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  • Java: Help constructing a fillTextFields() method

    - by Holly
    I have a Java project where I am to connect to a database and create buttons (next, new, save, delete, previous) to navigate through the database content where there are appropriate text fields and labels for the specific information. I'll use the code below as an example (each button is set up very similar)... I have it as follows: JButton jbtnNext = new JButton("Next ->"); jbtnNext.addActionListener(this); if (e.getSource() == jbtnNext) jbtnNext_Click(); private void jbtnNext_Click() { JOptionPane.showMessageDialog(null, "Next" ,"Button Pressed", JOptionPane.INFORMATION_MESSAGE); try { if (rset.next()) { fillTextFields(true); }else{ //Display result in a dialog box JOptionPane.showMessageDialog(null, "Not found"); } } catch (SQLException ex) { ex.printStackTrace(); } } The professor gave the following outline of logic to construct the fillTextFields() method: Construct the method to provide reusable code that would fill the JTextFields on the GUI with appropriate values from current record from the database (when "Previous or "Next" buttons are pressed) or blank values (when the new Button is pressed). To determine when the current record was to provide values (next and previous) or the value would be blank (new button) pass a boolean argument into the method. If data from the current record was to be used as fill values, pass true for both previous and next button code after moving the record pointer. If the new button was pressed and want to fill with blank values, pass false to the method. Inside the method, use a conditional expression to evaluate the boolean variable. If true, The appropriate get----() resultset method is used to fill the JTextFields. If false, fill them with "". The .setText() method of the JTextField is used to fill each JTextField. Make sure the fillTextFields method throws the appropriate exception. I understand and have the previous and next button methods passing true, while the new button method is passing false, but I don't quite understand how to set up the fillTextFields() method correctly or how to "throw the appropriate exception"... Any help would really be appreciated, thank you!

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  • Stopping cookies being set from a domain (aka "cookieless domain") to increase site performance

    - by Django Reinhardt
    I was reading in Google's documentation about improving site speed. One of their recommendations is serving static content (images, css, js, etc.) from a "cookieless domain": Static content, such as images, JS and CSS files, don't need to be accompanied by cookies, as there is no user interaction with these resources. You can decrease request latency by serving static resources from a domain that doesn't serve cookies. Google then says that the best way to do this is to buy a new domain and set it to point to your current one: To reserve a cookieless domain for serving static content, register a new domain name and configure your DNS database with a CNAME record that points the new domain to your existing domain A record. Configure your web server to serve static resources from the new domain, and do not allow any cookies to be set anywhere on this domain. In your web pages, reference the domain name in the URLs for the static resources. This is pretty straight forward stuff, except for the bit where it says to "configure your web server to serve static resources from the new domain, and do not allow any cookies to be set anywhere on this domain". From what I've read, there's no setting in IIS that allows you to say "serve static resources", so how do I prevent ASP.NET from setting cookies on this new domain? At present, even if I'm just requesting a .jpg from the new domain, it sets a cookie on my browser, even though our application's cookies are set to our old domain. For example, ASP.NET sets an ".ASPXANONYMOUS" cookie that (as far as I'm aware) we're not telling it to do. Apologies if this is a real newb question, I'm new at this! Thanks.

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  • How do I build a filtered_streambuf based on basic_streambuf?

    - by swestrup
    I have a project that requires me to insert a filter into a stream so that outgoing data will be modified according to the filter. After some research, it seems that what I want to do is create a filtered_streambuf like this: template <class StreamBuf class filtered_streambuf: public StreamBuf { ... } And then insert a filtered_streambuf<> into whichever stream I need to be filtered. My problem is that I don't know what invariants I need to maintain while filtering a stream, in order to ensure that Derived classes can work as expected. In particular, I may find I have filtered_streambufs built over other filtered_streambufs. All the various stream inserters, extractors and manipulators work as expected. The trouble is that I just can't seem to work out what the minimal interface is that I need to supply in order to guarantee that an iostream will have what it needs to work correctly. In particular, do I need to fake the movement of the protected pointer variables, or not? Do I need a fake data buffer, or not? Can I just override the public functions, rewriting them in terms of the base streambuf, or is that too simplistic?

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  • c++ File input/output

    - by Myx
    Hi: I am trying to read from a file using fgets and sscanf. In my file, I have characters on each line of the while which I wish to put into a vector. So far, I have the following: FILE *fp; fp = fopen(filename, "r"); if(!fp) { fprintf(stderr, "Unable to open file %s\n", filename); return 0; } // Read file int line_count = 0; char buffer[1024]; while(fgets(buffer, 1023, fp)) { // Increment line counter line_count++; char *bufferp = buffer; ... while(*bufferp != '\n') { char *tmp; if(sscanf(bufferp, "%c", tmp) != 1) { fprintf(stderr, "Syntax error reading axiom on " "line %d in file %s\n", line_count, filename); return 0; } axiom.push_back(tmp); printf("put %s in axiom vector\n", axiom[axiom.size()-1]); // increment buffer pointer bufferp++; } } my axiom vector is defined as vector<char *> axiom;. When I run my program, I get a seg fault. It happens when I do the sscanf. Any suggestions on what I'm doing wrong?

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  • Question about Virtual Inheritance hierarchy

    - by Summer_More_More_Tea
    Hi there: I encounter this problem when tackling with virtual inheritance. I remember that in a non-virtual inheritance hierarchy, object of sub-class hold an object of its direct super-class. What about virtual inheritance? In this situation, does object of sub-class hold an object of its super-class directly or just hold a pointer pointing to an object of its super-class? By the way, why the output of the following code is: sizeof(A): 8 sizeof(B): 20 sizeof(C): 20 sizeof(C): 36 Code: #include <iostream> using namespace std; class A{ char k[ 3 ]; public: virtual void a(){}; }; class B : public virtual A{ char j[ 3 ]; public: virtual void b(){}; }; class C : public virtual B{ char i[ 3 ]; public: virtual void c(){}; }; class D : public B, public C{ char h[ 3 ]; public: virtual void d(){}; }; int main( int argc, char *argv[] ){ cout << "sizeof(A): " << sizeof( A ) << endl; cout << "sizeof(B): " << sizeof( B ) << endl; cout << "sizeof(C): " << sizeof( C ) << endl; cout << "sizeof(D): " << sizeof( D ) << endl; return 0; } Thanks in advance. Kind regards.

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  • Implementing list position locator in C++?

    - by jfrazier
    I am writing a basic Graph API in C++ (I know libraries already exist, but I am doing it for the practice/experience). The structure is basically that of an adjacency list representation. So there are Vertex objects and Edge objects, and the Graph class contains: list<Vertex *> vertexList list<Edge *> edgeList Each Edge object has two Vertex* members representing its endpoints, and each Vertex object has a list of Edge* members representing the edges incident to the Vertex. All this is quite standard, but here is my problem. I want to be able to implement deletion of Edges and Vertices in constant time, so for example each Vertex object should have a Locator member that points to the position of its Vertex* in the vertexList. The way I first implemented this was by saving a list::iterator, as follows: vertexList.push_back(v); v->locator = --vertexList.end(); Then if I need to delete this vertex later, then rather than searching the whole vertexList for its pointer, I can call: vertexList.erase(v->locator); This works fine at first, but it seems that if enough changes (deletions) are made to the list, the iterators will become out-of-date and I get all sorts of iterator errors at runtime. This seems strange for a linked list, because it doesn't seem like you should ever need to re-allocate the remaining members of the list after deletions, but maybe the STL does this to optimize by keeping memory somewhat contiguous? In any case, I would appreciate it if anyone has any insight as to why this happens. Is there a standard way in C++ to implement a locator that will keep track of an element's position in a list without becoming obsolete? Much thanks, Jeff

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  • Do ORMs normally allow circular relations? If so, how would they handle it?

    - by SeanJA
    I was hacking around trying to make a basic orm that has support for the one => one and one => many relationships. I think I succeeded somewhat, but I am curious about how to handle circular relationships. Say you had something like this: user::hasOne('car'); car::hasMany('wheels'); car::property('type'); wheel::hasOne('car'); You could then do this (theoretically): $u = new user(); echo $u->car->wheels[0]->car->wheels[1]->car->wheels[2]->car->wheels[3]->type; #=> "monster truck" Now, I am not sure why you would want to do this. It seems like it wastes a whole pile of memory and time just to get to something that could have been done in a much shorter way. In my small ORM, I now have 4 copies of the wheel class, and 4 copies of the car class in memory, which causes a problem if I update one of them and save it back to the database, the rest get out of date, and could overwrite the changes that were already made. How do other ORMs handle circular references? Do they even allow it? Do they go back up the tree and create a pointer to one of the parents? DO they let the coder shoot themselves in the foot if they are silly enough to go around in circles?

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  • Jquery cycle plugin and image tag from code behind

    - by Geetha
    Hi All, I am using cycle plugin to show images. I am binding the html code for image from code behind. Problem: Images are not getting displayed. If i hard coded the image tag it is working. Code: $(window).load(function() { $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", data: "{}", url: "Default.aspx/GetImage", dataType: "json", success: function(data) { alert(data.d); $("#sample").html(data.d); $('#sample').cycle({ fx: 'fade', continuous: true, speed: 7500, timeout: 55000, pause: 1, sync: 1 }); } }); }); Data.d will give: <img src="Images/Frontbanner/s0.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s111.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s112.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s113.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s114.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s115.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s116.jpg" width="664" height="428" border="0" />

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  • Who's setting TCP window size down to 0, Indy or Windows?

    - by François
    We have an application server which have been observed sending headers with TCP window size 0 at times when the network had congestion (at a client's site). We would like to know if it is Indy or the underlying Windows layer that is responsible for adjusting the TCP window size down from the nominal 64K in adaptation to the available throughput. And we would be able to act upon it becoming 0 (nothing gets send, users wait = no good). So, any info, link, pointer to Indy code are welcome... Disclaimer: I'm not a network specialist. Please keep the answer understandable for the average me ;-) Note: it's Indy9/D2007 on Windows Server 2003 SP2. More gory details: The TCP zero window cases happen on the middle tier talking to the DB server. It happens at the same moments when end users complain of slowdowns in the client application (that's what triggered the network investigation). 2 major Network issues causing bottlenecks have been identified. The TCP zero window happened when there was network congestion, but may or may not be caused by it. We want to know when that happen and have a way to do something (logging at least) in our code. So where to hook (in Indy?) to know when that condition occurs?

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  • Static Vs Non-Static Method Performance C#

    - by dotnetguts
    Hello All, I have few global methods declared in public class in my asp.net web application. I have habbit of declaring all global methods in public class in following format public static string MethodName(parameters) { } I want to know how it would impact on performance point of view? 1) Which one is Better? Static Method or Non-Static Method? 2) Reason why it is better? Following link shows Non-Static methods are good because, static methods are using locks to be Thread-safe. The always do internally a Monitor.Enter() and Monitor.exit() to ensure Thread-safety. http://bytes.com/topic/c-sharp/answers/231701-static-vs-non-static-function-performance And Following link shows Static Methods are good static methods are normally faster to invoke on the call stack than instance methods. There are several reasons for this in the C# programming language. Instance methods actually use the 'this' instance pointer as the first parameter, so an instance method will always have that overhead. Instance methods are also implemented with the callvirt instruction in the intermediate language, which imposes a slight overhead. Please note that changing your methods to static methods is unlikely to help much on ambitious performance goals, but it can help a tiny bit and possibly lead to further reductions. http://dotnetperls.com/static-method I am little confuse which one to use? Thanks

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  • Can some tell me why I am seg faulting in this simple C program?

    - by user299648
    I keep on getting seg faulted after I end my first for loop, and for the life of me I don't why. The file I'm scanning is just 18 strings in 18 lines. I thinks the problem is the way I'm mallocing the double pointer called picks, but I don't know exactly why. I'm am only trying to scanf strings that are less than 15 chars long, so I don't see the problem. Can someone please help. #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_LENGTH 100 int main( int argc,char *argv[] ) { char* string = malloc( 15*sizeof(char) ); char** picks = malloc(15*sizeof(char*)); FILE* pick_file = fopen( argv[l], "r" ); int num_picks; for( num_picks=0 ; fgets( string, MAX_LENGTH, pick_file ) != NULL ; num_picks++ ) { scanf( "%s", picks+num_picks ); } //this is where i seg fault int x; for(x=0; x<num_picks;x++) printf("s\n", picks+x); }

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  • How can I get type information at runtime from a DMP file in a Windbg extension?

    - by pj4533
    This is related to my previous question, regarding pulling objects from a dmp file. As I mentioned in the previous question, I can successfully pull object out of the dmp file by creating wrapper 'remote' objects. I have implemented several of these so far, and it seems to be working well. However I have run into a snag. In one case, a pointer is stored in a class, say of type 'SomeBaseClass', but that object is actually of the type 'SomeDerivedClass' which derives from 'SomeBaseClass'. For example it would be something like this: MyApplication!SomeObject +0x000 field1 : Ptr32 SomeBaseClass +0x004 field2 : Ptr32 SomeOtherClass +0x008 field3 : Ptr32 SomeOtherClass I need someway to find out what the ACTUAL type of 'field1' is. To be more specific, using example addresses: MyApplication!SomeObject +0x000 field1 : 0cae2e24 SomeBaseClass +0x004 field2 : 0x262c8d3c SomeOtherClass +0x008 field3 : 0x262c8d3c SomeOtherClass 0:000> dt SomeBaseClass 0cae2e24 MyApplication!SomeBaseClass +0x000 __VFN_table : 0x02de89e4 +0x038 basefield1 : (null) +0x03c basefield2 : 3 0:000> dt SomeDerivedClass 0cae2e24 MyApplication!SomeDerivedClass +0x000 __VFN_table : 0x02de89e4 +0x038 basefield1 : (null) +0x03c basefield2 : 3 +0x040 derivedfield1 : 357 +0x044 derivedfield2 : timecode_t When I am in WinDbg, I can do this: dt 0x02de89e4 And it will show the type: 0:000> dt 0x02de89e4 SomeDerivedClass::`vftable' Symbol not found. But how do get that inside an extension? Can I use SearchMemory() to look for 'SomeDerivedClass::`vftable'? If you follow my other question, I need this type information so I know what type of wrapper remote classes to create. I figure it might end up being some sort of case-statement, where I have to match a string to a type? I am ok with that, but I still don't know where I can get that string that represents the type of the object in question (ie SomeObject-field1 in the above example).

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  • How can I modified the value of a string defined in a struc?

    - by Eric
    Hi, I have the following code in c++: define TAM 4000 define NUMPAGS 512 struct pagina { bitset<12 direccion; char operacion; char permiso; string *dato; int numero; }; void crearPagina(pagina* pag[], int pos, int dir) { pagina * paginas = (pagina*)malloc(sizeof(char) * TAM); paginas - direccion = bitset<12 (dir); paginas - operacion = 'n'; paginas - permiso = 'n'; string **tempDato = &paginas - dato; char *temp = " "; **tempDato = temp; paginas - numero = 0; pag[pos] = paginas; } I want to modify the value of the variable called "string *dato" in the struct pagina but, everytime I want to assing a new value, the compiler throws a segmentation fault. In this case I'm using a pointer to string, but I have also tried with a string. In a few words I want to do the following: pagina - dato = "test"; Any idea? Thanks in advance!!!

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  • Jquery drag /drop and clone

    - by Sajeev
    Hi I need to achive this .. I have a set of droppable items ( basically I am droping designs on a apparel ) and I am dropping a clone.. If I don't like the dropped object (designs) - I want to delete that by doing something like hidden . But I am unable to do that. Please help me.. here is the code var clone; $(document).ready(function(){ $(".items").draggable({helper: 'clone',cursor: 'hand'}); $(".droparea").droppable({ accept: ".items", hoverClass: 'dropareahover', tolerance: 'pointer', drop: function(ev, ui) { var dropElemId = ui.draggable.attr("id"); var dropElem = ui.draggable.html(); clone = $(dropElem).clone(); // clone it and hold onto the jquery object clone.id="newId"; clone.css("position", "absolute"); clone.css("top", ui.absolutePosition.top); clone.css("left", ui.absolutePosition.left); clone.draggable({ containment: 'parent' ,cursor: 'crosshair'}); $(this).append(clone); alert("done dragging "); /lets assume I have a delete button when I click that clone should dissapear so that I can drop another design - but the following code has no effect //and the item is still visible , how to make it dissapear ? $('#newId').css("visibility","hidden"); } }); });

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  • Documentation about difference between javacript src and javascript library in grails

    - by damian
    I know that if you write in a view: <g:javascript src="myscript.js" /> <g:javascript src="myscript.js" /> <g:javascript src="myscript.js" /> <!-- other try --> <g:javascript library="myscript" /> <g:javascript library="myscript" /> <g:javascript library="myscript" /> It will out output: <script type="text/javascript" src="/vip/js/myscript.js"></script> <script type="text/javascript" src="/vip/js/myscript.js"></script> <script type="text/javascript" src="/vip/js/myscript.js"></script> <!-- other try --> <script type="text/javascript" src="/vip/js/myscript.js"></script> Conclution: with library it will try to include only once. I have been try to find documentation about it without success. Do you have any pointer?

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  • Animation management in COCOS2D iphone.

    - by shreya
    Hi All, I have near about 255 image frames for background animation, 99 frames of enemy sprite and 125 frames of player sprite. All animations are running simultaneously on the screen. That is background animation is running and 4-5 enemies are on the screen are present at a time, also player is there at the same time. Take a look at the code below, CCAnimation *_enemyAnimation = [CCAnimation animationWithName:@"Enemy" delay:0.1f]; for (int i = 1; i<99; i++) { [_enemyAnimation addFrameWithFilename:[NSString stringWithFormat:@"enemy %02d.jpg",i]]; } id action1 = [CCAnimate actionWithAnimation: _enemyAnimation]; [_enemySprite runAction:[CCRepeatForever actionWithAction: action1]]; [self schedule:@selector(BackToGameLogic:) interval:5.0]; This makes my game too slower and consumes memory about 65MB in the allocations. How should I manage my animations so there will be improvement in speed and memory consumption will be reduced?. Please suggest me the way. Thanks.

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  • JQuery drag, drop and save via cookie - how to?

    - by RussP
    Sorry to be back folks, but you guys & girls seem to know much more about this than I do ... anyhow, here is my question/problem I want to use drag, drop, sort (the interface plugin does me even though I have read it's out of date? but have looked at UI and to be honest is not clear and to me appears heavier than interface?) Anyhow, how do I set a cookie to save positions from this: $(document).ready( function () { $('a.closeEl').bind('click', toggleContent); $('div.groupWrapper').Sortable( { accept: 'groupItem', helperclass: 'sortHelper', activeclass : 'sortableactive', hoverclass : 'sortablehover', handle: 'div.itemHeader', tolerance: 'pointer', onChange : function(ser) { }, onStart : function() { $.iAutoscroller.start(this, document.getElementsByTagName('body')); }, onStop : function() { $.iAutoscroller.stop(); } } ); } ); var toggleContent = function(e) { var targetContent = $('div.itemContent', this.parentNode.parentNode); if (targetContent.css('display') == 'none') { targetContent.slideDown(300); $(this).html('[-]'); } else { targetContent.slideUp(300); $(this).html('[+]'); } return false; }; var ser = function (s) { serial = $.SortSerialize(s); alert(serial.hash); }; which is the "standard" interface demo, PLUS How do I then get to read that cookie so that when I next visit the page the order is as I set it in the cookie? Hopefully from that I can work out the rest .......? Thanks for help in advance.

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  • How is external memory, internal memory, and cache organized?

    - by goldenmean
    Consider a system as follows:= A hardware board having say ARM Cortex-A8 and Neon Vector coprocessor, and Embedded Linux OS running on Cortex-A8. On this environment, if there is some application - say, a video decoder is executing - then: How is it decided that which buffers would be in external memory, which ones would be allocated in internal SRAM, etc. When one says calloc/malloc on such system/code, the pointer returned is from which memory: internal or external? Can a user make buffers to be allocated to the memories of his choice (internal/external)? In ARM architectures, there is another memory called as Tightly coupled memory (TCM). What is that and how can user enable and use it? Can I declare buffers in this memory? Do I need to see the memory map (if any) of the hardware board to understand about all these different physical memories present in a typical hardware board? How much of a role does the OS play in distinguishing these different memories? Sorry for multiple questions, but i think they all are interlinked.

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  • Program structure in long running data processing python script

    - by fmark
    For my current job I am writing some long-running (think hours to days) scripts that do CPU intensive data-processing. The program flow is very simple - it proceeds into the main loop, completes the main loop, saves output and terminates: The basic structure of my programs tends to be like so: <import statements> <constant declarations> <misc function declarations> def main(): for blah in blahs(): <lots of local variables> <lots of tightly coupled computation> for something in somethings(): <lots more local variables> <lots more computation> <etc., etc.> <save results> if __name__ == "__main__": main() This gets unmanageable quickly, so I want to refactor it into something more manageable. I want to make this more maintainable, without sacrificing execution speed. Each chuck of code relies on a large number of variables however, so refactoring parts of the computation out to functions would make parameters list grow out of hand very quickly. Should I put this sort of code into a python class, and change the local variables into class variables? It doesn't make a great deal of sense tp me conceptually to turn the program into a class, as the class would never be reused, and only one instance would ever be created per instance. What is the best practice structure for this kind of program? I am using python but the question is relatively language-agnostic, assuming a modern object-oriented language features.

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  • Good way to identify similar images?

    - by Nick
    I've developed a simple and fast algorithm in PHP to compare images for similarity. Its fast (~40 per second for 800x600 images) to hash and a unoptimised search algorithm can go through 3,000 images in 22 mins comparing each one against the others (3/sec). The basic overview is you get a image, rescale it to 8x8 and then convert those pixels for HSV. The Hue, Saturation and Value are then truncated to 4 bits and it becomes one big hex string. Comparing images basically walks along two strings, and then adds the differences it finds. If the total number is below 64 then its the same image. Different images are usually around 600 - 800. Below 20 and extremely similar. Are there any improvements upon this model I can use? I havent looked at how relevant the different components (hue, saturation and value) are to the comparison. Hue is probably quite important but the others? To speed up searches I could probably split the 4 bits from each part in half, and put the most significant bits first so if they fail the check then the lsb doesnt need to be checked at all. I dont know a efficient way to store bits like that yet still allow them to be searched and compared easily. I've been using a dataset of 3,000 photos (mostly unique) and there havent been any false positives. Its completely immune to resizes and fairly resistant to brightness and contrast changes.

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  • Fast, Unicode-capable, cross-platform programmer's text editor that shows invisibles like ZWSP?

    - by Roger_S
    Our publishing workflow includes Windows and Linux machines (there are some Macs too, but not in the critical-path workflow). Many texts include both English and Khmer and are marked-up in XML. XML Copy Editor is the best cross-platform open-source XML editor I've discovered. It utilizes the Scintilla editing component, which is generally good with Unicode but which does not enable non-printing or invisible characters like U+200B (zero-width space) and U+200C (zero-width non-joiner) to be displayed. Khmer does not separate words with a space character as Western languages do, so ZWSP is used in electronic texts to enable applications to break lines easily. Ideally I'd edit the markup and the content in a single editor, but XML awareness is less important at times than being able to display invisibles. (OpenOffice.org Writer and Microsoft Word are the only two apps I know that will display ZWSP. They are not suitable for the markup and text manipulations that need to be done to prepare manuscripts for publication, unfortunately, although I guess they're fine for authoring.) I tried out a promising editor last week, but a search-and-replace regex operation that took under a second in TextPad 4.7.3 lasted over twenty seconds. So I want to mention that speed and the ability to handle large (up to 150mb) files is also a concern. Is there a good, fast, free or not too expensive text editor, with versions on Windows and Linux and maybe mac too, Unicode-aware and capable of displaying invisibles like ZWSP? That has syntax highlighting, can handle large files and is customizable enough that I won't tear my hair out in frustration? Thanks, Roger_S

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  • How to partition bits in a bit array with less than linear time

    - by SiLent SoNG
    This is an interview question I faced recently. Given an array of 1 and 0, find a way to partition the bits in place so that 0's are grouped together, and 1's are grouped together. It does not matter whether 1's are ahead of 0's or 0's are ahead of 1's. An example input is 101010101, and output is either 111110000 or 000011111. Solve the problem in less than linear time. Make the problem simpler. The input is an integer array, with each element either 1 or 0. Output is the same integer array with integers partitioned well. To me, this is an easy question if it can be solved in O(N). My approach is to use two pointers, starting from both ends of the array. Increases and decreases each pointer; if it does not point to the correct integer, swap the two. int * start = array; int * end = array + length - 1; while (start < end) { // Assume 0 always at the end if (*end == 0) { --end; continue; } // Assume 1 always at the beginning if (*start == 1) { ++start; continue; } swap(*start, *end); } However, the interview insists there is a sub-linear solution. This makes me thinking hard but still not get an answer. Can anyone help on this interview question?

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  • Can someone tell me why I'm seg faulting in this simple C program?

    - by user299648
    I keep on getting seg faulted, and for the life of me I dont why. The file I'm scanning is just 18 strings in 18 lines. I thinks the problem is the way I'm mallocing the double pointer called picks, but I dont know exactly why. I'm am only trying to scanf strings that are less than 15 chars long, so I don't see the problem. Can someone please help. #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_LENGTH 100 int main( int argc,char *argv[] ) { char* string = malloc( sizeof(char) ); char** picks = malloc(15*sizeof(char)); FILE* pick_file = fopen( argv[l], "r" ); int num_picks; for( num_picks=0 ; fgets( string, MAX_LENGTH, pick_file ) != NULL ; num_picks++ ) { printf("pick a/an %s ", string ); scanf( "%s", picks+num_picks ); } int x; for(x=0; x<num_picks;x++) printf("s\n", picks+x); }

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  • How can I accelerate the generation of the an MD5 Checksum within vb.net?

    - by Richard
    I'm working with some very large files residing on P2 (Panasonic) cards. Part of the process we employ is to first generate a checksum of the file we are going to copy, then copy the file, then run a checksum on the file to confirm that it copied OK. The problem is, is that files are large (70 GB+) and take a long time to complete. It's an issue since we will eventually be dealing with thousands of these files. I would like to find a faster way to generate the checksum other than using the System.Security.Cryptography.MD5CryptoServiceProvider I don't care if this means using a specialized hardware card, provided it works and is not to ungodly expensive. I would prefer to have a method of encoding that provided some feedback as to how far the process has gone along so I can display it like I do now. The application is written in vb.net. I would prefer to be able to use it as component, library, reference within my application, but I'm willing to call an outside application if there is enough improvement in the speed of generating the checksum. Needless to say, the checksum must be consistent and correct. :-) Thank you in advance for your time and efforts, Richard

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  • Java abstract visitor - guarantueed to succeed? If so, why?

    - by disown
    I was dealing with hibernate, trying to figure out the run-time class behind proxied instances by using the visitor pattern. I then came up with an AbstractVisitable approach, but I wonder if it will always produce correct results. Consider the following code: interface Visitable { public void accept(Visitor v); } interface Visitor { public void visit(Visitable visitorHost); } abstract class AbstractVisitable implements Visitable { @Override public void accept(Visitor v) { v.visit(this); } } class ConcreteVisitable extends AbstractVisitable { public static void main(String[] args) { final Visitable visitable = new ConcreteVisitable(); final Visitable proxyVisitable = (Visitable) Proxy.newProxyInstance( Thread.currentThread().getContextClassLoader(), new Class<?>[] { Visitable.class }, new InvocationHandler() { @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { return method.invoke(visitable, args); } }); proxyVisitable.accept(new Visitor() { @Override public void visit(Visitable visitorHost) { System.out.println(visitorHost.getClass()); } }); } } This makes a ConcreteVisitable which inherits the accept method from AbstractVisitable. In c++, I would consider this risky, since this in AbstractVisitable could be referencing to AbstractVisitable::this, and not ConcreteVisitable::this. I was worried that the code under certain circumstances would print class AbstractVisible. Yet the code above outputs class ConcreteVisitable, even though I hid the real type behind a dynamic proxy (the most difficult case I could come up with). Is the abstract visitor approach above guaranteed to work, or are there some pitfalls with this approach? What guarantees are given in Java with respect to the this pointer?

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