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  • Function to register functions to be called if event invoked.

    - by zaidwaqi
    Hi, I have a Panel which contains 20 PictureBox controls. If a user clicks on any of the controls, I want a method within the Panel to be called. How do I do this? public class MyPanel : Panel { public MyPanel() { for(int i = 0; i < 20; i++) { Controls.Add(new PictureBox()); } } // DOESN'T WORK. // function to register functions to be called if the pictureboxes are clicked. public void RegisterFunction( <function pointer> func ) { foreach ( Control c in Controls ) { c.Click += new EventHandler( func ); } } } How do I implement RegisterFunction()? Also, if there are cool C# features that can make the code more elegant, please share. Thanks.

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  • How to get notified of modification in the memory in Linux

    - by Song Yuan
    In a userspace program in Linux, I get a piece of memory via allocation from the heap, then the pointer is distributed to a lot of other components running in other threads to use. I would like to get notified when the said piece of memory is modified. I can of course develop a custom userspace solution for other components to use when they try to modify the memory. The problem in my case is that these are legacy components and they can write to memory in many occasions. So I'm wondering whether there is a similar API like inotify (get notified when file is changed) or other approaches in order to get notified when a piece of memory is changed. I considered using mmap and inotify, which obviously won't work if the changes are not flushed. Any suggestions are appreciated :-)

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  • Passing arguments to Shared Function - C

    - by SpyrosR
    I have used dlopen to load an object and dlsym to get a function pointer to a shared object function. Everything works fine. I have tested it calling then the shared function which (for now) only prints and it works-prints fine in the main program calling it. Now I want to pass two arguments to this function. An int and a char * .Can anyone help me understand how can I pass arguments to a shared function? I have searched in the web but I cannot understand how it works.

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  • C++ operator[] syntax.

    - by Lanissum
    Just a quick syntax question. I'm writing a map class (for school). If I define the following operator overload: template<typename Key, typename Val> class Map {... Val* operator[](Key k); What happens when a user writes: Map<int,int> myMap; map[10] = 3; Doing something like that will only overwrite a temporary copy of the [null] pointer at Key k. Is it even possible to do: map[10] = 3; printf("%i\n", map[10]); with the same operator overload?

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  • c++ - FIFO implementation

    - by Narek
    While implementing a FIFO I have used the following structure: struct Node { T info_; Node* link_; Node(T info, Node* link=0): info_(info), link_(link) {} }; I think this a well known trick for lots of STL containers (for example for List). Is this a good practice? What it means for compiler when you say that Node has a member with a type of it's pointer? Is this a kind of infinite loop? And finally, if this is a bad practice, how I could implement a better FIFO.

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  • lambda+for_each+delete on STL containers

    - by rubenvb
    I'm trying to get a simple delete every pointer in my vector/list/... function written with an ultra cool lambda function. Mind you, I don't know c**p about those things :) template <typename T> void delete_clear(T const& cont) { for_each(T.begin(), T.end(), [](???){ ???->delete() } ); T.clear(); } I have no clue what to fill in for the ???'s. Any help is greatly appreciated!

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  • Strange type in c++

    - by Cemre
    I have a method with the prototype: bool getAssignment(const Query& query, Assignment *&result); I am a bit confused about the type of the second param (Assignment *&result) since I don't think I have seen something like that before. It is used like: Assignment *a; if (!getAssignment(query, a)) return false; Is it a reference to a pointer or the other way around ? or neither ? Any explanation is appreciated. Thanks.

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  • Can I reproduce Scala's behavior for == ?

    - by JPP
    In Programming in Scala, I can read that the == operator behaves as if it was defined like this: final def == (that: Any): Boolean = if (null eq this) {null eq that} else {this equals that} But there must actually be compiler magic to avoid null pointer exceptions, right? Is there any way for me to replicate this behavior with pure Scala; i.e., have an operator/method return one thing if the receiver is null and another one if it isn't? What I mean is an actual implementation of null eq this. I suppose I can write a "pimp" and then define the method on the wrapper class, but is there a more direct way to do this?

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  • jQuery Mobile button js control

    - by David
    I have a button that is not triggering event in jQuery mobile. It was working but I had to remove the css. It was screwing up my all my ul lists. Any help would greatly appreciated Here is the code for the button at the bottom of the form : <div class="next"> <a class="btnNext">Next &gt;&gt;</a> </div> Which is supposed to do this on a separate js file: init: function(){ $('.btnNext').onclick(function(){ if ($('input[type=radio]:checked:visible').length == 0) { return false; } $(this).parents('.questionContainer').fadeOut(500, function(){ Here is the css I removed: a { border: 1px solid #000; padding: 2px 5px; font-weight: bold; font-size: 10px; background: #FFF; cursor: pointer; } a:hover { background: none; }

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  • SetWindowLongPtr with DialogBoxParam?

    - by templatetypedef
    Hey all- A while back I was writing a C++ program with the Win32 API that would display a dialog box and then listen to the messages it generated. At one point, I was interested in associating a piece of data with the dialog window. Were I manually creating the window and attaching a window proc, I'd just use SetWindowLongPtr to set the GWLP_USERDATA field to a pointer to the data to associate. However, in this case I was creating and displaying the window with DialogBoxParam, and it wasn't clear whether this function was associating that data with its own internal state. Since the MSDN didn't have a description of what would happen in this case, I ended up using some other approach to solve the problem. My question is this - is it safe to use SetWindowLongPtr to overwrite the GWLP_USERDATA value in a window created by DialogBoxParam? Thanks!

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  • In PHP can I check a boolean on a function call?

    - by Chris
    I have a function which checks the passed value and returns false or true, if false I want it to add something to an array. The code I've written is below. if(!check_input($_POST['username'])){ $errors[] = "Username"; } Right now it adds to my array anyway, regardless of what is entered in the form. Is the way I've written that the correct way to check if the return from check_input() is false? I've checked the function's logic by altering the returns to echoes and it's returning the correct value, I'm just not sure if I'm checking it wrong. I'd previously attempted to write it as $X=check_input etc, and then if(check_value == false) but that doesn't seem to give me the desired result either. Hmmm a quick pointer please!

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  • ANSI C++: Diferences between delete and delete[]

    - by Sunscreen
    I was looking a snipset of code: int* ip; ip = new int[100]; delete ip; The example above states that: "This code will work with many compilers, but it should instead read:" int* ip; ip = new int[100]; delete [] ip; Is this indeed the case? I use the compiler "Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 11.00.7022 for 80x86" and does not complain (first example) while compiling. At runtime the pointer is set to NULL. Other compilers behave diferrently? Can a compiler not compain and issues can appear at runtime? Thanks, Sun

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  • C++ syntax of constructors " 'Object1 a (1, Object1(2))''

    - by osgx
    Hello I have a such syntax in program class Object1 : BaseClass { BaseClass *link; int i; public: Object1(int a){i=a;} Object1(int a, Object1 /*place1*/ o) {i=a; link= &o;} }; int main(){ Object1 a(1, /*place2*/ Object1(2)); ... } What do I need in place1? I want to save a link (pointer) to the second object in the first object. Should I use in place1 reference "&"? What type will have "Object1(2)" in place2? Is it a constructor of the anonymous object? Will it have a "auto" storage type?

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  • Extract data from uint8 to double

    - by HADJ AMOR HASSEN
    I have a C function receiving a uint8 pointer with another parameter which is its size (number of bytes). I want to extract double data from this buffer. Here is my code: Write(uint8* data, uint8 size) /* data and size are given by a callback to my function)*/ { double d; for (i = 0; i < size; i++) { d = ((double*)&data)[i]; printf(" d = %d\n"); } } The problem is that I am not receiving what I am sending within an external hardware. I guess that my cast is wrong. I tried other methods but without any good result. I am still not able to get what I send.

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  • freeing malloc and checkin it is empty or not

    - by gcc
    char *p; p="kjkjk"; . .//there are codes which are checking another command . if(.....)//i used pointer p in only that area free(p); . . //there are codes which are checking another command . if(p==NULL) //i check whether is empty .... if(p==-1) //can we use "EOF==p " in if statement ... //are there any usage like that EOF==p else .... I think there is big error , but where?

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  • What is the difference between these two ways of creating NSStrings?

    - by adame
    NSString *myString = @"Hello"; NSString *myString = [NSString stringWithString:@"Hello"]; I understand that using method (1) creates a pointer to a string literal that is defined as static memory (and cannot be deallocated) and that using (2) creates an NSString object that will be autoreleased. Is using method (1) bad? What are the major differences? Is there any instances where you would want to use (1)? Is there a performance difference? P.S. I have searched extensively on Stack Overflow and while there are questions on the same topic, none of them have answers to the questions I have posted above.

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  • question abouut string sort

    - by davit-datuashvili
    i have question from programming pearls problem is following show how to use lomuto's partitioning scheme to sort varying length bit strings in time proportional to the sum oof their length and algorithm is following each record in x[0..n-1] has an integer length and pointer to the array bit[0..length-1] code void bsort(l,u,depth){ if (l>=u) return; for (int i=l;i<u;i++) if (x[i].length<depth) swap(i,l++); m=l; if (x[i].bit[depth] ==0) swap(i,m++); bsort(l,m-1,depth+1); bsort(m,u,depth+1); please help me i need following things 1. how this algorith works 2.how implement in java?

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  • C++ Iterators and inheritance

    - by jomnis
    Have a quick question about what would be the best way to implement iterators in the following: Say I have a templated base class 'List' and two subclasses "ListImpl1" and "ListImpl2". The basic requirement of the base class is to be iterable i.e. I can do: for(List<T>::iterator it = list->begin(); it != list->end(); it++){ ... } I also want to allow iterator addition e.g.: for(List<T>::iterator it = list->begin()+5; it != list->end(); it++){ ... } So the problem is that the implementation of the iterator for ListImpl1 will be different to that for ListImpl2. I got around this by using a wrapper ListIterator containing a pointer to a ListIteratorImpl with subclasses ListIteratorImpl2 and ListIteratorImpl2, but it's all getting pretty messy, especially when you need to implement operator+ in the ListIterator. Any thoughts on a better design to get around these issues?

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  • How can Java assignment be made to point to an object instead of making a copy?

    - by Matthew Piziak
    In a class, I have: private Foo bar; public Constructor(Foo bar) { this.bar = bar; } Instead of creating a copy of bar from the object provided in the parameter, is it possible to include a pointer to bar in the constructor such that changing the original bar changes the field in this object? Another way of putting it: int x = 7; int y = x; x = 9; System.out.print(y); //Prints 7. It is possible to set it up so that printing y prints 9 instead of 7?

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  • Need guidance for my first Android application: how many activities should I use?

    - by jul
    Hi, I'm starting Android doing an application for searching restaurants, and some guidance would be welcome! On the first screen I'd like to have a search field with a submit button (I get the data from a web service), and below a list with the results of the search. When clicking on one of the items of the list it will show a screen with the restaurant details as well as a map showing its location. My questions are: Can I do everything in one single activity or should I do an activity for the search, one for the result list, one for the restaurant description, and another for the map? Would doing one single activity make the application more responsive? How can I use a list and a map within a normal activity (without ListActivity and MapActivity)? Any help, pointer, example application or sample code is very appreciated! Thank you Jul

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  • Method to register method to be called when event is raised

    - by zaidwaqi
    I have a Panel which contains 20 PictureBox controls. If a user clicks on any of the controls, I want a method within the Panel to be called. How do I do this? public class MyPanel : Panel { public MyPanel() { for(int i = 0; i < 20; i++) { Controls.Add(new PictureBox()); } } // DOESN'T WORK. // function to register functions to be called if the pictureboxes are clicked. public void RegisterFunction( <function pointer> func ) { foreach ( Control c in Controls ) { c.Click += new EventHandler( func ); } } } How do I implement RegisterFunction()? Also, if there are cool C# features that can make the code more elegant, please share.

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  • CUDA Global Memory, Where is it?

    - by gamerx
    I understand that in CUDA's memory hierachy, we have things like shared memory, texture memory, constant memory, registers and of course the global memory which we allocate using cudaMalloc(). I've been searching through whatever documentations I can find but I have yet to come across any that explicitly explains what is the global memory. I believe that the global memory allocated is on the GDDR of graphics card itself and not the RAM that is shared with the CPU since one of the documentations did state that the pointer cannot be dereferenced by the host side. Am I right?

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  • Best way to access nested data structures?

    - by Blackshark
    I would like to know what the best way (performance wise) to access a large data structure is. There are about hundred ways to do it but what is the most accessible for the compiler to optimize? One can access a value by foo[someindex].bar[indexlist[i].subelement[j]].baz[0] or create some pointer aliases like sometype_t* tmpfoo = &foo[someindex]; tmpfoo->bar[indexlist[i].subelement[j]].baz[0] or create reference aliases like sometype_t &tmpfoo = foo[someindex]; tmpfoo.bar[indexlist[i].subelement[j]].baz[0] and so forth...

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  • Layout of popup components changes while moving

    - by Le_Coeur
    I have designed some popup moving menu with JQuery, it looks perfekt in webkit browsers, but i have one problem in mozilla, when i move my popup window, layout of some components in this window changes! For example button add changes from: to: or to: , and it's absolutly random. What can it be? This image is in span: <span class="sw_link_add"></span> .sw_link_add { background:url("/img/confirm_new.png") no-repeat scroll right center transparent; cursor:pointer; padding-right:30px; padding-top:2px; }

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  • How does the stream manipulators work?

    - by Narek
    It is well known that the user can define stream manipulators like this: ostream& tab(ostream & output) { return output<< '\t'; } And this can be used in main() like this: cout<<'a'<<tab<<'b'<<'c'<<endl; Please explain me how does this all work? If operator<< assumes as a second parameter a pointer to the function that takes and returns ostream &, then please explain my why it is necessary? What would be wrong if the function does not take and return ostream & but it was void instead of ostream &? Also it is interesting why “dec”, “hex” manipulators take effect until I don’t change between them, but user defined manipulators should be always used in order to take effect for each streaming?

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