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  • Simple encryption - Sum of Hashes in C

    - by Dogbert
    I am attempting to demonstrate a simple proof of concept with respect to a vulnerability in a piece of code in a game written in C. Let's say that we want to validate a character login. The login is handled by the user choosing n items, (let's just assume n=5 for now) from a graphical menu. The items are all medieval themed: eg: _______________________________ | | | | | Bow | Sword | Staff | |-----------|-----------|-------| | Shield | Potion | Gold | |___________|___________|_______| The user must click on each item, then choose a number for each item. The validation algorithm then does the following: Determines which items were selected Drops each string to lowercase (ie: Bow becomes bow, etc) Calculates a simple string hash for each string (ie: `bow = b=2, o=15, w=23, sum = (2+15+23=40) Multiplies the hash by the value the user selected for the corresponding item; This new value is called the key Sums together the keys for each of the selected items; this is the final validation hash IMPORTANT: The validator will accept this hash, along with non-zero multiples of it (ie: if the final hash equals 1111, then 2222, 3333, 8888, etc are also valid). So, for example, let's say I select: Bow (1) Sword (2) Staff (10) Shield (1) Potion (6) The algorithm drops each of these strings to lowercase, calculates their string hashes, multiplies that hash by the number selected for each string, then sums these keys together. eg: Final_Validation_Hash = 1*HASH(Bow) + 2*HASH(Sword) + 10*HASH(Staff) + 1*HASH(Shield) + 6*HASH(Potion) By application of Euler's Method, I plan to demonstrate that these hashes are not unique, and want to devise a simple application to prove it. in my case, for 5 items, I would essentially be trying to calculate: (B)(y) = (A_1)(x_1) + (A_2)(x_2) + (A_3)(x_3) + (A_4)(x_4) + (A_5)(x_5) Where: B is arbitrary A_j are the selected coefficients/values for each string/category x_j are the hash values for each string/category y is the final validation hash (eg: 1111 above) B,y,A_j,x_j are all discrete-valued, positive, and non-zero (ie: natural numbers) Can someone either assist me in solving this problem or point me to a similar example (ie: code, worked out equations, etc)? I just need to solve the final step (ie: (B)(Y) = ...). Thank you all in advance.

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  • Stored procedure woes ... inserting binary ...

    - by Wardy
    Ok so I have this storedproc in my SQL 2008 database (works in 2005 too / used to) ... CREATE PROCEDURE [dbo].[SetBinaryContent] @Ref nvarchar(50), @Content varbinary(MAX), @ObjectID uniqueidentifier AS BEGIN DELETE ObjectContent WHERE ObjectId = @ObjectID AND Ref = @Ref IF DATALENGTH(@Content) > 5 BEGIN INSERT INTO ObjectContent (Ref,BinaryContent,ObjectId) VALUES (@Ref,@Content,@ObjectId) END UPDATE Objects SET [Status] = 1 WHERE ID = @ObjectID END Relatively simple, I take a byte array in C# and chuck it in @Content i then give it a guid and string for the other params and off we go. ... Great, it used to work ... but it don't anymore ... so erm ... What's wrong with this stored proc? I've stepped through my C# code thinking I screwed up somehow in that but it definately adds the params and gives them the correct values so what would cause the server to just stop executing this storedproc correctly? When called this proc executes but nothing changes in the db ... no new records are added to the ObjectContent table. Weird huh ...

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  • Bind a generic list to a listbox and also use a datatemplate

    - by muku
    Hello, I'm trying to implement something quite simple but I'm on my first steps in WPF and I'm having some problems. I have a class called Component which has a property called Vertices. Vertices is a generic List of type Point. What I want is to bind the vertices property to a listbox. This is easy by using this code in my XAML in the listbox declaration: ItemsSource="{Binding Path=Component.Vertices, Mode=OneWay, Converter={StaticResource verticesconverter},UpdateSourceTrigger=PropertyChanged}" The tricky part is when I try to create a datatemplate for the listbox. I want each row of the listbox to display a textbox with the values of the Vertex (Point.X, Point.Y) and a button to allow me to delete the item. Could you help me on the datatemplate definition. The code below doesn't work to bind the X,Y values into two separate textboxes. Could you point me on the mistake and why nothing is displayed in the textboxes? <ListBox ItemsSource="{Binding Path=Component.Vertices, Mode=OneWay,UpdateSourceTrigger=PropertyChanged}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal" Margin="0,10,0,0"> <TextBox Text="{Binding X}" MinWidth="35" MaxWidth="35"/> <TextBox Text="{Binding Y}" MinWidth="35" MaxWidth="35"/> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> /ListBox>

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  • Is there a language with native pass-by-reference/pass-by-name semantics, which could be used in mod

    - by Bubba88
    Hi! This is a reopened question. I look for a language and supporting platform for it, where the language could have pass-by-reference or pass-by-name semantics by default. I know the history a little, that there were Algol, Fortran and there still is C++ which could make it possible; but, basically, what I look for is something more modern and where the mentioned value pass methodology is preferred and by default (implicitly assumed). I ask this question, because, to my mind, some of the advantages of pass-by-ref/name seem kind of obvious. For example when it is used in a standalone agent, where copyiong of values is not necessary (to some extent) and performance wouldn't be downgraded much in that case. So, I could employ it in e.g. rich client app or some game-style or standalone service-kind application. The main advantage to me is the clear separation between identity of a symbol, and its current value. I mean when there is no reduntant copying, you know that you're working with the exact symbol/path you have queried/received. And intristing boxing of values will not interfere with the actual logic of program. I know that there is C# ref keyword, but it's something not so intristic, though acceptable. Equally, I realize that pass-by-reference semantics could be simulated in virtually any language (Java as an instant example) and so on.. not sure about pass by name :) What would you recommend - create a something like DSL for such needs wherever it be appropriate; or use some languages that I already know? Maybe, there is something that I'm missing? Thank you!

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  • Using the contents of an array to set individual pixels in a Quartz bitmap context

    - by Magic Bullet Dave
    I have an array that contains the RGB colour values for each pixel in a 320 x 180 display. I would like to be able to set individual pixel values in the a bitmap context of the same size offscreen then display the bitmap context in a view. It appears that I have to create 1x1 rects and either put a stroke on them or a line of length 1 at the point in question. Is that correct? I'm looking for a very efficient way of getting the array data onto the graphics context as you can imagine this is going to be an image buffer that cycles at 25 frames per second and drawing in this way seems inefficient. I guess the other question is should I use OPENGL ES instead? Thoughts/best practice would be much appreciated. Regards Dave OK, have come a short way, but can't make the final hurdle and I am not sure why this isn't working: - (void) displayContentsOfArray1UsingBitmap: (CGContextRef)context { long bitmapData[WIDTH * HEIGHT]; // Build bitmap int i, j, h; for (i = 0; i < WIDTH; i++) { for (j = 0; j < HEIGHT; j++) { h = frameBuffer01[i][j]; bitmapData[i * j] = h; } } // Blit the bitmap to the context CGDataProviderRef providerRef = CGDataProviderCreateWithData(NULL, bitmapData,4 * WIDTH * HEIGHT, NULL); CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB(); CGImageRef imageRef = CGImageCreate(WIDTH, HEIGHT, 8, 32, WIDTH * 4, colorSpaceRef, kCGImageAlphaFirst, providerRef, NULL, YES, kCGRenderingIntentDefault); CGContextDrawImage(context, CGRectMake(0.0, HEIGHT, WIDTH, HEIGHT), imageRef); CGImageRelease(imageRef); CGColorSpaceRelease(colorSpaceRef); CGDataProviderRelease(providerRef); }

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  • copy rows before updating them to preserve archive in Postgres

    - by punkish
    I am experimenting with creating a table that keeps a version of every row. The idea is to be able to query for how the rows were at any point in time even if the query has JOINs. Consider a system where the primary resource is books, that is, books are queried for, and author info comes along for the ride CREATE TABLE authors ( author_id INTEGER NOT NULL, version INTEGER NOT NULL CHECK (version > 0), author_name TEXT, is_active BOOLEAN DEFAULT '1', modified_on TIMESTAMP DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (author_id, version) ) INSERT INTO authors (author_id, version, author_name) VALUES (1, 1, 'John'), (2, 1, 'Jack'), (3, 1, 'Ernest'); I would like to be able to update the above like so UPDATE authors SET author_name = 'Jack K' WHERE author_id = 1; and end up with 2, 1, Jack, t, 2012-03-29 21:35:00 2, 2, Jack K, t, 2012-03-29 21:37:40 which I can then query with SELECT author_name, modified_on FROM authors WHERE author_id = 2 AND modified_on < '2012-03-29 21:37:00' ORDER BY version DESC LIMIT 1; to get 2, 1, Jack, t, 2012-03-29 21:35:00 Something like the following doesn't really work CREATE OR REPLACE FUNCTION archive_authors() RETURNS TRIGGER AS $archive_author$ BEGIN IF (TG_OP = 'UPDATE') THEN -- The following fails because author_id,version PK already exists INSERT INTO authors (author_id, version, author_name) VALUES (OLD.author_id, OLD.version, OLD.author_name); UPDATE authors SET version = OLD.version + 1 WHERE author_id = OLD.author_id AND version = OLD.version; RETURN NEW; END IF; RETURN NULL; -- result is ignored since this is an AFTER trigger END; $archive_author$ LANGUAGE plpgsql; CREATE TRIGGER archive_author AFTER UPDATE OR DELETE ON authors FOR EACH ROW EXECUTE PROCEDURE archive_authors(); How can I achieve the above? Or, is there a better way to accomplish this? Ideally, I would prefer to not create a shadow table to store the archived rows.

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  • Designing a silverlight dashboard with mef - is it possible? (with dynamic loading of xaps)

    - by Tim Robbin
    Hello! I am just trying to wrap my head around MEF. And as I am really going to love it ( I guess ) I started my first sample project and immediatly stumbled into a big problem and now I am asking myself if I can use MEF for my scenario at all and that is the following: Imagine that one got some kind of dashboard with, let's say, five regions and above each region there are two comboboxes. The values in the first combobox represent different possible views (for example, chartControl, tableControl, pictureControl, ...) and the values of the second combobox represents the different data sources for the currently selected control. As the controls are very big in size one wants to download them as needed. If the user selects one comboboxitem the corresponding control xap should be loaded and displayed in this specific region. If the user selectes another control in the same combobox the control should be removed from the visualtree and the next control should be downloaded and displayed. If the user changes the selection in a different combobox the corresponding control should be loaded again only in this specific region, with perhaps different data. And to make it a little more interesting - as this is some kind of dashboard one can change the layout from five regions to - for example - ten regions. I've seen the video "MVVM with MEF in Silverlight Video Tutorial Part 2: Plugins and Metadata" ( http://csharperimage.jeremylikness.com/2010/03/mvvm-with-mef-in-silverlight-video_09.html ) but he is using an ItemsControl and is working with Visibility and he only got ONE region. So I think that this technique is not working for me... Puh, I hope I could make myself clear! Thanks a lot for any piece of information!!! Greetings, Tim.

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  • Why is Core Data not persisting these changes to disk?

    - by scott
    I added a new entity to my model and it loads fine but no changes made in memory get persisted to disk. My values set on the car object work fine in memory but aren't getting persisted to disk on hitting the home button (in simulator). I am using almost exactly the same code on another entity in my application and its values persist to disk fine (core data - sqlite3); Does anyone have a clue what I'm overlooking here? Car is the managed object, cars in an NSMutableArray of car objects and Car is the entity and Visible is the attribute on the entity which I am trying to set. Thanks for you assistance. Scott - (void)viewDidLoad { myAppDelegate* appDelegate = (myAppDelegate*)[[UIApplication sharedApplication] delegate]; NSManagedObjectContext* managedObjectContex = appDelegate.managedObjectContext; NSFetchRequest* request = [[NSFetchRequest alloc] init]; NSEntityDescription* entity = [NSEntityDescription entityForName:@"Car" inManagedObjectContext:managedObjectContex]; [request setEntity:entity]; NSSortDescriptor* sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Name" ascending:YES]; NSArray* sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [sortDescriptor release]; NSError* error = nil; cars = [[managedObjectContex executeFetchRequest:request error:&error] mutableCopy]; if (cars == nil) { NSLog(@"Can't load the Cars data! Error: %@, %@", error, [error userInfo]); } [request release]; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath { Car* car = [cars objectAtIndex:indexPath.row]; if (car.Visible == [NSNumber numberWithBool:YES]) { car.Visible = [NSNumber numberWithBool:NO]; [tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryNone; } else { car.Visible = [NSNumber numberWithBool:YES]; [tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryCheckmark; } }

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  • Stored Procedure Does Not Fire Last Command

    - by jp2code
    On our SQL Server (Version 10.0.1600), I have a stored procedure that I wrote. It is not throwing any errors, and it is returning the correct values after making the insert in the database. However, the last command spSendEventNotificationEmail (which sends out email notifications) is not being run. I can run the spSendEventNotificationEmail script manually using the same data, and the notifications show up, so I know it works. Is there something wrong with how I call it in my stored procedure? [dbo].[spUpdateRequest](@packetID int, @statusID int output, @empID int, @mtf nVarChar(50)) AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; DECLARE @id int SET @id=-1 -- Insert statements for procedure here SELECT A.ID, PacketID, StatusID INTO #act FROM Action A JOIN Request R ON (R.ID=A.RequestID) WHERE (PacketID=@packetID) AND (StatusID=@statusID) IF ((SELECT COUNT(ID) FROM #act)=0) BEGIN -- this statusID has not been entered. Continue SELECT ID, MTF INTO #req FROM Request WHERE PacketID=@packetID WHILE (0 < (SELECT COUNT(ID) FROM #req)) BEGIN SELECT TOP 1 @id=ID FROM #req INSERT INTO Action (RequestID, StatusID, EmpID, DateStamp) VALUES (@id, @statusID, @empID, GETDATE()) IF ((@mtf IS NOT NULL) AND (0 < LEN(RTRIM(@mtf)))) BEGIN UPDATE Request SET MTF=@mtf WHERE ID=@id END DELETE #req WHERE ID=@id END DROP TABLE #req SELECT @id=@@IDENTITY, @statusID=StatusID FROM Action SELECT TOP 1 @statusID=ID FROM Status WHERE (@statusID<ID) AND (-1 < Sequence) EXEC spSendEventNotificationEmail @packetID, @statusID, 'http:\\cpweb:8100\NextStep.aspx' END ELSE BEGIN SET @statusID = -1 END DROP TABLE #act END Idea of how the data tables are connected:

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  • Why does a simple ApplicationSetting PropertyBinding for a Form does not work in C#?

    - by Mike Rosenblum
    My question involves this simple walkthrough shown in the article Preserve Size and Location of Windows Forms – Part I by Dennis Wallentin. This approach works 100% fine when using VB.NET. When using the same steps in C#, however, the settings within the Settings tab of the application's properties looks correct, and the app.config file looks right, but the values are not saved when you run it. The app.config file winds up looking like this: <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" > <section name="WindowsAppCs.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" /> </sectionGroup> </configSections> <userSettings> <WindowsAppCs.Properties.Settings> <setting name="Location" serializeAs="String"> <value>0, 0</value> </setting> <setting name="Size" serializeAs="String"> <value>284, 262</value> </setting> </WindowsAppCs.Properties.Settings> </userSettings> </configuration> It looks right to me, but the values do not update when running hosted within Visual Studio or when running the compiled EXE. I am sure that something very simple needs to be added or done, but I don't know what. Does anyone have any ideas here? Much thanks in advance...

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  • How can I pass a const array or a variable array to a function in C?

    - by CSharperWithJava
    I have a simple function Bar that uses a set of values from a data set that is passed in in the form of an Array of data structures. The data can come from two sources: a constant initialized array of default values, or a dynamically updated cache. The calling function determines which data is used and should be passed to Bar. Bar doesn't need to edit any of the data and in fact should never do so. How should I declare Bar's data parameter so that I can provide data from either set? union Foo { long _long; int _int; } static const Foo DEFAULTS[8] = {1,10,100,1000,10000,100000,1000000,10000000}; static Foo Cache[8] = {0}; void Bar(Foo* dataSet, int len);//example function prototype Note, this is C, NOT C++ if that makes a difference; Edit Oh, one more thing. When I use the example prototype I get a type qualifier mismatch warning, (because I'm passing a mutable reference to a const array?). What do I have to change for that?

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  • Fastest way to modify a decimal-keyed table in MySQL?

    - by javanix
    I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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  • Call Python From PHP And Get Return Code

    - by seaboy
    Hello everyone, I am calling a python script from PHP. The python program has to return some value according to the arguments passed to it. Here is a sample python program, which will give you a basic idea of what i am doing currently: #!/usr/bin/python import sys #get the arguments passed argList = sys.argv #Not enough arguments. Exit with a value of 1. if len(argList) < 3: #Return with a value of 1. sys.exit(1) arg1 = argList[1] arg2 = argList[2] #Check arguments. Exit with the appropriate value. if len(arg1) > 255: #Exit with a value of 4. sys.exit(4) if len(arg2) < 2: #Exit with a value of 8. sys.exit(8) #Do further coding using the arguments------ #If program works successfully, exit with a value of 0 As you can see from the above code, my basic aim is for the python program to return some values (0,1,4,8 etc) depending on the arguments. And then the calling PHP program to access these returned values and do the appropriate operation. Currently i have used "sys.exit(n)", for that purpose. Am i right in using sys.exit, or do I need to use something else? And also what method exists in PHP so that I can access the return code from python? Sorry for the long question, but hopefully it will help in you understanding my dilemma Thanks a ton

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  • Reading from txt ruins formatting

    - by Sorin Grecu
    I'm saving some values to a txt file and after that i want to be able to show it in a dialog.All good,done that but though the values in the txt file are formated nicely,like this : Aaaaaaaa 0.55 1 Bbbbb 1 2.2 CCCCCCCCC 3 0.22 When reading and setting them to a textview they get all messy like this : Aaaaaaaa 0.55 1 Bbbbb 1 2.2 CCCCCCCCC 3 0.22 My writting method : FileOutputStream f = new FileOutputStream(file); PrintWriter pw = new PrintWriter(f); for (int n = 0; n < allpret.size() - 1; n++) { if (cant[n] != Float.toString(0) && pret[n] != Float.toString(0)) { String myFormat = "%-20s %-5s %-5s%n"; pw.println(String.format(myFormat, prod[n], cant[n], pret[n])); My reading method : StringBuilder text = new StringBuilder(); try { BufferedReader br = new BufferedReader(new FileReader(file)); String line; while ((line = br.readLine()) != null) { text.append(line); text.append('\n'); } } catch (IOException e) { } Why does it ruin the amount of spaces and how can i fix this ? Thanks and have a good night !

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  • Segmentation in Linux : Segmentation & Paging are redundant?

    - by claws
    Hello, I'm reading "Understanding Linux Kernel". This is the snippet that explains how Linux uses Segmentation which I didn't understand. Segmentation has been included in 80 x 86 microprocessors to encourage programmers to split their applications into logically related entities, such as subroutines or global and local data areas. However, Linux uses segmentation in a very limited way. In fact, segmentation and paging are somewhat redundant, because both can be used to separate the physical address spaces of processes: segmentation can assign a different linear address space to each process, while paging can map the same linear address space into different physical address spaces. Linux prefers paging to segmentation for the following reasons: Memory management is simpler when all processes use the same segment register values that is, when they share the same set of linear addresses. One of the design objectives of Linux is portability to a wide range of architectures; RISC architectures in particular have limited support for segmentation. All Linux processes running in User Mode use the same pair of segments to address instructions and data. These segments are called user code segment and user data segment , respectively. Similarly, all Linux processes running in Kernel Mode use the same pair of segments to address instructions and data: they are called kernel code segment and kernel data segment , respectively. Table 2-3 shows the values of the Segment Descriptor fields for these four crucial segments. I'm unable to understand 1st and last paragraph.

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  • SQL using sum to count results of multiple subqueries

    - by asdas
    I have a table with 2 columns: integer and var char. I am given only the integer values but need to do work on the var char (string) values. Given an integer, and a list of other integers (no overlap), I want to find the string for that single integer. Then I want to take that string and do the INSTR command with that string, and all the other strings for all the other integers. Then I want the sum of all the INSTR so the result is one number. So lets say I have int x, and list y=[y0, y1, y2]. I want to do 3 INSTR commands like SUM(INSTR(string for x, string for y0), INSTR(string for x, string for y1), INSTR(string for x, string for y2)) I think im going in the wrong direction, this is what I have. Im not good with sub queries. SELECT SUM ( SELECT INSTR ( SELECT string FROM pages WHERE int=? LIMIT 1, ( SELECT string FROM pages WHERE id=? OR id=? OR id=? LIMIT 3 ) ) )

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  • Display a ranking grid for game : optimization of left outer join and find a player

    - by Jerome C.
    Hello, I want to do a ranking grid. I have a table with different values indexed by a key: Table SimpleValue : key varchar, value int, playerId int I have a player which have several SimpleValue. Table Player: id int, nickname varchar Now imagine these records: SimpleValue: Key value playerId for 1 1 int 2 1 agi 2 1 lvl 5 1 for 6 2 int 3 2 agi 1 2 lvl 4 2 Player: id nickname 1 Bob 2 John I want to display a rank of these players on various SimpleValue. Something like: nickname for lvl Bob 1 5 John 6 4 For the moment I generate an sql query based on which SimpleValue key you want to display and on which SimpleValue key you want to order players. eg: I want to display 'lvl' and 'for' of each player and order them on the 'lvl' The generated query is: SELECT p.nickname as nickname, v1.value as lvl, v2.value as for FROM Player p LEFT OUTER JOIN SimpleValue v1 ON p.id=v1.playerId and v1.key = 'lvl' LEFT OUTER JOIN SimpleValue v2 ON p.id=v2.playerId and v2.key = 'for' ORDER BY v1.value This query runs perfectly. BUT if I want to display 10 different values, it generates 10 'left outer join'. Is there a way to simplify this query ? I've got a second question: Is there a way to display a portion of this ranking. Imagine I've 1000 players and I want to display TOP 10, I use the LIMIT keyword. Now I want to display the rank of the player Bob which is 326/1000 and I want to display 5 rank player above and below (so from 321 to 331 position). How can I achieve it ? thanks.

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  • Programming style question on how to code functions

    - by shawnjan
    Hey all! So, I was just coding a bit today, and I realized that I don't have much consistency when it comes to a coding style when programming functions. One of my main concerns is whether or not its proper to code it so that you check that the input of the user is valid OUTSIDE of the function, or just throw the values passed by the user into the function and check if the values are valid in there. Let me sketch an example: I have a function that lists hosts based on an environment, and I want to be able to split the environment into chunks of hosts. So an example of the usage is this: listhosts -e testenv -s 2 1 This will get all the hosts from the "testenv", split it up into two parts, and it is displaying part one. In my code, I have a function that you pass it in a list, and it returns a list of lists based on you parameters for splitting. BUT, before I pass it a list, I first verify the parameters in my MAIN during the getops process, so in the main I check to make sure there are no negatives passed by the user, I make sure the user didnt request to split into say, 4 parts, but asking to display part 5 (which would not be valid), etc. tl;dr: Would you check the validity of a users input the flow of you're MAIN class, or would you do a check in your function itself, and either return a valid response in the case of valid input, or return NULL in the case of invalid input? Obviously both methods work, I'm just interested to hear from experts as to which approach is better :) Thanks for any comments and suggestions you guys have!

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  • Refactoring code/consolidating functions (e.g. nested for-loop order)

    - by bmay2
    Just a little background: I'm making a program where a user inputs a skeleton text, two numbers (lower and upper limit), and a list of words. The outputs are a series of modifications on the skeleton text. Sample inputs: text = "Player # likes @." (replace # with inputted integers and @ with words in list) lower = 1 upper = 3 list = "apples, bananas, oranges" The user can choose to iterate over numbers first: Player 1 likes apples. Player 2 likes apples. Player 3 likes apples. Or words first: Player 1 likes apples. Player 1 likes bananas. Player 1 likes oranges. I chose to split these two methods of outputs by creating a different type of dictionary based on either number keys (integers inputted by the user) or word keys (from words in the inputted list) and then later iterating over the values in the dictionary. Here are the two types of dictionary creation: def numkey(dict): # {1: ['Player 1 likes apples', 'Player 1 likes...' ] } text, lower, upper, list = input_sort(dict) d = {} for num in range(lower,upper+1): l = [] for i in list: l.append(text.replace('#', str(num)).replace('@', i)) d[num] = l return d def wordkey(dict): # {'apples': ['Player 1 likes apples', 'Player 2 likes apples'..] } text, lower, upper, list = input_sort(dict) d = {} for i in list: l = [] for num in range(lower,upper+1): l.append(text.replace('#', str(num)).replace('@', i)) d[i] = l return d It's fine that I have two separate functions for creating different types of dictionaries but I see a lot of repetition between the two. Is there any way I could make one dictionary function and pass in different values to it that would change the order of the nested for loops to create the specific {key : value} pairs I'm looking for? I'm not sure how this would be done. Is there anything related to functional programming or other paradigms that might help with this? The question is a little abstract and more stylistic/design-oriented than anything.

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  • PHP array value becomes blank. What is going on?

    - by Michael Bruce
    I have written a web page that works fine expect for some weird behavior. The code below gets all expected values and populates them correctly except for $v-data["quick_phone_id"] and $v-data["quick_email_id"] which are integers. Those values come out blank in the string I am creating. The value for $v-data["id"] is another integer and works as expected. My only clue is that when I uncomment the commented out line, the code works properly. So I'm guessing this has to do with referencing getting broken for the array. Any ideas? I'd like to fix my code and my PHP knowledge. $contacts = ContactInfo::loadMyContacts($userId); $sb = new StringBuilder(); $idx = 0; //$vals = "vals: ".$contacts[0]->data["quick_phone_id"]; $sb->append(' dataRows = ['); foreach($contacts as $k => $v) { $sb->append('{ id:"'.strval($v->data["id"]).'",'); $sb->append('url:"edit_contact.php?id='.$v->data["id"].'",'); $sb->append('gname:"'.$v->data["given_name"].'",'); $sb->append('fname:"'.$v->data["family_name"].'",'); $sb->append('phone1id2:"'.strval($v->data["quick_phone_id"]).'",'); $sb->append('phone1type:"'.$v->data["quick_phone_type"].'",'); $sb->append('phone1:"'.$v->data["quick_phone"].'",'); $sb->append("email1id2:'".strval($v->data["quick_email_id"])."',"); $sb->append('email1type:"'.$v->data["quick_email_type"].'",'); $sb->append("email1:'".$v->data["quick_email"]."',"); $sb->append("dirty:false },\n"); } $sb->append('];');

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  • How can you transform a set of numbers into mostly whole ones?

    - by Alice
    Small amount of background: I am working on a converter that bridges between a map maker (Tiled) that outputs in XML, and an engine (Angel2D) that inputs lua tables. Most of this is straight forward However, Tiled outputs in pixel offsets (integers of absolute values), while Angel2D inputs OpenGL units (floats of relative values); a conversion factor between these two is needed (for example, 32px = 1gu). Since OpenGL units are abstract, and the camera can zoom in or out if the objects are too small or big, the actual conversion factor isn't important; I could use a random number, and the user would merely have to zoom in or out. But it would be best if the conversion factor was selected such that most numbers outputted were small and whole (or fractions of small whole numbers), because that makes it easier to work with (and the whole point of the OpenGL units is that they are easy to work with). How would I find such a conversion factor reliably? My first attempt was to use the smallest number given; this resulted in no fractions below 1, but often lead to lots of decimal places where the factors didn't line up. Then I tried the mode of the sequence, which lead to the largest number of 1's possible, but often lead to very long floats for background images. My current approach gets the GCD of the whole sequence, which, when it works, works great, but can easily be thrown off course by a single bad apple. Note that while I could easily just pass the numbers I am given along, or pick some fixed factor, or use one of the conversions I specified above, I am looking for a method to reliably scale this list of integers to small, whole numbers or simple fractions, because this would most likely be unsurprising to the end user; this is not a one off conversion. The end users tend to use 1.0 as their "base" for manipulations (because it's simple and obvious), so it would make more sense for the sizes of entities to cluster around this.

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  • MySQL default value based on view

    - by Jake
    Basically I have a bunch of views based on a simple discriminator column (eg. CREATE VIEW tablename AS SELECT * FROM tablename WHERE discrcolumn = "discriminator value"). Upon inserting a new row into this view, it should insert "discriminator value" into discrcolumn. I tried this, but apparently MySQL doesn't figure this out itself, as it throws an error "Field of view viewname underlying table does not have a default value". The discriminator column is set to NOT NULL of course. How do I mend this? Perhaps a pre-insert trigger? UPDATE: Triggers won't work on views, see below comment. Would it work to create a trigger on the table which uses a variable, and set that variable at establishing the connection? For each connection the value of that variable would be the same, but it could differ from other connections. EDIT: This appears to work... Setup: CREATE TRIGGER insert_[tablename] BEFORE INSERT ON [tablename] FOR EACH ROW SET NEW.[discrcolumn] = @variable Runtime: SET @variable = [descrvalue]; INSERT INTO [viewname] ([columnlist]) VALUES ([values]);

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  • android upload progressbarr not working

    - by pieter
    I'm a beginner in Android programming and I was tryinh to upload an image to a server. I found some code here on stackoverflow, I adjusted it and it still doesn't work. The problem is my image still won't upload. edit I solved the problem, I had no rights on the folder on the server. Now I have a new problem. the progresbarr doesn't work. it keeps saying 0 % transmitted does anyone sees an error in my code? import android.app.Activity; import android.app.AlertDialog; import android.app.Dialog; import android.app.ProgressDialog; import android.content.Context; import android.content.DialogInterface; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.location.Location; import android.location.LocationListener; import android.location.LocationManager; import android.os.AsyncTask; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.Window; import android.widget.Button; import android.widget.ImageView; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.net.HttpURLConnection; import java.net.URL; public class PreviewActivity extends Activity { /** The captured image file. Get it's path from the starting intent */ private File mImage; public static final String EXTRA_IMAGE_PATH = "extraImagePath" /** Log tag */ private static final String TAG = "DFH"; /** Progress dialog id */ private static final int UPLOAD_PROGRESS_DIALOG = 0; private static final int UPLOAD_ERROR_DIALOG = 1; private static final int UPLOAD_SUCCESS_DIALOG = 2; /** Handler to confirm button */ private Button mConfirm; /** Handler to cancel button */ private Button mCancel; /** Uploading progress dialog */ private ProgressDialog mDialog; /** * Called when the activity is created * * We load the captured image, and register button callbacks */ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); setContentView(R.layout.preview); setResult(RESULT_CANCELED); // Import image Bundle extras = getIntent().getExtras(); String imagePath = extras.getString(FotoActivity.EXTRA_IMAGE_PATH); Log.d("DFHprev", imagePath); mImage = new File(imagePath); if (mImage.exists()) { setResult(RESULT_OK); loadImage(mImage); } registerButtonCallbacks(); } @Override protected void onPause() { super.onPause(); } /** * Register callbacks for ui buttons */ protected void registerButtonCallbacks() { // Cancel button callback mCancel = (Button) findViewById(R.id.preview_send_cancel); mCancel.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { PreviewActivity.this.finish(); } }); // Confirm button callback mConfirm = (Button) findViewById(R.id.preview_send_confirm); mConfirm.setEnabled(true); mConfirm.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { new UploadImageTask().execute(mImage); } }); } /** * Initialize the dialogs */ @Override protected Dialog onCreateDialog(int id) { switch(id) { case UPLOAD_PROGRESS_DIALOG: mDialog = new ProgressDialog(this); mDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); mDialog.setCancelable(false); mDialog.setTitle(getString(R.string.progress_dialog_title_connecting)); return mDialog; case UPLOAD_ERROR_DIALOG: AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setTitle(R.string.upload_error_title) .setIcon(android.R.drawable.ic_dialog_alert) .setMessage(R.string.upload_error_message) .setCancelable(false) .setPositiveButton(getString(R.string.retry), new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { PreviewActivity.this.finish(); } }); return builder.create(); case UPLOAD_SUCCESS_DIALOG: AlertDialog.Builder success = new AlertDialog.Builder(this); success.setTitle(R.string.upload_success_title) .setIcon(android.R.drawable.ic_dialog_info) .setMessage(R.string.upload_success_message) .setCancelable(false) .setPositiveButton(getString(R.string.success), new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { PreviewActivity.this.finish(); } }); return success.create(); default: return null; } } /** * Prepare the progress dialog */ @Override protected void onPrepareDialog(int id, Dialog dialog) { switch(id) { case UPLOAD_PROGRESS_DIALOG: mDialog.setProgress(0); mDialog.setTitle(getString(R.string.progress_dialog_title_connecting)); } } /** * Load the image file into the imageView * * @param image */ protected void loadImage(File image) { Bitmap bm = BitmapFactory.decodeFile(image.getPath()); ImageView view = (ImageView) findViewById(R.id.preview_image); view.setImageBitmap(bm); } /** * Asynchronous task to upload file to server */ class UploadImageTask extends AsyncTask<File, Integer, Boolean> { /** Upload file to this url */ private static final String UPLOAD_URL = "http://www.xxxx.x/xxxx/fotos"; /** Send the file with this form name */ private static final String FIELD_FILE = "file"; /** * Prepare activity before upload */ @Override protected void onPreExecute() { super.onPreExecute(); setProgressBarIndeterminateVisibility(true); mConfirm.setEnabled(false); mCancel.setEnabled(false); showDialog(UPLOAD_PROGRESS_DIALOG); } /** * Clean app state after upload is completed */ @Override protected void onPostExecute(Boolean result) { super.onPostExecute(result); setProgressBarIndeterminateVisibility(false); mConfirm.setEnabled(true); mDialog.dismiss(); if (result) { showDialog(UPLOAD_SUCCESS_DIALOG); } else { showDialog(UPLOAD_ERROR_DIALOG); } } @Override protected Boolean doInBackground(File... image) { return doFileUpload(image[0], "UPLOAD_URL"); } @Override protected void onProgressUpdate(Integer... values) { super.onProgressUpdate(values); if (values[0] == 0) { mDialog.setTitle(getString(R.string.progress_dialog_title_uploading)); } mDialog.setProgress(values[0]); } private boolean doFileUpload(File file, String uploadUrl) { HttpURLConnection connection = null; DataOutputStream outputStream = null; DataInputStream inputStream = null; String pathToOurFile = file.getPath(); String urlServer = "http://www.xxxx.x/xxxx/upload.php"; String lineEnd = "\r\n"; String twoHyphens = "--"; String boundary = "*****"; // log pathtoourfile Log.d("DFHinUpl", pathToOurFile); int bytesRead, bytesAvailable, bufferSize; byte[] buffer; int maxBufferSize = 1*1024*1024; int sentBytes = 0; long fileSize = file.length(); // log filesize String files= String.valueOf(fileSize); String buffers= String.valueOf(maxBufferSize); Log.d("fotosize",files); Log.d("buffers",buffers); try { FileInputStream fileInputStream = new FileInputStream(new File(pathToOurFile) ); URL url = new URL(urlServer); connection = (HttpURLConnection) url.openConnection(); // Allow Inputs & Outputs connection.setDoInput(true); connection.setDoOutput(true); connection.setUseCaches(false); // Enable POST method connection.setRequestMethod("POST"); connection.setRequestProperty("Connection", "Keep-Alive"); connection.setRequestProperty("Content-Type", "multipart/form-data;boundary="+boundary); outputStream = new DataOutputStream( connection.getOutputStream() ); outputStream.writeBytes(twoHyphens + boundary + lineEnd); outputStream.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\"" + pathToOurFile +"\"" + lineEnd); outputStream.writeBytes(lineEnd); bytesAvailable = fileInputStream.available(); bufferSize = Math.min(bytesAvailable, maxBufferSize); buffer = new byte[bufferSize]; // Read file bytesRead = fileInputStream.read(buffer, 0, bufferSize); while (bytesRead > 0) { outputStream.write(buffer, 0, bufferSize); bytesAvailable = fileInputStream.available(); bufferSize = Math.min(bytesAvailable, maxBufferSize); bytesRead = fileInputStream.read(buffer, 0, bufferSize); sentBytes += bufferSize; publishProgress((int)(sentBytes * 100 / fileSize)); bytesAvailable = fileInputStream.available(); bufferSize = Math.min(bytesAvailable, maxBufferSize); bytesRead = fileInputStream.read(buffer, 0, bufferSize); } outputStream.writeBytes(lineEnd); outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd); // Responses from the server (code and message) int serverResponseCode = connection.getResponseCode(); String serverResponseMessage = connection.getResponseMessage(); fileInputStream.close(); outputStream.flush(); outputStream.close(); try { int responseCode = connection.getResponseCode(); return responseCode == 200; } catch (IOException ioex) { Log.e("DFHUPLOAD", "Upload file failed: " + ioex.getMessage(), ioex); return false; } catch (Exception e) { Log.e("DFHUPLOAD", "Upload file failed: " + e.getMessage(), e); return false; } } catch (Exception ex) { String msg= ex.getMessage(); Log.d("DFHUPLOAD", msg); } return true; } } } the PHP code that handles this upload is following: <?php $date=getdate(); $urldate=$date['year'].$date['month'].$date['month'].$date['hours'].$date['minutes'].$date[ 'seconds']; $target_path = "./"; $target_path = $target_path . basename( $_FILES['uploadedfile']['name']) . $urldate; if(move_uploaded_file($_FILES['uploadedfile']['tmp_name'], $target_path)) { echo "The file ". basename( $_FILES['uploadedfile']['name']). " has been uploaded"; } else{ echo "There was an error uploading the file, please try again!"; } ?> would really appreciate it if someone could help me.

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  • DSP - Filter sweep effect

    - by Trap
    I'm implementing a 'filter sweep' effect (I don't know if it's called like that). What I do is basically create a low-pass filter and make it 'move' along a certain frequency range. To calculate the filter cut-off frequency at a given moment I use a user-provided linear function, which yields values between 0 and 1. My first attempt was to directly map the values returned by the linear function to the range of frequencies, as in cf = freqRange * lf(x). Although it worked ok it looked as if the sweep ran much faster when moving through low frequencies and then slowed down during its way to the high frequency zone. I'm not sure why is this but I guess it's something to do with human hearing perceiving changes in frequency in a non-linear manner. My next attempt was to move the filter's cut-off frequency in a logarithmic way. It works much better now but I still feel that the filter doesn't move at a constant perceived speed through the range of frequencies. How should I divide the frequency space to obtain a constant perceived sweep speed? Thanks in advance.

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  • Improving my first Clojure program

    - by StackedCrooked
    After a few weekends exploring Clojure I came up with this program. It allows you to move a little rectangle in a window. Here's the code: (import java.awt.Color) (import java.awt.Dimension) (import java.awt.event.KeyListener) (import javax.swing.JFrame) (import javax.swing.JPanel) (def x (ref 0)) (def y (ref 0)) (def panel (proxy [JPanel KeyListener] [] (getPreferredSize [] (Dimension. 100 100)) (keyPressed [e] (let [keyCode (.getKeyCode e)] (if (== 37 keyCode) (dosync (alter x dec)) (if (== 38 keyCode) (dosync (alter y dec)) (if (== 39 keyCode) (dosync (alter x inc)) (if (== 40 keyCode) (dosync (alter y inc)) (println keyCode))))))) (keyReleased [e]) (keyTyped [e]))) (doto panel (.setFocusable true) (.addKeyListener panel)) (def frame (JFrame. "Test")) (doto frame (.add panel) (.pack) (.setDefaultCloseOperation JFrame/EXIT_ON_CLOSE) (.setVisible true)) (defn drawRectangle [p] (doto (.getGraphics p) (.setColor (java.awt.Color/WHITE)) (.fillRect 0 0 100 100) (.setColor (java.awt.Color/BLUE)) (.fillRect (* 10 (deref x)) (* 10 (deref y)) 10 10))) (loop [] (drawRectangle panel) (Thread/sleep 10) (recur)) Despite being an experienced C++ programmer I found it very challenging to write even a simple application in a language that uses a radically different style than what I'm used to. On top of that, this code probably sucks. I suspect the globalness of the various values is a bad thing. It's also not clear to me if it's appropriate to use references here for the x and y values. Any hints for improving this code are welcome.

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