Search Results

Search found 5712 results on 229 pages for 'j random coder'.

Page 187/229 | < Previous Page | 183 184 185 186 187 188 189 190 191 192 193 194 | Next Page >

What is the best "forgot my password" method?

- by Edward Tanguay

I'm programming a community website. I want to build a "forgot my password" feature. Looking around at different sites, I've found they employ one of three options: send the user an email with a link to a unique, hidden URL that allows him to change his password (Gmail and Amazon) send the user an email with a new, randomly generated password (Wordpress) send the user his current password (www.teach12.com) Option #3 seems the most convenient to the user but since I save passwords as an MD5 hash, I don't see how option #3 would be available to me since MD5 is irreversible. This also seems to be insecure option since it means that the website must be saving the password in clear text somewhere, and at the least the clear-text password is being sent over insecure e-mail to the user. Or am I missing something here? So if I can't do option #1, option #2 seems to be the simplest to program since I just have to change the user's password and send it to him. Although this is somewhat insecure since you have to have a live password being communicated via insecure e-mail. However, this could also be misused by trouble-makers to pester users by typing in random e-mails and constantly changing passwords of various users. Option #1 seems to be the most secure but requires a little extra programming to deal with a hidden URL that expires etc., but it seems to be what the big sites use. What experience have you had using/programming these various options? Are there any options I've missed?

Read the article
Preventing iframe caching in browser

- by Zarjay

How do you prevent Firefox and Safari from caching iframe content? I have a simple webpage with an iframe to a page on a different site. Both the outer page and the inner page have HTTP response headers to prevent caching. When I click the "back" button in the browser, the outer page works properly, but no matter what, the browser always retrieves a cache of the iframed page. IE works just fine, but Firefox and Safari are giving me trouble. My webpage looks something like this: <html> <head></head> <body>  <iframe src="webpage2.html?var=xxx" />  </body> </html> The var variable always changes. Despite the fact that the URL of the iframe has changed (and thus, the browser should be making a new request to that page), the browser just fetches the cached content. I've examined the HTTP requests and responses going back and forth, and I noticed that even if the outer page contains <iframe src="webpage2.html?var=222" />, the browser will still fetch webpage2.html?var=111. Here's what I've tried so far: Changing iframe URL with random var value Adding Expires, Cache-Control, and Pragma headers to outer webpage Adding Expires, Cache-Control, and Pragma headers to inner webpage I'm unable to do any JavaScript tricks because I'm blocked by the same-origin policy. I'm running out of ideas. Does anyone know how to stop the browser from caching the iframed content?

Read the article
Editing 8bpp indexed Bitmaps

- by Pedro Sá

hi, i'm trying to edit the pixels of a 8bpp. Since this PixelFormat is indexed i'm aware that it uses a Color Table to map the pixel values. Even though I can edit the bitmap by converting it to 24bpp, 8bpp editing is much faster (13ms vs 3ms). But, changing each value when accessing the 8bpp bitmap results in some random rgb colors even though the PixelFormat remains 8bpp. I'm currently developing in c# and the algorithm is as follows: (C#) 1- Load original Bitmap at 8bpp 2- Create Empty temp Bitmap with 8bpp with the same size as the original 3-LockBits of both bitmaps and, using P/Invoke, calling c++ method where I pass the Scan0 of each BitmapData object. (I used a c++ method as it offers better performance when iterating through the Bitmap's pixels) (C++) 4- Create a int[256] palette according to some parameters and edit the temp bitmap bytes by passing the original's pixel values through the palette. (C#) 5- UnlockBits. My question is how can I edit the pixel values without having the strange rgb colors, or even better, edit the 8bpp bitmap's Color Table? Regards, Pedro

Read the article
Versioning friendly, extendible binary file format

- by Bas Bossink

In the project I'm currently working on there is a need to save a sizable data structure to disk (edit: think dozens of MB's). Being an optimist, I thought that there must be a standard solution for such a problem; however, up to now I haven't found a solution that satisfies the following requirements: .NET 2.0 support, preferably with a FOSS implementation Version friendly (this should be interpreted as: reading an old version of the format should be relatively simple if the changes in the underlying data structure are simple, say adding/dropping fields) Ability to do some form of random access where part of the data can be extended after initial creation (think of this as extending intermediate results) Space and time efficient (XML has been excluded as option given this requirement) Options considered so far: Protocol Buffers: was turned down by verdict of the documentation about Large Data Sets - since this comment suggested adding another layer on top, this would call for additional complexity which I wish to have handled by the file format itself. HDF5,EXI: do not seem to have .net implementations SQLite/SQL Server Compact edition: the data structure at hand would result in a pretty complex table structure that seems too heavyweight for the intended use BSON: does not appear to support requirement 3. Fast Infoset: only seems to have paid .NET implementations. Any recommendations or pointers are greatly appreciated. Furthermore if you believe any of the information above is not true, please provide pointers/examples to prove me wrong.

Read the article
Perl script matching a certain patern

- by kivien

Assuming the file.txt is as follows:- John Depp is a great guy. He is very inteligent. He can do anything. Come and meet John Depp. The perl code is as follows:- open ( FILE, "file.txt" ) || die "can't open file!"; @lines = <FILE>; close (FILE); $string = "John Depp"; foreach $line (@lines) { if ($line =~ $string) { print "$line"; } } The output is going to be first and fourth line. I want to make it working for the file having random line breaks rather than one English sentence per line. I mean it should also work for the following:- John Depp is a great guy. He is very inteligent. He can do anything. Come and meet John Depp. The output should be first and fourth sentence. Any ideas please?

Read the article
Duration of Excessive GC Time in "java.lang.OutOfMemoryError: GC overhead limit exceeded"

- by jilles de wit

Occasionally, somewhere between once every 2 days to once every 2 weeks, my application crashes in a seemingly random location in the code with: java.lang.OutOfMemoryError: GC overhead limit exceeded. If I google this error I come to this SO question and that lead me to this piece of sun documentation which expains: The parallel collector will throw an OutOfMemoryError if too much time is being spent in garbage collection: if more than 98% of the total time is spent in garbage collection and less than 2% of the heap is recovered, an OutOfMemoryError will be thrown. This feature is designed to prevent applications from running for an extended period of time while making little or no progress because the heap is too small. If necessary, this feature can be disabled by adding the option -XX:-UseGCOverheadLimit to the command line. Which tells me that my application is apparently spending 98% of the total time in garbage collection to recover only 2% of the heap. But 98% of what time? 98% of the entire two weeks the application has been running? 98% of the last millisecond? I'm trying to determine a best approach to actually solving this issue rather than just using -XX:-UseGCOverheadLimit but I feel a need to better understand the issue I'm solving.

Read the article
Calling web service using javascript error

- by politrok

Hi , I try to call webservice using json , when i call to web service without excepted parameters , its work , but when i'm try to send parameter , ive got an error : This is my code: function GetSynchronousJSONResponse(url, postData) { var xmlhttp = null; if (window.XMLHttpRequest) xmlhttp = new XMLHttpRequest(); else if (window.ActiveXObject) { if (new ActiveXObject("Microsoft.XMLHTTP")) xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); else xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); } url = url + "?rnd=" + Math.random(); // to be ensure non-cached version xmlhttp.open("POST", url, false); xmlhttp.setRequestHeader("Content-Type", "application/json; charset=utf-8"); xmlhttp.send(postData); var responseText = xmlhttp.responseText; return responseText; } function Test() { var result = GetSynchronousJSONResponse('http://localhost:1517/Mysite/Myservice.asmx/myProc', '{"MyParam":"' + 'test' + '"}'); result = eval('(' + result + ')'); alert(result.d); } This is the error : System.InvalidOperationException: Request format is invalid: application/json; charset=utf-8. at System.Web.Services.Protocols.HttpServerProtocol.ReadParameters() at System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest What is wrong ? Thanks in advance .

Read the article
iPhone: UIImagePickerController Randomly Fails to Take Picture

- by pion

I use a UIPickerViewController to take picture. It works 80% but seemingly at random it fails to take a picture. In tracing the code I found out that it occasionally goes to -PinRecordNewTableViewController:viewDidUnload. That is where it fails because it set nil to all ivars. @interface PinRecordNewTableViewController : UITableViewController { } ... @implementation PinRecordNewTableViewController ... - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { ... PinRecordNewPicture *pinRecordNewPicture = [[PinRecordNewPicture alloc] initWithNibName:@"PinRecordNewPicture" bundle:nil]; pinRecordNewPicture.delegate = self; [self.navigationController pushViewController:pinRecordNewPicture animated:YES]; [pinRecordNewPicture release]; ... } @interface PinRecordNewPicture : UIViewController ... @implementation PinRecordNewPicture ... - (void)picturePicker:(UIImagePickerControllerSourceType)theSource { UIImagePickerController *picker = [[UIImagePickerController alloc] init]; picker.delegate = self; picker.sourceType = theSource; picker.allowsEditing = YES; [self presentModalViewController:picker animated:YES]; [picker release]; } - (IBAction) takePicture:(id)sender { UIImagePickerControllerSourceType source = UIImagePickerControllerSourceTypeCamera; if ([UIImagePickerController isSourceTypeAvailable:source]) { [self picturePicker:source]; } What did I do wrong? Did I miss something that causes it to behave "randomly"? Thanks in advance for your help.

Read the article
How to get the coordinate of Gridlayout

- by Jessy

Hi, I set my JPanel to GridLayout (6,6), with dimension (600,600) Each cell of the grid will display one pictures with different widths and heights. The picture first add to a JLabel, and the JLabel then added to the cells. How can retrieved the coordinate of the pictures in the cells and not the coordinate of cells? So far the out give these coordinate which equal height and width even on screen the pictures showed in different sizes. e.g. java.awt.Rectangle[x=100,y=100,width=100,height=100] java.awt.Rectangle[x=200,y=100,width=100,height=100] java.awt.Rectangle[x=300,y=100,width=100,height=100] The reason why I used GridLayout instead of gridBagLayout is that, I want each pictures to have boundary. If I use GridBagLayout, the grid will expand according to the picture size. I want grid size to be in fix size. JPanel pDraw = new JPanel(new GridLayout(6,6)); pDraw.setPreferredSize(new Dimension(600,600)); for (int i =0; i<(6*6); i++) { //get random number for height and width of the image int x = rand.nextInt(40)+(50); int y = rand.nextInt(40)+(50); ImageIcon icon = createImageIcon("bird.jpg"); //rescale the image according to the size selected Image img = icon.getImage().getScaledInstance(x,y,img.SCALE_SMOOTH); icon.setImage(img ); JLabel label = new JLabel(icon); pDraw.add(label); } for(Component component:components) { //retrieve the coordinate System.out.println(component.getBounds()); }

Read the article
How to detect hidden field tampering?

- by Myron

On a form of my web app, I've got a hidden field that I need to protect from tampering for security reasons. I'm trying to come up with a solution whereby I can detect if the value of the hidden field has been changed, and react appropriately (i.e. with a generic "Something went wrong, please try again" error message). The solution should be secure enough that brute force attacks are infeasible. I've got a basic solution that I think will work, but I'm not security expert and I may be totally missing something here. My idea is to render two hidden inputs: one named "important_value", containing the value I need to protect, and one named "important_value_hash" containing the SHA hash of the important value concatenated with a constant long random string (i.e. the same string will be used every time). When the form is submitted, the server will re-compute the SHA hash, and compare against the submitted value of important_value_hash. If they are not the same, the important_value has been tampered with. I could also concatenate additional values with the SHA's input string (maybe the user's IP address?), but I don't know if that really gains me anything. Will this be secure? Anyone have any insight into how it might be broken, and what could/should be done to improve it? Thanks!

Read the article
LINQ to SQL - Tracking New / Dirty Objects

- by Joseph Sturtevant

Is there a way to determine if a LINQ object has not yet been inserted in the database (new) or has been changed since the last update (dirty)? I plan on binding my UI to LINQ objects (using WPF) and need it to behave differently depending whether or not the object is already in the database. MyDataContext context = new MyDataContext(); MyObject obj; if (new Random().NextDouble() > .5) obj = new MyObject(); else obj = context.MyObjects.First(); // How can I distinguish these two cases? The only simple solution I can think of is to set the primary key of new records to a negative value (my PKs are an identity field and will therefore be set to a positive integer on INSERT). This will only work for detecting new records. It also requires identity PKs, and requires control of the code creating the new object. Is there a better way to do this? It seems like LINQ must be internally tracking the status of these objects so that it can know what to do on context.SubmitChanges(). Is there some way to access that "object status"? Clarification Apparently my initial question was confusing. I'm not looking for a way to insert or update records. I'm looking for a way, given any LINQ object, to determine if that object has not been inserted (new) or has been changed since its last update (dirty).

Read the article
Alternative native api for Process.Start

- by Akash Kava

Ok this is not duplicate of "http://stackoverflow.com/questions/2065592/alternative-to-process-start" because my question is something different here. I need to run a process and wait till execution of process and get the output of console. There is way to set RedirectStandardOutput and RedirectStandardError to true, however this does not function well on some machines, (where .NET SDK is not installed), only .NET runtime is installed, now it works on some machines and doesnt work on some machines so we dont know where is the problem. I have following code, ProcessStartInfo info = new ProcessStartInfo("myapp.exe", cmd); info.CreateNoWindow = true; info.UseShellExecute = false; info.RedirectStandardError = true; info.RedirectStandardOutput = true; Process p = Process.Start(info); p.WaitForExit(); Trace.WriteLine(p.StandardOutput.ReadToEnd()); Trace.WriteLine(p.StandardError.ReadToEnd()); On some machines, this will hang forever on p.WaitForExit(), and one some machine it works correctly, the behaviour is so random and there is no clue. Now if I can get a real good workaround for this using pinvoke, I will be very happy.

Read the article
iPad + OpenGL ES2. Why the Puzzling Virtual Memory Spike During Device Reorientation?

- by dugla

I've been spending the afternoon starring at Xcode Instruments memory monitor trying to decipher the following memory issue. I have a fullscreen OpenGL ES2 app running on iPad. I am fanatical about memory issues so my retains/releases are all nicely balanced. I closely monitor memory leaks. My app is basically squeeky clean. Except occassionally when I reorient the device. Portrait to Landscape. Back and forth I rock the device stress testing my discarding and rebuilding of the OpenGL framebuffer. The ambient memory footprint of my app is about 70MB Real Mems and 180MB Virtual Mems. Real memory hardly varies at all during device rotations. However the virtual mems reading sometimes briefly spikes up to 250MB and then recedes back to 180MB. No real pattern. But clearly related discarding/rebuilding the framebuffer. I see random memory warnings in my NSlogs but the app just hums along, no worries. 1) Since iPhone OS devices don't have VM could someone explain to me what the VM reading actually means? 2) My app totally leak free and generally bulletproof dispite the VM spikes. Never crashes. Rock solid. Should I be concerned about this? 3) There is clearly something happening in OpenGL framebuffer land that is causing this but I am using the API in the proper way: paraphrasing: Discarding the framebuffer: glDeleteRenderbuffers(1, &m_colorbuffer); glDeleteFramebuffers(1, &m_framebuffer); Rebuilding the framebuffer: glGenFramebuffers(1, &m_framebuffer); glGenRenderbuffers(1, &m_colorbuffer); Is there some other memory flushing trick I have missed? Thanks for any insight. Cheers, Doug

Read the article
What Is The Proper Location For One-Offs In VCS Repos?

- by Joe Clark

I have recently started using Mercurial as our VCS. Over the years, I have used RCS, CVS, and - for the last 5 years - SVN. Back 13 years ago, when I primarily used CVS and RCS, large projects went into CVS and one-offs were edited in place on the specific server and stored in RCS. This worked well as the one-offs were usually specific to the server and the servers were backed up nightly. Jump forward a decade and a lot of the one-off scripts became less centralized - they might be needed on any server at some random time. This was also OK, because now I was a begrudging SVN user. Everything (except for docs) got dumped into one repo. Jump to 2010. Now I am using Mercurial and am putting large projects in their own repo again. But what to do with the one-offs? The options as I see them: A repo for each script. It seems a bit cluttered to create a repo for every one page script that might get ran once a year. RCS Not an option. There are many possible servers that might need a specific script. Continuing to use SVN just for one-offs. No. There no advantage I see over the next option. Create a repo in Mercurial named "one-offs". This seems the most workable. The last option seems the best to me - however; is there a best practice regarding this? You also might be wondering if these scripts are truly one-offs if they will be reused. Some of them may be reused 6 months or a year from now - some, never. However, nearly all of them involve several man-hours of work due to either complex logic or extensive error checking. Simply discarding them is not efficient.

Read the article
Media query from a specific folder

- by sensei

I would like to understand how I can use a cursor to jpg files in a folder specified in the sdcard. I'm trying to select with a cursor the jpg files in a specific folder, and I tried this: This is the code: public static Uri getRandomImage(ContentResolver resolver) { String[] projection = new String[] { BaseColumns._ID, }; String folder = "/sdcard/DCIM/Wallpaper/"; folder = folder + "%"; Uri uri = Media.EXTERNAL_CONTENT_URI; String[] whereArgs = new String[]{folder}; Cursor cursor = resolver.query(uri, projection, null, whereArgs, MediaColumns._ID); if (cursor == null || cursor.getCount() <= 0) { return null; } cursor.moveToPosition(new Random().nextInt(cursor.getCount())); return Uri.withAppendedPath(uri, cursor.getString(0)); } but this code gives me error here is the logcat: E/AndroidRuntime(11986): FATAL EXCEPTION: main E/AndroidRuntime(11986): android.database.sqlite.SQLiteException: bind or column index out of range: handle 0x26a490 E/AndroidRuntime(11986): at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:158) E/AndroidRuntime(11986): at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:114) E/AndroidRuntime(11986): at android.content.ContentProviderProxy.bulkQueryInternal(ContentProviderNative.java:330) E/AndroidRuntime(11986): at android.content.ContentProviderProxy.query(ContentProviderNative.java:366) E/AndroidRuntime(11986): at android.content.ContentResolver.query(ContentResolver.java:245) E/AndroidRuntime(11986): at it.bisemanuDEV.slidepuzzle.SelectImagePreference.getRandomImage(SelectImagePreference.java:126) E/AndroidRuntime(11986): at it.bisemanuDEV.slidepuzzle.TileView.newGame(TileView.java:156) E/AndroidRuntime(11986): at it.bisemanuDEV.slidepuzzle.SlidePuzzleActivity.onOptionsItemSelected(SlidePuzzleActivity.java:377) E/AndroidRuntime(11986): at android.app.Activity.onMenuItemSelected(Activity.java:2762) E/AndroidRuntime(11986): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:730) E/AndroidRuntime(11986): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:143) E/AndroidRuntime(11986): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:855) E/AndroidRuntime(11986): at com.android.internal.view.menu.IconMenuView.invokeItem(IconMenuView.java:532) E/AndroidRuntime(11986): at com.android.internal.view.menu.IconMenuItemView.performClick(IconMenuItemView.java:122) E/AndroidRuntime(11986): at android.view.View$PerformClick.run(View.java:8819) E/AndroidRuntime(11986): at android.os.Handler.handleCallback(Handler.java:603) E/AndroidRuntime(11986): at android.os.Handler.dispatchMessage(Handler.java:92) E/AndroidRuntime(11986): at android.os.Looper.loop(Looper.java:123) E/AndroidRuntime(11986): at android.app.ActivityThread.main(ActivityThread.java:4627) E/AndroidRuntime(11986): at java.lang.reflect.Method.invokeNative(Native Method) E/AndroidRuntime(11986): at java.lang.reflect.Method.invoke(Method.java:521) E/AndroidRuntime(11986): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) E/AndroidRuntime(11986): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) E/AndroidRuntime(11986): at dalvik.system.NativeStart.main(Native Method)

Read the article
Bubble Breaker Game Solver better than greedy?

- by Gregory

For a mental exercise I decided to try and solve the bubble breaker game found on many cell phones as well as an example here:Bubble Break Game The random (N,M,C) board consists N rows x M columns with C colors The goal is to get the highest score by picking the sequence of bubble groups that ultimately leads to the highest score A bubble group is 2 or more bubbles of the same color that are adjacent to each other in either x or y direction. Diagonals do not count When a group is picked, the bubbles disappear, any holes are filled with bubbles from above first, ie shift down, then any holes are filled by shifting right A bubble group score = n * (n - 1) where n is the number of bubbles in the bubble group The first algorithm is a simple exhaustive recursive algorithm which explores going through the board row by row and column by column picking bubble groups. Once the bubble group is picked, we create a new board and try to solve that board, recursively descending down Some of the ideas I am using include normalized memoization. Once a board is solved we store the board and the best score in a memoization table. I create a prototype in python which shows a (2,15,5) board takes 8859 boards to solve in about 3 seconds. A (3,15,5) board takes 12,384,726 boards in 50 minutes on a server. The solver rate is ~3k-4k boards/sec and gradually decreases as the memoization search takes longer. Memoization table grows to 5,692,482 boards, and hits 6,713,566 times. What other approaches could yield high scores besides the exhaustive search? I don't seen any obvious way to divide and conquer. But trending towards larger and larger bubbles groups seems to be one approach Thanks to David Locke for posting the paper link which talks above a window solver which uses a constant-depth lookahead heuristic.

Read the article
mysql error in php

- by fusion

i'm trying to run this php code which should display a quote from mysql, but can't figure out where is it going wrong. the result variable is null or empty. can someone help me out. thanks! <?php include 'config.php'; // 'text' is the name of your table that contains // the information you want to pull from $rowcount = mysql_query("select count(*) as rows from quotes"); // Gets the total number of items pulled from database. while ($row = mysql_fetch_assoc($rowcount)) { $max = $row["rows"]; //print_r ($max); } // Selects an item's index at random $rand = rand(1,$max)-1; print_r ($rand); $result = mysql_query("select * from quotes limit $rand, 1") or die ('Error: '.mysql_error()); if (!$result or mysql_num_rows($result)) { echo "Empty"; } else{ while ($row = mysql_fetch_array($result)) { $randomOutput = $row['cQuotes']; echo '<p>' . $randomOutput . '</p>'; } }

Read the article
Silverlight 4 race condition with DataGrid master details control

- by Simon_Weaver

Basically I want a DataGrid (master) and details (textbox), where DataGrid is disabled during edit of details (forcing people to save/cancel)... Here's what I have... I have a DataGrid which serves as my master data. <data:DataGrid IsEnabled="{Binding CanLoad,ElementName=dsReminders}" ItemsSource="{Binding Data, ElementName=dsReminders}" > Its data comes from a DomainDataSource: <riaControls:DomainDataSource Name="dsReminders" AutoLoad="True" ... I have a bound Textbox which is the 'details' (very simple right now). There are buttons (Save/Cancel) which should be enabled when user tries to edit the text. Unfortunately Silverlight doesn't support UpdateSourceTrigger=PropertyChanged so I have to raise an event: <TextBox Text="{Binding SelectedItem.AcknowledgedNote, Mode=TwoWay, UpdateSourceTrigger=Explicit, ElementName=gridReminders}" TextChanged="txtAcknowledgedNote_TextChanged"/> The event to handle this calls BindingExpression.UpdateSource to update the source immediately: private void txtAcknowledgedNote_TextChanged(object sender, TextChangedEventArgs e) { BindingExpression be = txtAcknowledgedNote.GetBindingExpression(TextBox.TextProperty); be.UpdateSource(); } IN other words - typing in the textbox causes CanLoad of the DomainDataSource to become False (because we're editing). This in turn disables the DataGrid (IsEnabled is bound to it) and enables 'Cancel' and 'Save' buttons. However I'm running up against a race condition if I move quickly through rows in the DataGrid (just clicking random rows). The TextChanged presumably is being called on the textbox and confusing the DomainDataSource which then thinks there's been a change. So how should I disable the DataGrid while editing without having the race condition? One obvious solution would be to use KeyDown events to trigger the call to UpdateSource but I always hate having to do that.

Read the article
Programming Technique: How to create a simple card game

- by Shyam

Hi, As I am learning the Ruby language, I am getting closer to actual programming. So I was thinking of creating a simple card game. My question isn't Ruby orientated, but I do know want to learn how to solve this problem with a genuine OOP approach. In my card game I want to have four players. Using a standard deck with 52 cards, no jokers/wildcards. In the game I won't use the Ace as a dual card, it is always the highest card. So, the programming problems I wonder about are the following: How can I sort/randomize the deck of cards? There are four types, each having 13 values. Eventually there can be only unique values, so picking random values could generate duplicates. How can I implement a simple AI? As there are tons of card games, someone would have figured this part out already, so references would be great. I am a truly Ruby nuby, and my goal here is to learn to solve problems, so pseudo code would be great, just to understand how to solve the problem programmatically. I apologize for my grammar and writing style if it's unclear, for it is not my native language. Also pointers to sites where such challenges are explained, would be a great resource! Thank you for your comments, answers and feedback!

Read the article
Concat LPSTR in C++

- by Cat Man Do

Trying to use as basic C++ as I can to build a list of numbers from 1-52 in a random order (deck of cards). Unfortauntely, all my attempts to concat the strings and get a result end in failure. Any suggestions? NOTE: This is not homework it's something I'm using to create a game. // Locals char result[200] = ""; // Result int card[52]; // Array of cards srand(time(0)); // Initialize seed "randomly" // Build for (int i=0; i<52; i++) { card[i] = i; // fill the array in order } // Shuffle cards for (int i=0; i<(52-1); i++) { int r = i + (rand() % (52-i)); int temp = card[i]; card[i] = card[r]; card[r] = temp; } // Build result for (int c=0; c<52; c++) { // Build sprintf(result, "%d", card[c]); // Comma? if ( c < 51 ) { sprintf(result, "%s", ","); } } My end result is always garbled text. Thanks for the help.

Read the article
Securely store a password in program code?

- by Nick

My application makes use of the RijndaelManaged class to encrypt data. As a part of this encryption, I use a SecureString object loaded with a password which get's get converted to a byte array and loaded into the RajindaelManaged object's Key at runtime. The question I have is the storage of this SecureString. A user entered password can be entered at run-time, and that can be "securely" loaded into a SecureString object, but if no user entered password is given, then I need to default to something. So ultimately the quesiton comes down to: If I have to have some known string or byte array to load into a SecureString object each time my application runs, how do I do that? The "encrypted" data ultimately gets decrypted by another application, so even if no user entered password is specified, I still need the data to be encrypted while it goes from one app to another. This means I can't have the default password be random, because the other app wouldn't be able to properly decrypt it. One possible solution I'm thinking is to create a dll which only spits out a single passphrase, then I use that passphrase and run it through a couple of different hashing/reorganizing functions at runtime before I ultimately feed it into the secureString object. Would this be secure enough?

Read the article
Trouble with Berkeley DB JE Base API Secondary Databases and Sequences

- by milosz

I have a class Document which consists of Id (int) and Url (String). I would like to have a primary index on Id and secondary index on Url. I would also like to have a sequence for Id auto-incrementation. So I create a SecondaryDatabase and then I create a Sequence. During initialisation of the Sequence I get an exception: Exception in thread "main" java.lang.IllegalArgumentException at com.sleepycat.util.UtfOps.getCharLength(UtfOps.java:137) at com.sleepycat.util.UtfOps.bytesToString(UtfOps.java:259) at com.sleepycat.bind.tuple.TupleInput.readString(TupleInput.java:152) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyDocumentBiding.entryToObject(MyDocumentBiding.java:12) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyDocumentBiding.entryToObject(MyDocumentBiding.java:1) at com.sleepycat.bind.tuple.TupleBinding.entryToObject(TupleBinding.java:76) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.UrlKeyCreator.createSecondaryKey(UrlKeyCreator.java:20) at com.sleepycat.je.SecondaryDatabase.updateSecondary(SecondaryDatabase.java:835) at com.sleepycat.je.SecondaryTrigger.databaseUpdated(SecondaryTrigger.java:42) at com.sleepycat.je.Database.notifyTriggers(Database.java:2004) at com.sleepycat.je.Cursor.putNotify(Cursor.java:1692) at com.sleepycat.je.Cursor.putInternal(Cursor.java:1616) at com.sleepycat.je.Cursor.putNoOverwrite(Cursor.java:663) at com.sleepycat.je.Sequence.<init>(Sequence.java:188) at com.sleepycat.je.Database.openSequence(Database.java:546) at pl.edu.mimuw.zbd.berkeley.zadanie.rozwiazanie.MyFullTextSearchEngine.init(MyFullTextSearchEngine.java:131) at pl.edu.mimuw.zbd.berkeley.zadanie.testy.MyFullTextSearchEngineTest.main(MyFullTextSearchEngineTest.java:18) It seems that during the initialisation of the sequence the secondary database is forced to update. When I debug the entryToObject method of MyDocumentBiding the bytes that it tries to convert to object seem random. What am I doing wrong?

Read the article
Excel VBA Userform Combobox problem

- by Marc

I'm having difficulties with a Combobox in a userform in an Excel document. The combobox either doesn't appear in the userform, or the combobox remains blank, and when I enter any character in it, the list of items appears, but 2 or 3 times, instead of just once. When I select an item, the chosen item doesn't appear in the box. It seems as if Excel^picks one at random, and whichever item I choose from the list, it's always the same one that ends up being displayed in the box. Can anyone help me on this one? Thanks a lot!!! This is the code I used: Private Sub ComboBox1_Change() Select Case ComboBox1.Text Case "Een nieuwe start" Case "Alles heeft zijn tijd" Case "De wereld aan je voeten" Case "Een levend boek" Case "Drempels" Case "Kerstmis" Case "Confituur of choco" Case "Hoe groot is de hemel?" Case "Ongelovige Thomas" Case "Feesten" Case "Er is er één jarig!" Case "Eén van hart" Case "Ervoor gaan" Case "Groen gras" Case "RELatie" Case "Vele plaatjes" Case "Iedereen fan" Case "Schattenjacht" Case "Lichtbakens" Case "Rijke Luis" Case "Hemel op aarde" Case "Op bezoek" Case Else End Select End Sub Private Sub UserForm1_Initialize() ComboBox1.Clear ComboBox1.AddItem "Een nieuwe start" ComboBox1.AddItem "Alles heeft zijn tijd" ComboBox1.AddItem "De wereld aan je voeten" ComboBox1.AddItem "Een levend boek" ComboBox1.AddItem "Drempels" ComboBox1.AddItem "Kerstmis" ComboBox1.AddItem "Confituur of choco" ComboBox1.AddItem "Hoe groot is de hemel?" ComboBox1.AddItem "Ongelovige Thomas" ComboBox1.AddItem "Feesten" ComboBox1.AddItem "Er is er één jarig!" ComboBox1.AddItem "Eén van hart" ComboBox1.AddItem "Ervoor gaan" ComboBox1.AddItem "Groen gras" ComboBox1.AddItem "RELatie" ComboBox1.AddItem "Vele plaatjes" ComboBox1.AddItem "Iedereen fan" ComboBox1.AddItem "Schattenjacht" ComboBox1.AddItem "Lichtbakens" ComboBox1.AddItem "Rijke Luis" ComboBox1.AddItem "Hemel op aarde" ComboBox1.AddItem "Op bezoek" ComboBox1.Text = ComboBox1.List(0) End Sub

Read the article
Learning AES: the KeyBytes

- by Tom Brito

I got the following example from here: import java.security.Security; import javax.crypto.Cipher; import javax.crypto.spec.SecretKeySpec; public class MainClass { public static void main(String[] args) throws Exception { Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider()); byte[] input = "www.java2s.com".getBytes(); byte[] keyBytes = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17 }; SecretKeySpec key = new SecretKeySpec(keyBytes, "AES"); Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC"); System.out.println(new String(input)); // encryption pass cipher.init(Cipher.ENCRYPT_MODE, key); byte[] cipherText = new byte[cipher.getOutputSize(input.length)]; int ctLength = cipher.update(input, 0, input.length, cipherText, 0); ctLength += cipher.doFinal(cipherText, ctLength); System.out.println(new String(cipherText)); System.out.println(ctLength); // decryption pass cipher.init(Cipher.DECRYPT_MODE, key); byte[] plainText = new byte[cipher.getOutputSize(ctLength)]; int ptLength = cipher.update(cipherText, 0, ctLength, plainText, 0); ptLength += cipher.doFinal(plainText, ptLength); System.out.println(new String(plainText)); System.out.println(ptLength); } } I imagine that the byte[] keyBytes should be random generated, so I gone to test the max size before do it. When adding one more byte 0x18 to the array, the exception raised: InvalidKeyException: Key length not 128/192/256 bits. But the original 18 bytes (from 0 to 17) are not multiple of nither 128, 192 or 256. I would like to understand the math here.. can anyone explain me? Thanks!

Read the article
Evolutionary Algorithms: Optimal Repopulation Breakdowns

- by Brian MacKay

It's really all in the title, but here's a breakdown for anyone who is interested in Evolutionary Algorithms: In an EA, the basic premise is that you randomly generate a certain number of organisms (which are really just sets of parameters), run them against a problem, and then let the top performers survive. You then repopulate with a combination of crossbreeds of the survivors, mutations of the survivors, and also a certain number of new random organisms. Do that several thousand times, and efficient organisms arise. Some people also do things like introduce multiple "islands" of organisms, which are seperate populations that are allowed to crossbreed once in awhile. So, my question is: what are the optimal repopulation percentages? I have been keeping the top 10% performers, and repopulating with 30% crossbreeds and 30% mutations. The remaining 30% is for new organisms. I have also tried out the multiple island theory, and I'm interested in your results on that as well. It is not lost on me that this is exactly the type of problem an EA could solve. Are you aware of anyone trying that? Thanks in advance!

Read the article

< Previous Page | 183 184 185 186 187 188 189 190 191 192 193 194 | Next Page >