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  • C#. Whats the fastest way to make an integer positive

    - by maxima120
    I asked wrong question previously and was swamped with negative votes... Let me try again... What is absolutely fastest way to make an int positive (given 50/50 distribution of pos/neg over time). To be nominated for an answer I will require MSIL analysis and not a guess or measuring of time with granny's watch... P.S. as one of variations I proposed i * i not because I wanted to do Sqrt(i * i) afterwards but because i will be used only once to be compared to a const. And if i * i will win competition I simply multiply the const.. Hence the following solution is valid: int trigger = realTrigger * realTrigger; i = SomeCalcs(); i = i * i; if(i < trigger) DoSomething(); P.P.S. pointless rant is not acceptable.. like: why do you need this, its BS! C# cannot tolerate developers like you!

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  • Core Animation performance on iphone

    - by nico
    I'm trying to do some animations using Core Animation on the iphone. I'm using CABasicAnimation on CALayer. It's a straight forward animation from a random place at the top of the screen to the bottom of the screen at random speed, I have 30 elements that doing the same animation continuously until another action happens. But the performance on the iPhone 3G is very sluggish when the animations start. The image is only 8k. Is this the right approach? How should I change so it performs better. // image cached somewhere else. CGImageRef imageRef = [[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:name ofType:@"png"]] CGImage]; - (void)animate:(NSTimer *)timer { int startX = round(radom() % 320); float speed = 1 / round(random() % 100 + 2); CALayer *layer = [CALayer layer]; layer.name = @"layer"; layer.contents = imageRef; // cached image layer.frame = CGRectMake(0, 0, CGImageGetWidth(imageRef), CGImageGetHeight(imageRef)); int width = layer.frame.size.width; int height = layer.frame.size.height; layer.frame = CGRectMake(startX, self.view.frame.origin.y, width, height); [effectLayer addSublayer:layer]; CGPoint start = CGPointMake(startX, 0); CGPoint end = CGPointMake(startX, self.view.frame.size.height); float repeatCount = 1e100; CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position"]; animation.delegate = self; animation.fromValue = [NSValue valueWithCGPoint:start]; animation.toValue = [NSValue valueWithCGPoint:end]; animation.duration = speed; animation.repeatCount = repeatCount; animation.autoreverses = NO; animation.removedOnCompletion = YES; animation.fillMode = kCAFillModeForwards; [layer addAnimation:animation forKey:@"position"]; } The animations are fired off using a NSTimer. animationTimer = [NSTimer timerWithTimeInterval:0.2 target:self selector:@selector(animate:) userInfo:nil repeats:YES]; [[NSRunLoop currentRunLoop] addTimer:animationTimer forMode:NSDefaultRunLoopMode];

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  • pthread and recursively calling execvp in C

    - by eduke
    To begin I'm sorry for my english :) I looking for a way to create a thread each time my program finds a directory, in order to call the program itself but with a new argv[2] argument (which is the current dir). I did it successfully with fork() but with pthread I've some difficulties. I don't know if I can do something like that : #include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <dirent.h> int main(int argc, char **argv) { pthread_t threadID[10] = {0}; DIR * dir; struct dirent * entry; struct stat status; pthread_attr_t attr; pthread_attr_init(&attr); int i = 0; char *res; char *tmp; char *file; if(argc != 3) { printf("Usage : %s <file> <dir>\n", argv[0]); exit(EXIT_FAILURE); } if(stat(argv[2],&status) == 0) { dir = opendir(argv[2]); file = argv[1]; } else exit(EXIT_FAILURE); while ((entry = readdir(dir))) { if (strcmp(entry->d_name, ".") && strcmp(entry->d_name, "..")) { tmp = malloc(strlen(argv[2]) + strlen(entry->d_name) + 2); strcpy(tmp, argv[2]); strcat(tmp, "/"); strcat(tmp, entry->d_name); stat(tmp, &status); if (S_ISDIR(status.st_mode)) { argv[2] = tmp; pthread_create( &threadID[i], &attr, execvp(argv[0], argv), NULL); printf("New thread created : %d", i); i++; } else if (!strcmp(entry->d_name, file)) { printf(" %s was found - Thread number = %d\n",tmp, i); break; } free(tmp); } } pthread_join( threadID[i] , &res ); exit(EXIT_SUCCESS); } Actually it doesn't works : pthread_create( &threadID[i], &attr, execvp(argv[0], argv), NULL); I have no runtime error, but when the file to find is in another directory, the thread is not created and so execvp(argv[0], argv) is not called... Thank you for you help, Simon

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  • Crash in OS X Core Data Utility Tutorial

    - by vinogradov
    I'm trying to follow Apple's Core Data utility Tutorial. It was all going nicely, until... The tutorial uses a custom sub-class of NSManagedObject, called 'Run'. Run.h looks like this: #import <Foundation/Foundation.h> #import <CoreData/CoreData.h> @interface Run : NSManagedObject { NSInteger processID; } @property (retain) NSDate *date; @property (retain) NSDate *primitiveDate; @property NSInteger processID; @end Now, in Run.m we have an accessor method for the processID variable: - (void)setProcessID:(int)newProcessID { [self willChangeValueForKey:@"processID"]; processID = newProcessID; [self didChangeValueForKey:@"processID"]; } In main.m, we use functions to set up a managed object model and context, instantiate an entity called run, and add it to the context. We then get the current NSprocessInfo, in preparation for setting the processID of the run object. NSManagedObjectContext *moc = managedObjectContext(); NSEntityDescription *runEntity = [[mom entitiesByName] objectForKey:@"Run"]; Run *run = [[Run alloc] initWithEntity:runEntity insertIntoManagedObjectContext:moc]; NSProcessInfo *processInfo = [NSProcessInfo processInfo]; Next, we try to call the accessor method defined in Run.m to set the value of processID: [run setProcessID:[processInfo processIdentifier]]; And that's where it's crashing. The object run seems to exist (I can see it in the debugger), so I don't think I'm messaging nil; on the other hand, it doesn't look like the setProcessID: message is actually being received. I'm obviously still learning this stuff (that's what tutorials are for, right?), and I'm probably doing something really stupid. However, any help or suggestions would be gratefully received! ===MORE INFORMATION=== Following up on Jeremy's suggestions: The processID attribute in the model is set up like this: NSAttributeDescription *idAttribute = [[NSAttributeDescription alloc]init]; [idAttribute setName:@"processID"]; [idAttribute setAttributeType:NSInteger32AttributeType]; [idAttribute setOptional:NO]; [idAttribute setDefaultValue:[NSNumber numberWithInteger:-1]]; which seems a little odd; we are defining it as a scalar type, and then giving it an NSNumber object as its default value. In the associated class, Run, processID is defined as an NSInteger. Still, this should be OK - it's all copied directly from the tutorial. It seems to me that the problem is probably in there somewhere. By the way, the getter method for processID is defined like this: - (int)processID { [self willAccessValueForKey:@"processID"]; NSInteger pid = processID; [self didAccessValueForKey:@"processID"]; return pid; } and this method works fine; it accesses and unpacks the default int value of processID (-1). Thanks for the help so far!

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  • NerdDinner difficulties

    - by George
    Hello guys, I'm having a problem with the Create method of the NerdDinner tutorial, which is very good BTW. As you can see here http://nerddinnerbook.s3.amazonaws.com/Part5.htm in the Create method, he removed the ID field of the aspx page. I did that too, but I cannot add any dinners because I get a primary key violation. How is NerdDinner controlling the ids of each dinner? I revised the tutorial and could not see any references to identity fields on SQL database. I even created a method to get me the highest id in the table: public int GetHighestDinnerId() { int resultado = (from dinner in dataContext.Dinners select dinner.DinnerId).Max(); return resultado; } which does not work either. Any thoughts? Thank you

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  • Python Beginner: Selective Printing in loops

    - by Jonathan Straus
    Hi there. I'm a very new python user (had only a little prior experience with html/javascript as far as programming goes), and was trying to find some ways to output only intermittent numbers in my loop for a basic bicycle racing simulation (10,000 lines of biker positions would be pretty excessive :P). I tried in this loop several 'reasonable' ways to communicate a condition where a floating point number equals its integer floor (int, floor division) to print out every 100 iterations or so: for i in range (0,10000): i = i + 1 t = t + t_step #t is initialized at 0 while t_step is set at .01 acceleration_rider1 = (power_rider1 / (70 * velocity_rider1)) - (force_drag1 / 70) velocity_rider1 = velocity_rider1 + (acceleration_rider1 * t_step) position_rider1 = position_rider1 + (velocity_rider1 * t_step) force_drag1 = area_rider1 * (velocity_rider1 ** 2) acceleration_rider2 = (power_rider2 / (70 * velocity_rider1)) - (force_drag2 / 70) velocity_rider2 = velocity_rider2 + (acceleration_rider2 * t_step) position_rider2 = position_rider2 + (velocity_rider2 * t_step) force_drag2 = area_rider1 * (velocity_rider2 ** 2) if t == int(t): #TRIED t == t // 1 AND OTHER VARIANTS THAT DON'T WORK HERE:( print t, "biker 1", position_rider1, "m", "\t", "biker 2", position_rider2, "m"

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  • LNK2001: What have I forgotton to set?

    - by graham.reeds
    Following on from my previous question regarding debugging of native code, I decided to create a simple test from a console app as I wasn't getting anywhere with debugging the service directly. So I created a vc6 console app, added the dll project to the workspace and ran it. Instead of executing as expected it spat out the following linker errors: main.obj : error LNK2001: unresolved external symbol "int __stdcall hmDocumentLAdd(char *,char *,long,char *,char *,long,long,long,long *)" (?hmDocumentLAdd@@YGHPAD0J00JJJPAJ@Z) main.obj : error LNK2001: unresolved external symbol "int __stdcall hmGetDocBasePath(char *,long)" (?hmGetDocBasePath@@YGHPADJ@Z) Debug/HazManTest.exe : fatal error LNK1120: 2 unresolved externals This seems to be a simple case of forgetting something in the linker options: However everything seems to be normal, and the lib file, dll and source is available. If I change the lib file to load to nonsense it kicks up the fatal error LNK1104: cannot open file "asdf.lib", so that isn't a problem. I have previously linked to dll and they have just worked, so what I have forgotton to do?

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  • Establishing a tcp connection from within a DLL

    - by Nicholas Hollander
    I'm trying to write a piece of code that will allow me to establish a TCP connection from within a DLL file. Here's my situation: I have a ruby application that needs to be able to send and receive data over a socket, but I can not access the native ruby socket methods because of the environment in which it will be running. I can however access a DLL file and run the functions within that, so I figured I would create a wrapper for winsock. Unfortunately, attempting to take a piece of code that should connect to a TCP socket in a normal C++ application throws a slew of LNK2019 errors that I can not for the life of me resolve. This is the method I'm using to connect: //Socket variable SOCKET s; //Establishes a connection to the server int server_connect(char* addr, int port) { //Start up Winsock WSADATA wsadata; int error = WSAStartup(0x0202, &wsadata); //Check if something happened if (error) return -1; //Verify Winock version if (wsadata.wVersion != 0x0202) { //Clean up and close WSACleanup(); return -2; } //Get the information needed to finalize a socket SOCKADDR_IN target; target.sin_family = AF_INET; //Address family internet target.sin_port = _WINSOCKAPI_::htons(port); //Port # target.sin_addr.s_addr = inet_addr(addr); //Create the socket s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if (s == INVALID_SOCKET) { return -3; } //Try connecting if (connect(s, (SOCKADDR *)&target, sizeof(target)) == SOCKET_ERROR) { //Failed to connect return -4; } else { //Success return 1; } } The exact errors that I'm receiving are: Error 1 error LNK2019: unresolved external symbol _closesocket@4 referenced in function _server_disconnect [Project Path] Error 2 error LNK2019: unresolved external symbol _connect@12 referenced in function _server_connect [Project Path] Error 3 error LNK2019: unresolved external symbol _htons@4 referenced in function _server_connect [Project Path] Error 4 error LNK2019: unresolved external symbol _inet_addr@4 referenced in function _server_connect [Project Path] Error 5 error LNK2019: unresolved external symbol _socket@12 referenced in function _server_connect [Project Path] Error 6 error LNK2019: unresolved external symbol _WSAStartup@8 referenced in function _server_connect [Project Path] Error 7 error LNK2019: unresolved external symbol _WSACleanup@0 referenced in function _server_connect [Project Path] Error 8 error LNK1120: 7 unresolved externals [Project Path] 1 1 Many thanks!

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  • How to get the running of time of my program with gettimeofday()

    - by Mechko
    So I get the time at the beginning of the code, run it, and then get the time. struct timeval begin, end; gettimeofday(&begin, NULL); //code to time gettimeofday(&end, NULL); //get the total number of ms that the code took: unsigned int t = end.tv_usec - begin.tv_usec; Now I want to print it out in the form "**code took 0.007 seconds to run" or something similar. So two problems: 1) t seems to contain a value of the order 6000, and I KNOW the code didn't take 6 seconds to run. 2) How can I convert t to a double, given that it's an unsigned int? Or is there an easier way to print the output the way I wanted to?

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  • Array subscript is not an integer

    - by Dimitri
    Hello folks, following this previous question Malloc Memory Corruption in C, now i have another problem. I have the same code. Now I am trying to multiply the values contained in the arrays A * vc and store in res. Then A is set to zero and i do a second multiplication with res and vc and i store the values in A. (A and Q are square matrices and mc and vc are N lines two columns matrices or arrays). Here is my code : int jacobi_gpu(double A[], double Q[], double tol, long int dim){ int nrot, p, q, k, tid; double c, s; double *mc, *vc, *res; int i,kc; double vc1, vc2; mc = (double *)malloc(2 * dim * sizeof(double)); vc = (double *)malloc(2 * dim * sizeof(double)); vc = (double *)malloc(dim * dim * sizeof(double)); if( mc == NULL || vc == NULL){ fprintf(stderr, "pb allocation matricre\n"); exit(1); } nrot = 0; for(k = 0; k < dim - 1; k++){ eye(mc, dim); eye(vc, dim); for(tid = 0; tid < floor(dim /2); tid++){ p = (tid + k)%(dim - 1); if(tid != 0) q = (dim - tid + k - 1)%(dim - 1); else q = dim - 1; printf("p = %d | q = %d\n", p, q); if(fabs(A[p + q*dim]) > tol){ nrot++; symschur2(A, dim, p, q, &c, &s); mc[2*tid] = p; vc[2 * tid] = c; mc[2*tid + 1] = q; vc[2*tid + 1] = -s; mc[2*tid + 2*(dim - 2*tid) - 2] = p; vc[2*tid + 2*(dim - 2*tid) - 2 ] = s; mc[2*tid + 2*(dim - 2*tid) - 1] = q; vc[2 * tid + 2*(dim - 2*tid) - 1 ] = c; } } for( i = 0; i< dim; i++){ for(kc=0; kc < dim; kc++){ if( kc < floor(dim/2)) { vc1 = vc[2*kc + i*dim]; vc2 = vc[2*kc + 2*(dim - 2*kc) - 2]; }else { vc1 = vc[2*kc+1 + i*dim]; vc2 = vc[2*kc - 2*(dim - 2*kc) - 1]; } res[kc + i*dim] = A[mc[2*kc] + i*dim]*vc1 + A[mc[2*kc + 1] + i*dim]*vc2; } } zero(A, dim); for( i = 0; i< dim; i++){ for(kc=0; kc < dim; k++){ if( k < floor(dim/2)){ vc1 = vc[2*kc + i*dim]; vc2 = vc[2*kc + 2*(dim - 2*kc) - 2]; }else { vc1 = vc[2*kc+1 + i*dim]; vc2 = vc[2*kc - 2*(dim - 2*kc) - 1]; } A[kc + i*dim] = res[mc[2*kc] + i*dim]*vc1 + res[mc[2*kc + 1] + i*dim]*vc2; } } affiche(mc,dim,2,"Matrice creuse"); affiche(vc,dim,2,"Valeur creuse"); } free(mc); free(vc); free(res); return nrot; } When i try to compile, i have this error : jacobi_gpu.c: In function ‘jacobi_gpu’: jacobi_gpu.c:103: error: array subscript is not an integer jacobi_gpu.c:103: error: array subscript is not an integer jacobi_gpu.c:118: error: array subscript is not an integer jacobi_gpu.c:118: error: array subscript is not an integer make: *** [jacobi_gpu.o] Erreur 1 The corresponding lines are where I store the results in res and A : res[kc + i*dim] = A[mc[2*kc] + i*dim]*vc1 + A[mc[2*kc + 1] + i*dim]*vc2; and A[kc + i*dim] = res[mc[2*kc] + i*dim]*vc1 + res[mc[2*kc + 1] + i*dim]*vc2; Can someone explain me what is this error and how can i correct it? Thanks for your help. ;)

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  • query optimization

    - by Gaurav
    I have a query of the form SELECT uid1,uid2 FROM friend WHERE uid1 IN (SELECT uid2 FROM friend WHERE uid1='.$user_id.') and uid2 IN (SELECT uid2 FROM friend WHERE uid1='.$user_id.') The problem now is that the nested query SELECT uid2 FROM friend WHERE uid1='.$user_id.' returns a very large number of ids(approx. 5000). The table structure of the friend table is uid1(int), uid2(int). This table is used to determine whether two users are linked together as friends. Any workaround? Can I write the query in a different way? Or is there some other way to solve this issue. I'm sure I am not the first person to face such a problem. Any help would be greatly appreciated.

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  • C#/.NET: Separation of multipage tiff with compression "CCITT T.6" very slow

    - by Alex B
    I need to separate multiframe tiff files, and use the following method: public static Image[] GetFrames(Image sourceImage) { Guid objGuid = sourceImage.FrameDimensionsList[0]; FrameDimension objDimension = new FrameDimension(objGuid); int frameCount = sourceImage.GetFrameCount(objDimension); Image[] images = new Image[frameCount]; for (int i = 0; i < frameCount; i++) { MemoryStream ms = new MemoryStream(); sourceImage.SelectActiveFrame(objDimension, i); sourceImage.Save(ms, ImageFormat.Tiff); images[i] = Image.FromStream(ms); } return images; } It works fine, butt if the source was encoded using the CCITT T.6 compression, separating a 20-frame-file takes up to 15 seconds on my 2,5ghz CPU. Saving the images afterwards to a single file using standard compression (LZW), the separation time is under 1 second. Is there a way to speed up the process?

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  • InvalidOperationException When XML Serializing Inherited Class

    - by Nick
    I am having an issue serializing a c# class to an XML file that has a base class... here is a simple example: namespace Domain { [Serializable] public class ClassA { public virtual int MyProperty { get; set; } } } namespace Derived { public class ClassA : Domain.ClassA { public override int MyProperty { get { return 1; } set { /* Do Nothing */ } } } } When I attempt to serialize an instance of Derived.ClassA, I receive the following exception: InvalidOperationException(Types 'Domain.ClassA' and 'Derived.ClassA' both use the XML type name 'ClassA', from the namespace ". Use XML attributes to specify a unique XML name and/or namespace for the type.) The problem is that I want to create a single base class that simply defines the structure of the XML file, and then allow anyone else to derive from that class to insert business rules, but that the formatting will come through from the base. Is this possible, and if so, how do I attribute the base class to allow this?

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  • [Java/Android] Multidimensional array to ListView.. how?

    - by Yverman
    I have a query result set which I like to edit first and then put it to my ListView. Without editing my data first, I could use SimpleCursorAdapter like that: ListAdapter adapter = new SimpleCursorAdapter( this, R.layout.list_item, mCursor, new String[] { "address", "city" }, new int[] { R.id.address, R.id.zip_city }); this.setListAdapter(adapter); But now, I put everything in a multidimensional array like that: if(mCursor.isFirst()) { //create a new array String[][] listData = new String[mCursor.getCount()][3]; int i = 0; do { listData[i] = new String[] { mCursor.getString(mCursor.getColumnIndex("address")), mCursor.getString(mCursor.getColumnIndex("zip")) + " " + mCursor.getString(mCursor.getColumnIndex("city")), calculateDistance(Double.parseDouble(mCursor.getString(mCursor.getColumnIndex("diff")))) }; i++; } while(mCursor.moveToNext()); } So my problem is now, I have no idea how to put this to my ListView. Could someone help me here? Sorry for my bad english and Java knowledge. :)

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  • MySQL - getting SUM of MAX results from 2 tables

    - by SODA
    Hi, Here's my problem: I have 2 identical tables (past month data, current month data) - data_2010_03, data_2010_04: Content_type (VARCHAR), content_id (INT), month_count (INT), pubDate (DATETIME) Data in month_count is updated hourly, so for each combination of content_type and content_id we insert new row, where value of month_count is incrementally updated. Now I try something like this: SELECT MAX(t1.month_count) AS max_1, MAX(t2.month_count) AS max_2, SUM(max_1 + max_2) AS result, t1.content_type, t1.content_id FROM data_2010_03 AS t1 JOIN data_2010_04 AS t2 ON t1.content_type = t2.content_type AND t1.content_id = t2.content_id WHERE t2.pubDate < '2010-04-08' AND t1.content_type = 'video' GROUP BY t1.content_id ORDER BY result desc, max_1 desc, max_2 desc LIMIT 0,10 I get an error "Unknown column 'max_1' in 'field list'. Please help.

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  • Method hiding with interfaces

    - by fearofawhackplanet
    interface IFoo { int MyReadOnlyVar { get; } } class Foo : IFoo { int MyReadOnlyVar { get; set; } } public IFoo GetFoo() { return new Foo { MyReadOnlyVar = 1 }; } Is the above an acceptable way of implementing a readonly/immutable object? The immutability of IFoo can be broken with a temporary cast to Foo. In general (non-critical) cases, is hiding functionality through interfaces a common pattern? Or is it considered lazy coding? Or even an anti-pattern?

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  • [Hibernate Mapping] relationship set between table and mapping table to use joins.

    - by Matthew De'Loughry
    Hi guys, I have two table a "Module" table and a "StaffModule" I'm wanting to display a list of modules by which staff are present on the staffmodule mapping table. I've tried from Module join Staffmodule sm with ID = sm.MID with no luck, I get the following error Path Expected for join! however I thought I had the correct join too allow this but obviously not can any one help StaffModule HBM <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Apr 26, 2010 9:50:23 AM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="Hibernate.Staffmodule" schema="WALK" table="STAFFMODULE"> <composite-id class="Hibernate.StaffmoduleId" name="id"> <key-many-to-one name="mid" class="Hibernate.Module"> <column name="MID"/> </key-many-to-one> <key-property name="staffid" type="int"> <column name="STAFFID"/> </key-property> </composite-id> </class> </hibernate-mapping> and Module.HBM <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Apr 26, 2010 9:50:23 AM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="Hibernate.Module" schema="WALK" table="MODULE"> <id name="id" type="int"> <column name="ID"/> <generator class="assigned"/> </id> <property name="modulename" type="string"> <column length="50" name="MODULENAME"/> </property> <property name="teacherid" type="int"> <column name="TEACHERID" not-null="true"/> </property> </class> hope thats enough information! and thanks in advance.

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  • std::map default value for build-in type

    - by Qifa Zhao
    Recently, I was confused by the std::map operator[] function. In the MSDN library, it says: "If the argument key value is not found, then it is inserted along with the default value of the data type." I tryed to search much more exactly explanation for this issue. For example here: std::map default value In this page, Michael Anderson said that "the default value is constructed by the default constructor(zero parameter constructor)". Now my quest comes to this:"what the default value for the build-in type?". Was it compiler related? Or is there a standard for this issue by the c++ stardard committee? I did a test on visual studio 2008 for the "int" type, and found the "int" type is construted with the value 0.

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  • Constructor or Explicit cast

    - by Felan
    In working with Linq to Sql I create a seperate class to ferry data to a web page. To simplify creating these ferry objects I either use a specialized constructor or an explicit conversion operator. I have two questions. First which approach is better from a readibility perspective? Second while the clr code that is generated appeared to be the same to me, are there situations where one would be treated different than the other by the compiler (in lambda's or such). Example code (DatabaseFoo uses specialized constructor and BusinessFoo uses explicit operator): public class DatabaseFoo { private static int idCounter; // just to help with generating data public int Id { get; set; } public string Name { get; set; } public DatabaseFoo() { Id = idCounter++; Name = string.Format("Test{0}", Id); } public DatabaseFoo(BusinessFoo foo) { this.Id = foo.Id; this.Name = foo.Name; } } public class BusinessFoo { public int Id { get; set; } public string Name { get; set; } public static explicit operator BusinessFoo(DatabaseFoo foo) { return FromDatabaseFoo(foo); } public static BusinessFoo FromDatabaseFoo(DatabaseFoo foo) { return new BusinessFoo {Id = foo.Id, Name = foo.Name}; } } public class Program { static void Main(string[] args) { Console.WriteLine("Creating the initial list of DatabaseFoo"); IEnumerable<DatabaseFoo> dafoos = new List<DatabaseFoo>() { new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo()}; foreach(DatabaseFoo dafoo in dafoos) Console.WriteLine(string.Format("{0}\t{1}", dafoo.Id, dafoo.Name)); Console.WriteLine("Casting the list of DatabaseFoo to a list of BusinessFoo"); IEnumerable<BusinessFoo> bufoos = from x in dafoos select (BusinessFoo) x; foreach (BusinessFoo bufoo in bufoos) Console.WriteLine(string.Format("{0}\t{1}", bufoo.Id, bufoo.Name)); Console.WriteLine("Creating a new list of DatabaseFoo by calling the constructor taking BusinessFoo"); IEnumerable<DatabaseFoo> fufoos = from x in bufoos select new DatabaseFoo(x); foreach(DatabaseFoo fufoo in fufoos) Console.WriteLine(string.Format("{0}\t{1}", fufoo.Id, fufoo.Name)); } }

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  • Can/Should you throw exceptions in a c# switch statement?

    - by Kettenbach
    Hi All, I have an insert query that returns an int. Based on that int I may wish to throw an exception. Is this appropriate to do within a switch statement? switch (result) { case D_USER_NOT_FOUND: throw new ClientException(string.Format("D User Name: {0} , was not found.", dTbx.Text)); case C_USER_NOT_FOUND: throw new ClientException(string.Format("C User Name: {0} , was not found.", cTbx.Text)); case D_USER_ALREADY_MAPPED: throw new ClientException(string.Format("D User Name: {0} , is already mapped.", dTbx.Text)); case C_USER_ALREADY_MAPPED: throw new ClientException(string.Format("C User Name: {0} , is already mapped.", cTbx.Text)); default: break; } I normally add break statements to switches but they will not be hit. Is this a bad design? Please share any opinions/suggestions with me. Thanks, ~ck in San Diego

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  • referencing ints from other classes

    - by user357032
    if i wanted to reference an int from another class how would i go about doing that??? public class Zoom extends View { private Drawable image; public int zoomControler=20; public Zoom(Context context) { super(context); image=context.getResources().getDrawable(R.drawable.icon); setFocusable(true); } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler); image.draw(canvas); } } class HelloOnTouchListener implements OnTouchListener{ @Override public boolean onTouch(View arg0, MotionEvent arg1) { return true; } } in this case i want to reference the zoomControler from the first class in the second helloontouchlistener class

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  • best practice on precedence of variable declaration and error handling in C

    - by guest
    is there an advantage in one of the following two approaches over the other? here it is first tested, whether fopen succeeds at all and then all the variable declarations take place, to ensure they are not carried out, since they mustn't have had to void func(void) { FILE *fd; if ((fd = fopen("blafoo", "+r")) == NULL ) { fprintf(stderr, "fopen() failed\n"); exit(EXIT_FAILURE); } int a, b, c; float d, e, f; /* variable declarations */ /* remaining code */ } this is just the opposite. all variable declarations take place, even if fopen fails void func(void) { FILE *fd; int a, b, c; float d, e, f; /* variable declarations */ if ((fd = fopen("blafoo", "+r")) == NULL ) { fprintf(stderr, "fopen() failed\n"); exit(EXIT_FAILURE); } /* remaining code */ } does the second approach produce any additional cost, when fopen fails? would love to hear your thoughts!

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  • Help me understand this C code

    - by Benjamin
    INT GetTree (HWND hWnd, HTREEITEM hItem, HKEY *pRoot, TCHAR *pszKey, INT nMax) { TV_ITEM tvi; TCHAR szName[256]; HTREEITEM hParent; HWND hwndTV = GetDlgItem (hWnd, ID_TREEV); memset (&tvi, 0, sizeof (tvi)); hParent = TreeView_GetParent (hwndTV, hItem); if (hParent) { // Get the parent of the parent of the... GetTree (hWnd, hParent, pRoot, pszKey, nMax); // Get the name of the item. tvi.mask = TVIF_TEXT; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); TreeView_GetItem (hwndTV, &tvi); //send the TVM_GETITEM message? lstrcat (pszKey, TEXT ("\\")); lstrcat (pszKey, szName); } else { *pszKey = TEXT ('\0'); szName[0] = TEXT ('\0'); // Get the name of the item. tvi.mask = TVIF_TEXT | TVIF_PARAM; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); if (TreeView_GetItem (hwndTV, &tvi)) //*pRoot = (HTREEITEM)tvi.lParam; //original hItem = (HTREEITEM)tvi.lParam; else { INT rc = GetLastError(); } } return 0; } The block of code that begins with the comment "Get the name of the item" does not make sense to me. If you are getting the listview item why does the code set the parameters of the item being retrieved? If you already had the values there would be no need to retrieve them. Secondly near the comment "original" is the original line of code which will compile with a warning under embedded visual c++ 4.0, but if you copy the exact same code into visual studio 2008 it will not compile. Since I did not write any of this code, and am trying to learn, is it possible the original author made a mistake on this line? The *pRoot should point to HKEY type yet he is casting to an HTREEITEM type which should never work since the data types don't match?

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  • Change Layout Of Text Created In Java [Android]

    - by Dan
    Ok right , i asked how to create a random number from 1-100 for android and i came to this TextView tv = new TextView(this); int random = (int)Math.ceil(Math.random()*101); tv.setText("Your Number Is..."+ random ); What this does is create the default kinda "hello world" style text view and says "Your Number Is.... [Then Random Number] My problem is that i cant change the layout of this text , because it is not defined in XML, if someone could tell me how to change the style , or like make the random number into a string so i could use it for any Textview layout that would be great .. Thanks :)

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  • error in finding out the lexems and no of lines of a text file in C

    - by mekasperasky
    #include<stdio.h> #include<ctype.h> #include<string.h> int main() { int i=0,j,k,lines_count[2]={1,1},operand_count[2]={0},operator_count[2]={0},uoperator_count[2]={0},control_count[2]={0,0},cl[13]={0},variable_dec[2]={0,0},l,p[2]={0},ct,variable_used[2]={0,0},constant_count[2],s[2]={0},t[2]={0}; char a,b[100],c[100]; char d[100]={0}; j=30; FILE *fp1[2],*fp2; fp1[0]=fopen("program1.txt","r"); fp1[1]=fopen("program2.txt","r"); //the source file is opened in read only mode which will passed through the lexer fp2=fopen("ccv1ouput.txt","wb"); //now lets remove all the white spaces and store the rest of the words in a file if(fp1[0]==NULL) { perror("failed to open program1.txt"); //return EXIT_FAILURE; } if(fp1[1]==NULL) { perror("failed to open program2.txt"); //return EXIT_FAILURE; } i=0; k=0; ct=0; while(ct!=2) { while(!feof(fp1[ct])) { a=fgetc(fp1[ct]); if(a!=' '&&a!='\n') { if (!isalpha(a) && !isdigit(a)) { switch(a) { case '+':{ i=0; cl[0]=1; operator_count[ct]=operator_count[ct]+1;break;} case '-':{ cl[1]=1; operator_count[ct]=operator_count[ct]+1;i=0;break;} case '*':{ cl[2]=1; operator_count[ct]=operator_count[ct]+1;i=0;break;} case '/':{ cl[3]=1; operator_count[ct]=operator_count[ct]+1;i=0;break;} case '=':{a=fgetc(fp1[ct]); if (a=='='){cl[4]=1; operator_count[ct]=operator_count[ct]+1; operand_count[ct]=operand_count[ct]+1;} else { cl[5]=1; operator_count[ct]=operator_count[ct]+1; operand_count[ct]=operand_count[ct]+1; ungetc(1,fp1[ct]); } break;} case '%':{ cl[6]=1; operator_count[ct]=operator_count[ct]+1;i=0;break;} case '<':{ a=fgetc(fp1[ct]); if (a=='=') {cl[7]=1; operator_count[ct]=operator_count[ct]+1;} else { cl[8]=1; operator_count[ct]=operator_count[ct]+1; ungetc(1,fp1[ct]); } break; } case '>':{ ; a=fgetc(fp1[ct]); if (a=='='){cl[9]=1; operator_count[ct]=operator_count[ct]+1;} else { cl[10]=1; operator_count[ct]=operator_count[ct]+1; ungetc(1,fp1[ct]); } break;} case '&':{ cl[11]=1; a=fgetc(fp1[ct]); operator_count[ct]=operator_count[ct]+1; operand_count[ct]=operand_count[ct]+1; variable_used[ct]=variable_used[ct]-1; break; } case '|':{ cl[12]=1; a=fgetc(fp1[ct]); operator_count[ct]=operator_count[ct]+1; operand_count[ct]=operand_count[ct]+1; variable_used[ct]=variable_used[ct]-1; break; } case '#':{ while(a!='\n') { a=fgetc(fp1[ct]); } } } } else { d[i]=a; i=i+1; k=k+1; } } else { //printf("%s \n",d); if((strcmp(d,"if")==0)){ memset ( d, 0, 100 ); i=0; control_count[ct]=control_count[ct]+1; } else if(strcmp(d,"then")==0){ i=0;memset ( d, 0, 100 );control_count[ct]=control_count[ct]+1;} else if(strcmp(d,"else")==0){ i=0;memset ( d, 0, 100 );control_count[ct]=control_count[ct]+1;} else if(strcmp(d,"while")==0){ i=0;memset ( d, 0, 100 );control_count[ct]=control_count[ct]+1;} else if(strcmp(d,"int")==0){ while(a != '\n') { a=fgetc(fp1[ct]); if (isalpha(a) ) variable_dec[ct]=variable_dec[ct]+1; } memset ( d, 0, 100 ); lines_count[ct]=lines_count[ct]+1; } else if(strcmp(d,"char")==0){while(a != '\n') { a=fgetc(fp1[ct]); if (isalpha(a) ) variable_dec[ct]=variable_dec[ct]+1; } memset ( d, 0, 100 ); lines_count[ct]=lines_count[ct]+1; } else if(strcmp(d,"float")==0){while(a != '\n') { a=fgetc(fp1[ct]); if (isalpha(a) ) variable_dec[ct]=variable_dec[ct]+1; } memset ( d, 0, 100 ); lines_count[ct]=lines_count[ct]+1; } else if(strcmp(d,"printf")==0){while(a!='\n') a=fgetc(fp1[ct]); memset(d,0,100); } else if(strcmp(d,"scanf")==0){while(a!='\n') a=fgetc(fp1[ct]); memset(d,0,100);} else if (isdigit(d[i-1])) { memset ( d, 0, 100 ); i=0; constant_count[ct]=constant_count[ct]+1; operand_count[ct]=operand_count[ct]+1; } else if (isalpha(d[i-1]) && strcmp(d,"int")!=0 && strcmp(d,"char")!=0 && strcmp(d,"float")!=0 && (strcmp(d,"if")!=0) && strcmp(d,"then")!=0 && strcmp(d,"else")!=0 && strcmp(d,"while")!=0 && strcmp(d,"printf")!=0 && strcmp(d,"scanf")!=0) { memset ( d, 0, 100 ); i=0; operand_count[ct]=operand_count[ct]+1; } else if(a=='\n') { lines_count[ct]=lines_count[ct]+1; memset ( d, 0, 100 ); } } } fclose(fp1[ct]); operand_count[ct]=operand_count[ct]-5; variable_used[0]=operand_count[0]-constant_count[0]; variable_used[1]=operand_count[1]-constant_count[1]; for(j=0;j<12;j++) uoperator_count[ct]=uoperator_count[ct]+cl[j]; fprintf(fp2,"\n statistics of program %d",ct+1); fprintf(fp2,"\n the no of lines ---> %d",lines_count[ct]); fprintf(fp2,"\n the no of operands --->%d",operand_count[ct]); fprintf(fp2,"\n the no of operator --->%d",operator_count[ct]); fprintf(fp2,"\n the no of control statments --->%d",control_count[ct]); fprintf(fp2,"\n the no of unique operators --->%d",uoperator_count[ct]); fprintf(fp2,"\n the no of variables declared--->%d",variable_dec[ct]); fprintf(fp2,"\n the no of variables used--->%d",variable_used[ct]); fprintf(fp2,"\n ---------------------------------"); fprintf(fp2,"\n \t \t \t"); ct=ct+1; } t[0]=lines_count[0]+control_count[0]+uoperator_count[0]; t[1]=lines_count[1]+control_count[1]+uoperator_count[1]; s[0]=operator_count[0]+operand_count[0]+variable_dec[0]+variable_used[0]; s[1]=operator_count[1]+operand_count[1]+variable_dec[1]+variable_used[1]; fprintf(fp2,"\n the time complexity of program 1 is %d",t[0]); fprintf(fp2,"\n the time complexity of program 2 is %d",t[1]); fprintf(fp2,"\n the space complexity of program 1 is %d",s[0]); fprintf(fp2,"\n the space complexity of program 2 is %d",s[1]); if((t[0]>t[1]) && (s[0] >s[1])) fprintf(fp2,"\n the efficiency of program 2 is greater than program 1"); else if(t[0]<t[1] && s[0] < s[1]) fprintf(fp2,"\n the efficiency of program 1 is greater than program 2 " ); else if (t[0]+s[0] > t[1]+s[1]) fprintf(fp2,"\n the efficiency of program 1 is greater than program 2"); else if (t[0]+s[0] < t[1]+s[1]) fprintf(fp2,"\n the efficiency of program 2 is greater than program 1"); else if (t[0]+s[0] == t[1]+s[1]) fprintf(fp2,"\n the efficiency of program 1 is equal to that of program 2"); fclose(fp2); return 0; } this code basically compares two c codes and finds out the no. of variables declared , used , no. of control statements , no. of lines and no. of unique operators , and operands , so as to find out the time complexity and space complexity of of the two programs given in the text file program1.txt and program2.txt ... Lets say program1.txt is this #include<stdio.h> #include<math.h> int main () { FILE *fp; fp=fopen("output.txt","w"); long double t,y=0,x=0,e=5,f=1,w=1; for (t=0;t<10;t=t+0.01) { //if (isnan(y) || isinf(y)) //break; fprintf(fp,"%ld\t%ld\n",y,x); y = y + ((e*(1 - (x*x))*y) - x + f*cos(w*0.1))*0.1; x = x + y*0.1; } fclose(fp); return (0); } i havent indented it as its just a text file . But my output is totally faulty . Its not able to find the any of the ouput that i need . Where is the bug in this ? I am not able to figure out as the algorithm looks fine .

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