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• Help to solve "Robbery Problem"

  - by peiska

  Hello, Can anybody help me with this problem in C or Java? The problem is taken from here: http://acm.pku.edu.cn/JudgeOnline/problem?id=1104 Inspector Robstop is very angry. Last night, a bank has been robbed and the robber has not been caught. And this happened already for the third time this year, even though he did everything in his power to stop the robber: as quickly as possible, all roads leading out of the city were blocked, making it impossible for the robber to escape. Then, the inspector asked all the people in the city to watch out for the robber, but the only messages he got were of the form "We don't see him." But this time, he has had enough! Inspector Robstop decides to analyze how the robber could have escaped. To do that, he asks you to write a program which takes all the information the inspector could get about the robber in order to find out where the robber has been at which time. Coincidentally, the city in which the bank was robbed has a rectangular shape. The roads leaving the city are blocked for a certain period of time t, and during that time, several observations of the form "The robber isn't in the rectangle Ri at time ti" are reported. Assuming that the robber can move at most one unit per time step, your program must try to find the exact position of the robber at each time step. Input The input contains the description of several robberies. The first line of each description consists of three numbers W, H, t (1 <= W,H,t <= 100) where W is the width, H the height of the city and t is the time during which the city is locked. The next contains a single integer n (0 <= n <= 100), the number of messages the inspector received. The next n lines (one for each of the messages) consist of five integers ti, Li, Ti, Ri, Bi each. The integer ti is the time at which the observation has been made (1 <= ti <= t), and Li, Ti, Ri, Bi are the left, top, right and bottom respectively of the (rectangular) area which has been observed. (1 <= Li <= Ri <= W, 1 <= Ti <= Bi <= H; the point (1, 1) is the upper left hand corner, and (W, H) is the lower right hand corner of the city.) The messages mean that the robber was not in the given rectangle at time ti. The input is terminated by a test case starting with W = H = t = 0. This case should not be processed. Output For each robbery, first output the line "Robbery #k:", where k is the number of the robbery. Then, there are three possibilities: If it is impossible that the robber is still in the city considering the messages, output the line "The robber has escaped." In all other cases, assume that the robber really is in the city. Output one line of the form "Time step : The robber has been at x,y." for each time step, in which the exact location can be deduced. (x and y are the column resp. row of the robber in time step .) Output these lines ordered by time . If nothing can be deduced, output the line "Nothing known." and hope that the inspector will not get even more angry. Output a blank line after each processed case.

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• Unable to host WCF service correctly in IIS7

  - by user206736

  I have a WCF Service library written in .NET 4.0. I have a WCF application (in order to host this service in IIS) within the same solution. It contains the WCF library assembly reference and a service.svc file pointing to the service from the library along with a web.config that is a replica of the WCF service library's app.config. The WCF application is set to host the service in IIS7 (the virtual directory has been set). The same solution contains an ASP.NET Webforms solution to which I have added a service reference pointing to the WCF service I hosted in IIS (as mentioned). When i start an instance of this ASP.NET Web application, I get a message saying that "The WCF service has been hosted" and the ASP.NET application can access the data from it correctly. However, when i try and access this data via a service reference added to an MVC 2 Web Application on the same machine in a different solution (pointing to the service hosted in IIS), I get a "The remote server returned an error: (405) Method Not Allowed." protocol exception . However, the MVC application is able to access the service data if I manually invoke an instance of the WCF Application that I was using to host the WCF Service Library from the other solution. I am using VS2010 Beta 2 as my development IDE. I have been stuck with this issue for a while now. Any help would be appreciated. My service config is as follows:- <system.serviceModel> <services> <service behaviorConfiguration="CruxServices.BasicSearchServiceBehavior" name="CruxServices.BasicSearch.BasicSearch"> <endpoint address="" binding="wsHttpBinding" name="WSBindingEndpoint" bindingConfiguration="WSBindingConfig" contract="CruxServices.BasicSearch.Interfaces.IPropertyListFilter"> <identity> <dns value="localhost" /> </identity> </endpoint> <endpoint address="mex" binding="mexHttpBinding" name="MexEndpoint" contract="IMetadataExchange" /> <host> <baseAddresses> <add baseAddress="http://localhost/CruxServices" /> </baseAddresses> </host> </service> </services> <behaviors> <serviceBehaviors> <behavior name="CruxServices.BasicSearchServiceBehavior"> <serviceMetadata httpGetEnabled="true" /> <serviceDebug includeExceptionDetailInFaults="false" /> </behavior> </serviceBehaviors> </behaviors> <bindings> <wsHttpBinding> <binding name="WSBindingConfig"> <security mode="None"> <transport clientCredentialType="None"/> <message establishSecurityContext="false"/> </security> </binding> </wsHttpBinding> </bindings>

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• How to implement an offline reader writer lock

  - by Peter Morris

  Some context for the question All objects in this question are persistent. All requests will be from a Silverlight client talking to an app server via a binary protocol (Hessian) and not WCF. Each user will have a session key (not an ASP.NET session) which will be a string, integer, or GUID (undecided so far). Some objects might take a long time to edit (30 or more minutes) so we have decided to use pessimistic offline locking. Pessimistic because having to reconcile conflicts would be far too annoying for users, offline because the client is not permanently connected to the server. Rather than storing session/object locking information in the object itself I have decided that any aggregate root that may have its instances locked should implement an interface ILockable public interface ILockable { Guid LockID { get; } } This LockID will be the identity of a "Lock" object which holds the information of which session is locking it. Now, if this were simple pessimistic locking I'd be able to achieve this very simply (using an incrementing version number on Lock to identify update conflicts), but what I actually need is ReaderWriter pessimistic offline locking. The reason is that some parts of the application will perform actions that read these complex structures. These include things like Reading a single structure to clone it. Reading multiple structures in order to create a binary file to "publish" the data to an external source. Read locks will be held for a very short period of time, typically less than a second, although in some circumstances they could be held for about 5 seconds at a guess. Write locks will mostly be held for a long time as they are mostly held by humans. There is a high probability of two users trying to edit the same aggregate at the same time, and a high probability of many users needing to temporarily read-lock at the same time too. I'm looking for suggestions as to how I might implement this. One additional point to make is that if I want to place a write lock and there are some read locks, I would like to "queue" the write lock so that no new read locks are placed. If the read locks are removed withing X seconds then the write lock is obtained, if not then the write lock backs off; no new read-locks would be placed while a write lock is queued. So far I have this idea The Lock object will have a version number (int) so I can detect multi-update conflicts, reload, try again. It will have a string[] for read locks A string to hold the session ID that has a write lock A string to hold the queued write lock Possibly a recursion counter to allow the same session to lock multiple times (for both read and write locks), but not sure about this yet. Rules: Can't place a read lock if there is a write lock or queued write lock. Can't place a write lock if there is a write lock or queued write lock. If there are no locks at all then a write lock may be placed. If there are read locks then a write lock will be queued instead of a full write lock placed. (If after X time the read locks are not gone the lock backs off, otherwise it is upgraded). Can't queue a write lock for a session that has a read lock. Can anyone see any problems? Suggest alternatives? Anything? I'd appreciate feedback before deciding on what approach to take.

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• Getting Custom NSCell with NSButtonCell instance to handle mouse click/mouse events

  - by sidha

  OK I'm really stumped on this one. I want to make a checkbox with a NSTextFieldCell combined together. It's important that the checkbox goes ON if the mouse hits the box, NOT the text. I've accomplished this, more or less, but the issue is receiving the mouse event because I click one checkbox in a row, but ALL of them turn to NSOnState. I will show what I've done and my various failed attempts in order to get this to work. So this is how I've done it so far: header: @interface MyCheckboxCellToo : NSTextFieldCell { NSButtonCell *_checkboxCell; } implementation: - (NSUInteger)hitTestForEvent:(NSEvent *)event inRect:(NSRect)cellFrame ofView:(NSView *)controlView { NSPoint point = [controlView convertPoint:[event locationInWindow] fromView:nil]; NSLog(@"%@", NSStringFromPoint(point)); NSRect checkFrame; NSDivideRect(cellFrame, &checkFrame, &cellFrame, cellFrame.size.height/*3 + [[_checkboxCell image] size].width*/, NSMinXEdge); if (NSMouseInRect(point, checkFrame, [controlView isFlipped])) { // the checkbox, or the small region around it, was hit. so let's flip the state NSCellStateValue checkState = ([_checkboxCell state] == NSOnState) ? NSOffState:NSOnState; [self setState:checkState]; [_checkboxCell setState:checkState]; [controlView setNeedsDisplay:YES]; return NSCellHitTrackableArea; } return [super hitTestForEvent:event inRect:cellFrame ofView:controlView]; } I know I probably shouldn't be doing: [self setState:checkState]; [_checkboxCell setState:checkState]; [controlView setNeedsDisplay:YES]; in there... because the result is that EVERY checkbox in every goes to NSOnState. Is this because cells are re-used? How come the ImageAndTextCell can have different images in the same tableview? How do I handle the mouse event? I have tried: - (BOOL)trackMouse:(NSEvent *)theEvent inRect:(NSRect)cellFrame ofView:(NSView *)controlView untilMouseUp:(BOOL)untilMouseUp { NSLog(@"%s %@", _cmd, theEvent); return [_checkboxCell trackMouse:theEvent inRect:cellFrame ofView:controlView untilMouseUp:untilMouseUp]; // return YES; // return [super trackMouse:theEvent inRect:cellFrame ofView:controlView untilMouseUp:untilMouseUp]; } - (BOOL)startTrackingAt:(NSPoint)startPoint inView:(NSView *)controlView { NSLog(@"%s %@", _cmd, NSStringFromPoint(startPoint)); return [super startTrackingAt:startPoint inView:controlView]; } - (BOOL)continueTracking:(NSPoint)lastPoint at:(NSPoint)currentPoint inView:(NSView *)controlView { NSLog(@"%s %@", _cmd, NSStringFromPoint(currentPoint)); return [super continueTracking:lastPoint at:currentPoint inView:controlView]; } - (void)stopTracking:(NSPoint)lastPoint at:(NSPoint)stopPoint inView:(NSView *)controlView mouseIsUp:(BOOL)flag { NSLog(@"%s %d %@", _cmd, flag, NSStringFromPoint(stopPoint)); } trackMouse: ... DOES gets called but startTrackingAt:..., continueTracking:..., and stopTracking:.... DO NOT get called when I click on the checkbox "hit area" in trackMouse:... I have tried return [_checkboxCell trackMouse:theEvent inRect:cellFrame ofView:controlView untilMouseUp:untilMouseUp]; and return [super trackMouse:theEvent inRect:cellFrame ofView:controlView untilMouseUp:untilMouseUp]; and neither seems to result in the mouse event being handled by the checkbox. How do I get that single checkbox to go NSOnState? I know I'm pretty close but after a lot of doc reading and google searching I haven't been successful at solving this. suggestions and comments welcome.. OK here is a bit more to show creation and destruction of the object.. - (id)init { if ((self = [super init])) { _checkboxCell = [[NSButtonCell alloc] init]; [_checkboxCell setButtonType:NSSwitchButton]; [_checkboxCell setTitle:@""]; [_checkboxCell setTarget:self]; [_checkboxCell setImagePosition:NSImageLeft]; [_checkboxCell setControlSize:NSRegularControlSize]; } return self; } - copyWithZone:(NSZone *)zone { MyCheckboxCellToo *cell = (MyCheckboxCellToo *)[super copyWithZone:zone]; cell->_checkboxCell = [_checkboxCell copyWithZone:zone]; return cell; } - (void)dealloc { [_checkboxCell release]; [super dealloc]; }

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• JS: using 'var me = this' to reference an object instead of using a global array

  - by Marco Demaio

  The example below, is just an example, I know that I don't need an object to show an alert box when user clicks on div blocks, but it's just a simple example to explain a situation that frequently happens when writing JS code. In the example below I use a globally visible array of objects to keep a reference to each new created HelloObject, in this way events called when clicking on a div block can use the reference in the arry to call the HelloObject's public function hello(). 1st have a look at the code: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html><head><meta http-equiv="Content-Type" content="text/html; charset=windows-1252"> <title>Test </title> <script type="text/javascript"> /***************************************************** Just a cross browser append event function, don't need to understand this one to answer my question *****************************************************/ function AppendEvent(html_element, event_name, event_function) {if(html_element) {if(html_element.attachEvent) html_element.attachEvent("on" + event_name, event_function); else if(html_element.addEventListener) html_element.addEventListener(event_name, event_function, false); }} /****************************************************** Just a test object ******************************************************/ var helloobjs = []; var HelloObject = function HelloObject(div_container) { //Adding this object in helloobjs array var id = helloobjs.length; helloobjs[id] = this; //Appending click event to show the hello window AppendEvent(div_container, 'click', function() { helloobjs[id].hello(); //THIS WORKS! }); /***************************************************/ this.hello = function() { alert('hello'); } } </script> </head><body> <div id="one">click me</div> <div id="two">click me</div> <script type="text/javascript"> var t = new HelloObject(document.getElementById('one')); var t = new HelloObject(document.getElementById('two')); </script> </body></html> In order to achive the same result I could simply replace the code //Appending click event to show the hello window AppendEvent(div_container, 'click', function() { helloobjs[id].hello(); //THIS WORKS! }); with this code: //Appending click event to show the hello window var me = this; AppendEvent(div_container, 'click', function() { me.hello(); //THIS WORKS TOO AND THE GLOBAL helloobjs ARRAY BECOMES SUPEFLOUS! }); thus would make the helloobjs array superflous. My question is: does this 2nd option in your opinion create memoy leaks on IE or strange cicular references that might lead to browsers going slow or to break??? I don't know how to explain, but coming from a background as a C/C++ coder, doing in this 2nd way sounds like a some sort of circular reference that might break memory at some point. I also read on internet about the IE closures memory leak issue http://jibbering.com/faq/faq_notes/closures.html (I don't know if it was fixed in IE7 and if yes, I hope it does not come out again in IE8). Thanks

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• Single DispatcherServlet with Multiple Controllers

  - by jwmajors81

  I am trying to create some restful web services using Spring MVC 3.0. I currently have an issue that only 1 of my 2 controllers will work at any given time. As it turns out, whichever class comes first when sorted alphabetically will work properly. The error I get is: handleNoSuchRequestHandlingMethod No matching handler method found for servlet request: path '/polinq.xml', method 'GET', parameters map[[empty]] I had a very simliar message earlier also, except instead of the map being empty it was something like map[v--String(array)] Regardless of the message though, currently the LocationCovgController works and the PolicyInquiryController doesn't. If I change the change of the PolicyInquiryController to APolicyInquiryController, then it will start funcitoning properly and the LocationCovgController will stop working. Any assistance would be greatly appreciated. Thank you very much, Jeremy The information provided below includes the skeleton of both controller classes and also the servlet config file that defines how spring should be setup. Controller 1 package org.example; @Controller @RequestMapping(value = "/polinq.*") public class PolicyInquiryController { @RequestMapping(value = "/polinq.*?comClientId={comClientId}") public ModelAndView getAccountSummary( @PathVariable("comClientId") String commercialClientId) { // setup of variable as was removed. ModelAndView mav = new ModelAndView("XmlView", BindingResult.MODEL_KEY_PREFIX + "accsumm", as); return mav; } } Controller 2 package org.example; @Controller @RequestMapping(value = "/loccovginquiry.*") public class LocationCovgController { @RequestMapping(value = "/loccovginquiry.*method={method}") public ModelAndView locationCovgInquiryByPolicyNo( @PathVariable("method")String method) { ModelAndView mav = new ModelAndView("XmlView", BindingResult.MODEL_KEY_PREFIX + "loccovg", covgs); return mav; } } Servlet Config <context:component-scan base-package="org.example." /> <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver" p:order="0"> <property name="mediaTypes"> <map> <entry key="atom" value="application/atom+xml"/> <entry key="xml" value="application/xml"/> <entry key="json" value="application/json"/> <entry key="html" value="text/html"/> </map> </property> <property name="defaultContentType" value="text/html"/> <property name="ignoreAcceptHeader" value="true"/> <property name="favorPathExtension" value="true"/> <property name="viewResolvers"> <list> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/jsp/"/> <property name="suffix" value=".jsp"/> </bean> </list> </property> <property name="defaultViews"> <list> <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView"/> </list> </property> </bean> <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" /> <bean id="XmlView" class="org.springframework.web.servlet.view.xml.MarshallingView"> <property name="marshaller" ref="marshaller"/> </bean> <oxm:jaxb2-marshaller id="marshaller"> <oxm:class-to-be-bound name="org.example.policy.dto.AccountSummary"/> <oxm:class-to-be-bound name="org.example.policy.dto.InsuredName"/> <oxm:class-to-be-bound name="org.example.policy.dto.Producer"/> <oxm:class-to-be-bound name="org.example.policy.dto.PropertyLocCoverage"/> <oxm:class-to-be-bound name="org.example.policy.dto.PropertyLocCoverages"/> </oxm:jaxb2-marshaller>

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• Running an allocation simulation repeatedly breaks after the first run.

  - by Az

  Background I have a bunch of students, their desired projects and the supervisors for the respective projects. I'm running a battery of simulations to see which projects the students end up with, which will allow me to get some useful statistics required for feedback. So, this is essentially a Monte-Carlo simulation where I'm randomising the list of students and then iterating through it, allocating projects until I hit the end of the list. Then the process is repeated again. Note that, within a single session, after each successful allocation of a project the following take place: + the project is set to allocated and cannot be given to another student + the supervisor has a fixed quota of students he can supervise. This is decremented by 1 + Once the quota hits 0, all the projects from that supervisor become blocked and this has the same effect as a project being allocated Code def resetData(): for student in students.itervalues(): student.allocated_project = None for supervisor in supervisors.itervalues(): supervisor.quota = 0 for project in projects.itervalues(): project.allocated = False project.blocked = False The role of resetData() is to "reset" certain bits of the data. For example, when a project is successfully allocated, project.allocated for that project is flipped to True. While that's useful for a single run, for the next run I need to be deallocated. Above I'm iterating through thee three dictionaries - one each for students, projects and supervisors - where the information is stored. The next bit is the "Monte-Carlo" simulation for the allocation algorithm. sesh_id = 1 for trial in range(50): for id in randomiseStudents(1): stud_id = id student = students[id] if not student.preferences: # Ignoring the students who've not entered any preferences for rank in ranks: temp_proj = random.choice(list(student.preferences[rank])) if not (temp_proj.allocated or temp_proj.blocked): alloc_proj = student.allocated_proj_ref = temp_proj.proj_id alloc_proj_rank = student.allocated_rank = rank successActions(temp_proj) temp_alloc = Allocated(sesh_id, stud_id, alloc_proj, alloc_proj_rank) print temp_alloc # Explained break sesh_id += 1 resetData() # Refer to def resetData() above All randomiseStudents(1) does is randomise the order of students. Allocated is a class defined as such: class Allocated(object): def __init__(self, sesh_id, stud_id, alloc_proj, alloc_proj_rank): self.sesh_id = sesh_id self.stud_id = stud_id self.alloc_proj = alloc_proj self.alloc_proj_rank = alloc_proj_rank def __repr__(self): return str(self) def __str__(self): return "%s - Student: %s (Project: %s - Rank: %s)" %(self.sesh_id, self.stud_id, self.alloc_proj, self.alloc_proj_rank) Output and problem Now if I run this I get an output such as this (truncated): 1 - Student: 7720 (Project: 1100241 - Rank: 1) 1 - Student: 7832 (Project: 1100339 - Rank: 1) 1 - Student: 7743 (Project: 1100359 - Rank: 1) 1 - Student: 7820 (Project: 1100261 - Rank: 2) 1 - Student: 7829 (Project: 1100270 - Rank: 1) . . . 1 - Student: 7822 (Project: 1100280 - Rank: 1) 1 - Student: 7792 (Project: 1100141 - Rank: 7) 2 - Student: 7739 (Project: 1100267 - Rank: 1) 3 - Student: 7806 (Project: 1100272 - Rank: 1) . . . 45 - Student: 7806 (Project: 1100272 - Rank: 1) 46 - Student: 7714 (Project: 1100317 - Rank: 1) 47 - Student: 7930 (Project: 1100343 - Rank: 1) 48 - Student: 7757 (Project: 1100358 - Rank: 1) 49 - Student: 7759 (Project: 1100269 - Rank: 1) 50 - Student: 7778 (Project: 1100301 - Rank: 1) Basically, it works perfectly for the first run, but on subsequent runs leading upto the nth run, in this case 50, only a single student-project allocation pair is returned. Thus, the main issue I'm having trouble with is figuring out what is causing this anomalous behaviour especially since the first run works smoothly. Thanks in advance, Az

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• How do I solve an unresolved external when using C++ Builder packages?

  - by David M

  I'm experimenting with reconfiguring my application to make heaving use of packages. Both I and another developer running a similar experiment are running into a bit of trouble when linking using several different packages. We're probably both doing something wrong, but goodness knows what :) The situation is this: The first package, PackageA.bpl, contains C++ class FooA. The class is declared with the PACKAGE directive. The second package, PackageB.bpl, contains a class inheriting from FooA, called FooB. It includes FooB.h, and the package is built using runtime packages, and links to PackageA by adding a reference to PackageA.bpi. When building PackageB, it compiles fine but linking fails with a number of unresolved externals, the first few of which are: [ILINK32 Error] Error: Unresolved external '__tpdsc__ FooA' referenced from C:\blah\FooB.OBJ [ILINK32 Error] Error: Unresolved external 'FooA::' referenced from C:\blah\FooB.OBJ [ILINK32 Error] Error: Unresolved external '__fastcall FooA::~FooA()' referenced from blah\FooB.OBJ etc. Running TDump on PackageA.bpl shows: Exports from PackageA.bpl 14 exported name(s), 14 export addresse(s). Ordinal base is 1. Sorted by Name: RVA Ord. Hint Name -------- ---- ---- ---- 00002A0C 8 0000 __tpdsc__ FooA 00002AD8 10 0001 __linkproc__ FooA::Finalize 00002AC8 9 0002 __linkproc__ FooA::Initialize 00002E4C 12 0003 __linkproc__ PackageA::Finalize 00002E3C 11 0004 __linkproc__ PackageA::Initialize 00006510 14 0007 FooA:: 00002860 5 0008 FooA::FooA(FooA&) 000027E4 4 0009 FooA::FooA() 00002770 3 000A __fastcall FooA::~FooA() 000028DC 6 000B __fastcall FooA::Method1() const 000028F4 7 000C __fastcall FooA::Method2() const 00001375 2 000D Finalize 00001368 1 000E Initialize 0000610C 13 000F ___CPPdebugHook So the class definitely seems to be exported and available to link. I can see entries for the specific things ILink32 says it's looking for and not finding. Running TDump on the BPI file shows similar entries. Other info The class does descend from TObject, though originally before refactoring into packages it was a normal C++ class. (More detail below. It seems "safer" using VCL-style classes when trying to solve problems with a very Delphi-ish thing like this anyway. Changing this only changes the order of unresolved externals to first not find Method1 and Method2, then others.) Declaration for FooA: class PACKAGE FooA: public TObject { public: FooA(); virtual __fastcall ~FooA(); FooA(const FooA&); virtual __fastcall long Method1() const; virtual __fastcall long Method2() const; }; and FooB: class FooB: public FooA { public: FooB(); virtual __fastcall ~FooB(); ... other methods... }; All methods definitely are implemented in the .cpp files, so it's not not finding them because they don't exist! The .cpp files also contain #pragma package(smart_init) near the top, under the includes. Questions that might help... Are packages reliable using C++, or are they only useable with Delphi code? Is linking to the first package by adding a reference to its BPI correct - is that how you're supposed to do it? I could use a LIB but it seems to make the second package much larger, and I suspect it's statically linking in the contents of the first. Can we use the PACKAGE directive only on TObject-derived classes? There is no compiler warning using it on standard C++ classes. Is splitting code into packages the best way to achieve the goal of isolating code and communicating through defined layers / interfaces? I've been investigating this path because it seems to be the C++Builder / Delphi Way, and if it worked it looks attractive. But are there better alternatives? I'm very new to using packages and have only known about them through using components before. Any general words of advice would be great! We're using C++Builder 2010. I've fabricated the class and method names in the above code examples, but other than that the details are exactly what we're seeing. Cheers, David

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• Optimal storage of data structure for fast lookup and persistence

  - by Mikael Svenson

  Scenario I have the following methods: public void AddItemSecurity(int itemId, int[] userIds) public int[] GetValidItemIds(int userId) Initially I'm thinking storage on the form: itemId -> userId, userId, userId and userId -> itemId, itemId, itemId AddItemSecurity is based on how I get data from a third party API, GetValidItemIds is how I want to use it at runtime. There are potentially 2000 users and 10 million items. Item id's are on the form: 2007123456, 2010001234 (10 digits where first four represent the year). AddItemSecurity does not have to perform super fast, but GetValidIds needs to be subsecond. Also, if there is an update on an existing itemId I need to remove that itemId for users no longer in the list. I'm trying to think about how I should store this in an optimal fashion. Preferably on disk (with caching), but I want the code maintainable and clean. If the item id's had started at 0, I thought about creating a byte array the length of MaxItemId / 8 for each user, and set a true/false bit if the item was present or not. That would limit the array length to little over 1mb per user and give fast lookups as well as an easy way to update the list per user. By persisting this as Memory Mapped Files with the .Net 4 framework I think I would get decent caching as well (if the machine has enough RAM) without implementing caching logic myself. Parsing the id, stripping out the year, and store an array per year could be a solution. The ItemId - UserId[] list can be serialized directly to disk and read/write with a normal FileStream in order to persist the list and diff it when there are changes. Each time a new user is added all the lists have to updated as well, but this can be done nightly. Question Should I continue to try out this approach, or are there other paths which should be explored as well? I'm thinking SQL server will not perform fast enough, and it would give an overhead (at least if it's hosted on a different server), but my assumptions might be wrong. Any thought or insights on the matter is appreciated. And I want to try to solve it without adding too much hardware :) [Update 2010-03-31] I have now tested with SQL server 2008 under the following conditions. Table with two columns (userid,itemid) both are Int Clustered index on the two columns Added ~800.000 items for 180 users - Total of 144 million rows Allocated 4gb ram for SQL server Dual Core 2.66ghz laptop SSD disk Use a SqlDataReader to read all itemid's into a List Loop over all users If I run one thread it averages on 0.2 seconds. When I add a second thread it goes up to 0.4 seconds, which is still ok. From there on the results are decreasing. Adding a third thread brings alot of the queries up to 2 seonds. A forth thread, up to 4 seconds, a fifth spikes some of the queries up to 50 seconds. The CPU is roofing while this is going on, even on one thread. My test app takes some due to the speedy loop, and sql the rest. Which leads me to the conclusion that it won't scale very well. At least not on my tested hardware. Are there ways to optimize the database, say storing an array of int's per user instead of one record per item. But this makes it harder to remove items.

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• Chaining CSS classes in IE6 - Trying to find a jQuery solution?

  - by Mike Baxter

  Right, perhaps I ask the impossible? I consider myself fairly new to Javscript and jQuery, but that being said, I have written some fairly complex code recently so I am definitely getting there... however I am now possed with a rather interesting issue at my current freelance contract. The previous web coder has taken a Grid-960 approach to the HTML and as a result has used chained classes to style many of the elements. The example below is typical of what can be found in the code: <div class='blocks four-col-1 orange highlight'>Some content</div> And in the css there will be different declarations for: (not actual css... but close enough) .blocks {margin-right:10px;} .orange {background-image:url(someimage.jpg);} .highlight {font-weight:bold;} .four-col-1 {width:300px;} and to make matters worse... this is in the CSS: .blocks.orange.highlight {background-colour:#dd00ff;} Anyone not familiar with this particular bug can read more on it here: http://www.ryanbrill.com/archives/multiple-classes-in-ie/ it is very real and very annoying. Without wanting to go into the merrits of not chaining classes (I told them this, but it is no longer feasible to change their approach... 100 hand coded pages into a 150 page website, no CMS... sigh) and without the luxury of being able to change the way these blocks are styled... can anyone advise me on the complexity and benefits between any of my below proposed approaches or possible other options that would adequately solve this problem. Potential Solution 1 Using conditional comments I am considering loading a jquery script only for IE6 that: Reads the class of all divs in a certain section of the page and pushes to an array creates empty boxes off screen with only one of the classes applied at a time Reads the applied CSS values for each box Re-applies these styles to the individual box, somehow bearing in mind the order in which they are called and overwriting conflicting instructions as required Potential Solution 2 read the class of all divs in a certain section of the page and push to an array Scan the document for links to style sheets Ajax grab the stylesheets and traverse looking for matching names to those in class array Apply styles as needed Potential Solution 3 Create an IE6 only stylesheet containing the exact style to be applied as a unique name (ie: class='blocks orange highlight' becomes class='blocks-orange-highlight') Traverse the document in IE6 and convert all spaces in class declarations to hyphens and reapply classes based on new style name Summary: Solution 1 allows the people at this company to apply any styles in the future and the script will adjust as needed. However it does not allow for the chained style to be added, only the individual style... it is also processor intensive and time consuming, but also the most likely to be converted into a plugin that could be used the world over Solution 2 is a potential nightmare to code. But again will allow for an endless number of updates without breaking Solution 3 will require someone at the companty to hardcode the new styles every time they make a change, and if they don't, IE6 will break. Ironically the site, whilst needing to conform to IE6 in a limited manner, does not need to run wihtout javascript (they've made the call... have JS or go away), so consider all jQuery and JS solutions to be 'game on'. Did I mention how much i hate IE6? Anyway... any thoughts or comments would be appreciated. I will continue to develop my own solution and if I discover one that can be turned into a jQuery plugin I will post it here in the comments. Regards, Mike.

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• Thread Synchronisation 101

  - by taspeotis

  Previously I've written some very simple multithreaded code, and I've always been aware that at any time there could be a context switch right in the middle of what I'm doing, so I've always guarded access the shared variables through a CCriticalSection class that enters the critical section on construction and leaves it on destruction. I know this is fairly aggressive and I enter and leave critical sections quite frequently and sometimes egregiously (e.g. at the start of a function when I could put the CCriticalSection inside a tighter code block) but my code doesn't crash and it runs fast enough. At work my multithreaded code needs to be a tighter, only locking/synchronising at the lowest level needed. At work I was trying to debug some multithreaded code, and I came across this: EnterCriticalSection(&m_Crit4); m_bSomeVariable = true; LeaveCriticalSection(&m_Crit4); Now, m_bSomeVariable is a Win32 BOOL (not volatile), which as far as I know is defined to be an int, and on x86 reading and writing these values is a single instruction, and since context switches occur on an instruction boundary then there's no need for synchronising this operation with a critical section. I did some more research online to see whether this operation did not need synchronisation, and I came up with two scenarios it did: The CPU implements out of order execution or the second thread is running on a different core and the updated value is not written into RAM for the other core to see; and The int is not 4-byte aligned. I believe number 1 can be solved using the "volatile" keyword. In VS2005 and later the C++ compiler surrounds access to this variable using memory barriers, ensuring that the variable is always completely written/read to the main system memory before using it. Number 2 I cannot verify, I don't know why the byte alignment would make a difference. I don't know the x86 instruction set, but does mov need to be given a 4-byte aligned address? If not do you need to use a combination of instructions? That would introduce the problem. So... QUESTION 1: Does using the "volatile" keyword (implicity using memory barriers and hinting to the compiler not to optimise this code) absolve a programmer from the need to synchronise a 4-byte/8-byte on x86/x64 variable between read/write operations? QUESTION 2: Is there the explicit requirement that the variable be 4-byte/8-byte aligned? I did some more digging into our code and the variables defined in the class: class CExample { private: CRITICAL_SECTION m_Crit1; // Protects variable a CRITICAL_SECTION m_Crit2; // Protects variable b CRITICAL_SECTION m_Crit3; // Protects variable c CRITICAL_SECTION m_Crit4; // Protects variable d // ... }; Now, to me this seems excessive. I thought critical sections synchronised threads between a process, so if you've got one you can enter it and no other thread in that process can execute. There is no need for a critical section for each variable you want to protect, if you're in a critical section then nothing else can interrupt you. I think the only thing that can change the variables from outside a critical section is if the process shares a memory page with another process (can you do that?) and the other process starts to change the values. Mutexes would also help here, named mutexes are shared across processes, or only processes of the same name? QUESTION 3: Is my analysis of critical sections correct, and should this code be rewritten to use mutexes? I have had a look at other synchronisation objects (semaphores and spinlocks), are they better suited here? QUESTION 4: Where are critical sections/mutexes/semaphores/spinlocks best suited? That is, which synchronisation problem should they be applied to. Is there a vast performance penalty for choosing one over the other? And while we're on it, I read that spinlocks should not be used in a single-core multithreaded environment, only a multi-core multithreaded environment. So, QUESTION 5: Is this wrong, or if not, why is it right? Thanks in advance for any responses :)

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• Drawing a TextBox in an extended Glass Frame w/o WPF

  - by Lazlo

  I am trying to draw a TextBox on the extended glass frame of my form. I won't describe this technique, it's well-known. Here's an example for those who haven't heard of it: http://www.danielmoth.com/Blog/Vista-Glass-In-C.aspx The thing is, it is complex to draw over this glass frame. Since black is considered to be the 0-alpha color, anything black disappears. There are apparently ways of countering this problem: drawing complex GDI+ shapes are not affected by this alpha-ness. For example, this code can be used to draw a Label on glass (note: GraphicsPath is used instead of DrawString in order to get around the horrible ClearType problem): public class GlassLabel : Control { public GlassLabel() { this.BackColor = Color.Black; } protected override void OnPaint(PaintEventArgs e) { GraphicsPath font = new GraphicsPath(); font.AddString( this.Text, this.Font.FontFamily, (int)this.Font.Style, this.Font.Size, Point.Empty, StringFormat.GenericDefault); e.Graphics.SmoothingMode = SmoothingMode.HighQuality; e.Graphics.FillPath(new SolidBrush(this.ForeColor), font); } } Similarly, such an approach can be used to create a container on the glass area. Note the use of the polygons instead of the rectangle - when using the rectangle, its black parts are considered as alpha. public class GlassPanel : Panel { public GlassPanel() { this.BackColor = Color.Black; } protected override void OnPaint(PaintEventArgs e) { Point[] area = new Point[] { new Point(0, 1), new Point(1, 0), new Point(this.Width - 2, 0), new Point(this.Width - 1, 1), new Point(this.Width -1, this.Height - 2), new Point(this.Width -2, this.Height-1), new Point(1, this.Height -1), new Point(0, this.Height - 2) }; Point[] inArea = new Point[] { new Point(1, 1), new Point(this.Width - 1, 1), new Point(this.Width - 1, this.Height - 1), new Point(this.Width - 1, this.Height - 1), new Point(1, this.Height - 1) }; e.Graphics.FillPolygon(new SolidBrush(Color.FromArgb(240, 240, 240)), inArea); e.Graphics.DrawPolygon(new Pen(Color.FromArgb(55, 0, 0, 0)), area); base.OnPaint(e); } } Now my problem is: How can I draw a TextBox? After lots of Googling, I came up with the following solutions: Subclassing the TextBox's OnPaint method. This is possible, although I could not get it to work properly. It should involve painting some magic things I don't know how to do yet. Making my own custom TextBox, perhaps on a TextBoxBase. If anyone has good, valid and working examples, and thinks this could be a good overall solution, please tell me. Using BufferedPaintSetAlpha. (http://msdn.microsoft.com/en-us/library/ms649805.aspx). The downsides of this method may be that the corners of the textbox might look odd, but I can live with that. If anyone knows how to implement that method properly from a Graphics object, please tell me. I personally don't, but this seems the best solution so far. To be honest, I found a great C++ article, but I am way too lazy to convert it. http://weblogs.asp.net/kennykerr/archive/2007/01/23/controls-and-the-desktop-window-manager.aspx Note: If I ever succeed with the BufferedPaint methods, I swear to s/o that I will make a simple DLL with all the common Windows Forms controls drawable on glass.

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• XSL to show highest number of copies in catalog.xml file

  - by SANJAY RAO

  In this the catalog.xml file. I have two books who have the same inventory (i.e. 20). I want to write an XSL file that will display the highest number of copies of a book in a catalog. If there are two or more books of the same inventory then they have to be displayed. <catalog> <Book> <sku>12345</sku> <title>Beauty Secrets</title> <condition>New</condition> <current_inventory>20</current_inventory> <price>99.99</price> </Book> <Book> <sku>54321</sku> <title>Picturescapes</title> <current_inventory>20</current_inventory> <condition>New</condition> <price>50.00</price> </Book> <Book> <sku>33333</sku> <title>Tourist Perspectives</title> <condition>New</condition> <current_inventory>0</current_inventory> <price>75.00</price> </Book> <Book> <sku>10001</sku> <title>Fire in the Sky</title> <condition>Used</condition> <current_inventory>0</current_inventory> <price>10.00</price> </Book> </catalog> Below is my catalog3.xsl file which is able to display only one out of the two books: <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" > <xsl:variable name="max"/> <xsl:template match="/"> <html> <body> <h2>Titles of Books for which Most Copies are Available</h2> <table border="2"> <tr bgcolor="#9acd32"> <th>Title</th> <th>No of Copies</th> </tr> <xsl:apply-templates/> </table> </body> </html> </xsl:template> <xsl:template match="catalog"> <xsl:for-each select="Book"> <xsl:sort select="current_inventory" data-type="number" order="descending"/> <tr> <xsl:if test="position()= 1"> <p><xsl:value-of select="$max = "/></p> <td><xsl:value-of select="title"/></td> <td><xsl:value-of select="current_inventory"/></td> </xsl:if> </tr> </xsl:for-each> </xsl:template> </xsl:stylesheet> Could anybody correct me to achieve my goal of displaying all the copies having the same maximum inventory in the catalog. Thanks.

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• XML Parsing Error: junk after document element

  - by Jake

  I am using the following script to generate a RSS feed for my site: <?php class RSS { public function RSS() { $root = $_SERVER['DOCUMENT_ROOT']; require_once ("../connect.php"); } public function GetFeed() { return $this->getDetails() . $this->getItems(); } private function dbConnect() { DEFINE ('LINK', mysql_connect (DB_HOST, DB_USER, DB_PASSWORD)); } private function getDetails() { $detailsTable = "rss_feed_details"; $this->dbConnect($detailsTable); $query = "SELECT * FROM ". $detailsTable ." WHERE feed_category = ''"; $result = mysql_db_query (DB_NAME, $query, LINK); while($row = mysql_fetch_array($result)) { $details = '<?xml version="1.0" encoding="ISO-8859-1" ?> <rss version="2.0"> <channel> <title>'. $row['title'] .'</title> <link>'. $row['link'] .'</link> <description>'. $row['description'] .'</description> <language>'. $row['language'] .'</language> <image> <title>'. $row['image_title'] .'</title> <url>'. $row['image_url'] .'</url> <link>'. $row['image_link'] .'</link> <width>'. $row['image_width'] .'</width> <height>'. $row['image_height'] .'</height> </image>'; } return $details; } private function getItems() { $itemsTable = "rss_posts"; $this->dbConnect($itemsTable); $query = "SELECT * FROM ". $itemsTable ." ORDER BY id DESC"; $result = mysql_db_query (DB_NAME, $query, LINK); $items = ''; while($row = mysql_fetch_array($result)) { $items .= '<item> <title>'. $row["title"] .'</title> <link>'. $row["link"] .'</link> <description><![CDATA['.$row["readable_date"]."<br /><br />".$row["description"]."<br /><br />".']]></description> </item>'; } $items .= '</channel> </rss>'; return $items; } } ?> The baffling thing is, the script works perfectly fine on my localhost but gives the following error on my remote server: XML Parsing Error: junk after document element Location: http://mysite.com/rss/main/ Line Number 2, Column 1:<b>Parse error</b>: syntax error, unexpected T_STRING in <b>/home/studentw/public_html/rss/global-reach/rssClass.php</b> on line <b>1</b><br /> ^ Can someone please tell me what's wrong?

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• Encoding Problem with Zend Navigation using Zend Translate Spanish in XMLTPX File Special Characters

  - by Routy

  Hello, I have been attempting to use Zend Translate to display translated menu items to the user. It works fine until I introduce special characters into the translation files. I instantiate the Zend_Translate object in my bootstrap and pass it in as a translator into Zend_Navigation: $translate = new Zend_Translate( array('adapter' => 'tmx', 'content' => APPLICATION_PATH .'/languages/translation.tmx', 'locale' => 'es' ) ); $navigation->setUseTranslator($translate); I have used several different adapters (array,tmx) in order to see if that made a difference. I ended up with a TMX file that is encoded using ISO-8859-1 (otherwise that throws an XML parse error when introducing the menu item "Administrar Applicación". <?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE tmx SYSTEM "tmx14.dtd"> <tmx version="1.4"> <header creationtoolversion="1.0.0" datatype="tbx" segtype="sentence" adminlang="en" srclang="en" o-tmf="unknown" creationtool="XYZTool" > </header> <body> <tu tuid='link_signout'> <tuv xml:lang="en"><seg>Sign Out</seg></tuv> <tuv xml:lang="es"><seg>Salir</seg></tuv> </tu> <tu tuid='link_signin'> <tuv xml:lang="en"><seg>Login</seg></tuv> <tuv xml:lang="es"><seg>Acceder</seg></tuv> </tu> <tu tuid='Manage Application'> <tuv xml:lang="en"><seg>Manage Application</seg></tuv> <tuv xml:lang="es"><seg>Administrar Applicación</seg></tuv> </tu> </body> </tmx> Once I display the menu in the layout: echo $this->navigation()->menu(); It will display all menu items just fine, EXCEPT the one using special characters. It will simply be blank. NOW - If I use PHP's UTF8-encode inside of the zend framework class 'Menu' which I DO NOT want to do: Line 215 in Zend_View_Helper_Navigation_Menu: if ($this->getUseTranslator() && $t = $this->getTranslator()) { if (is_string($label) && !empty($label)) { $label = utf8_encode($t->translate($label)); } if (is_string($title) && !empty($title)) { $title = utf8_encode($t->translate($title)); } } Then it works. The menu item display correctly and all is joyful. The thing is, I do not want to modify the library. Is there some kind of an encoding setting in either zend translate or zend navigation that I am not finding? Please Help! Zend Library Version: 1.11

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• highlight navigation PHP

  - by Kira

  I've launched a website a while back and successfully used Javascript + CSS to highlight the current page on the navigation. However, it is not working in Safari and it does not validate well, when using Javascript, so I decided to have PHP assign the CSS id to the HTML elements. So far, it works fine, compared to the other times where there was two of each link displayed, when it was attempted in PHP. My problem is that all links look normal and the CSS property is not applied. I have a feeling that it has to do with my PHP code, but I'm not certain. The site address is here As for the PHP code, here it is: <?php echo('<li><span class="bold">Main</span>'); echo('<ul>'); if ($page=="home") { echo('<li><a id="current" href="index.shtml">Home</a></li>'); } else { echo('<li><a href="index.shtml">Home</a></li>'); } if ($page=="faq") { echo('<li><a id="current" href="faq.shtml">FAQ</a></li>'); } else { echo('<li><a href="faq.shtml">FAQ</a></li>'); } if ($page=="about") { echo('<li><a id="current" href="about.shtml">About Bryce</a></li>'); } else { echo('<li><a href="about.shtml">About Bryce</a></li>'); } echo('<li><a href="contact.php">Contact Bryce</a></li>'); if ($page=="sign guestbook") { echo('<li><a id="current" href="sign.shtml">Sign Guestbook</a></li>'); } else { echo('<li><a href="sign.shtml">Sign Guestbook</a></li>'); } if ($page=="view guestbook") { echo('<li><a id="current" href="view.shtml">View Guestbook</a></li>'); } else { echo('<li><a href="view.shtml">View Guestbook</a></li>'); } echo('</ul>'); echo('</li>'); echo('<li><span class="bold">Info</span>'); echo('<ul>'); if ($page=="projects") { echo('<li><a id="current" href="projects.shtml">Projects</a></li>'); } else { echo('<li><a href="projects.shtml">Projects</a></li>'); } if ($page=="books") { echo('<li><a id="current" href="books.shtml">Books</a></li>'); } else { echo('<li><a href="books.shtml">Books</a></li>'); } echo('</ul>'); echo('</li>'); echo('<li><span class="bold">Misc.</span>'); echo('<ul>'); if ($page=="cover designs") { echo('<li><a id="current" href="coverdesigns.shtml">Cover Designs</a></li>'); } else { echo('<li><a href="coverdesigns.shtml">Cover Designs</a></li>'); } echo('<li><a target="_blank" href="http://www.lulu.com/brycecampbellsbooks">Lulu Store</a></li>'); echo('<li><a href="rss/">RSS</a></li>'); echo('</ul>'); echo('</li>'); ?> In order to give you guys an idea of what the highlighting effect should look like, here is the CSS that is supposed to be applied to the current page: #current { font-style: italic; text-decoration: none; color: #000000; } When looking up what I was doing wrong, it told me that I was implementing it right, but it does not seem that the PHP is getting the values.

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• The problem about use the exist sqlite database,

  - by flybirdtt

  I have a sqlite database, and i put this file in "assets" folder. The code like below, Pls help and tell what's wrong in this code, How to use my own sqlite database. public class DataBaseHelper extends SQLiteOpenHelper { private static String DB_PATH = "/data/data/com.SGMalls/databases/"; private static String DB_NAME = "mallMapv2.sqlite"; private SQLiteDatabase myDataBase; private final Context myContext; public DataBaseHelper(Context context) { super(context, DB_NAME, null, 1); this.myContext = context; } public void createDataBase() throws IOException { File dbDir = new File(DB_PATH); if (!dbDir.exists()) { dbDir.mkdir(); } boolean dbExist = checkDataBase(); if (dbExist) { } else { this.getReadableDatabase(); try { copyDataBase(); } catch (IOException e) { throw new Error("Error copying database"); } } close(); } private boolean checkDataBase() { SQLiteDatabase checkDB = null; boolean isnull=false; try { String myPath = DB_PATH + DB_NAME; checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } catch (SQLiteException e) { // database does't exist yet. } if (checkDB != null) { isnull=true; checkDB.close(); } return isnull; } private void copyDataBase() throws IOException { InputStream myInput = myContext.getAssets().open(DB_NAME); String outFileName = DB_PATH + DB_NAME; OutputStream myOutput = new FileOutputStream(outFileName); byte[] buffer = new byte[1024]; int length; while ((length = myInput.read(buffer)) > 0) { myOutput.write(buffer, 0, length); } // Close the streams myOutput.flush(); myOutput.close(); myInput.close(); } public void openDataBase() throws SQLException { // Open the database String myPath = DB_PATH + DB_NAME; myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } @Override public synchronized void close() { if (myDataBase != null) myDataBase.close(); super.close(); } @Override public void onCreate(SQLiteDatabase db) { } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { } } public class GetData { private static String DB_PATH = "/data/data/com.SGMalls/databases/mallMapv2.sqlite"; // private static String DB_NAME = "mallMapv2.sqlite"; public static ArrayList<Mall> getMalls() { ArrayList<Mall> mallsList = new ArrayList<Mall>(); SQLiteDatabase malldatabase = SQLiteDatabase.openDatabase(DB_PATH, null, SQLiteDatabase.OPEN_READONLY); String queryString="select id,title from malls order by title"; Cursor cursor=malldatabase.rawQuery(queryString, null); if(cursor!=null){ cursor.moveToFirst(); while(!cursor.isLast()){ Mall mall=new Mall(); mall.setMallid(cursor.getInt(0)); mall.setMallname(cursor.getString(0)); mallsList.add(mall); cursor.moveToNext(); } } malldatabase.close(); return mallsList; } } The error message: ERROR/Database(725): sqlite3_open_v2("/data/data/com.SGMalls/databases/ mallMapv2.sqlite", &handle, 1, NULL) failed 03-15 22:34:11.747: ERROR/AndroidRuntime(725): Uncaught handler: thread main exiting due to uncaught exception 03-15 22:34:11.766: ERROR/AndroidRuntime(725): java.lang.Error: Error copying database Thanks very much

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• wpf display staggered content

  - by Chris Cap

  I am trying to display a rather dynamic list of data in WPF. I have essentially a LineItem class that contains a list of strings and a line type. The line type separates different categories of line items. All line items with the same type should be displayed the same and their data should line up. For example, this list will contain an order summary. And the there will be a line type that represents something with a width and height. The width and height must line up vertically. However, there may be other line types that don't have to line up vertically. I want to produce a table similar to what you see below: ------------------------------------------------------------------ | some content here | some more content here | last content here | |----------------------------------------------------------------| | some content here | | last content here | |----------------------------------------------------------------| | spanning content that is longer then most | last content here | |----------------------------------------------------------------| | some content that can span a really long distance | ------------------------------------------------------------------ I attempted to do this by creating ListView with a single column that had a datatemplate that contained a grid with a fixed number of fields and then bind to the Colspan value. Unfortunately, this didn't work. I ended up with incorrect or overlapping content anytime I tried to do a column span. Here's the XAML I was working with <ListView ItemsSource="{Binding}" > <ListView.View> <GridView> <GridViewColumn Header="Content"> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition /> <ColumnDefinition /> <ColumnDefinition /> </Grid.ColumnDefinitions> <TextBlock Grid.Column="0" Grid.ColumnSpan="{Binding Path=Tokens[0].ColumnSpan}" Text="{Binding Path=Tokens[0].Content}" ></TextBlock> <TextBlock Grid.Column="1" Grid.ColumnSpan="{Binding Path=Tokens[1].ColumnSpan}" Text="{Binding Path=Tokens[1].Content}" ></TextBlock> <TextBlock Grid.Column="2" Text="{Binding Path=Tokens[2].Content}"></TextBlock> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> </GridView> </ListView.View> And here's the classes I was binding to public class DisplayLine { public LineType Linetype { get; set; } public List<Token> Tokens { get; set; } public DisplayLine() { Tokens = new List<Token>(); } } public class Token { public string Content { get; set; } public bool IsEmpty { get { return string.IsNullOrEmpty(Content); } } public int ColumnSpan { get; set; } public Token() { ColumnSpan = 1; } } Does anyone have any suggestions of maybe a way of making this work. I may be taking the wrong approach. I'm trying to avoid any solutions where I explcitily build something in the code behind as I'm using the MVVM pattern so it has to be something that I can bind from exposed through the controller. My intial plan was to create a factory and separate classes that display the data differently based on type. However, I'm struggling coming up with a strategy for this using MVVM as I really can't just build something and display it. I have toyed with the idea of making some kind of UI service class that is injected, but it would still require some pretty detailed UI information from the controller to do it's work.

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• being able to solve google code jam problem sets

  - by JPro

  This is not a homework question, but rather my intention to know if this is what it takes to learn programming. I keep loggin into TopCoder not to actually participate but to get the basic understand of how the problems are solved. But to my knowledge I don't understand what the problem is and how to translate the problem into an algorithm that can solve it. Just now I happen to look at ACM ICPC 2010 World Finals which is being held in china. The teams were given problem sets and one of them is this: Given at most 100 points on a plan with distinct x-coordinates, find the shortest cycle that passes through each point exactly once, goes from the leftmost point always to the right until it reaches the rightmost point, then goes always to the left until it gets back to the leftmost point. Additionally, two points are given such that the the path from left to right contains the first point, and the path from right to left contains the second point. This seems to be a very simple DP: after processing the last k points, and with the first path ending in point a and the second path ending in point b, what is the smallest total length to achieve that? This is O(n^2) states, transitions in O(n). We deal with the two special points by forcing the first path to contain the first one, and the second path contain the second one. Now I have no idea what I am supposed to solve after reading the problem set. and there's an other one from google code jam: Problem In a big, square room there are two point light sources: one is red and the other is green. There are also n circular pillars. Light travels in straight lines and is absorbed by walls and pillars. The pillars therefore cast shadows: they do not let light through. There are places in the room where no light reaches (black), where only one of the two light sources reaches (red or green), and places where both lights reach (yellow). Compute the total area of each of the four colors in the room. Do not include the area of the pillars. Input * One line containing the number of test cases, T. Each test case contains, in order: * One line containing the coordinates x, y of the red light source. * One line containing the coordinates x, y of the green light source. * One line containing the number of pillars n. * n lines describing the pillars. Each contains 3 numbers x, y, r. The pillar is a disk with the center (x, y) and radius r. The room is the square described by 0 = x, y = 100. Pillars, room walls and light sources are all disjoint, they do not overlap or touch. Output For each test case, output: Case #X: black area red area green area yellow area Is it required that people who program should be should be able to solve these type of problems? I would apprecite if anyone can help me interpret the google code jam problem set as I wish to participate in this years Code Jam to see if I can do anthing or not. Thanks.

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• Foreign keys and pagination

  - by whitstone86

  This is my pagination script: <?php /*********************************** * PhpMyCoder Paginator * * Created By PhpMyCoder * * 2010 PhpMyCoder * * ------------------------------- * * You may use this code as long * * as this notice stays intact and * * the proper credit is given to * * the author. * ***********************************/ ?> <head> <title> Pagination Test - Created By PhpMyCoder</title> <style type="text/css"> #nav { font: normal 13px/14px Arial, Helvetica, sans-serif; margin: 2px 0; } #nav a { background: #EEE; border: 1px solid #DDD; color: #000080; padding: 1px 7px; text-decoration: none; } #nav strong { background: #000080; border: 1px solid #DDD; color: #FFF; font-weight: normal; padding: 1px 7px; } #nav span { background: #FFF; border: 1px solid #DDD; color: #999; padding: 1px 7px; } </style> </head> <?php //Require the file that contains the required classes include("pmcPagination.php"); //PhpMyCoder Paginator $paginator = new pmcPagination(20, "page"); //Connect to the database mysql_connect("localhost","root","PASSWORD"); //Select DB mysql_select_db("tvguide"); //Select only results for today and future $result = mysql_query("SELECT programme, channel, airdate, expiration, episode, setreminder FROM epdata1 where airdate >= now() order by expiration GROUP BY airdate"); //You can also add reuslts to paginate here mysql_data_seek($queryresult,0) ; while($row = mysql_fetch_array($result)) { $paginator->add(new paginationData($row['programme'], $row['channel'], $row['airdate'], $row['expiration'], $row['episode'], $row['setreminder'])); } ?> <?php //Show the paginated results $paginator->paginate (); ?><? include("pca-footer1.php"); ?> <?php //Show the navigation $paginator->navigation(); ?> However, I have two tables in this, and they are epdata1 (where the airtimes for my show House M.D. are) and housemdep plus the setreminder table. How can I use foreign keys in relation to this? I'm not sure if this will work for my script, but am willing to try. What I would like to do is to select certain episodes from the table housemdep (episodes of the show) and if any are selected it shows them as this: House M.D. showing on Channel 1 June 6th - 8:00pm "Wilson" Set Reminder House M.D. showing on Channel 1 June 7th - 1:30am "Wilson" Set Reminder House M.D. showing on Channel 1 June 7th - 12:55pm "House's Head" Set Reminder or like this, if I have not selected an episode from the row: House M.D. showing on Channel 1 June 7th - 8:00pm "House's Head" Set Reminder House M.D. showing on Channel 1 June 8th - 9:00pm Set Reminder House M.D. showing on Channel 1 June 9th - 2:30pm Set Reminder House M.D. showing on Channel 1 June 7th - 8:00pm "Que Sera Sera" Set Reminder Foreign keys and relationship of interlinked tables are new to me, if anyone could help I'd appreciate this. I've tried some of what Google suggested on foreign keys in another version of this script (this is a clone of the original on my localhost server running Apache and PHP 5.28/MySQL), but am not sure how to implement this. Thanks.

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• SQL query mixing aggregated results and single values

  - by Paul Flowerdew

  I have a table with transactions. Each transaction has a transaction ID, and accounting period (AP), and a posting value (PV), as well as other fields. Some of the IDs are duplicated, usually because the transaction was done in error. To give an example, part of the table might look like: ID PV AP 123 100 2 123 -100 5 In this case the transaction was added in AP2 then removed in AP5. Another example would be: ID PV AP 456 100 2 456 -100 5 456 100 8 In the first example, the problem is that if I am analyzing what was spent in AP2, there is a transaction in there which actually shouldn't be taken into account because it was taken out again in AP5. In the second example, the second two transactions shouldn't be taken into account because they cancel each other out. I want to label as many transactions as possible which shouldn't be taken into account as erroneous. To identify these transactions, I want to find the ones with duplicate IDs whose PVs sum to zero (like ID 123 above) or transactions where the PV of the earliest one is equal to sum(PV), as in the second example. This second condition is what is causing me grief. So far I have SELECT * FROM table WHERE table.ID IN (SELECT table.ID FROM table GROUP BY table.ID HAVING COUNT(*) > 1 AND (SUM(table.PV) = 0 OR SUM(table.PV) = <PV of first transaction in each group>)) ORDER BY table.ID; The bit in chevrons is what I'm trying to do and I'm stuck. Can I do it like this or is there some other method I can use in SQL to do this? Edit 1: Btw I forgot to say that I'm using SQL Compact 3.5, in case it matters. Edit 2: I think the code snippet above is a bit misleading. I still want to mark out transactions with duplicate IDs where sum(PV) = 0, as in the first example. But where the PV of the earliest transaction = sum(PV), as in the second example, what I actually want is to keep the earliest transaction and mark out all the others with the same ID. Sorry if that caused confusion. Edit 3: I've been playing with Clodoaldo's solution and have made some progress, but still can't get quite what I want. I'm trying to get the transactions I know for certain to be erroneous. Suppose the following transactions are also in the table: ID PV AP 789 100 2 789 200 5 789 -100 8 In this example sum(PV) < 0 and the earliest PV < sum(PV) so I don't want to mark any of these out. If I modify Clodoaldo's query as follows: select t.* from t left join ( select id, min(ap) as ap, sum(pv) as sum_pv from t group by id having sum(pv) <> 0 ) s on t.id = s.id and t.ap = s.ap and t.pv = s.sum_pv where s.id is null This gives the result ID PV AP 123 100 2 123 -100 5 456 -100 5 456 100 8 789 100 3 789 200 5 789 -100 8 Whilst the first 4 transactions are ok (they would be marked out), the 789 transactions are also there, and I don't want them. But I can't figure out how to modify the query so that they're not included. Any ideas?

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• JQuery - Adding Cells to Dynamic Tree Table

  - by BPotocki

  I can't quite wrap my head around this one... A table like the one below is spit out by a renderer from some XML. The XML it comes from has a variable depth. (Please point out if I'm using the rowspans in a horrific manner as well, I just came to this table with some experimentation). <table border="1"> <tr> <td rowspan="12">> 1</td> </tr> <tr> <td rowspan="3">1 > 2</td> </tr> <tr> <td>1 > 2 > 5</td> </tr> <tr> <td>1 > 2 > 6</td> </tr> <tr> <td rowspan="3">1 > 3</td> </tr> <tr> <td>1 > 3 > 7</td> </tr> <tr> <td>1 > 3 > 8</td> </tr> <tr> <td rowspan="3">1 > 4</td> </tr> <tr> <td>1 > 4 > 9</td> </tr> <tr> <td>1 > 4 > 10</td> </tr> </table> What I'm trying to accomplish in JQuery is this... User clicks cell "1 2" (which will have an ID). An item is dynamically added to the third level, but UNDER "1 2 6". What I could do is just add another row underneath "1 2" and increase the rowspan from "1 2", but the new cell would then appear out of order amongst "1 2 5" and "1 2 6". I don't really need the exact code to do this, just something to stop my head from spinning around this...Thanks!

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• Windows NT Service shutdown issues

  - by Jeremiah Gowdy

  I have developed middleware that provides RPC functionality to multiple client applications on multiple platforms within our organization. The middleware is written in C# and runs as a Windows NT Service. It handles things like file access to network shares, database access, etc. The middleware is hosted on two high end systems running Windows Server 2008 R2. When one of our server administrators goes to reboot the machine, primarily to do Windows Updates, there are serious problems with how the system behaves in regards to my NT Service. My service is designed to immediately stop listening for new connections, immediately start refusing new requests on existing connections, and otherwise shut down as rapidly as possible in the case of an OnStop or OnShutdown request from the SCM. Still, to maintain system integrity, operations that are currently in progress are allowed to continue for a reasonable time. Usually the server shuts down inside of 30 seconds (when the service is manually stopped for example). However, when the system is instructed to restart, my service immediately loses access to network drives and UNC paths, causing data integrity problems for any open files and partial writes to those locations. My service does list Workstation (and thus SMB Redirector) as a dependency, so I would think that my service would need to be stopped prior to Workstation/Redirector being stopped if Windows were honoring those dependencies. Basically, my application is forced to crash and burn, failing remote procedure calls and eventually being forced to terminate by the operating system after a timeout period has elapsed (seems to be on the order of 20-30 seconds). Unlike a Windows application, my Windows NT Service doesn't seem to have any power to stop a system shutdown in progress, delay the system shutdown, or even just the opportunity to save out any pending network share disk writes before being forcibly disconnected and shutdown. How is an NT Service developer supposed to have any kind of application integrity in this environment? Why is it that Forms Applications get all of the opportunity to finish their business prior to shutdown, while services seem to get no such benefits? I have tried: Calling SetProcessShutdownParameters via p/invoke to try to notify my application of the shutdown sooner to avoid Redirector shutting down before I do. Calling ServiceBase.RequestAdditionalTime with a value less than or equal to the two minute limit. Tweaking the WaitToKillServiceTimeout Everything I can think of to make my service shutdown faster. But in the end, I still get ~30 seconds of problematic time in which my service doesn't even seem to have been notified of an OnShutdown event yet, but requests are failing due to redirector no longer servicing my network share requests. How is this issue meant to be resolved? What can I do to delay or stop the shutdown, or at least be allowed to shut down my active tasks without Redirector services disappearing out from under me? I can understand what Microsoft is trying to do to prevent services from dragging their feet and showing shutdowns, but that seems like a great goal for Windows client operating systems, not for servers. I don't want my servers to shutdown fast, I want operational integrity and graceful shutdowns. Thanks in advance for any help you can provide. PS in regards to writing my own middleware, this is for a telephony application with sub-second "soft-realtime" response time requirements. It does make sense, and it's not a point I'm looking to debate. :)

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• Incremental PCA

  - by smichak

  Hi, Lately, I've been looking into an implementation of an incremental PCA algorithm in python - I couldn't find something that would meet my needs so I did some reading and implemented an algorithm I found in some paper. Here is the module's code - the relevant paper on which it is based is mentioned in the module's documentation. I would appreciate any feedback from people who are interested in this. Micha #!/usr/bin/env python """ Incremental PCA calculation module. Based on P.Hall, D. Marshall and R. Martin "Incremental Eigenalysis for Classification" which appeared in British Machine Vision Conference, volume 1, pages 286-295, September 1998. Principal components are updated sequentially as new observations are introduced. Each new observation (x) is projected on the eigenspace spanned by the current principal components (U) and the residual vector (r = x - U(U.T*x)) is used as a new principal component (U' = [U r]). The new principal components are then rotated by a rotation matrix (R) whose columns are the eigenvectors of the transformed covariance matrix (D=U'.T*C*U) to yield p + 1 principal components. From those, only the first p are selected. """ __author__ = "Micha Kalfon" import numpy as np _ZERO_THRESHOLD = 1e-9 # Everything below this is zero class IPCA(object): """Incremental PCA calculation object. General Parameters: m - Number of variables per observation n - Number of observations p - Dimension to which the data should be reduced """ def __init__(self, m, p): """Creates an incremental PCA object for m-dimensional observations in order to reduce them to a p-dimensional subspace. @param m: Number of variables per observation. @param p: Number of principle components. @return: An IPCA object. """ self._m = float(m) self._n = 0.0 self._p = float(p) self._mean = np.matrix(np.zeros((m , 1), dtype=np.float64)) self._covariance = np.matrix(np.zeros((m, m), dtype=np.float64)) self._eigenvectors = np.matrix(np.zeros((m, p), dtype=np.float64)) self._eigenvalues = np.matrix(np.zeros((1, p), dtype=np.float64)) def update(self, x): """Updates with a new observation vector x. @param x: Next observation as a column vector (m x 1). """ m = self._m n = self._n p = self._p mean = self._mean C = self._covariance U = self._eigenvectors E = self._eigenvalues if type(x) is not np.matrix or x.shape != (m, 1): raise TypeError('Input is not a matrix (%d, 1)' % int(m)) # Update covariance matrix and mean vector and centralize input around # new mean oldmean = mean mean = (n*mean + x) / (n + 1.0) C = (n*C + x*x.T + n*oldmean*oldmean.T - (n+1)*mean*mean.T) / (n + 1.0) x -= mean # Project new input on current p-dimensional subspace and calculate # the normalized residual vector g = U.T*x r = x - (U*g) r = (r / np.linalg.norm(r)) if not _is_zero(r) else np.zeros_like(r) # Extend the transformation matrix with the residual vector and find # the rotation matrix by solving the eigenproblem DR=RE U = np.concatenate((U, r), 1) D = U.T*C*U (E, R) = np.linalg.eigh(D) # Sort eigenvalues and eigenvectors from largest to smallest to get the # rotation matrix R sorter = list(reversed(E.argsort(0))) E = E[sorter] R = R[:,sorter] # Apply the rotation matrix U = U*R # Select only p largest eigenvectors and values and update state self._n += 1.0 self._mean = mean self._covariance = C self._eigenvectors = U[:, 0:p] self._eigenvalues = E[0:p] @property def components(self): """Returns a matrix with the current principal components as columns. """ return self._eigenvectors @property def variances(self): """Returns a list with the appropriate variance along each principal component. """ return self._eigenvalues def _is_zero(x): """Return a boolean indicating whether the given vector is a zero vector up to a threshold. """ return np.fabs(x).min() < _ZERO_THRESHOLD if __name__ == '__main__': import sys def pca_svd(X): X = X - X.mean(0).repeat(X.shape[0], 0) [_, _, V] = np.linalg.svd(X) return V N = 1000 obs = np.matrix([np.random.normal(size=10) for _ in xrange(N)]) V = pca_svd(obs) print V[0:2] pca = IPCA(obs.shape[1], 2) for i in xrange(obs.shape[0]): x = obs[i,:].transpose() pca.update(x) U = pca.components print U

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• Accessing Oracle 6i and 9i/10g Databases using C#

  - by Mike M

  Hi all, I am making two build files using NAnt. The first aims to automatically compile Oracle 6i forms and reports and the second aims to compile Oracle 9i/10g forms and reports. Within the NAnt task is a C# script which prompts the developer for database credentials (username, password, database) in order to compile the forms and reports. I want to then run these credentials against the relevant database to ensure the credentials entered are correct and, if they are not, prompt the user to re-enter their credentials. My script currently looks as follows: class GetInput { public static void ScriptMain(Project project) { Console.Clear(); Console.WriteLine("==================================================================="); Console.WriteLine("Welcome to the Compile and Deploy Oracle Forms and Reports Facility"); Console.WriteLine("==================================================================="); Console.WriteLine(); Console.WriteLine("Please enter the acronym of the project to work on from the following list:"); Console.WriteLine(); Console.WriteLine("--------"); Console.WriteLine("- BCS"); Console.WriteLine("- COPEN"); Console.WriteLine("- FCDD"); Console.WriteLine("--------"); Console.WriteLine(); Console.Write("Selection: "); project.Properties["project.type"] = Console.ReadLine(); Console.WriteLine(); Console.Write("Please enter username: "); string username = Console.ReadLine(); project.Properties["username"] = username; string password = ReturnPassword(); project.Properties["password"] = password Console.WriteLine(); Console.Write("Please enter database: "); string database = Console.ReadLine(); project.Properties["database"] = database Console.WriteLine(); //Call method to verify user credentials Console.WriteLine(); Console.WriteLine("Compiling files..."; } public static string ReturnPassword() { Console.Write("Please enter password: "); string password = ""; ConsoleKeyInfo nextKey = Console.ReadKey(true); while (nextKey.Key != ConsoleKey.Enter) { if (nextKey.Key == ConsoleKey.Backspace) { if (password.Length > 0) { password = password.Substring(0, password.Length - 1); Console.Write(nextKey.KeyChar); Console.Write(" "); Console.Write(nextKey.KeyChar); } } else { password += nextKey.KeyChar; Console.Write("*"); } nextKey = Console.ReadKey(true); } return password; } } Having done a bit of research, I find that you can connect to Oracle databases using the System.Data.OracleClient namespace clicky. However, as mentioned in the link, Microsoft is discontinuing support for this so it is not a desireable solution. I have also fonud that Oracle provides its own classes for connecting to Oracle databases clicky. However, this only seems to support connecting to Oracle 9 or newer databases (clicky) so it is not feasible solution as I also need to connect to Oracle 6i databases. I could achieve this by calling a bat script from within the C# script, but I would much prefer to have a single build file for simplicity. Ideally, I would like to run a series of commands such as is contained in the following .bat script: rem -- Set Database SID -- set ORACLE_SID=%DBSID% sqlplus -s %nameofuser%/%password%@%dbsid% set cmdsep on set cmdsep '"'; --" set term on set echo off set heading off select '========================================' || CHR(10) || 'Have checked and found both Password and ' || chr(10) || 'Database Identifier are valid, continuing ...' || CHR(10) || '========================================' from dual; exit; This requires me to set the environment variable of ORACLE_SID and then run sqlplus in silent mode (-s) followed by a series of sql set commands (set x), the actual select statement and an exit command. Can I achieve this within a c# script without calling a bat script, or am I forced to call a bat script? Thanks in advance!

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