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  • C# thread safety for class instances

    - by Steveng
    I am learning C# and I am confused with the thread safety of the copies of the class instances as below: eg: classA objA; classA objB = objA; objA.field1 = value2; //do I need lock around modification of field1? //let say we pass the objB to another thread objB.field1 = value1 //do I need a lock for objB because of the modification of field1? I am confused because coming from the background of C++, the class in C# is the reference type. If both objA and objB refer to the same memory underlying, then I would need a lock to protect the simultaneous writing to the field1. Could someone confirm with this or am I missing something? Thanks.

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  • Flipping an image using a one dimensional array of characters.

    - by Jeff
    I have the data of an image loaded into memory as a one dimensional array. Since I'm trying to use OpenGL to draw it, and since it reads from the bottom up, I want to try and flip the elements of the array before they're sent to OpenGL. Maybe there's a way to tell OpenGL to read from the top to the bottom? Anyways, I tried using a few methods of sorting arrays and they also flip the image horizontally, which is very much like the original problem. So can I flip the data only one way?

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  • C++ vector reference parameter

    - by Archanimus
    Hello folks, let's say we have a class class MyClass { vector<vector<int > > myMatrice; public : MyClass(vector<vector<int > > &); } MyClass::MyClass(vector<vector<int > > & m) { myMatrice = m; } During the instanciation of MyClass, I pass a big vector < vector < int and I find that the object is actually copied and not only the reference, so it takes the double of the memory ... Please, can anyone help me out with this problem, I'm stuck since too many time ... And thanks a lot!

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  • Size of a class with 'this' pointer

    - by psvaibhav
    The size of a class with no data members is returned as 1 byte, even though there is an implicit 'this' pointer declared. Shouldn't the size returned be 4 bytes(on a 32 bit machine)? I came across articles which indicated that 'this' pointer is not counted for calculating the size of the object. But I am unable to understand the reason for this. Also, if any member function is declared virtual, the size of the class is now returned as 4 bytes. This means that the vptr is counted for calculating the size of the object. Why is the vptr considered and 'this' pointer ignored for calculating the size of object?

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  • Uploading files wont work on production server

    - by Camran
    I have a php script which uploads images to a temporary folder on the server. This works on my local computer with the local (virtual) server. (wampserver). However, on the production server (linux) I cant get it working. Everything is loading as it should, except for that the file doesn't show up on the server. My Q is, is there anything I should think about when moving to a production server with uploading images or files? I have set permissions on the folder where the images are supposed to go to 777 and also the php-code which uploads them to 777. Thanks

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  • a macro question for c language (#define)

    - by Daniel
    I am reading source code of hoard memory allocator, and in the file of gnuwrapper.cpp, there are the following code #define CUSTOM_MALLOC(x) CUSTOM_PREFIX(malloc)(x) What's the meaning of CUSTOM_PREFIX(malloc)(x)? is CUSTOM_PREFIX a function? But as a function it didn't defined anywhere. If it's variable, then how can we use variable like var(malloc)(x)? more code: #ifndef __GNUC__ #error "This file requires the GNU compiler." #endif #include <string.h> #include <stdlib.h> #include <stdio.h> #include <malloc.h> #ifndef CUSTOM_PREFIX ==> here looks like it's a variable, so if it doesn't define, then define here. #define CUSTOM_PREFIX #endif #define CUSTOM_MALLOC(x) CUSTOM_PREFIX(malloc)(x) ===> what's the meaning of this? #define CUSTOM_FREE(x) CUSTOM_PREFIX(free)(x) #define CUSTOM_REALLOC(x,y) CUSTOM_PREFIX(realloc)(x,y) #define CUSTOM_MEMALIGN(x,y) CUSTOM_PREFIX(memalign)(x,y)

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  • Should I put a try-finally block after every Object.Create?

    - by max
    I have a general question about best practice in OO Delphi. Currently, I put try-finally blocks anywhere I create an object to free that object after usage (to avoid memory leaks). E.g.: aObject := TObject.Create; try aOBject.AProcedure(); ... finally aObject.Free; end; instead of: aObject := TObject.Create; aObject.AProcedure(); .. aObject.Free; Do you think it is good practice, or too much overhead? And what about the performance?

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  • How should I store this information?

    - by 5YrsLaterDBA
    I have a PrivilegeGroup table, a Privileges table and a link table because the PrivilegeGroup table and the Privileges table is a many to many relationship. I am thinking about load all contents of PrivilegeGroup table and Privilege table into memory from database at beginning when application started. I want to save them in a form easily to look up. Usually we will look up the PrivilegeCode via GroupId. Which structure is good for this purpose? array of list? dictionary?

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  • pointers for getting elements of an array in C

    - by Manolo
    I am a newbie in C and I would like to get the elements of an array with a function, I have tried different options, but I still do not get the elements. My function is: void getelements(int *a, int cl) { int *p; for (p=&a[0];p<&a[cl];p++) { printf("%d\n",*p); } } I know that the solution should work like that, but it only prints the first element and then memory positions. I am calling my function with: int v={10,12,20,34,45}; getelements(&v,5); Any help? I need to use arithmetic of pointers. Thanks

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  • Zend_Soap with attachments (server)

    - by Tom
    i'm trying to build a SOAP service with Zend_Soap. Everything is working great but the client needs the ability to send attachments to the service (not base64 encoded strings, as this service will be called multiple times a day with various file sizes so processing all that in memory is not possible. So I'd like to handle a normal SOAP attachment (DIME/MIME) with the SOAP server in Zend Framework however I'm unable to find documentation about it. Can I access it with $_FILES[] or any other way? Is it even possible in Zend_Soap (as there's not that much info available). SOAP is a must - so thanks for the advice but it has to be SOAP, not REST.

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  • ordering a collection by an association's property

    - by neiled
    class Person belongs_to :team class Status #has last_updated property class Team has_many :members, :class => "Person" Ok, so I have a Team class which has many People in it and each of those people has a status and each status has a last_updated property. I'm currently rendering a partial with a collection similar to: =render :partial => "user", :collection => current_user.team.members Now how do I go about sorting the collection by the last_updated property of the Status class? Thanks in advance! p.s. I've just written the ruby code from memory, it's just an example, it's not meant to compile but I hope you get the idea!

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  • Deleting a element from a vector of pointers in C++.

    - by Kranar
    I remember hearing that the following code is not C++ compliant and was hoping someone with much more C++ legalese than me would be able to confirm or deny it. std::vector<int*> intList; intList.push_back(new int(2)); intList.push_back(new int(10)); intList.push_back(new int(17)); for(std::vector<int*>::iterator i = intList.begin(); i != intList.end(); ++i) { delete *i; } intList.clear() The rationale was that it is illegal for a vector to contain pointers to invalid memory. Now obviously my example will compile and it will even work on all compilers I know of, but is it standard compliant C++ or am I supposed to do the following, which I was told is in fact the standard compliant approach: while(!intList.empty()) { int* element = intList.back(); intList.pop_back(); delete element; }

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  • Why don't hardware failures show up at the programming language level?

    - by Julian Cienfuegos
    I am wondering if anyone can give my a good answer, or at least point me in the direction of a good reference to the following question: How come I have never heard of a computer breaking in a very fundamental way? How come when I declare x to be a double it stays as a double? How come there is never a short circuit that robs it of some bytes and makes it an integer? Why do we have faith that when we initialize x to 10, there will never be a power surge that will cause it to become 11, or something similar? I think I need a better understanding of memory. Thanks, and please don't bash me over the head for such a simple/abstract question.

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  • Reading a bmp file and inverting it in C

    - by user1763396
    I have an assignment that deals with reading a bmp file into memory, inverts the pixels, and then saves the inverted image to a new file. From this description it seems fairly easy, however I don't think my professor did a great job in explaining the necessary steps to go about doing so. He taught us about fread and fwrite but there is so much more. Can anyone explain the process in going about this problem (I'm no looking for a direct answer just an explanation). Here is the link to the problem's description: https://engineering.purdue.edu/OOSD/F2012/Exercises/ex5.html Thanks in advance for any sort of help. NOTE: I actually have looked into this problem but since I don't have a good standing on this info it's not quite "clicking".

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  • Load big XML files to mySQL database (PHP)

    - by Kees
    Hello There, For a new project I need to load big XML files (200MB+) to a mySQL database. There are +- 20 feeds i need to match with that (not all fields are the same). Now when i want to catch the XML I get this error: Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 171296569 bytes) in E:\UsbWebserver\Root\****\application\libraries\MY_xml.php on line 21 Is there an easy solution for this? It's not possible to get te feed in parts of a few MB's each. Thank you very much! P.s. has somebody an idea to match xml-feeds easy?

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  • JBoss 4.0.5 startup takes 15 minutes deploying a single war file

    - by dkblinux98
    This instance of JBoss deploys several war files. The rest of the JBoss startup takes about 5 minutes or less. But when it gets to one particular war file, startup just hangs with no further output to the jboss log. It waits there for about 15 minutes and then suddenly the war starts deploying. The rest of the JBoss startup is then fine. What I want to know is what steps do you recommend I take to diagnose the cause of this condition? It is not possible to upgrade this site to a newer version of JBoss nor java (currently 1.5.0.7). It is running on 32-bit CentOS 5.3 Linux on 3 xen-based virtual servers in a load balanced configuration. The code is common to all three servers via an nfs share. This same issue was seen, however, when the 3 servers were physical and the code was local to each server. The servers are each 2 cpu, 4GB RAM servers.

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  • Create object of unknown class (two inherited classes)

    - by Paul
    I've got the following classes: class A { void commonFunction() = 0; } class Aa: public A { //Some stuff... } class Ab: public A { //Some stuff... } Depending on user input I want to create an object of either Aa or Ab. My imidiate thought was this: A object; if (/*Test*/) { Aa object; } else { Ab object; } But the compiler gives me: error: cannot declare variable ‘object’ to be of abstract type ‘A’ because the following virtual functions are pure within ‘A’: //The functions... Is there a good way to solve this?

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  • How to return data structure from stored procedure

    - by rodnower
    Hello, I have C# application that retrieve data from AQ with some oracle stored procedure, that stored in package. The scheme is: C# code - Stored Procedure in Package - AQ Inside of this stored procedure I use DBMS_AQ for dequeue the data to some object of some type. Now I have this object. My question is how I return it? Previously I: Created some virtual table, Make EXTEND() to table Inserted the data from object to table, Perform select on the table, And return sys_refcursor. In side of C# I filled DataSet with help of OracleDataAdapter.Fill() After that I upgraded it to return data fields during OUT parameters. But now I have much fields, and I may not to create so much OUT parameters... What the best way to do this? Thank you for ahead.

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  • Java SWT - dissolve (fade) from one image to the next.

    - by carillonator
    I'm pretty new to Java and SWT, hoping to have one image dissolve into the next. I have one image now in a Label (relevant code): Device dev = shell.getDisplay(); try { Image photo = new Image(dev, "photo.jpg"); } catch(Exception e) { } Label label = new Label(shell, SWT.IMAGE_JPEG); label.setImage(photo); Now I'd like photo to fade into a different image at a speed that I specify. Is this possible as set up here, or do I need to delve more into the org.eclipse.swt.graphics api? Also, this will be a slide show that may contain hundreds of photos, only ever moving forward (never back to a previous image)---considering this, is there something I explicitly need to do in order to remove the old images from memory? Thanks!!

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  • Difficulty understanding behavior of free()

    - by Rasmi Ranjan Nayak
    int main() { int *ptr, **ptr1; ptr = (int*)malloc(sizeof(int)); ptr1 = (int**)malloc(sizeof(int)); free(ptr); *ptr = 12345; ptr1 = &ptr; //free(ptr); //**ptr1 = 23456; printf("%d \n", **ptr1); system("pause"); return 0; } How does *ptr store the value 12345, when the memory has already been freed? So, now ptr should be pointing to garbage. Why is this happening?

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  • how to render custom columns with a GenericTreeModel

    - by Giorgio Gelardi
    I have to display some data in a treeview. The "real" data model is huge and I cannot copy all the stuff in a TreeStore, so I guess I should use a GenericTreeModel to act like a virtual treeview. Btw the first column is the classic icon+text style and I think I should declare a column with a CellRendererPixbuf (faq sample), but I'm not sure what the model methods on_get_n_columns() and on_get_value() should return. It's both a Pixbuf and a string value for the same column. Any help will be appreciated.

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  • Can JQuery/JavaScript be used to write a substantial client side application?

    - by Ian
    I have an unusual situation - I have an embedded video streaming device with a complicated UI, and I need to use an embedded web server to reproduce that UI through a web browser. I'm thinking of using JavaScript/JQuery on a C++ backend (I am NOT coding all this myself, I need to hire people for the grunt work). The embedded web server is much less powerful than a PC, so I want to write an application that runs the entire UI in the browser, and only communicates with the server to pass new program settings back and forth, get status updates from the device, and control video playback. In other words, the client gets one big page or a small number of big pages (effectively downloading the application), the application maintains significant local memory storage, and once the pages are first loaded the server never sends anything layout-related. The application has two rows of tabs to navigate ~40 menu pages, drag-and-select controls to pick cells in a grid, sorted lists, lots of standard data entry options, and it should be able to control up to 16 embedded video players at once (preferably VLC). Is this possible in JavaScript/JQuery with a C++ backend?

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  • Sharepoint always down on the weekend?

    - by TheGambler
    For some reason, our sharepoint site always goes down on Saturday. It's the stangest thing and I can't figure out why. I'm a total noob at sharepoint and have been thrown into being the go to guy for sharepoint with my current employer. I've tried bouncing IIS on Fridays to see if there is anything I can do before hand. Is there anything that might be scheduled that I may not know about that would cause sharepoint to go down? Remember I'm a total noob as sharepoint. Thanks to all that reply. Edit: Also this our front-end and database instances are on virtual servers.

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  • Calling inheriting class methods via interface.

    - by Stacey
    Given the scenario... interface IBase{ void Process(int value); } abstract class Base : IBase { public virtual void Process(int value){ throw new NotImplementedException(); } } class Implemented: Base, IBase { public void Process(int value) { // .. some code here.. } } I'm trying to write a loop similar to the following. foreach( Base b in CollectionOfImplemented ) { b.Process( // something will go here // ); } Trying this, it keeps calling Base.Process, instead of Implemented.Process; but the type in the collection is Implemented, not Base. Boxing it seems to work, but I was hoping to see if I could find a more intelligent approach to it, since the Collection will contain other types of objects that also inherit from Base.

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  • used structdelete and now Elementemployee.id is undefined in SESSION.

    - by Robert
    using coldfuion 9 I used structdelete(session,"Elementemployee.id") in one of my .cfm display files.Also in my application.cfc it defined as is <cfset tArray[1][2] = "#session.employee_id#"> and the error is `Elementemployee.id is undefined in SESSION.` Is there a way that i can reset it without following the method shown below Navigate to the page Server Settings => Memory Variablesin the Coldfusion Administrator. Uncheck the option Use J2EE session variables and check the options Enable Application Variables and Enable Session Variables. Click the button to submit the changes.

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