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• How to set background image in Java?

  - by Dew

  I am developing a simple platform game using Java using BlueJ as the IDE. Right now I have player/enemy sprites, platforms and other items in the game drawn using polygons and simple shapes. Eventually I hope to replace them with actual images. For now I would like to know what is the simplest solution to setting an image (either URL or from local source) as the 'background' of my game window/canvas? I would appreciate it if it isn't something long or complex as my programming skills aren't very good and I want to keep my program as simple as possible. Kindly provide example codes with comments to elaborate on their function, and also if it's in its own class, how to call on relevant methods used by it on other classes. Thank you very much.

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• Style question: Writing "this." before instance variable and methods: good or bad idea?

  - by Uri

  One of my nasty (?) programming habits in C++ and Java is to always precede calls or accesses to members with a this. For example: this.process(this.event). A few of my students commented on this, and I'm wondering if I am teaching bad habits. My rationale is: 1) Makes code more readable — Easier to distinguish fields from local variables. 2) Makes it easier to distinguish standard calls from static calls (especially in Java) 3) Makes me remember that this call (unless the target is final) could end up on a different target, for example in an overriding version in a subclass. Obviously, this has zero impact on the compiled program, it's just readability. So am I making it more or less readable? Related Question Note: I turned it into a CW since there really isn't a correct answer.

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• How do I create a view with a picker on the bottom and a table view on the top?

  - by Andy

  Hi - first time asker, long-time lurker. I am trying to create an iPhone view that has a date/time picker on the bottom half of the screen, and a grouped, single-section, four-row table view on the top half of the screen (almost identical to the one Apple shows in Fig. 2-4 of their View Controller Programming Guide (but then never goes on to explain). Conceptually, I think I understand that what I need is a main view with a pair of subviews - one for the picker, and one for the table view. I'm pretty sure I can make the picker function once I have it on-screen, and I'm pretty sure I can make the table view function too. What I can't for the life of me figure out is how, programmatically speaking, to get the two views onto the screen simultaneously. I can lay it out perfectly in Interface Builder, but then it all goes to hell when I switch to Xcode...the view appears with the picker, but no table view. Thanks, in advance, for any help you can offer.

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• c arrays: setting size dynamically?

  - by user336994

  Hello, I am new to C programming. I am trying to set the size of the array using a variable but I am getting an error: Storage size of 'array' isn't constant !! 01 int bound = bound*4; 02 static GLubyte vertsArray[bound]; I have noticed that when I replace bounds (within the brackets on line 02) with the number say '20', the program would run with no problems. But I am trying to set the size of the array dynamically ... Any ideas why I am getting this error ? thanks much,

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• Creating a program to find longest path

  - by stef89

  Hi everyone, I'm fairly new to programming and I'm having a few problems. Basically I have to make a function that will find the lengths of all the paths through a network diagram. I've been working on this for hours but I can't seem to get anywhere. Using recursion I can navigate through every path but I'm just unsure as to how I should record the lengths of the paths. Any help would be greatly appreciated. Thanks! $dependencies = array("","","","1","3","4,2"); $durations = array("5","3","4","11","9","10"); function tracePath($path,$dependencies,$durations,$returnArray=array()) { if($dependencies[$path] != "") { $currentTaskDependencies = preg_split("/[\s]*[,][\s]*/", $dependencies[$path]); for($i=0;$i<count($currentTaskDependencies);$i++) { tracePath($currentTaskDependencies[$i]-1,$dependencies,$durations,$returnArray[$i]); } } return $returnArray; } tracePath(6,$dependencies,$durations);

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• Write a function in c that includes the following sequence of statements [Wont Compile]

  - by Cody

  There is a question in my programming languages textbook that is as follows: Write a C function that includes the following sequence of statements: x = 21; int x; x = 42; Run the program and explain the results. Rewrite the same code in C++ and Java and compare the results. I have written code, and played with it in all three languages but I can not even get it to compile. This includes declaring x above the three lines as well as in the calling function (as this question is obviously attempting to illustrate scoping issues) I'd like to explain the results and do the comparisons on my own, as it is an assignment question but I was wondering if anyone had any insight as to how to get this code to compile? Thanks

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• How do you make Python wait so that you can read the output?

  - by anonnoir

  I've always been a heavy user of Notepad2, as it is fast, feature-rich, and supports syntax highlighting. Recently I've been using it for Python. My problem: when I finish editing a certain Python source code, and try to launch it, the screen disappears before I can see the output pop up. Is there any way for me to make the results wait so that I can read it, short of using an input() or time-delay function? Otherwise I'd have to use IDLE, because of the output that stops for you to read. (My apologies if this question is a silly one, but I'm very new at Python and programming in general.)

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• How do you design a database to allow fast multicolumn searching?

  - by Fletcher Moore

  I am creating a real estate search from RETS data, but this is a general question. When you have a variety of columns that you would like the user to be able to filter their search result by, how do you optimize this? For example, http://www.charlestonrealestateguide.com/listings.php has 16 or so optional filters. Granted, he only has up to 11,000 entries (I have the same data), but I don't imagine the search is performed with just a giant WHERE AND AND AND ... clause. Or is this typically accomplished with one giant multicolumn index? Newegg, Amazon, and countless others also have cool & fast filtering systems for large amounts of data. How do they do it? And is there a database optimization reason for the tendency to provide ranges instead of empty inputs, or is that merely for user convenience?

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• How do I use compiler intrinsic __fmul_?

  - by Eric Thoma

  I am writing a massively parallel GPU application. I have been optimizing it by hand. I received a 20% performance increase with _fdividef(x, y), and according to The Cuda C Programming Guide (section C.2.1), using similar functions for multiplication and adding is also beneficial. The function is stated as this: "_fmulrn,rz,ru,rd". __fdividef(x,y) was not stated with the arguments in brackets. I was wondering, what are those brackets? If I run the simple code: int t = __fmul_(5,4); I a compiler error about how _fmul is undefined. I have the CUDA runtime included, so I don't think it is a setup thing; rather it is something to do with those square brackets. How do I correctly use this function? Thank you.

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• C++ library for Coordinate Transformation Matrices (CTM)?

  - by BastiBense

  I'm looking for a C++ library which allows for easy integration of Coordinate Transformation Matrices (CTM) in my application. You might know CTMs from PDF or PostScript. For one project we are using C++/Qt4 as a framework, which offers a QTransform class, which provides methods like .translate(double x, double y) or .rotate(double degrees). After doing some transformations, it would allow me to get all 6 CTM values, which I could feed into a PDF library or use a transformation matrix in export files. Qt's API also allows for arbitrary mapping of polygons (QPolygon), rectangles (QRect) and other primitive data structures into transformed coordinate systems. So basically I'm looking for something similar to what Qt provides, but without the need of using Qt. I know I could do the matrix multiplications myself, but I'm not really interested in doing so, as I'm very sure that someone already solved this problem, so please no links to books or other guides on how to multiply matrices. Thanks!

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• Preallocate memory for a program in Linux before it gets started

  - by Fyg

  Hi, folks, I have a program that repeatedly solves large systems of linear equations using cholesky decomposition. Characterising is that I sometimes need to store the complete factorisation which can exceed about 20 GB of memory. The factorisation happens inside a library that I call. Furthermore, this matrix and the resulting factorisation changes quite frequently and as such the memory requirements as well. I am not the only person to use this compute-node. Therefore, is there a way to start the program under Linux and preallocate free memory for the process? Something like: $: prealloc -m 25G ./program

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• How does this Perl grep work to determine the union of several hashes?

  - by titaniumdecoy

  I don't understand the last line of this function from Programming Perl 3e. Here's how you might write a function that does a kind of set intersection by returning a list of keys occurring in all the hashes passed to it: @common = inter( \%foo, \%bar, \%joe ); sub inter { my %seen; for my $href (@_) { while (my $k = each %$href) { $seen{$k}++; } } return grep { $seen{$_} == @_ } keys %seen; } I understand that %seen is a hash which maps each key to the number of times it was encountered in any of the hashes provided to the function.

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• What are the best blogs for staying up to date on C#, ASP.NET, LINQ, SQL, C++, Ruby, Java, Python?

  - by Arj

  Apologies if this repeats another - but I couldn't fine one like it. My day to day programming spans a fair number of technologies: C#, ASP.NET, LINQ / SQL, C++, Ruby, Java, Python in approximately that order. It's a struggle to keep up to date on any of best practices, new ideas, innovation and improvements, let alone all. Therefore, what would your top 1 blog be in each of these technologies and which technology do you find easiest to stay up to date with? I'd have a bias towards blogs with broad and high level rather than narrow and detailed content / solutions / examples.

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• Mysqldump create empty sql file? [php & mysql on Windows]

  - by mysqllearner

  Hi all, I tried to dump a database: <?php $dbhost = "localhost"; $dbuser = "XXXX"; $dbpass = "XXXXXXXX"; $dbname = 'testdb'; $list = shell_exec ("C:\wamp\bin\mysql\mysql5.1.33\bin\mysqldump.exe $dbname --user=$dbuser--password=$dbpass > dumpfile.sql"); ?> I tried both specified full path to mysqldump.exe or just use mysqldump, it still give me a 0kb dumpfile.sql Details: Programming Language: PHP Database: MySql 5.XX OS(server): Windows Server 2003. (currently testing on Windows Vista machine) EDIT @ Jeremy Heslop: I tried: shell_exec("C:\wamp\bin\mysql\mysql5.1.33\bin\mysqldump.exe --opt -h $dbhost -u$dbuser -p$dbpass $dbname > test.sql"); safe_mode = off Still no luck man.

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• Finding the angle of a fleeing dodo.

  - by donthackmyacc

  I'm coding some critter AI for a game i am working on for my Unity 3D project. I have no programming background and have been stumbling through this using tutorials and other peoples scripts. My problem is that i want my critter to run directly away from the player when the player kicks it. I need the dodo to run directly away from the player when kicked, and i dont know the math nor the syntax to calculate that angle. They are two characters moving independently through worldspace. Here is what i got so far: waypoint = (fleeWP.transform.position); transform.LookAt(Vector3(waypoint.x, transform.position.y, waypoint.z)); transform.Translate (Vector3.forward * speed * Time.deltaTime); This currently makes the critter move towards the waypoint, rather than away. I might be attacking this all wrong. Please chastise me.

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• PHP vs JSP Which is should I use/learn for my project?

  - by Jon

  I'm planning on making a fitness planning web application for my senior project at school. However, I don't know anything about either technology and my only experience with web development previously was with python and django. I was wondering what people might recommend to learn, what is most useful to learn for the job market, and what would be best for this project. If it matters, the programming languages I know are, C, C++, Java, and Python. My goal of the project is to learn technologies that will make me a more marketable person. Thanks

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• Sending mail via sendmail from python

  - by Nate

  If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process? Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice? I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP. As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to popen('/usr/bin/sendmail', 'w') is a little closer to the metal than I'd like. If the answer is 'go write a library,' so be it ;-)

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• What webservers have support for HTML5 WebSocket?

  - by Jonas

  I would like to experiment with HTML5 WebSockets, and I am looking for a mature webserver with support for websockets. Is there a list of webservers that support websockets? What popular webservers has support for websockets? The server programming language doesn't matter, I know, Java, PHP, Erlang, Python and more... Just want to do some small experiments. I have looked at a few that doesn't support websockets (yet), i.e. Nginx, Apache and Mochiweb.

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• What's the best way to match a query to a set of keywords?

  - by Ryan Detzel

  Pretty much what you would assume Google does. Advertisers come in and big on keywords, lets say "ipod", "ipod nano", "ipod 60GB", "used ipod", etc. Then we have a query, "I want to buy an ipod nano" or "best place to buy used ipods" what kind of algorithms and systems are used to match those queries to the keyword set. I would imagine that some of those keyword sets are huge, 100k keywords made up of one or more actual words. on top of that queries can be 1-n words as well. Any thoughts, links to wikipedia I can start reading? From what I know already I would use some stemmed hash in disk(CDB?) and a bloom filter to check to see if I should even go to disk.

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• Need help for this syntax: "#define LEDs (char *) 0x0003010"

  - by Noge

  I'm doing programming of a softcore processor, Nios II from Altera, below is the code in one of the tutorial, I manage to get the code working by testing it on the hardware (DE2 board), however, I could not understand the code. #define Switches (volatile char *) 0x0003000 #define LEDs (char *) 0x0003010 void main() { while (1) *LEDs = *Switches; } What I know about #define is that, it is either used to define a constant, or a macro, but why in the above code, there are casting like, (char *) 0x0003010, in #define? why the 2 constants, Switches and LEDs act like a variable instead of a constant? Thanks in advance !

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• AVD Failed to Load ~ Failed to Parse Properties ~ Mac OSX

  - by C.D. OKeefe

  I'm going to say upfront, please forgive me. I'm a newbie to android development and fairly new to programming. Also on a Mac. You're going to have to talk...real...slow. I can't get an AVD to load. I've tried it from Eclipse and from the Android SDK Manager. Failed multiple times. Received the same error each time, "Failed to parse properties from Users/myname/.android/avd/nameIGaveEmulator/config.ini." I've the forum here and saw that others have had similar problems, but of the answers given, no one came back to say if they worked, and I don't see anyone with a similar problem on a Mac. If the path needs to be "changed" what exactly does that mean and how do I go about doing so?

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• How to call/execute another ASP.net page from the parent ASP.Net page without disrupting the flow of

  - by NJTechGuy

  When a button/link is clicked, I want this URL to be called followed by the execution of the following statements. The ASP.Net page is in C# btw. Function A statement A call abc.apsx statement B abc.aspx is a silent page, doesn't display anything on the page but creates an output.txt file. So when abc.aspx is called, output.txt file is created and Statement B is executed seamlessly. Hope I made sense. I have no .Net programming knowledge. Please help me. Thank you..

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• How to write applications that modifies the Windows UI?

  - by StevenGilligan

  Hi, I have this programming question that's been bothering me for some time now. I'm wondering how is it possible to write applications that change the Windows UI? More precisely how could you write an application that modifies the Windows Taskbar or the Windows Desktop? I'm really interested in this topic but cannot find a lot of information. I've read about extending the Windows Shell but I can't seem to find anything related to modifying the Taskbar and the Desktop. I'm looking for something along the lines of Rainmeter. How did those guys create an application that lives inside the Windows Desktop? I'd like to point out that my prefered language for this would be C# but if you want to give me hints in other languages I'm fine with it and I am running on Windows 7. Thank you

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• Wanting a type of grid for a pixel editor

  - by wiggles

  Hi, I am currently trying to develop a basic pixel editor application to build up my programming experience with Java. I am designing it so the user has several colour options on, they click on an option and then they can drag over the cells in the grid and they change colour (like a typical image editor, but with a sort of snap on to each grid cell) Any idea of what Java component, if any, is able to implement this type of grid in Java? I had thought of each cell being a JButton, but this seemed terribly inefficient and I don't think it would be possible to change the colour of each cell(button) with out individually clicking on each one. Any help appreciated.

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• What should I do to practice?

  - by simion

  I start a year long industrial placement in September where i will be coding in Java predominantly. I am going to use the summer to brush up on my Java as in year one of the degree Java was the main language taught for OOP modules. However this year i have had no Java exposure except for an algorithms module, which was one of eight, so as you can see i am probably getting really rusty!. What i wanted to know is, how does the "real world" java programming differ from university coding and what do you suggest i brush up on that would be different to my normal workings. As a start I definitely need to get familiar with a professional IDE like NetBeans, opposed to having used BlueJ throughout but more specifically what coding practices should I get more familiar with. I appreciate they wont expect me to be a qualified full developer and will give me time, but I would like to hit the ground running as it were, with me having full hopes to secure a permanent position after I finish my degree.

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