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• Sending BLOBs in a JSON service,... how?

  - by Marten Sytema

  Hello I have a webservice (ie. servlet) implemented in Java. It gets some data from a MySQL table, with one column being of type BLOB (an image), and some other columns are just plain text. Normally I would store the file outside the database with a pointer to it in the database, but due to circumstance I now have to use this BLOB column... What is the proper way to send this? How to encode the image in a JSONObject, and how to parse (and RENDER!) it on the otherside ? I want to use JSONP, to avoid having to proxy it through the consumer's webserver. So that the consumer can just put in a tag pointing to the webservice, calling a callback. Any thoughts how to handle images in this situation? Also thoughts on performance etc. are interesting!

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• Performance intensive string splitting and manipulation in java

  - by juhanic

  What is the most efficient way to split a string by a very simple separator? Some background: I am porting a function I wrote in C with a bunch of pointer arithmetic to java and it is incredibly slow(After some optimisation still 5* slower). Having profiled it, it turns out a lot of that overhead is in String.split The function in question takes a host name or ip address and makes it generic: 123.123.123.123-*.123.123.123 a.b.c.example.com-*.example.com This can be run over several million items on a regular basis, so performance is an issue.

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• Returning a C++ reference in a const member functionasses

  - by Chris Kaminski

  A have a class hierarchy that looks somethign like this: class AbstractDataType { public: virtual int getInfo() = 0; }; class DataType: public AbstractDataType { public: virtual int getInfo() { }; } class Accessor { DataType data; public: const AbstractDataType& getData() const { return(data); } } Well, GCC 4.4 reports: In member function ‘const AbstractDataType& Accessor::getData() const’: error: invalid initialization of reference of type ‘const AbstractDataType&’ from expression of type ‘const DataType’ Where am I going wrong - is this a case where I MUST use a pointer?

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• Data-separation in a Symfony Multi-tenant app using Doctrine

  - by Prasad

  I am trying to implement a multi-tenant application, that is - data of all clients in a single database - each shared table has a tenant_id field to separate data I wish to achieve data separation by adding where('tenant_id = ', $user->getTenantID()) {pseudoc-code} to all SELECT queries I could not find any solution up-front, but here are possible approaches I am considering. 1) crude approach: customizing all fetchAll and fetchOne functions in every class (I will go mad!) 2) using listeners: possibly coding for the preDqlSelect event and adding the 'where' to all queries 3) override buildQuery(): could not find an example of this for front-end 4) implement contentformfilter: again need a pointer Would appreciate if someone could validate these & comment on efficieny, suitability. Also, if anyone has achieved multitenancy using another strategy, pl share. Thanks

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• FORTRAN function returning an array causes a segfault (calling from C++)

  - by Dane Larsen

  Basically, here's my problem. I'm calling someone else's FORTRAN functions from my C++ code, and it's giving me headaches. Some code: function c_error_message() character(len = 255) :: c_error_message errmsg(1:9) = 'ERROR MSG' return end That's the FORTRAN function. My first question is: Is there anything in there that would cause a segfault? If not, then second: What does that return? A pointer? I'm trying to call it with the following C statement: char *e = c_error_message_(); That causes a segfault. c_error_message(); That too causes a segfault. I declared c_error_message_() earlier on with the following code: extern"C" { char* c_error_message_(); } Would declaring a function with a different return type than the actual return type cause a segfault? I'm at a loss. Thanks for any replies.

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• addObjectsFromArray

  - by derek.lo

  I have a question about memory management when using the addObjectsFromArray method. Basically, I have 2 arrays defined in the appDelegate. I need these 2 arrays for the duration of my application's runtime. I therefore release them in my appDelegate's dealloc method. When I go to use these two arrays in a class, I want one array to store the values from the other, so that the other can have it's contents removed, but still stick around for use. Something like this: [appDelegate.arrayTwo addObjectsFromArray:appDelegate.arrayOne]; [appDelegate.arrayOne removeAllObjects]; I'm getting the compiler error: EXC_BAD_ACCESS because of a pointer issue? retaining issue? Any help would be greatly appreciated! Thanks

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• IO completion port key confusion

  - by Richard Tew

  I'm writing an IO completion port based server (source code here) using the Windows DLL API in Python using the ctypes module. But this is a pretty direct usage of the API and this question is directed at those who have a knowledge of IOCP, not Python. As I understand the documentation for CreateIoCompletionPort, you specify your "user defined" completion key when you call this function with a file handle (in my case a socket) you are associating with the created IOCP. When you get around to calling GetQueuedCompletionStatus, you get a completion key value along with a pointer to an overlapped object. The completion key should identify what overlapped object and request has completed. However, let's say I pass in 100 as the completion key in my CreateIoCompletionPort call with an overlapped object. When the same overlapped object has its IO completed and it arrives back through GetQueuedCompletionStatus, the completion key that accompanies it is much larger and bares no resemblance to the original value of 100. Am I misunderstanding how the completion key works, or must I be doing it wrong in the source code I linked above?

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• C++ - Opening a file inside a function using fopen. (Noob problem)

  - by Josh

  I am using Visual Studio 2005 (C++). I am passing a string into a function as a char array. I want to open the file passed in as a parameter and use it. I know my code works to an extent, because if I hardcode the filename as the first parameter it works perfectly. I do notice if I look at the value as a watch, the value includes the address aside the string literal. I have tried passing in the filename as a pointer, but it then complains about type conversion with __w64. As I said before it works fine with "filename.txt" in place of fileName. I am stumped. void read(char fileName[50],int destArray[MAX_R][MAX_C],int demSize[2]) { int rows=0; int cols=0; int row=0; int col=0; FILE * f = fopen(fileName,"r"); ...

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• Are there any Python reference counting/garbage collection gotchas when dealing with C code?

  - by Jason Baker

  Just for the sheer heck of it, I've decided to create a Scheme binding to libpython so you can embed Python in Scheme programs. I'm already able to call into Python's C API, but I haven't really thought about memory management. The way mzscheme's FFI works is that I can call a function, and if that function returns a pointer to a PyObject, then I can have it automatically increment the reference count. Then, I can register a finalizer that will decrement the reference count when the Scheme object gets garbage collected. I've looked at the documentation for reference counting, and don't see any problems with this at first glance (although it may be sub-optimal in some cases). Are there any gotchas I'm missing? Also, I'm having trouble making heads or tails of the cyclic garbage collector documentation. What things will I need to bear in mind here? In particular, how do I make Python aware that I have a reference to something so it doesn't collect it while I'm still using it?

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• How to unmangle exported symbols from C++ in dynamic libraries in XCode on OSX

  - by Gerald

  I've been trying to develop a dynamic library in C++ that can be run-time loaded in an application. I finally got it working, but it's a little ugly. I have a function that takes a pointer to a C++ class as an argument, which looks like this: bool registerGrindPlugin( Grind::PluginManager* mgr ); But of course it's being exported as: _Z19registerGrindPluginPN5Grind13PluginManagerE I tried a .c file with a simple function and it exported fine as "registerGrindPlugin", but of course I can't pass a C++ class as the argument that way. Soo... my question is, is there a way to unmangle or alias the exported symbol so that I don't have to use a monstrosity like Z19registerGrindPluginPN5Grind13PluginManagerE in my dlsym call? I did see something about -alias_list as a linker option, but I haven't quite figured out how to use it in XCode. If that is the solution, can somebody provide some more details on how to use this?

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• Process for linking static ObjC libraries in XCode

  - by madmik3

  I'm trying to link to a static library and I keep getting linker errors. I've found a few sites that post examples but I have not been able to see what I am doing wrong. First I create a project that will link to my lib add existing files find my .xcodeproj file select "Copy items into destination groups folder"... Select my host project as Add To Targets. Then I add a direct dependency to my host app expand targets double click MyHost.app click + under direct dependencies select my lib Then I set build flags double click MyHost application icon in Groups and Files. click the build tab then I set the OtherLinerFlag to -ObjC then I set Header Search Paths to my header file location for my static library. I pass the compile stage but any classes in my static lib cause linker error: literal-pointer@_OBJC@_cls_refs@SomeClass in MyHost.o thanks!

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• Objective c key path operators @avg,@max .....

  - by davide

  arr = [[NSMutableArray alloc]init]; [arr addObject:[NSNumber numberWithInt:4]]; [arr addObject:[NSNumber numberWithInt:45]]; [arr addObject:[NSNumber numberWithInt:23]]; [arr addObject:[NSNumber numberWithInt:12]]; NSLog(@"The avg = %@", [arr valueForKeyPath:@"@avg.intValue"]); This code works fine, but why? valueForKeyPath:@"@avg.intValue" is requesting (int) from each NSNumber, but we are outputting a %@ string in the log. If i try to output a decimal %d i get a number that possibly is a pointer to something. Can somebody explain why the integers become NSNumbers when i call the @avg operator?

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• Struct size containing vector<T> different sizes between DLL and EXE..

  - by Michael Peddicord

  I have this situation where an EXE program imports a DLL for a single function call. It works by passing in a custom structure and returning a different custom structure. Up till now it's worked fine until I wanted one of the structs data members to be a vector < MyStruct When I do a sizeof(vector< MyStruct ) in my program I get a size of 20 but when I do it from inside the DLL I get a size of 24. This size inconsistency is causing a ESP pointer error. Can anyone tell me why a Vector < MyStruct would be a different size in the DLL than in the program? I have reverified that my structs in both the DLL and the Program are identical. I would appreciate any help on the subject. Thank you.

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• C# SendMessage to C++ WinProc

  - by jws

  I need to send a string from C# to a C++ WindowProc. There are a number of related questions on SO related to this, but none of the answers have worked for me. Here's the situation: PInvoke: [DllImport("user32", CharSet = CharSet.Auto)] public extern static int SendMessage(IntPtr hWnd, uint wMsg, IntPtr wParam, string lParam); C#: string lparam = "abc"; NativeMethods.User32.SendMessage(handle, ConnectMsg, IntPtr.Zero, lparam); C++: API LRESULT CALLBACK HookProc (int code, WPARAM wParam, LPARAM lParam) { if (code >= 0) { CWPSTRUCT* cwp = (CWPSTRUCT*)lParam; ... (LPWSTR)cwp->lParam <-- BadPtr ... } return ::CallNextHookEx(0, code, wParam, lParam); } I've tried a number of different things, Marshalling the string as LPStr, LPWStr, also tried creating an IntPtr from unmanaged memory, and writing to it with Marshal.WriteByte. The pointer is the correct memory location on the C++ side, but the data isn't there. What am I missing?

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• Advanced LINQ Update Statement

  - by user1902490

  I have a data base with Price_old like: Date --- Hour --- Price _____________________________ Jan 1 --- 1 --- $3.0 Jan 1 --- 2 --- $3.1 Jan 1 --- 3 --- $3.3 Jan 1 --- 4 --- $3.15 Jan 2 --- 1 --- $2.95 Jan 2 --- 2 --- $3.2 Jan 2 --- 3 --- $3.05 What I then have is a spreadsheet, with the same structure, that I will be reading into a datatable, I'll call the new datatable Price_New, note that price new may not have all the same date/hours as Price_Old So, I end up with 2 datatables, Price_Old, and Price_New, and what I need to do is update Price_old with the new prices in Price_New, and then commit those new prices to the Database. I am kinda new to LINQ (about 30 mins of experience) and would really appreciate if someone could give me a pointer or two on whether or not this is doing in LINQ and what the best method would be. Thanks

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• HierarchicalDataTemplate Link By Parent

  - by Andrew Kalashnikov

  Hello colleagues. I want bind my treeview. There are a lot of samples binding treeview by object, which contains children collection. I've got domain having just Parent pointer. public class Service : BaseDomain { public virtual string Name { get; set; } public virtual string Description { get; set; } public virtual Service Parent { get; set; } } Can I bind collection of this objects to my treeView. Thanks

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• Jquery clickable block

  - by Clint

  HI, I have this code for extracting the href and adding it to a parent block... $(".new-dev").hover(function(){ $(this).css('cursor','pointer'); $('this').$('a').css('color','#696969'); },function(){ $('this').$('a').css('color','#000'); }); What I want to do is make the a within the block change color on rollover. Unsure of how to do this when using $(this). Any advice welcome. Thanks, C

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• How can I create a collection of references in C#

  - by Jonathan Kaufman

  Ok I am having a cross language hiccup. In C# with it's great collections like List and I have: a Map class with properties of: List<byte[]> Images; List<Tile> Tiles; a Tile Class of: byte[] ImageData; int X; int Y; Now I want to add an image to the Map class and have the ImageData property of the Tile Classes to "reference" it. I have discovered I can't just assign it Images[0]. You can't have a reference to an object of a List. My fix was to create a Dictionary. Is this the best way or can I somehow have a "pointer" to a collection of objects?

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• got a question about Linked-List in java code.

  - by glacier89

  Linked-List: Mirror Consider the following private class for a node of a singly-linked list of integers: private class Node{ public int value; public Node next; } A wrapper-class, called, ListImpl, contains a pointer, called start to the first node of a linked list of Node. Write an instance-method for ListImpl with the signature: public void mirror(); That makes a reversed copy of the linked-list pointed to by start and appends that copy to the end of the list. So, for example the list: start 1 2 3 after a call to mirror, becomes: start 1 2 3 3 2 1 Note: in your answer you do not need to dene the rest of the class for ListImpl just the mirror method.

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• Pass 2d array to function in C?

  - by Evelyn

  I know it's simple, but I can't seem to make this work. My function is like so: int GefMain(int array[][5]) { //do stuff return 1; } In my main: int GefMain(int array[][5]); int main(void) { int array[1800][5]; GefMain(array); return 0; } I referred to this helpful resource, but I am still getting the error "warning: passing argument 1 of GefMain from incompatible pointer type." What am I doing wrong?

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• Are there any C++ tools that detect misuse of static_cast, dynamic_cast, and reinterpret_cast?

  - by chrisp451

  The answers to the following question describe the recommended usage of static_cast, dynamic_cast, and reinterpret_cast in C++: http://stackoverflow.com/questions/332030/when-should-static-cast-dynamic-cast-and-reinterpret-cast-be-used Do you know of any tools that can be used to detect misuse of these kinds of cast? Would a static analysis tool like PC-Lint or Coverity Static Analysis do this? The particular case that prompted this question was the inappropriate use of static_cast to downcast a pointer, which the compiler does not warn about. I'd like to detect this case using a tool, and not assume that developers will never make this mistake.

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• iSightAudio.plugin error when playing video using MediaPlayer

  - by Elisabeth

  I am working on creating a simple iPhone app that plays a movie via URL. When I Build&Run to test in the simulator, it works fine; as soon as I start playing the movie, I get the following message in the console: [1757:4b03] Cannot find executable for CFBundle/CFPlugIn 0x820ffe0 </Library/Audio/Plug-Ins/HAL/iSightAudio.plugin> (not loaded) [1757:4b03] Cannot find function pointer iSightAudioNewPlugIn for factory 9BE7661E-8AEF-11D7-8692-000A959F49B0 in CFBundle/CFPlugIn 0x820ffe0 </Library/Audio/Plug-Ins/HAL/iSightAudio.plugin> (not loaded) I don't get this error on other programs, so I assume it has something to do with this specific program, which uses the MediaPlayer.framework. Does anyone know what is causing this problem and how to fix it? Thank you

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• How to modify TList<record> value?

  - by Astronavigator

  How to modify TList < record value ? type TTest = record a,b,c:Integer end; var List:TList<TTest>; A:TTest; P:Pointer; .... .... List[10] := A; <- OK List[10].a:=1; <- Here compiler error : Left side cannot be assined to P:=@List[10]; <- Error: Variable requied

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• vector<string> or vector<char *>?

  - by Aaron

  Question: What is the difference between: vector<string> and vector<char *>? How would I pass a value of data type: string to a function, that specifically accepts: const char *? For instance: vector<string> args(argv, argv + argc); vector<string>::iterator i; void foo (const char *); //*i I understand using vector<char *>: I'll have to copy the data, as well as the pointer Edit: Thanks for input!

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• Determining a location's side of the road position with MapKit

  - by idStar

  Is there a way to use MapKit in iOS7 to not only get geocoding for an address, but determine what side of the road it is on? I'm not trying to build a full function navigation app, but similar to navigation apps that tell you things like "Your destination is in 100 feet on the right", I'd like to be able to obtain this information. Does MapKit give one a way to do this? Do I need to adopt routing privileges to access such, or is this just not available in the SDK period? If not available in the iOS7 SDK, knowing what options exist as services, would be a helpful pointer.

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