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  • EF 4.0 Code only assocation from abstract to derived

    - by Jeroen
    Using EF 4.0 Code only i want to make an assocation between an abstract and normal class. I have class 'Item', 'ContentBase' and 'Test'. 'ContentBase' is abstract and 'Test' derives from it. 'ContentBase' has a property 'Item' that links to an instance of 'Item'. So that 'Test.Item' or any class that derives from 'ContentBase' has an 'Item' navigation property. In my DB every record for Test has a matching record for Item. public class Item { public int Id { get; set;} } public abstract class ContentBase { public int ContentId { get; set;} public int Id { get; set;} public Item Item { get; set;} } public class Test : ContentBase { public string Name { get; set;} } now some init code public void SomeInitFunction() { var itemConfig = new EntityConfiguration<Item>(); itemConfig.HasKey(p => p.Id); itemConfig.Property(p => p.Id).IsIdentity(); this.ContextBuilder.Configurations.Add(itemConfig); var testConfig = new EntityConfiguration<Test>(); testConfig.HasKey(p => p.ContentId); testConfig.Property(p => p.ContentId).IsIdentity(); // the problem testConfig.Relationship(p => p.Item).HasConstraint((p, q) => p.Id == q.Id); this.ContextBuilder.Configurations.Add(testConfig); } This gives an error: A key is registered for the derived type 'Test'. Keys must be registered for the root type 'ContentBase'. anyway i try i get an error. What am i a doing wrong?

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  • How can I render an in-memory UIViewController's view Landscape?

    - by Aaron
    I'm trying to render an in-memory (but not in hierarchy, yet) UIViewController's view into an in-memory image buffer so I can do some interesting transition animations. However, when I render the UIViewController's view into that buffer, it is always rendering as though the controller is in Portrait orientation, no matter the orientation of the rest of the app. How do I clue this controller in? My code in RootViewController looks like this: MyUIViewController* controller = [[MyUIViewController alloc] init]; int width = self.view.frame.size.width; int height = self.view.frame.size.height; int bitmapBytesPerRow = width * 4; unsigned char *offscreenData = calloc(bitmapBytesPerRow * height, sizeof(unsigned char)); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef offscreenContext = CGBitmapContextCreate(offscreenData, width, height, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast); CGContextTranslateCTM(offscreenContext, 0.0f, height); CGContextScaleCTM(offscreenContext, 1.0f, -1.0f); [(CALayer*)[controller.view layer] renderInContext:offscreenContext]; At that point, the offscreen memory buffers contents are portrait-oriented, even when the window is in landscape orientation. Ideas?

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  • C++: static assert for const variables?

    - by shoosh
    Static asserts are very convenient for checking things in compile time. A simple static assert idiom looks like this: template<bool> struct StaticAssert; template<> struct StaticAssert<true> {}; #define STATIC_ASSERT(condition) do { StaticAssert<condition>(); } while(0) This is good for stuff like STATIC_ASSERT(sizeof(float) == 4) and: #define THIS_LIMIT (1000) ... STATIC_ASSERT(THIS_LIMIT > OTHER_LIMIT); But using #define is not the "C++" way of defining constants. C++ would have you use an anonymous namespace: namespace { const int THIS_LIMIT = 1000; } or even: static const int THIS_LIMIT = 1000; The trouble with this is that with a const int you can't use STATIC_ASSERT() and you must resort to a run-time check which is silly. Is there a way to properly solve this in current C++? I think I've read C++0x has some facility to do this...

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  • Search a string in a file and write the matched lines to another file in Java

    - by Geeta
    For searching a string in a file and writing the lines with matched string to another file it takes 15 - 20 mins for a single zip file of 70MB(compressed state). Is there any ways to minimise it. my source code: getting Zip file entries zipFile = new ZipFile(source_file_name); entries = zipFile.entries(); while (entries.hasMoreElements()) { ZipEntry entry = (ZipEntry)entries.nextElement(); if (entry.isDirectory()) { continue; } searchString(Thread.currentThread(),entry.getName(), new BufferedInputStream (zipFile.getInputStream(entry)), Out_File, search_string, stats); } zipFile.close(); Searching String public void searchString(Thread CThread, String Source_File, BufferedInputStream in, File outfile, String search, String stats) throws IOException { int count = 0; int countw = 0; int countl = 0; String s; String[] str; BufferedReader br2 = new BufferedReader(new InputStreamReader(in)); System.out.println(CThread.currentThread()); while ((s = br2.readLine()) != null) { str = s.split(search); count = str.length - 1; countw += count; //word count if (s.contains(search)) { countl++; //line count WriteFile(CThread,s, outfile.toString(), search); } } br2.close(); in.close(); } -------------------------------------------------------------------------------- public void WriteFile(Thread CThread,String line, String out, String search) throws IOException { BufferedWriter bufferedWriter = null; System.out.println("writre thread"+CThread.currentThread()); bufferedWriter = new BufferedWriter(new FileWriter(out, true)); bufferedWriter.write(line); bufferedWriter.newLine(); bufferedWriter.flush(); } Please help me. Its really taking 40 mins for 10 files using threads and 15 - 20 mins for a single file of 70MB after being compressed. Any ways to minimise the time.

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  • Nested loops through recursion with usable iterators

    - by narandzasto
    Help! I need to generate a query with loops,but there must be undefinitly numbers of loop or much as many a client wants. I know that it can be done with recursion,but don't know exectly how.One more thing. Notice,please,that I need to use those k,i,j iterators later in "if" condition and I don't know how to catch them. Thanks class Class1 { public void ListQuery() { for (int k = 0; k < listbox1.Count; k++) { for (int i = 0; i < listbox2.Count; i++) { for (int j = 0; j < listbox3.Count; j++) { if (k == listbox1.count-1 && i == listbox2.count-1 && j == listbox3.count-1) { if (!checkbox1) Query += resultset.element1 + "=" + listbox1[k]; if (!checkbox2) Query += resultset.element2 + "=" + listbox1[i]; if (!checkbox3) Query += resultset.element3 + "=" + listbox1[j]; } } } } } }

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  • MySQL - Structure for Permissions to Objects

    - by Kerry
    What would be an ideal structure for users permissions of objects. I've seen many related posts for general permissions, or what sections a user can access, which consists of a users, userGroups and userGroupRelations or something of that nature. In my system there are many different objects that can get created, and each one has to be able to be turned on or off. For instance, take a password manager that has groups and sub groups. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Group 9 Group 10 Each group can contain a set of passwords. A user can be given read, write, edit and delete permissions to any group. More groups can get created at any point in time. If someone has permission to a group, I should be able to make him have permissions to all sub groups OR restrict it to just that group. My current thought is to have a users table, and then a permissions table with columns like: permission_id (int) PRIMARY_KEY user_id (int) INDEX object_id (int) INDEX type (varchar) INDEX read (bool) write (bool) edit (bool) delete (bool) This has worked in the past, but the new system I'm building needs to be able to scale rapidly, and I am unsure if this is the best structure. It also makes the idea of having someone with all subgroup permissions of a group more difficult. So, as a question, should I use the above structure? Or can someone point me in the direction of a better one?

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  • How can I improve the performance of LinqToSql queries that use EntitySet properties?

    - by DanM
    I'm using LinqToSql to query a small, simple SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of what makes LinqToSql so appealing. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance besides resorting to doing all the joins manually? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view. Update Here are the table definitions for the example I used in my question: create table Order ( Id int identity(1, 1) primary key, ProductName ntext null ) create table Customer ( Id int identity(1, 1) primary key, OrderId int null references Order (Id) )

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  • Efficient algorithm for Next button on a MySQL result set

    - by David Grayson
    I have a website that lets people view rows in a table (each row is a picture). There are more than 100,000 rows. You can view different subsets of the rows, and you can view them with different sort orders. While you are viewing one of the rows, you can click the "Next" or "Previous" buttons to go the next/previous row in the list. How would you implement the "Next" and "Previous" features of the website? More specifically, if you have an arbitrary query that returns a list of up to 100,000+ rows, and you know some information about the current row someone is viewing, how do you determine the NEXT row efficiently? Here is the pseudo-code of the solution I came up with when the website was young, and it worked well when there were only 1000 rows, but now that there are 100,000 rows I think it is eating up too much memory. int nextRowId(string query, int currentRowId) { array allRowIds = mysql_query(query); // Takes up a lot of memory! int currentIndex = (index of currentRowId in allRowIds); // Takes time! return allRowIds[currentIndex+1]; } While you are thinking about this problem, remember that the website can store more information about the current row than just its ID (for example, the position of the current row in the result set), and this information can be used as a hint to help determine the ID of the next row. Edit: Sorry for not mentioning this earlier, but this isn't just a static website: rows can often be added to the list, and rows can be re-ordered in the list. (Much rarer, rows can be removed from the list.) I think that I should worry about that kind of thing, but maybe you can convince me otherwise.

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  • Update a list of things without hitting every entry

    - by bobobobo
    I have a list in a database that the user should be able to order. itemname| order value (int) --------+--------------------- salad | 1 mango | 2 orange | 3 apples | 4 On load from the database, I simply order by order_value. By drag 'n drop, he should be able to move apples so that it appears at the top of the list.. itemname| order value (int) --------+--------------------- apples | 4 salad | 1 mango | 2 orange | 3 Ok. So now internally I have to update EVERY LIST ITEM! If the list has 20 or 100 items, that's a lot of updates for a simple drag operation. itemname| order value (int) --------+--------------------- apples | 1 salad | 2 mango | 3 orange | 4 I'd rather do it with only one update. One way I thought of is if "internal Order" is a double value. itemname| order value (double) --------+--------------------- salad | 1.0 mango | 2.0 orange | 3.0 apples | 4.0 SO after the drag n' drop operation, I assign apples has a value that is less than the item it is to appear in front of: itemname| order value (double) --------+--------------------- apples | 0.5 salad | 1.0 mango | 2.0 orange | 3.0 .. and if an item is dragged into the middle somewhere, its order_value is bigger than the one it appears after .. here I moved orange to be between salad and mango: itemname| order value (double) --------+--------------------- apples | 0.5 salad | 1.0 orange | 1.5 mango | 2.0 Any thoughts on better ways to do this?

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  • SQL n:m Inheritance join

    - by Nightmares
    I want to join a table which contains n:m relationship between groups. (Groups are defined in a separate table). This table only has entries listing a member_group_id and a parent_group_id. Given this structure: id(int) | member_group_id(int) | parent_group_id(int) The "base" query looks like this: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.member_group_id = p1.member_group_id The "base" query correctly shows all relationships (I checked by doing it manually.) The problem is when I try to apply a where clause to this query to filter for a specific group as "point of origin" (the first group for which I want all parent groups) it returns only the closest parents. For example like this: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.member_group_id = p1.member_group_id where p1.group_id = 1 Can anyone give a clue how I can fix this? Or a different approach to realize this. (I suppose I could always do this in my C++ source code on the server side but I would have to transfer a entire table which has a high growth potential to the application server.) UPDATE: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.group_id = p1.member_group_id Typing mistake confirmed. Now I don't get past first level of inheritance period. Thanks at denied for pointing that out.

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  • Why doesn't this for-loop execute?

    - by Maulrus
    I'm writing a program for an exercise that will read data from a file and format it to be readable. So far, I have a bit of code that will separate a header from the data that goes under it. Here it is: int main() { ifstream in("records.txt"); ofstream out("formatted_records.txt"); vector<string> temp; vector<string> headers; for (int i = 0; getline(in,temp[i]); ++i) { static int k = -1; if (str_isalpha(temp[i])) { headers[++k] = temp[i]; temp.erase(temp.begin() + i); } else { temp[i] += "," + headers[k]; } } } (str_isalpha() is just a function that applies isalpha() to every character in a string.) Now, the for-loop in this program doesn't execute, and I can't figure out why. Does anybody know?

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  • MySQL SELECT combining 3 SELECTs INTO 1

    - by Martin Tóth
    Consider following tables in MySQL database: entries: creator_id INT entry TEXT is_expired BOOL other: creator_id INT entry TEXT userdata: creator_id INT name VARCHAR etc... In entries and other, there can be multiple entries by 1 creator. userdata table is read only for me (placed in other database). I'd like to achieve a following SELECT result: +------------+---------+---------+-------+ | creator_id | entries | expired | other | +------------+---------+---------+-------+ | 10951 | 59 | 55 | 39 | | 70887 | 41 | 34 | 108 | | 88309 | 38 | 20 | 102 | | 94732 | 0 | 0 | 86 | ... where entries is equal to SELECT COUNT(entry) FROM entries GROUP BY creator_id, expired is equal to SELECT COUNT(entry) FROM entries WHERE is_expired = 0 GROUP BY creator_id and other is equal to SELECT COUNT(entry) FROM other GROUP BY creator_id. I need this structure because after doing this SELECT, I need to look for user data in the "userdata" table, which I planned to do with INNER JOIN and select desired columns. I solved this problem with selecting "NULL" into column which does not apply for given SELECT: SELECT creator_id, COUNT(any_entry) as entries, COUNT(expired_entry) as expired, COUNT(other_entry) as other FROM ( SELECT creator_id, entry AS any_entry, NULL AS expired_entry, NULL AS other_enry FROM entries UNION SELECT creator_id, NULL AS any_entry, entry AS expired_entry, NULL AS other_enry FROM entries WHERE is_expired = 1 UNION SELECT creator_id, NULL AS any_entry, NULL AS expired_entry, entry AS other_enry FROM other ) AS tTemp GROUP BY creator_id ORDER BY entries DESC, expired DESC, other DESC ; I've left out the INNER JOIN and selecting other columns from userdata table on purpose (my question being about combining 3 SELECTs into 1). Is my idea valid? = Am I trying to use the right "construction" for this? Are these kind of SELECTs possible without creating an "empty" column? (some kind of JOIN) Should I do it "outside the DB": make 3 SELECTs, make some order in it (let's say python lists/dicts) and then do the additional SELECTs for userdata? Solution for a similar question does not return rows where entries and expired are 0. Thank you for your time.

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  • Within an aray of objects can one create a new instance of an object at an index?

    - by David
    Here's the sample code: class TestAO { int[] x; public TestAO () { this.x = new int[5] ; for (int i = 0; i<x.length; i++) x[i] = i; } public static void main (String[]arg) { TestAO a = new TestAO (); System.out.println (a) ; TestAO c = new TestAO () ; c.x[3] = 35 ; TestAO[] Z = new TestAO[3] ; Z[0] = a ; Z[1] = (TestAO b = new TestAO()) ; Z[2] = c ; } } When i try to compile this i get an error message at the line Z[1] which reads as follows: TestAO.java:22: ')' expected Z[1] = (TestAO b = new TestAO()) ; ^ What i'm trying to do here is create an instance of the object TestAO that i want to be in that index within the assignment of the value at that index instead of creating the instance of the object outside of the array like i did with a. Is this legal and i'm just making some syntax error that i can't see (thus causing the error message) or can what i'm trying to do just not be done?

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  • Updating an application OTA

    - by Bostjan
    I'm developing an application that will be available from a website (market probably as well). The problem I'm having at the moment is how to handle the updates to the app. I know how to check the version against the current one and I know if I need to update it. Question is...how? Is there a way I can download an APK from the website and start the install process? The user will have to confirm of course, but I just want to be able to start it for him. At the moment I'm doing this: private void doUpgrade() { // TODO Auto-generated method stub Builder builder = new AlertDialog.Builder(this); builder.setTitle(getString(R.string.upgrade)); builder.setIcon(R.drawable.help); builder.setMessage(getString(R.string.needUpgrade)); builder.setPositiveButton(getString(R.string.ok), new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub Map<String, String> data = new HashMap<String, String>(); try { HttpResponse re = Registration.doPost("http://www.android-town.com/appRelease/AndroidTown.apk",data); int statusCode = re.getStatusLine().getStatusCode(); closeApp(); } catch (ClientProtocolException e) { e.printStackTrace(); Toast.makeText(getApplicationContext(), getString(R.string.noURLAccess), Toast.LENGTH_SHORT).show(); closeApp(); } catch (IOException e) { e.printStackTrace(); Toast.makeText(getApplicationContext(), getString(R.string.noURLAccess), Toast.LENGTH_SHORT).show(); closeApp(); } } }); builder.setNegativeButton(getString(R.string.cancel), new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub dialog.cancel(); closeApp(); } }); builder.show(); } But it doesn't really do anything...should I open a webView with the URL? A new runnable thread? Any other way? Please help :) Cheers

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  • Problem with sending out variable to serial port using api JAVA

    - by sjaakensjon
    We are developing a java program for school. But we are experiencing problems with sending out a variable created by 3 sliders. The idea is that we have 3 sliders. One slider for every color. Red green and blue. The variable has to have a value between 0 and 255. Everytime the value of the slider changes is has to send a variable for the channel, that value is 1, 2 ,3. And after that it has to send the value of the slider through the serial port. Could you please help us out by creating an example program? Below is our code so far. Thanks in advance. Sjaak package main; import javax.swing.*; import javax.swing.event.*; import java.awt.*; import app.Com; import app.Parameters; public class menu{ JSlider sliderblauw; JLabel hoeveelblauw; JLabel blauw; JLabel rood; JSlider sliderrood; JLabel hoeveelrood; JLabel groen; JLabel hoeveelgroen; JSlider slidergroen; public menu(){ Frame venster = new JFrame("Color control"); JPanel blauwinstel = new JPanel(); ((JFrame) venster).setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); venster.setSize(500, 500); venster.setVisible(true); sliderblauw = new JSlider(JSlider.VERTICAL, 0, 255, 0); sliderblauw.addChangeListener(new veranderingblauw()); hoeveelblauw = new JLabel ("0"); blauwinstel.add(sliderblauw); blauwinstel.add(hoeveelblauw); venster.add(blauwinstel, BorderLayout.WEST); sliderblauw.setMajorTickSpacing(10); sliderblauw.setPaintTicks(true); JPanel roodinstel = new JPanel(); sliderrood = new JSlider(JSlider.VERTICAL, 0, 255, 0); sliderrood.addChangeListener(new veranderingrood()); hoeveelrood = new JLabel ("0"); roodinstel.add(sliderrood); roodinstel.add(hoeveelrood); venster.add(roodinstel, BorderLayout.EAST); sliderrood.setMajorTickSpacing(10); sliderrood.setPaintTicks(true); JPanel groeninstel = new JPanel(); slidergroen = new JSlider(JSlider.VERTICAL, 0, 255, 0); slidergroen.addChangeListener(new veranderinggroen()); hoeveelgroen = new JLabel ("0"); groeninstel.add(slidergroen); groeninstel.add(hoeveelgroen); venster.add(groeninstel, BorderLayout.CENTER); slidergroen.setMajorTickSpacing(10); slidergroen.setPaintTicks(true); } public class veranderingblauw implements ChangeListener{ public void stateChanged(ChangeEvent ce){ int value = sliderblauw.getValue(); String waarde_blauw = Integer.toString(value); hoeveelblauw.setText(waarde_blauw); }} public class veranderingrood implements ChangeListener{ public void stateChanged(ChangeEvent ce){ int value = sliderrood.getValue(); String waarde_rood = Integer.toString(value); hoeveelrood.setText(waarde_rood); }} public class veranderinggroen implements ChangeListener{ public void stateChanged(ChangeEvent ce){ int value = slidergroen.getValue(); String waarde_groen = Integer.toString(value); hoeveelgroen.setText(waarde_groen); }} public static void main( String[] args) { new menu(); } }

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  • socket timeout and remove O_NONBLOCK option

    - by juxstapose
    Hello, I implemented a socket timeout and retry but in order to do it I had to set the socket as a non-blocking socket. However, I need the socket to block. This was my attempt at a solution to these two problems. This is not working. Subsequent send calls block but never send any data. When I connect without the select and the timeout, subsequent send calls work normally. References: C: socket connection timeout How to reset a socket back to blocking mode (after I set it to nonblocking mode)? Code: fd_set fdset; struct timeval tv; fcntl(dsock, F_SETFL, O_NONBLOCK); tv.tv_sec = theDeviceTimeout; tv.tv_usec = 0; int retries=0; logi(theLogOutput, LOG_INFO, "connecting to device socket num retrys: %i", theDeviceRetry); for(retries=0;retries<theDeviceRetry;retries++) { connect(dsock, (struct sockaddr *)&daddr, sizeof daddr); FD_ZERO(&fdset); FD_SET(dsock, &fdset); if (select(dsock + 1, NULL, &fdset, NULL, &tv) == 1) { int so_error; socklen_t slen = sizeof so_error; getsockopt(dsock, SOL_SOCKET, SO_ERROR, &so_error, &slen); if (so_error == 0) { logi(theLogOutput, LOG_INFO, "connected to socket on port %i on %s", theDevicePort, theDeviceIP); break; } else { logi(theLogOutput, LOG_WARN, "connect to %i failed on ip %s because %s retries %i", theDevicePort, theDeviceIP, strerror(errno), retries); logi(theLogOutput, LOG_WARN, "failed to connect to device %s", strerror(errno)); logi(theLogOutput, LOG_WARN, "error: %i %s", so_error, strerror(so_error)); continue; } } } int opts; opts = fcntl(dsock,F_GETFL); logi(theLogOutput, LOG_DEBUG, "clearing nonblock option %i retries %i", opts, retries); opts ^= O_NONBLOCK; fcntl(dsock, F_SETFL, opts);

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  • Integer array or struct array - which is better?

    - by MusiGenesis
    In my app, I'm storing Bitmap data in a two-dimensional integer array (int[,]). To access the R, G and B values I use something like this: // read: int i = _data[x, y]; byte B = (byte)(i >> 0); byte G = (byte)(i >> 8); byte R = (byte)(i >> 16); // write: _data[x, y] = BitConverter.ToInt32(new byte[] { B, G, R, 0 }, 0); I'm using integer arrays instead of an actual System.Drawing.Bitmap because my app runs on Windows Mobile devices where the memory available for creating bitmaps is severely limited. I'm wondering, though, if it would make more sense to declare a structure like this: public struct RGB { public byte R; public byte G; public byte B; } ... and then use an array of RGB instead of an array of int. This way I could easily read and write the separate R, G and B values without having to do bit-shifting and BitConverter-ing. I vaguely remember something from days of yore about byte variables being block-aligned on 32-bit systems, so that a byte actually takes up 4 bytes of memory instead of just 1 (but maybe this was just a Visual Basic thing). Would using an array of structs (like the RGB example` above) be faster than using an array of ints, and would it use 3/4 the memory or 3 times the memory of ints?

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  • How to use dirent.h correctly.

    - by Nick
    Hello, I am new to C++ and I am experimenting with the dirent.h header to manipulate directory entries. The following little app compiles but pukes after you supple a directory name. Can someone give me a hint? The int quit is there to provide a while loop. I removed the loop in an attempt to isolate my problem. thanks! #include <iostream> #include <dirent.h> using namespace std; int main() { char *dirname = 0; DIR *pd = 0; struct dirent *pdirent = 0; int quit = 1; cout<< "Enter a directory path to open (leave blank to quit):\n"; cin >> dirname; if(dirname == NULL) { quit = 0; } pd = opendir(dirname); if(pd == NULL) { cout << "ERROR: Please provide a valid directory path.\n"; } return 0; }

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  • Link error for user defined class type template parameter

    - by isurulucky
    Hi, I implemented a Simple STL map in C++. Factored out the comparison as a type as I was instructed to, then implemented the comparison as shown below: template <typename T> int KeyCompare<T>::operator () (T tKey1, T tKey2) { if(tKey1 < tKey2) return -1; else if(tKey1 > tKey2) return 1; else return 0; } here, tKey1 and tKet2 are the two keys I'm comparing. This worked well for all the basic data types and string. I added a template specialization to compare keys of a user defined type named Test and added a specialization as follows: int KeyCompare<Test>::operator () (Test tKey1, Test tKey2) { if(tKey1.a < tKey2.a) return -1; else if(tKey1.a > tKey2.a) return 1; else return 0; } when I run this, I get a linking error saying SimpleMap.obj : error LNK2005: "public: int __thiscall KeyCompare::operator()(class Test,class Test)" (??R?$KeyCompare@VTest@@@@QAEHVTest@@0@Z) already defined in MapTest.obj SimpleMap.obj : error LNK2005: "public: __thiscall KeyCompare::~KeyCompare(void)" (??1?$KeyCompare@VTest@@@@QAE@XZ) already defined in MapTest.obj SimpleMap.obj : error LNK2005: "public: __thiscall KeyCompare::KeyCompare(void)" (??0?$KeyCompare@VTester@@@@QAE@XZ) already defined in MapTest.obj MapTest.cpp is the test harness class in which I wrote the test case. I have used include guards as well, to stop multiple inclusions. Any idea what the matter is?? Thank you very much!!

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  • Decimal problem in Java

    - by Jerome
    I am experimenting with writing a java class for financial engineering (hobby of mine). The algorithm that I desire to implement is: 100 / 0.05 = 2000 Instead I get: 100 / 0.05 = 2000.9999999999998 I understand the problem to be one with converting from binary numbers to decimals (float -- int). I have looked at the BigDecimal class on the web but have not quite found what I am looking for. Attached is the program and a class that I wrote: // DCF class public class DCF { double rate; double principle; int period; public DCF(double $rate, double $principle, int $period) { rate = $rate; principle = $principle; period = $period; } // returns the console value public double consol() { return principle/rate; } // to string Method public String toString() { return "(" + rate + "," + principle + "," + period + ")"; } } Now the actual program: // consol program public class DCFmain { public static void main(String[] args) { // create new DCF DCF abacus = new DCF(0.05, 100.05, 5); System.out.println(abacus); System.out.println("Console value= " + abacus.consol() ); } } Output: (0.05,100.05,5) Console value= 2000.9999999999998 Thanks!

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  • Getting an exception when trying to use extension method with SortedDictionary... why?

    - by Polaris878
    I'm trying to place custom objects into a sorted dictionary... I am then trying to use an extension method (Max()) on this sorted dictionary. However, I'm getting the exception: "At least one object must implement IComparable". I don't understand why I'm getting that, as my custom object obviously implements IComparable. Here is my code: public class MyDate : IComparable<MyDate> { int IComparable<MyDate>.CompareTo(MyDate obj) { if (obj != null) { if (this.Value.Ticks < obj.Value.Ticks) { return 1; } else if (this.Value.Ticks == obj.Value.Ticks) { return 0; } else { return -1; } } } public MyDate(DateTime date) { this.Value = date; } public DateTime Value; } class Program { static void Main(string[] args) { SortedDictionary<MyDate, int> sd = new SortedDictionary<MyDate,int>(); sd.Add(new MyDate(new DateTime(1)), 1); sd.Add(new MyDate(new DateTime(2)), 2); Console.WriteLine(sd.Max().Value); // Throws exception!! } } What on earth am I doing wrong???

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  • DDD and MVC Models hold ID of separate entity or the entity itself?

    - by Dr. Zim
    If you have an Order that references a customer, does the model include the ID of the customer or a copy of the customer object like a value object (thinking DDD)? I would like to do ths: public class Order { public int ID {get;set;} public Customer customer {get;set;} ... } right now I do this: public class Order { public int ID {get;set;} public int customerID {get;set;} ... } It would be more convenient to include the complete customer object rather than an ID to the View Model passed to the form. Otherwise, I need to figure out how to get the vendor information to the view that the order references by ID. This also implies that the repository understand how to deal with the customer object that it finds within the order object when they call save (if we select the first option). If we select the second option, we will need to know where in the view model to put it. It is certain they will select an existing customer. However, it is also certain they may want to change the information in-place on the display form. One could argue to have the controller extract the customer object, submit customer changes separately to the repository, then submit changes to the order, keeping the customerID in the order.

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  • Where do objects merge/join data in a 3-tier model?

    - by BerggreenDK
    Its probarbly a simple 3-tier problem. I just want to make sure we use the best practice for this and I am not that familiary with the structures yet. We have the 3 tiers: GUI: ASP.NET for Presentation-layer (first platform) BAL: Business-layer will be handling the logic on a webserver in C#, so we both can use it for webforms/MVC + webservices DAL: LINQ to SQL in the Data-layer, returning BusinessObjects not LINQ. DB: The SQL will be Microsoft SQL-server/Express (havent decided yet). Lets think of setup where we have a database of [Persons]. They can all have multiple [Address]es and we have a complete list of all [PostalCode] and corresponding citynames etc. The deal is that we have joined a lot of details from other tables. {Relations}/[tables] [Person]:1 --- N:{PersonAddress}:M --- 1:[Address] [Address]:N --- 1:[PostalCode] Now we want to build the DAL for Person. How should the PersonBO look and when does the joins occure? Is it a business-layer problem to fetch all citynames and possible addressses pr. Person? or should the DAL complete all this before returning the PersonBO to the BAL ? Class PersonBO { public int ID {get;set;} public string Name {get;set;} public List<AddressBO> {get;set;} // Question #1 } // Q1: do we retrieve the objects before returning the PersonBO and should it be an Array instead? or is this totally wrong for n-tier/3-tier?? Class AddressBO { public int ID {get;set;} public string StreetName {get;set;} public int PostalCode {get;set;} // Question #2 } // Q2: do we make the lookup or just leave the PostalCode for later lookup? Can anyone explain in what order to pull which objects? Constructive criticism is very welcome. :o)

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  • How to track auto-generated id's in select-insert statement

    - by k rey
    I have two tables detail and head. The detail table will be written first. Later, the head table will be written. The head is a summary of the detail table. I would like to keep a reference from the detail to the head table. I have a solution but it is not elegant and requires duplicating the joins and filters that were used during summation. I am looking for a better solution. The below is an example of what I currently have. In this example, I have simplified the table structure. In the real world, the summation is very complex. -- Preparation create table #detail ( detail_id int identity(1,1) , code char(4) , amount money , head_id int null ); create table #head ( head_id int identity(1,1) , code char(4) , subtotal money ); insert into #detail ( code, amount ) values ( 'A', 5 ); insert into #detail ( code, amount ) values ( 'A', 5 ); insert into #detail ( code, amount ) values ( 'B', 2 ); insert into #detail ( code, amount ) values ( 'B', 2 ); -- I would like to somehow simplify the following two queries insert into #head ( code, subtotal ) select code, sum(amount) from #detail group by code update #detail set head_id = h.head_id from #detail d inner join #head h on d.code = h.code -- This is the desired end result select * from #detail Desired end result of detail table: detail_id code amount head_id 1 A 5.00 1 2 A 5.00 1 3 B 2.00 2 4 B 2.00 2

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  • Will my LinqToSql execution be deffered if i filter with IEnumerable<T> instead of IQueryable<T>?

    - by cottsak
    I have been using these common EntityObjectFilters as a "pipes and filters" way to query from a collection a particular item with an ID: public static class EntityObjectFilters { public static T WithID<T>(this IQueryable<T> qry, int ID) where T : IEntityObject { return qry.SingleOrDefault<T>(item => item.ID == ID); } public static T WithID<T>(this IList<T> list, int ID) where T : IEntityObject { return list.SingleOrDefault<T>(item => item.ID == ID); } } ..but i wondered to myself: "can i make this simpler by just creating an extension for all IEnumerable<T> types"? So i came up with this: public static class EntityObjectFilters { public static T WithID<T>(this IEnumerable<T> qry, int ID) where T : IEntityObject { return qry.SingleOrDefault<T>(item => item.ID == ID); } } Now while this appears to yield the same result, i want to know that when applied to IQueryable<T>s will the expression tree be passed to LinqToSql for evaluating as SQL code or will my qry be evaluated in it's entirety first, then iterated with Funcs? I'm suspecting that (as per Richard's answer) the latter will be true which is obviously what i don't want. I want the same result, but the added benefit of the delayed SQL execution for IQueryable<T>s. Can someone confirm for me what will actually happen and provide simple explanation as to how it would work?

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