Search Results

Search found 30575 results on 1223 pages for 'number systems'.

Page 437/1223 | < Previous Page | 433 434 435 436 437 438 439 440 441 442 443 444  | Next Page >

• What is the best way to iterate over a large result set in JDBC/iBatis 3?

  - by paul_sns

  We're trying to iterate over a large number of rows from the database and convert those into objects. Behavior will be as follows: Result will be sorted by sequence id, a new object will be created when sequence id changes. The object created will be sent to an external service and will sometimes have to wait before sending another one (which means the next set of data will not be immediately used) We already have invested code in iBatis 3 so an iBatis solution will be the best approach for us (we've tried using RowBounds but haven't seen how it does the iteration under the hood). We'd like to balance minimizing memory usage and reducing number of DB trips. We're also open to pure JDBC approach but we'd like the solution to work on different databases. UPDATE: We need to make as few calls to DB as possible (1 call would be the ideal scenario) while also preventing the application to use too much memory. Are there any other solutions out there for this type of problem may it be pure JDBC or any other technology? Thanks and hope to hear your insights on this.

  Read the article

• Creating dynamic jQuery tooltips for dynamic content

  - by Mel

  I'm using the qTip jQuery plugin to create tooltips for a set of links. Two problems: How do I create a set of tooltips for three dynamically generated links where the content of the tooltip will also be dynamic: a href="books.cfm?bookID=11"Book One a href="books.cfm?bookID=22"Book Two a href="books.cfm?bookID=33"Book Three I would like to create a tooltip for each link. Each tooltip will then load details about each book. Thus I must pass the bookID to the tooltip: $('#catalog a[href]').each(function() { $(this).qtip( { content: { URL: 'cfcs/viewbooks.cfc?method=bookDetails', data: { bookID: <cfoutput>#indexView.bookID#</cfoutput> }, method: 'get' } }); }); Unfortunately the above code is not working correctly. I've gotten it to work when I've used a static 'bookID' instead of a dynamically generated number. Even when it does work (by using a static number for 'bookID', I can't format the data correctly. It comes back as a query result, or a bunch of text strings. Should I send back the results as HTML? Unsure. PS: I am an absolute NOVICE to Javascript and jQuery, so please try not to be as technical. Many thanks!

  Read the article

• Code bacteria: evolving mathematical behavior

  - by Stefano Borini

  It would not be my intention to put a link on my blog, but I don't have any other method to clarify what I really mean. The article is quite long, and it's in three parts (1,2,3), but if you are curious, it's worth the reading. A long time ago (5 years, at least) I programmed a python program which generated "mathematical bacteria". These bacteria are python objects with a simple opcode-based genetic code. You can feed them with a number and they return a number, according to the execution of their code. I generate their genetic codes at random, and apply an environmental selection to those objects producing a result similar to a predefined expected value. Then I let them duplicate, introduce mutations, and evolve them. The result is quite interesting, as their genetic code basically learns how to solve simple equations, even for values different for the training dataset. Now, this thing is just a toy. I had time to waste and I wanted to satisfy my curiosity. however, I assume that something, in terms of research, has been made... I am reinventing the wheel here, I hope. Are you aware of more serious attempts at creating in-silico bacteria like the one I programmed? Please note that this is not really "genetic algorithms". Genetic algorithms is when you use evolution/selection to improve a vector of parameters against a given scoring function. This is kind of different. I optimize the code, not the parameters, against a given scoring function.

  Read the article

• Why is it still so hard to write software?

  - by nornagon

  Writing software, I find, is composed of two parts: the Idea, and the Implementation. The Idea is about thinking: "I have this problem; how do I solve it?" and further, "how do I solve it elegantly?" The answers to these questions are obtainable by thinking about algorithms and architecture. The ideas come partially through analysis and partially through insight and intuition. The Idea is usually the easy part. You talk to your friends and co-workers and you nut it out in a meeting or over coffee. It takes an hour or two, plus revisions as you implement and find new problems. The Implementation phase of software development is so difficult that we joke about it. "Oh," we say, "the rest is a Simple Matter of Code." Because it should be simple, but it never is. We used to write our code on punch cards, and that was hard: mistakes were very difficult to spot, so we had to spend extra effort making sure every line was perfect. Then we had serial terminals: we could see all our code at once, search through it, organise it hierarchically and create things abstracted from raw machine code. First we had assemblers, one level up from machine code. Mnemonics freed us from remembering the machine code. Then we had compilers, which freed us from remembering the instructions. We had virtual machines, which let us step away from machine-specific details. And now we have advanced tools like Eclipse and Xcode that perform analysis on our code to help us write code faster and avoid common pitfalls. But writing code is still hard. Writing code is about understanding large, complex systems, and tools we have today simply don't go very far to help us with that. When I click "find all references" in Eclipse, I get a list of them at the bottom of the window. I click on one, and I'm torn away from what I was looking at, forced to context switch. Java architecture is usually several levels deep, so I have to switch and switch and switch until I find what I'm really looking for -- by which time I've forgotten where I came from. And I do that all day until I've understood a system. It's taxing mentally, and Eclipse doesn't do much that couldn't be done in 1985 with grep, except eat hundreds of megs of RAM. Writing code has barely changed since we were staring at amber on black. We have the theoretical groundwork for much more advanced tools, tools that actually work to help us comprehend and extend the complex systems we work with every day. So why is writing code still so hard?

  Read the article

• How do You Center a TextView in Layout?

  - by Ken

  I have a complex layout, part of which features a value centered over a label, with + and - buttons on either side of the value. I want the value to center between the buttons, whether it is "1" or "99". It looks fine when it's a 2-digit number like "99", but when it's a single digit the number is left-justified. How do I properly center that value? Here's the portion of my layout that does this: <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_above="@id/runway_label" android:layout_centerHorizontal="true" android:orientation="horizontal"> <ImageView android:id="@+id/dec_runway_button" android:src="@drawable/minus_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_vertical"/> <TextView android:id="@+id/runway_value" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textColor="#FFFFFF" android:textStyle="bold" android:textSize="40.0sp" android:minWidth="50sp" android:layout_centerInParent="true" android:layout_gravity="center" android:shadowColor="#333333" android:shadowDx="2.0" android:shadowDy="2.0" android:shadowRadius="3.0" /> <ImageView android:id="@+id/inc_runway_button" android:src="@drawable/plus_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_vertical"/> </LinearLayout>

  Read the article

• How do I exclude data from local table schema_migrations from being pushed to Heroku DB?

  - by Thierry Lam

  I was able to push my Ruby on Rails app with MySQL(local dev) to the Heroku server along with migrating my model with the command heroku rake db:migrate. I have also read the documentation on Database Import/Export. Is that doc referring to pushing actual data from my local dev DB to whichever Heroku's DB? Do I need to modify anything in the file database.yml to make it happen? I ran the following command: heroku db:push and I am getting the error: Sending data 2 tables, 3 records !!! Caught Server Exception | ETA: --:--:-- Taps Server Error: PGError ERROR: duplicate key value violates unique constraint "unique_schema_migrations" I have 2 tables, one I create for my app and the other schema_migrations. The total number of entries among the 2 tables is 3. I'm also printing the number of entries I have in the table I have created and it's showing 0. Any ideas what I might be missing or what I am doing wrong? EDIT: I figured out the above, Heroku's DB already have schema_migrations the moment I ran migrate. New question: Does anyone know how I can exclude data from a specific table from being pushed to Heroku DB. The table to exclude in this case will be schema_migrations. Not so good solution: I googled around and someone else was having the same issue. He suggested naming the schema_migrations table to zschema_migrations. In this way data from the other tables will be pushed properly until it fails on the last table. It's a pretty bad solution but will do for the time being. A better solution will be to use an existing Rails command which can reset a specific table from a database. I don't think Rake can do that.

  Read the article

• How to catch a carp-warning?

  - by sid_com

  I tried to catch a carp-warning ( carp "$start is $end" if (warnings::enabled()); ) with eval but it didn't work, so I looked in the eval-documentation and I discovered, that eval catches only syntax-errors, run-time-errors or executed die-statements. How could I catch a carp-warning? #!/usr/bin/env perl use warnings; use strict; use 5.012; use List::Util qw(max min); use Number::Range; my @array; my $max = 20; print "Input (max $max): "; my $in = <>; $in =~ s/\s+//g; $in =~ s/(?<=\d)-/../g; eval { my $range = new Number::Range( $in ); @array = sort { $a <=> $b } $range->range; }; if ( $@ =~ /\d+ is > \d+/ ) { die $@ }; # catch the carp-warning doesn't work die "Input greater than $max not allowed $!" if defined $max and max( @array ) > $max; die "Input '0' or less not allowed $!" if min( @array ) < 1; say "@array";

  Read the article

• iPhone code to create new NSUserDefaults objects?

  - by Rob

  I have NSUserDefaults storing a number of string variables for things like name, date of birth, address, etc. What I would like to know is how to write a code that will create a new object for each new user. For example, I have a spinning wheel that shows up immediately after the first time the user runs the app. What I want, is for that wheel to have one single option - "New User". Once that New User fills out a bunch of text fields that I am using NSUserDefaults to save, I want that user to be saved on that spinning wheel so that the next time they open up the app they have the option of returning to all of the variables that they previously put in, or creating a new user so they can input all new variables. I know how to do everything except write the code to create new users automatically. Potentially, the program should allow for a limitless number of these user objects and then just use something arbitrary like their last name to input into the spinning wheel. I would assume that the code would need to be put somewhere in the following code used to save the NSUserDefaults: NSUserDefaults *userData = [NSUserDefaults standardUserDefaults]; [userData setObject:txtName.text forKey:@"name"];

  Read the article

• Stop Excel from changing cell contents, ever

  - by Enable Manual-Correct

  I work with card numbers, like credit card and ID numbers. We do not do any calculations with card numbers, obviously. They are "text." I format them as text, I type them like text. I know how that works. Excel doesn't care. 16 digit card numbers get their last digit turned into a zero, changed into scientific notation, stupid stuff that I did not tell Excel to do. I need to do things like Find/Remove spaces from cells in files downloaded from our currently imperfect web-system. The system sends me files with 16 digit numbers, cells formatted as text, but due to bugs there are spaces at the end. I do Find/Remove all spaces and all my card numbers are transformed into scientific notation and the last digit turned into a 0. THEY ARE TEXT, they are formatted as text, I yelled into the screen that they are text, why does Excel refuse to acknowledge that they are text? (I would rather find a way to stop Excel's action than find a way to tell our programmers to put an apostrophe in every cell) How do I make it so that Excel just STOPS doing anything that I didn't tell it to do? Or at least stop it from doing anything to numbers it doesn't like. Maybe I can write a macro for whenever it discovers "Uhoh I should change that number to something different!" I'll make it format that cell to text a thousand times instead. Give me an error when I try calculating with a number larger than 15 digits, make my computer explode violently, that's fine. Just stop changing the numbers. Is it possible? I have many thousands of numbers that need changing in many different scenarios. I just want to stop it from trying to help. I can't understand why that would be difficult. I have 2007, but answers for other versions would be great as well. Thank you!

  Read the article

• Why use Buildr instead of Ant or Maven?

  - by Scott Markwell

  http://buildr.apache.org/ http://ant.apache.org/ http://maven.apache.org/ What does another build tool targeted at Java really get me? Is it so hard to write a plugin using Java versus writing it in Ruby? If you use Buildr over another tool, why? Side question: How many build systems does the Apache foundation need targeted at Java?

  Read the article

• Poor execution plans when using a filter and CONTAINSTABLE in a query

  - by Paul McLoughlin

  We have an interesting problem that I was hoping someone could help to shed some light on. At a high level the problem is as below: The following query executes quickly (1 second): SELECT SA.* FROM cg.SEARCHSERVER_ACTYS AS SA JOIN CONTAINSTABLE(CG.SEARCHSERVER_ACTYS, NOTE, 'reports') AS T1 ON T1.[Key]=SA.UNIQUE_ID but if we add a filter to the query, then it takes approximately 2 minutes to return: SELECT SA.* FROM cg.SEARCHSERVER_ACTYS AS SA JOIN CONTAINSTABLE(CG.SEARCHSERVER_ACTYS, NOTE, 'reports') AS T1 ON T1.[Key]=SA.UNIQUE_ID WHERE SA.CHG_DATE'19 Feb 2010' Looking at the execution plan for the two queries, I can see that in the second case there are two places where there are huge differences between the actual and estimated number of rows, these being: 1) For the FulltextMatch table valued function where the estimate is approx 22,000 rows and the actual is 29 million rows (which are then filtered down to 1670 rows before the join) and 2) For the index seek on the full text index, where the estimate is 1 row and the actual is 13,000 rows As a result of the estimates, the optimiser is choosing to use a nested loops join (since it assumes a small number of rows) hence the plan is inefficient. We can work around the problem by either (a) parameterising the query and adding an OPTION (OPTIMIZE FOR UNKNOWN) to the query or (b) by forcing a HASH JOIN to be used. In both of these cases the query returns in sub 1 second and the estimates appear reasonable. My question really is 'why are the estimates being used in the poorly performing case so wildly inaccurate and what can be done to improve them'? Statistics are up to date on the indexes on the indexed view being used here. Any help greatly appreciated.

  Read the article

• php POST response

  - by amit

  I am making a POST to another php file that I want to render in the browser. so clearly, using jquery POST wont work, since it works through AJAX. echo '<div class="showcase_URL"><a class="purl" name="'.$row->num.'" href="#">PROJECT URL</a></div>'; what I have till now in javascript is: $(".showcase_URL a").click(function() { //alert($(this).attr("name")); var number = $(this).attr("name"); $.post( "app-display.php", {app: number}, function(data){ top.location.href = 'app-display.php'; }); }); what I have in app-display.php: $query = 'SELECT num, title, thumb_url, url, type, cat, dated, details FROM app WHERE `num` = "$_POST[app]"'; but it is currently giving me a page without the contents of app-display.php. all the other fragments of the page are loading: header, footer etc. the PHP Response (in Firebug) I am getting is the normal html of the page. how should i do it?

  Read the article

• cross platform keyboard/mouse input recommendation

  - by Jay

  Does anyone have any suggestions for a good cross platform input library? I'd like to get: * at least keyboard and mouse input * on at least the big three operating systems * Small/fast * C or C++ * permissive licensing gpl2/mit/free/etc. So far I've seen: * OIS (used in Ogre) http://sourceforge.net/projects/wgois/ * SDL (used everywhere it seems, might be a clue) http://www.libsdl.org/index.php * Allegro http://www.talula.demon.co.uk/allegro/readme.html Has any one used any of these, or know of something else that might be good? Thanks

  Read the article

• Radix Sort in Python [on hold]

  - by Steven Ramsey

  I could use some help. How would you write a program in python that implements a radix sort? Here is some info: A radix sort for base 10 integers is a based on sorting punch cards, but it turns out the sort is very ecient. The sort utilizes a main bin and 10 digit bins. Each bin acts like a queue and maintains its values in the order they arrive. The algorithm begins by placing each number in the main bin. Then it considers the ones digit for each value. The rst value is removed and placed in the digit bin corresponding to the ones digit. For example, 534 is placed in digit bin 4 and 662 is placed in the digit bin 2. Once all the values in the main bin are placed in the corresponding digit bin for ones, the values are collected from bin 0 to bin 9 (in that order) and placed back in the main bin. The process continues with the tens digit, the hundreds, and so on. After the last digit is processed, the main bin contains the values in order. Use randint, found in random, to create random integers from 1 to 100000. Use a list comphrension to create a list of varying sizes (10, 100, 1000, 10000, etc.). To use indexing to access the digits rst convert the integer to a string. For this sort to work, all numbers must have the same number of digits. To zero pad integers with leading zeros, use the string method str.zfill(). Once main bin is sorted, convert the strings back to integers. I'm not sure how to start this, Any help is appreciated. Thank you.

  Read the article

• Mouse move panning

  - by Rudy

  Hi all, I'm trying to scroll a series of thumbnails horizontally based on the mouseX position. I can get it to scroll but it's very choppy and for some reason it's not reading my start and end numbers so it will stop scrolling. Can anyone point me in the right direction? Thanks. var thumbBounds:Object = new Object(); thumbBounds = thumbContainer.getBounds(this); thumbContainer.addEventListener(MouseEvent.MOUSE_OVER, setScrolling); private function setScrolling(me:MouseEvent):void { thumbContainer.removeEventListener(MouseEvent.MOUSE_OVER, setScrolling); stage.addEventListener(Event.ENTER_FRAME, scrollThumbs); } private function scrollThumbs(e:Event):void { if(mouseX <= thumbBounds.x || mouseX thumbBounds.width || mouseX < thumbBounds.y || mouseX thumbBounds.height) { thumbContainer.addEventListener(MouseEvent.MOUSE_OVER, setScrolling); stage.removeEventListener(Event.ENTER_FRAME, scrollThumbs); } if(thumbContainer.x = 0) { thumbContainer.x = 0; } if(thumbContainer.x <= -842) { thumbContainer.x = -842; } var xdist:Number = new Number(); xdist = mouseX - 382; thumbContainer.x += Math.round(-xdist / 10); }

  Read the article

• Simple description of worker and I/O threads in .NET

  - by Konstantin

  It's very hard to find detailed but simple description of worker and I/O threads in .NET What's clear to me regarding this topic (but may not be technically precise): Worker threads are threads that should employ CPU for their work; I/O threads (also called "completion port threads") should employ device drivers for their work and essentially "do nothing", only monitor the completion of non-CPU operations. What is not clear: Although method ThreadPool.GetAvailableThreads returns number of available threads of both types, it seems there is no public API to schedule work for I/O thread. You can only manually create worker thread in .NET? It seems that single I/O thread can monitor multiple I/O operations. Is it true? If so, why ThreadPool has so many available I/O threads by default? In some texts I read that callback, triggered after I/O operation completion is performed by I/O thread. Is it true? Isn’t this a job for worker thread, considering that this callback is CPU operation? To be more specific – do ASP.NET asynchronous pages user I/O threads? What exactly is performance benefit in switching I/O work to separate thread instead of increasing maximum number of worker threads? Is it because single I/O thread does monitor multiple operations? Or Windows does more efficient context switching when using I/O threads?

  Read the article

• Oracle - Getting Select Count(*) from ... as an output parameter in System.Data.OracleClient

  - by cbeuker

  Greetings all, I have a question. I am trying to build a parametrized query to get me the number of rows from a table in Oracle. Rather simple. However I am an Oracle newbie.. I know in SQL Server you can do something like: Select @outputVariable = count(*) from sometable where name = @SomeOtherVariable and then you can set up an Output parameter in the System.Data.SqlClient to get the @outputVariable. Thinking that one should be able to do this in Oracle as well, I have the following query Select count(*) into :theCount from sometable where name = :SomeValue I set up my oracle parameters (using System.Data.OracleClient - yes I know it will be deprecated in .Net 4 - but that's what I am working with for now) as follows IDbCommand command = new OracleCommand(); command.CommandText = "Select count(*) into :theCount from sometable where name = :SomeValue"); command.CommandType = CommandType.Text; OracleParameter parameterTheCount = new OracleParameter(":theCount ", OracleType.Number); parameterTheCount .Direction = ParameterDirection.Output; command.Parameters.Add(parameterTheCount ); OracleParameter parameterSomeValue = new OracleParameter(":SomeValue", OracleType.VarChar, 40); parameterSomeValue .Direction = ParameterDirection.Input; parameterSomeValue .Value = "TheValueToLookFor"; command.Parameters.Add(parameterSomeValue ); command.Connection = myconnectionObject; command.ExecuteNonQuery(); int theCount = (int)parameterTheCount.Value; At which point I was hoping the count would be in the parameter parameterTheCount that I could readily access. I keep getting the error ora-01036 which http://ora-01036.ora-code.com tells me to check my binding in the sql statement. Am I messing something up in the SQL statement? Am I missing something simple elsewhere? I could just use command.ExecuteScaler() as I am only getting one item, and am probably going to end up using that, but at this point, curiosity has got the better of me. What if I had two parameters I wanted back from my query (ie: select max(ColA), min(ColB) into :max, :min.....) Thanks..

  Read the article

• Replacing text inside textarea without focus

  - by asker

  I want to replace selected text(or insert new text after cursor position if nothing is selected). The new text is entered from another textbox. I want to be able to insert new text without clicking first (focusing) in the textarea. meaning: first select text to replace inside textarea, then enter new text into the textbox and click the button. <textarea id='text' cols="40" rows="20"> </textarea> <div id="opt"> <input id="input" type="text" size="35"> <input type="button" onclick='pasteIntoInput(document.getElementById("input").value)' value="button"/> </div> function pasteIntoInput(text) { el=document.getElementById("text"); el.focus(); if (typeof el.selectionStart == "number"&& typeof el.selectionEnd == "number") { var val = el.value; var selStart = el.selectionStart; el.value = val.slice(0, selStart) + text + val.slice(el.selectionEnd); el.selectionEnd = el.selectionStart = selStart + text.length; } else if (typeof document.selection != "undefined") { var textRange = document.selection.createRange(); textRange.text = text; textRange.collapse(false); textRange.select(); } } Online example: link text

  Read the article

• Assigning figure size to a figure with a given handle (MATLAB)

  - by James

  Hi, is there a way to assign the outerposition property of a figure to a figure with a given handle? For example, if I wanted to define a figure as say figure 1, I would use: figure(1) imagesc(Arrayname) % I.e. any array I can also change the properties of a figure using the code: figure('Name', 'Name of figure','NumberTitle','off','OuterPosition',[scrsz(1) scrsz(2) 700 700]); Is there a propertyname I can use to assign the outerposition property to the figure assigned as figure 1? The reason I am asking this is because I am using a command called save2word (from the MATLAB file exchange) to save some plots from a function I have made to a word file, and I want to limit the number of figures I have open as it does this. The rest of the code I have is: plottedloops = [1, 5:5:100]; % Specifies which loops I want to save GetGeometry = getappdata(0, 'GeometryAtEachLoop') % Obtains a 4D array containing geometry information at each loop NumSections = size(GetGeometry,4); %Defined by the fourth dimension of the 4D array for j = 1:NumSections for i = 1:plottedloops P = GetGeometry(:,:,i,j); TitleSize = 14; Fsize = 8; % Save Geometry scrsz = get(0,'ScreenSize'); %left, bottom, width height figure('Name', 'Geometry at each loop','NumberTitle','off','OuterPosition',[scrsz(1) scrsz(2) 700 700]); This specifies the figure name, dims etc., but also means multiple figures are opened as the command runs. % I have tried this, but it doesn't work: % figure(0, 'OuterPosition',[scrsz(1) scrsz(2) 700 700]); imagesc(P), title('Geometry','FontSize', TitleSize), axis([0 100 0 100]); text(20,110,['Loop:',num2str(i)], 'FontSize', TitleSize); % Show loop in figure text(70,110,['Section:',num2str(j)], 'FontSize', TitleSize);% Show Section number in figure save2word('Geometry at each loop'); % Saves figure to a word file end end Thanks

  Read the article

• Sparx Enterprise Architect for SQL Server modeling?

  - by Tone

  I have used MS SQL Server Management Studio for most of my database modeling to this point in my career. I am a database developer (not a DBA), but interested in the benefits with using Sparx systems Enterprise Architect for data modeling. I do not have the need to generate scripts for different databases, other than that what does using Sparx EA buy me that SQL Management Studio does not?

  Read the article

• How to use a linkedList and multiple classes with my Java GUI

  - by Asj

  How should I use a linked list with my GUI program? The program is supposed to have blocks with textareas and dropdown menus. The number of blocks depends on the number of times the user presses a button. It's supposed to be possible to put blocks within blocks. I want to store the information created, using a linked list and then saving to a file. I'm thinking, for the sub blocks, there would be linked lists within the linked list. Should I use Java.util.LinkedList? How do I add the information? A Node class? Should that be in a separate file? I started to try sitting up a linked list, but it's getting me confused. I'm still unsure about how a person is supposed to make GUI's. I've only seen really simple GUI's. Can anyone tell me how I should arrange things? At the moment, I have three files, one for the main GUI window, one for the question blocks to be inserted within that, and one for some tools to use within those two files to make the code easier to understand. But, there seems to be something wrong with the question block file, because I've been making the background white for each JPanel, and there's a gray outline around the question blocks when I run the program. I probably shouldn't paste a ton of code here... These are my files: http://asj127.webs.com/BuildAssessmentWindow.java http://asj127.webs.com/QuestionBlock.java http://asj127.webs.com/JPanelTools.java

  Read the article

• Link list usage in system programming

  - by Pwn

  Hi, in spite of having so many efficient data structures, why is only linked list used so heavily in systems programming? Is it because it allows least usage of heap/less buggy code? Regards, Pwn

  Read the article

• Modeling multiple polymorphic relationships using Hibernate

  - by f-potter

  Ruby on Rails has polymorphic relations which are really useful for implementing functionality such as commenting, tagging and rating to name a few. We can have a comment, tag or rating class which has a many to one polymorphic relationship with a commentable, taggable and rateable object. Also, a given domain object can choose to implement any combination of such relations. So, it can for example be commentable, taggable and rateable at the same time. I couldn't think up of a straightforward way to duplicate this functionality in Hibernate. Ideally, there would be a Comment class which will have a many to one relationship with a Commentable class and a Commentable class will conversely have a one to many relationship with Comments. It will be ideal if the concrete domain classes can inherit from a number of such classes, say Commentable and Taggable. Things seem a little complicated as a Java class can only extend one other class and some code might end up being duplicated across a number of classes. I wanted to know what are the best practices for modeling such relationships neatly and concisely using Hibernate?

  Read the article

• Problem with writing a hexadecimal string

  - by quilby

  Here is my code /* gcc -c -Wall -g main.c gcc -g -lm -o main main.o */ #include <stdlib.h> #include <stdio.h> #include <string.h> void stringToHex(const char* string, char* hex) { int i = 0; for(i = 0; i < strlen(string)/2; i++) { printf("s%x", string[2*i]); //for debugging sprintf(&hex[i], "%x", string[2*i]); printf("h%x\n", hex[i]); //for debugging } } void writeHex(char* hex, int length, FILE* file, long position) { fseek(file, position, SEEK_SET); fwrite(hex, sizeof(char), length, file); } int main(int argc, char** argv) { FILE* pic = fopen("hi.bmp", "w+b"); const char* string = "f2"; char hex[strlen(string)/2]; stringToHex(string, hex); writeHex(hex, strlen(string)/2, pic, 0); fclose(pic); return 0; } I want it to save the hexadecimal number 0xf2 to a file (later I will have to write bigger/longer numbers though). The program prints out - s66h36 And when I use hexedit to view the file I see the number '36' in it. Why is my code not working? Thanks!

  Read the article

• Casting to a struct from LPVOID - C

  - by Jamie Keeling

  Hello, I am writing a simple console application which will allow me to create a number of threads from a set of parameters passed through the arguments I provide. DWORD WINAPI ThreadFunc(LPVOID threadData) { } I am packing them into a struct and passing them as a parameter into the CreateThread method and trying to unpack them by casting them to the same type as my struct from the LPVOID. I'm not sure how to cast it to the struct after getting it through so I can use it in the method itself, i've tried various combinations (Example attatched) but it won't compile. Struct: #define numThreads 1 struct Data { int threads; int delay; int messages; }; Call to method: HANDLE hThread; DWORD threadId; struct Data *tData; tData->threads = numThreads; tData->messages = 3; tData->delay = 1000; // Create child thread hThread = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc, // lpStartAddress &tData, // lpParameter 0, // dwCreationFlags &threadId // lpThreadId (returned by function) ); My attempt: DWORD WINAPI ThreadFunc(LPVOID threadData) { struct Data tData = (struct Data)threadData; int msg; for(msg = 0; msg<5; msg++) { printf("Message %d from child\n", msg); } return 0; } Compiler error: error C2440: 'type cast' : cannot convert from 'LPVOID' to 'Data' As you can see I have implemented a way to loop through a number of messages already, I'm trying to make things slightly more advanced and add some further functionality.

  Read the article

< Previous Page | 433 434 435 436 437 438 439 440 441 442 443 444  | Next Page >