib: public class ClassA { public void MethodA(int i) { Console.Write(i.ToString()); } public void MethodA(float f) { Console.Write(f.ToString()); } public void MethodB(ref int i) { Console.Write(i.ToString()); i++; } public void MethodC(int i, string s) { Console.Write(s + i.ToString()); } public void MethodA(object o) { Console.Write("Argg! Type Trapped!"); } } "LINE_X" in the above code is the sticky part. For one, I have no idea how to assign value to a int or a ref int parameter even after I create it using Activator.CreatInstance or something else. The typeConverter does come to mind, but then that requires an explicit compile type casting as well. Am I looking at CLR with JavaScript glasses or there is way to do this?

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• Problem with saveToFile

  - by zp26

  Hi, I have a problem with a NSData writeToFile. I have implemented the code below but i have an anomaly. When i run my program on the simulator, the new file is created and the informations are stored; when i build the app in my device , the file isn't created. The debug don't give me any error but don/t save anything. Can you help me? Thanks so much and sorry for my english. -(void)saveXML:(NSString*)name:(float)x:(float)y:(float)z{ NSMutableData *data = [NSMutableData data]; NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]; [archiver setOutputFormat:NSPropertyListXMLFormat_v1_0]; [archiver encodeFloat:x forKey:@"x"]; [archiver encodeFloat:y forKey:@"y"]; [archiver encodeFloat:z forKey:@"z"]; [archiver encodeObject:name forKey:@"name"]; [archiver finishEncoding]; BOOL result = [data writeToFile:@"XML Position" atomically:YES]; if(result) [self updateTextView:@"success"]; [archiver release]; }

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• Why I do not see a static variable in a loop?

  - by Roman

  I have a static method which sets a variable: static String[] playersNames; public static void setParameters(String[] players) { playersNames = players; } Then I have a static block: static { JRadioButton option; ButtonGroup group = new ButtonGroup(); // Wright a short explanation of what the user should do. partnerSelectionPanel.add(new JLabel("Pleas select a partner:")); // Generate radio-buttons corresponding to the options available to the player. // Bellow is the problematic line causing the null pointer exception: for (String playerName: playersNames) { final String pn = playerName; option = new JRadioButton(playerName, false); option.addActionListener(new ActionListener(){ @Override public void actionPerformed(ActionEvent evt) { partner = pn; } }); partnerSelectionPanel.add(option); group.add(option); } partnerSelectionPanel.add(label); // Add the "Submit" button to the end of the "form". JButton submitButton = new JButton("Submit"); submitButton.addActionListener(new ActionListener(){ @Override public void actionPerformed(ActionEvent evt) { partnerSelected(); } }); partnerSelectionPanel.add(submitButton); } Compiler does not complain about anything but when I try to execute the code I get problems. In this place SelectPartnerGUI.setParameters(players); I have: Exception in thread "main" java.lang.ExceptionInitializerError. and it is cause by java.lang.NullpointerException at this place for (String playerName: playersNames). Does my program do not see the palyersNames?

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• mod_python req.subprocess_env not "seeing" PythonOptions

  - by Brandon

  I'm having trouble getting an environmental variable out of apache config. (don't ask why it's being done this way, I didn't originally code it) This is what I have in the apache config. <Location "/var/www"> SetHandler python-program PythonHandler mod_python.publisher PythonOption MYSQL_PWD ########### PythonDebug On </Location> This is the problem code... #this is the problem code in question. def index(req): req.add_common_vars() os.environ["MYSQL_PWD"] = req.subprocess_env["MYSQL_PWD"] req.content_type = "text/html" statText = getStatText() here is the traceback I'm getting from executing this. Traceback (most recent call last): File "/usr/lib/python2.5/site-packages/mod_python/importer.py", line 1537, in HandlerDispatch default=default_handler, arg=req, silent=hlist.silent) File "/usr/lib/python2.5/site-packages/mod_python/importer.py", line 1229, in _process_target result = _execute_target(config, req, object, arg) File "/usr/lib/python2.5/site-packages/mod_python/importer.py", line 1128, in _execute_target result = object(arg) File "/usr/lib/python2.5/site-packages/mod_python/publisher.py", line 213, in handler published = publish_object(req, object) File "/usr/lib/python2.5/site-packages/mod_python/publisher.py", line 425, in publish_object return publish_object(req,util.apply_fs_data(object, req.form, req=req)) File "/usr/lib/python2.5/site-packages/mod_python/util.py", line 554, in apply_fs_data return object(**args) File "/var/www/admin/Stat.py", line 299, in index os.environ["MYSQL_PWD"] = req.subprocess_env["MYSQL_PWD"] KeyError: 'MYSQL_PWD'

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• C++ error: expected initializer before ‘&’ token

  - by Werner

  Hi, the following piece of C++ code compiled two years ago in a suse 10.1 Linux machine. #ifndef DATA_H #define DATA_H #include <iostream> #include <iomanip> inline double sqr(double x) { return x*x; } enum Direction { X,Y,Z }; inline Direction next(const Direction d) { switch(d) { case X: return Y; case Y: return Z; case Z: return X; } } inline ostream& operator<<(ostream& os,const Direction d) { switch(d) { case X: return os << "X"; case Y: return os << "Y"; case Z: return os << "Z"; } } ... ... Now, I am trying to compile it on Ubuntu 9.10 and I get the error: data.h:20: error: expected initializer before ‘&’ token which is referred to the line of: inline ostream& operator<<(ostream& os,const Direction d) the g++ used on this machine is: Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.1-4ubuntu9' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu9) Could you give me some hint about this error? Thanks

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• How do interpreters functions written in the class C++ in the main

  - by T_Geek

  Hi I'm working on a project about Data structures. In the first , I wrote everything in main but it sounds like C . But as I learned, I tried to thinkk OOP and do as little as possible in my main() methods. I've implemented some opertation in my class like add,delet,find.it's too easy to implement its . class ARB { private: struct BT { int data; BT *l; BT *r; }; struct BT *p; public ARB(); ~ARB(); void del(int n); void add(int n); }; void ARB::del(int num) { //The code ,don't care about it }; main() { // BTR T; T.add(3); T.add(5); }; But I arrived to the big program How can I define a methode which have to use a binary tree and to get a stack STACK ARB::MyFunct(BT* p) { // The code don't care about it } How can I apply it in the main programme main() { // BT T; T.add(3); T.add(5); STACK S; BT* p S=T.MyFunct(p); // error C2664 cannot convert parametre 1 }; **mention :I implement STACK class

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• Saving and retrieving image in SQL database from C# problem

  - by Mobin

  I used this code for inserting records in a person table in my DB System.IO.MemoryStream ms = new System.IO.MemoryStream(); Image img = Image_Box.Image; img.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp); this.personTableAdapter1.Insert(NIC_Box.Text.Trim(), Application_Box.Text.Trim(), Name_Box.Text.Trim(), Father_Name_Box.Text.Trim(), DOB_TimePicker.Value.Date, Address_Box.Text.Trim(), City_Box.Text.Trim(), Country_Box.Text.Trim(), ms.GetBuffer()); but when i retrieve this with this code byte[] image = (byte[])Person_On_Application.Rows[0][8]; MemoryStream Stream = new MemoryStream(); Stream.Write(image, 0, image.Length); Bitmap Display_Picture = new Bitmap(Stream); Image_Box.Image = Display_Picture; it works perfectly fine but if i update this with my own generated Query like System.IO.MemoryStream ms = new System.IO.MemoryStream(); Image img = Image_Box.Image; img.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp); Query = "UPDATE Person SET Person_Image ='"+ms.GetBuffer()+"' WHERE (Person_NIC = '"+NIC_Box.Text.Trim()+"')"; the next time i use the same code for retrieving the image and displaying it as used above . Program throws an exception

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• dynamically created arrays

  - by DevAno1

  My task consists of two parts. First I have to create globbal char array of 100 elements, and insert some text to it using cin. Afterwards calculate amount of chars, and create dedicated array with the length of the inputted text. I was thinking about following solution : char[100]inputData; int main() { cin >> inputData >> endl; int length=0; for(int i=0; i<100; i++) { while(inputData[i] == "\0") { ++count; } } char c = new char[count]; Am I thinking good ? Second part of the task is to introduce in the first program dynamically created array of pointers to all inserted words. Adding a new word should print all the previous words and if there is no space for next words, size of the inputData array should be increased twice. And to be honest this is a bit too much for me. How I can create pointers to words specifically ? And how can I increase the size of global array without loosing its content ? With some temporary array ?

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• Is this GetEnumAsStrings<T>() method reinventing the wheel?

  - by Edward Tanguay

  I have a number of enums and need to get them as List<string> objects in order to enumerate through them and hence made the GetEnumAsStrings<T>() method. But it seems to me there would be an easier way. Is there not a built-in method to get an enum like this into a List<string>? using System; using System.Collections.Generic; namespace TestEnumForeach2312 { class Program { static void Main(string[] args) { List<string> testModes = StringHelpers.GetEnumAsStrings<TestModes>(); testModes.ForEach(s => Console.WriteLine(s)); Console.ReadLine(); } } public static class StringHelpers { public static List<string> GetEnumAsStrings<T>() { List<string> enumNames = new List<string>(); foreach (T item in Enum.GetValues(typeof(TestModes))) { enumNames.Add(item.ToString()); } return enumNames; } } public enum TestModes { Test, Show, Wait, Stop } }

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• Dependency isn't included in my assembly, although scope is "compile"

  - by Bernhard V

  Hi! I have the following dependency specified in my project's pom: <dependency> <groupId>org.jboss.client</groupId> <artifactId>jbossall-client</artifactId> <scope>compile</scope> </dependency> My project itself has to be the child of another pom. And in that one, the following is defined: <dependency> <groupId>jboss</groupId> <artifactId>jbossall-client</artifactId> <version>4.2.2</version> <scope>provided</scope> <type>jar</type> </dependency> When I now assembly my program, it seems that the "provided" scope of the parent pom overrides the scope of my project, since the jbossall-client-jar is not included in my assembly. Although it seems illogical to me, maybe it's this feature taking effect here. Do you know a way to include the dependency in my assembly without touching the parent pom?

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• How to set DocFlavor for printservice in Java for WIndows.

  - by om

  Hello, I have written code to run the printer programatically in Java.I have to set the value of docflavor to print the .txt file.When I set it for INPUT_STREAM.TEXT_PLAIN_UTF_8 and run my program on Linux , it prints the text file.but when i run the same code for windows.It can't print the text file.It only prints the jpeg format file.I am using HP Deskjet F735 printer for this. Following is my code . DocFlavor docflavor = DocFlavor.INPUT_STREAM.TEXT_PLAIN_UTF_8; PrintRequestAttributeSet attr_set = new HashPrintRequestAttributeSet(); attr_set.add(new Copies(2)); PrintService[] service = PrintServiceLookup.lookupPrintServices(docflavor, attr_set); if (service.length==0) { JOptionPane.showMessageDialog(null, "No Printer Selected"); } else if (service.length > 0) { System.out.println("Selected printer is " + service[0].getName()); DocPrintJob pj = service[0].createPrintJob(); { PrintService ps = pj.getPrintService(); FileInputStream fis = null; try { File file = new File("/home/ignu/Desktop/newfile"); fis = new FileInputStream(file); Doc doc = new SimpleDoc(fis, docflavor, null); pj.print(doc, attr_set);

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• How to restart a wcf server from within a client?

  - by djerry

  Hey guys, I'm using Wcf for server - client communication. The server will need to run as a service, so there's no GUI. The admin can change settings using the client program and for those changes to be made on server, it needs to restart. This is my server setup NetTcpBinding binding = new NetTcpBinding(SecurityMode.Message); Uri address = new Uri("net.tcp://localhost:8000"); //_svc = new ServiceHost(typeof(MonitoringSystemService), address); _monSysService = new MonitoringSystemService(); _svc = new ServiceHost(_monSysService, address); publishMetaData(_svc, "http://localhost:8001"); _svc.AddServiceEndpoint(typeof(IMonitoringSystemService), binding, "Monitoring Server"); _svc.Open(); MonitoringSystemService is a class i'm using to handle client - server comm. It looks like this: [CallbackBehavior(ConcurrencyMode = ConcurrencyMode.Reentrant)] [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, MaxItemsInObjectGraph = 2147483647)] public class MonitoringSystemService : IMonitoringSystemService {} So i need to call a restart method on the client to the server, but i don't know how to restart (even stop - start) the server. I hope i'm not missing any vital information. Thanks in advance.

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• How to get current datetime on windows command line, in a suitable format for using in a filename?

  - by Rory

  What's a windows command line statement(s) I can use to get the current datetime in a format that I can put into a filename? I want to have a .bat file that zips up a directory into an archive with the current date & time as part of the name, eg "Code_2008-10-14_2257.zip". Is there any easy way I can do this, independent of the regional settings of the machine? I don't really mind about the date format, ideally it'd be yyyy-mm-dd but anything simple is fine. So far I've got this, which on my machine gives me "Tue_10_14_2008_230050_91" rem Get the datetime in a format that can go in a filename. set _my_datetime=%date%_%time% set _my_datetime=%_my_datetime: =_% set _my_datetime=%_my_datetime::=% set _my_datetime=%_my_datetime:/=_% set _my_datetime=%_my_datetime:.=_% rem now use the timestamp by in a new zip file name "d:\Program Files\7-Zip\7z.exe" a -r Code_%_my_datetime%.zip Code I can live with this but it seems a bit clunky. Ideally it'd be briefer and have the format mentioned earlier. I'm using Windows Server 2003 and Win XP Pro. I don't want to install additional utilities to achieve this (although I realise there are some that will do nice date formatting).

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• Parse and read data frame in C?

  - by user253656

  I am writing a program that reads the data from the serial port on Linux. The data are sent by another device with the following frame format: |start | Command | Data | CRC | End | |0x02 | 0x41 | (0-127 octets) | | 0x03| ---------------------------------------------------- The Data field contains 127 octets as shown and octet 1,2 contains one type of data; octet 3,4 contains another data. I need to get these data I know how to write and read data to and from a serial port in Linux, but it is just to write and read a simple string (like "ABD") My issue is that I do not know how to parse the data frame formatted as above so that I can: get the data in octet 1,2 in the Data field get the data in octet 3,4 in the Data field get the value in CRC field to check the consistency of the data Here the sample snip code that read and write a simple string from and to a serial port in Linux: int writeport(int fd, char *chars) { int len = strlen(chars); chars[len] = 0x0d; // stick a <CR> after the command chars[len+1] = 0x00; // terminate the string properly int n = write(fd, chars, strlen(chars)); if (n < 0) { fputs("write failed!\n", stderr); return 0; } return 1; } int readport(int fd, char *result) { int iIn = read(fd, result, 254); result[iIn-1] = 0x00; if (iIn < 0) { if (errno == EAGAIN) { printf("SERIAL EAGAIN ERROR\n"); return 0; } else { printf("SERIAL read error %d %s\n", errno, strerror(errno)); return 0; } } return 1; } Does anyone please have some ideas? Thanks all.

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• Cleaning a string consisting of html/server-side tags in Java

  - by Denzil

  I have a text like: I've got a date with this fellow tomorrow. Well me and thousands of others. <br /><br /><img src="http://www.newwest.net/images/thumbnails_feature/barack_obama_westerners.jpg"><br /><br />Tomorrow morning I will be getting up at stupid o'clock and driving up to Manchester, NH to see Barak Obama speak. <br /><br />You all should come too!<br /><br /><a href="http://nh.barackobama.com/manchesterchange">RSVP for the event</a> I would want to like to clean it too : I've got a date with this fellow tomorrow. Well me and thousands of others http://www.newwest.net/images/thumbnails_feature/barack_obama_westerners.jpg Tomorrow morning I will be getting up at stupid o'clock and driving up to Manchester, NH to see Barak Obama speak.You all should come too! h**p://nh.barackobama.com/manchesterchange RSVP for the event I would like to write a JAVA program for the same. Any pointers/suggestions would be appreciated.The tags aren't limited to the above post. This was just an example. Thanks! PS: Replace *'s by t's in the second hyperlink as Stack Overflow doesn't allow me to post more than one link.

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• C++ wxWidgets Event Handling

  - by Wallter

  Q1:I am using wxWidgets (C++) and have come accost a problem that i can not locate any help. I have created several wxTextCtrl boxes and would like the program to update the simple calculations in them when the user 'kills the focus.' I could not find any documentation on this subject on the wxWidgets webpage and Googling it only brought up wxPython. The two events i have found are: EVT_COMMAND_KILL_FOCUS - EVT_KILL_FOCUS for neither of which I could find any snippet for. Could anyone give me a short example or lead me to a page that would be helpful? Q2:Would i have to create an event to handle the focus being killed for each of my 8 wxTextCtrl boxes? In the case that i have to create a different event: How would i get each event to differentiate from each other? I know i will have to create new wxID's for each of the wxTextCtrl boxes but how do I get the correct one to be triggered? class BasicPanel : public wxPanel { ... wxTextCtrl* one; wxTextCtrl* two; wxTextCtrl* three; wxTextCtrl* four; ... }

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• VBA compare and sort strings with quirky characters

  - by Smandoli

  I am comparing text values from two DAO recordsets in MS Access. I sort on the text field, then go through both recordsets comparing the values from each. The sets are substantially different and while they're mostly alpha-numeric, spaces and symbols like hyphens and periods are very common. My program depends on predictable sorting and fool-proof comparing. But unfortunately, the sort will rank two values differently than the comparison function. StrComp is the obvious first choice: varResult = StrComp(Val_1, Val_2) RFA-300 14.9044 RFA300 14-2044 But for the two pairs above, StrComp returns a different value than one would expect based on the sort. Including vbTextCompare or vbBinaryCompare affects StrComp's result, but not so as to solve the problem. Note the values must always be compared as strings. Of course I make sure that "14-2044" and "14.9044" aren't evaluated as -2030 and ~15. That's not the cause of my problem. I learned API-based functions are more reliable for quirky texts, so I tried these: varResult = CompareString(LOCALE_SYSTEM_DEFAULT, _ SORT_STRINGSORT, strVal_2, -1, strVal_1, -1) varResult = CompareString(LOCALE_SYSTEM_DEFAULT, _ NORM_IGNOREWIDTH, strVal_2, -1, strVal_1, -1) The first one returns the opposite of StrComp. The second one returns the same as StrComp. But neither yields a result that is consistent with the sort order. (NORM_IGNOREWIDTH is probably not relevant, but I needed a place-holder substitute and it looked as good as any.) UPDATE: This is a complete rewrite of the original post, deleting all the info about why I really need this -- just take my word for it and enjoy the brevity.

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• Help with java executors: wait for task termination.

  - by Raffo

  I need to submit a number of task and then wait for them until all results are available. Each of them adds a String to a Vector (that is synchronized by default). Then I need to start a new task for each result in the Vector but I need to do this only when all the previous tasks have stopped doing their job. I want to use Java Executor, in particular I tried using Executors.newFixedThreadPool(100) in order to use a fixed number of thread (I have a variable number of task that can be 10 or 500) but I'm new with executors and I don't know how to wait for task termination. This is something like a pseudocode of what my program needs to do: EecutorService e = Executors.newFixedThreadPool(100); while(true){ /*do something*/ for(...){ <start task> } <wait for all task termination> for each String in result{ <start task> } <wait for all task termination> } I can't do a e.shutdown because I'm in a while(true) and I need to reuse the executorService... Can you help me? Can you suggest me a guide/book about java executors??

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• How to delete a QProcess instance correctly?

  - by Kopfschmerzen

  Hi everyone! I have a class looking like this: class FakeRunner : public QObject { Q_OBJECT private: QProcess* proc; public: FakeRunner(); int run() { if (proc) return -1; proc = new QProcess(); QStringList args; QString programName = "fake.exe"; connect(comp, SIGNAL(started()), this, SLOT(procStarted())); connect(comp, SIGNAL(error(QProcess::ProcessError)), this, SLOT(procError(QProcess::ProcessError))); connect(comp, SIGNAL(finished(int, QProcess::ExitStatus)), this, SLOT(procFinished(int, QProcess::ExitStatus))); proc->start(programName, args); return 0; }; private slots: void procStarted() {}; void procFinished(int, QProcess::ExitStatus) {}; void procError(QProcess::ProcessError); } Since "fake.exe" does not exist on my system, proc emits the error() signal. If I handle it like following, my program crashes: void FakeRunner::procError(QProcess::ProcessError rc) { delete proc; proc = 0; } It works well, though, if I don't delete the pointer. So, the question is how (and when) should I delete the pointer to QProcess? I believe I have to delete it to avoid a memory leak. FakeRunner::run() can be invoked many times, so the leak, if there is one, will grow. Thanks!

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• Can't connect to MySql database from server using Devart

  - by annelie

  Hello, I'm having trouble connecting to a MySql database from a server. I'm using Devart to connect, and I'm not sure if I need to do something more than to simply reference the dlls. When I started working on this project it was referencing the CoreLabs dlls, which if I've understood is the previous name for Devart. That didn't work, so I downloaded the new Devart dlls instead. It works on my local machine, but when uploading to the server it crashes. I made a tiny console app to test the connection, and it fails when initialising, before I've even assigned a host etc. Do I need to do anything more than just upload my .exe file to the server? using System; using System.Collections.Generic; using System.Linq; using System.Text; using Devart.Data; using Devart.Data.MySql; namespace TestDatabaseConnection { public class Program { public static void Main(string[] args) { Console.WriteLine("about to connect"); ConnectToDatabase(); Console.ReadLine(); } public static void ConnectToDatabase() { MySqlConnection connection = new MySqlConnection(); } } } UPDATE: I can't see what the error is, I had a try catch around MySqlConnection connection = new MySqlConnection(); but no exception is thrown, it just crashes. Thanks, Annelie

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• libav/ffmpeg: avcodec_decode_video2() returns -1 when separating demultiplexing and decoding

  - by unbekannt

  I'm using libav (from a C++ program on Linux and Windows) to decode video streams from a file, which works fine (decoding various formats like H264 and MPEG2) using avformat_open_input(), av_read_frame() and avcodec_decode_video2(). Now I have to separate demultiplexing and decoding. One class will call avformat_open_input() and av_read_frame() and then pass the AVPackets into a queue that is read by another class. There I use avcodec_alloc_context3() to get the AVCodecContext needed for avcodec_decode_video2(). I've tested that with a MPEG2 video stream and it works. Problems arise if I try to decode a H264 stream: avcodec_decode_video2() always returns -1 and outputs "no frame". I understand that additional data (SPS/PPS) is needed to decode this stream, so I've tried to replicate the original AVCodecContext from the demultiplexer in the decoder, but it won't work: Copying the content of the extradata field and setting all other values that differ from the default ones in the decoder: -1 is returned Using the same context (i.e. passing along the pointer) results in a crash I also tried to set CODEC_FLAG2_CHUNKS. avcodec_decode_video2() then always returns packet.size - 3 (??) and frameFinished is never set to 1. In my opinion I have a general problem here that will arise whenever settings from the original CodecContext are needed to decode the AVPackets. I'd be grateful for any hints on how to solve that problem!

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• Foosball result prediction

  - by Wolf

  In our office, we regularly enjoy some rounds of foosball / table football after work. I have put together a small java program that generates random 2vs2 lineups from the available players and stores the match results in a database afterwards. The current prediction of the outcome uses a simple average of all previous match results from the 4 involved players. This gives a very rough estimation, but I'd like to replace it with something more sophisticated, taking into account things like: players may be good playing as attacker but bad as defender (or vice versa) players do well against a specific opponent / bad against others some teams work well together, others don't skills change over time What would be the best algorithm to predict the game outcome as accurately as possible? Someone suggested using a neural network for this, which sounds quite interesting... but I do not have enough knowledge on the topic to say if that could work, and I also suspect it might take too many games to be reasonably trained. EDIT: Had to take a longer break from this due to some project deadlines. To make the question more specific: Given the following mysql table containing all matches played so far: table match_result match_id int pk match_start datetime duration int (match length in seconds) blue_defense int fk to table player blue_attack int fk to table player red_defense int fk to table player red_attack int fk to table player score_blue int score_red int How would you write a function predictResult(blueDef, blueAtk, redDef, redAtk) {...} to estimate the outcome as closely as possible, executing any sql, doing calculations or using external libraries?

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• Java Polynomial Multiplication with ArrayList

  - by user1506919

  I am having a problem with one of my methods in my program. The method is designed to take 2 arraylists and the perform multiplication between the two like a polynomial. For example, if I was to say list1={3,2,1} and list2={5,6,7}; I am trying to get a return value of 15,28,38,20,7. However, all I can get is an error message that says: Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0. I have provided the method below: private static ArrayList<Integer> multiply(ArrayList<Integer> list1,ArrayList<Integer> list2) { ArrayList<Integer> array =new ArrayList<Integer>(list1.size()+list2.size()); for (int i=0;i<array.size();i++) array.add(i, 0); for (int i = 0; i < list1.size(); i++) for (int j = 0; j < list2.size(); j++) array.set(i+j, ((list1.get(i) * list2.get(j))+array.get(i+j))); return array; } Any help with solving this problem is greatly appreciated.

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