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  • What's the correct way to do a "catch all" error check on an fstream output operation?

    - by Truncheon
    What's the correct way to check for a general error when sending data to an fstream? UPDATE: My main concern regards some things I've been hearing about a delay between output and any data being physically written to the hard disk. My assumption was that the command "save_file_obj << save_str" would only send data to some kind of buffer and that the following check "if (save_file_obj.bad())" would not be any use in determining if there was an OS or hardware problem. I just wanted to know what was the definitive "catch all" way to send a string to a file and check to make certain that it was written to the disk, before carrying out any following actions such as closing the program. I have the following code... int Saver::output() { save_file_handle.open(file_name.c_str()); if (save_file_handle.is_open()) { save_file_handle << save_str.c_str(); if (save_file_handle.bad()) { x_message("Error - failed to save file"); return 0; } save_file_handle.close(); if (save_file_handle.bad()) { x_message("Error - failed to save file"); return 0; } return 1; } else { x_message("Error - couldn't open save file"); return 0; } }

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  • Problem with relative file path

    - by Richard Knop
    So here is my program, which works ok: import java.io.FileReader; import java.io.BufferedReader; import java.io.IOException; import java.util.Scanner; import java.util.Locale; public class ScanSum { public static void main(String[] args) throws IOException { Scanner s = null; double sum = 0; try { s = new Scanner(new BufferedReader(new FileReader("D:/java-projects/HelloWorld/bin/usnumbers.txt"))); s.useLocale(Locale.US); while (s.hasNext()) { if (s.hasNextDouble()) { sum += s.nextDouble(); } else { s.next(); } } } finally { s.close(); } System.out.println(sum); } } As you can see, I am using absolute path to the file I am reading from: s = new Scanner(new BufferedReader(new FileReader("D:/java-projects/HelloWorld/bin/usnumbers.txt"))); The problem arises when I try to use the relative path: s = new Scanner(new BufferedReader(new FileReader("usnumbers.txt"))); I get an error: Exception in thread "main" java.lang.NullPointerException at ScanSum.main(ScanSum.java:24) The file usnumbers.txt is in the same directory as the ScanSum.class file: D:/java-projects/HelloWorld/bin/ScanSum.class D:/java-projects/HelloWorld/bin/usnumbers.txt How could I solve this?

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  • How to create a "Shell IDList Array" to support drag-and-drop of virtual files from C# to Windows Ex

    - by JustABill
    I started trying to implement drag-and-drop of virtual files (from a C# 4/WPF app) with this codeplex tutorial. After spending some time trying to figure out a DV_E_FORMATETC error, I figured out I need to support the "Shell IDList Array" data format. But there seems to be next to zero documentation on what this format actually does. After some searching, I found this page on advanced data transfer which said that a Shell IDList Array was a pointer to a CIDA structure. This CIDA structure then contains the number of PIDLs, and a list of offsets to them. So what the hell is a PIDL? After some more searching, this page sort of implies it's a pointer to an ITEMIDLIST, which itself contains a single member that is a list of SHITEMIDs. My next idea was to try dragging a file from another application with virtual files. I just got a MemoryStream back for this format. At least I know what class to provide for the thing, but that doesn't help at all for explaining what to put in it. So now that that's explained, I still have no idea how to create one of these things so that it's valid. There's two real questions here: What is a valid "abID" member for a SHITEMID? These virtual files only exist with my program; will the thing they are dragged to pass the "abID" back later when it executes GetData? Do they have to be system-unique? Why are there two levels of lists; a list of PIDLs and each PIDL has a list of SHITEMIDs? I'm assuming one of them is one for each file, but what's the other one for? Multiple IDs for the same file? Any help or even links that explain what I should be doing would be greatly appreciated.

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  • Using game of life or other virtual environment for artificial (intelligence) life simulation? [clos

    - by Berlin Brown
    One of my interests in AI focuses not so much on data but more on biologic computing. This includes neural networks, mapping the brain, cellular-automata, virtual life and environments. Described below is an exciting project that includes develop a virtual environment for bots to evolve in. "Polyworld is a cross-platform (Linux, Mac OS X) program written by Larry Yaeger to evolve Artificial Intelligence through natural selection and evolutionary algorithms." http://en.wikipedia.org/wiki/Polyworld " Polyworld is a promising project for studying virtual life but it still is far from creating an "intelligent autonomous" agent. Here is my question, in theory, what parameters would you use create an AI environment? Possibly a brain environment? Possibly multiple self contained life organisms that have their own "brain" or life structures. I would like a create a spin on the game of life simulation. What if you have a 64x64 game of life grid. But instead of one grid, you might have N number of grids. The N number of grids are your "life force" If all of the game of life entities die in a particular grid then that entire grid dies. A group of "grids" makes up a life form. I don't have an immediate goal. First, I want to simulate an environment and visualize what is going on in the environment with OpenGL and see if there are any interesting properties to the environment. I then want to add "scarce resources" and see if the AI environment can manage resources adequately.

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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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  • Ruby - calling constructor without arguments & removal of new line characters

    - by Raj
    I am a newbie at Ruby, I have written down a sample program. I dont understand the following: Why constructor without any arguments are not called in Ruby? How do we access the class variable outside the class' definition? Why does it always append newline characters at the end of the string? How do we strip it? Code: class Employee attr_reader :empid attr_writer :empid attr_writer :name def name return @name.upcase end attr_accessor :salary @@employeeCount = 0 def initiaze() @@employeeCount += 1 puts ("Initialize called!") end def getCount return @@employeeCount end end anEmp = Employee.new print ("Enter new employee name: ") anEmp.name = gets() print ("Enter #{anEmp.name}'s employee ID: ") anEmp.empid = gets() print ("Enter salary for #{anEmp.name}: ") anEmp.salary = gets() theEmpName = anEmp.name.split.join("\n") theEmpID = anEmp.empid.split.join("\n") theEmpSalary = anEmp.salary.split.join("\n") anEmp = Employee.new() anEmp = Employee.new() theCount = anEmp.getCount puts ("New employee #{theEmpName} with employee ID #{theEmpID} has been enrolled, welcome to hell! You have been paid as low as $ #{theEmpSalary}") puts ("Total number of employees created = #{theCount}") Output: Enter new employee name: Lionel Messi Enter LIONEL MESSI 's employee ID: 10 Enter salary for LIONEL MESSI : 10000000 New employee LIONEL MESSI with employee ID 10 has been enrolled, welcome to hell! You have been paid as low as $ 10000000 Total number of employees created = 0 Thanks

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  • Problems initializing a final variable in Java

    - by froadie
    I keep running into slight variations of a problem in Java and it's starting to get to me, and I can't really think of a proper way to get around it. I have an object property that is final, but dynamic. That is, I want the value to be constant once assigned, but the value can be different each runtime. So I declare the class level variable at the beginning of the class - say private final FILE_NAME;. Then, in the constructor, I assign it a value - say FILE_NAME = buildFileName(); The problem begins when I have code in the buildFileName() method that throws an exception. So I try something like this in the constructor: try{ FILE_NAME = buildFileName(); } catch(Exception e){ ... System.exit(1); } Now I have an error - "The blank final field FILE_NAME may not have been initialized." This is where I start to get slightly annoyed at Java's strict compiler. I know that this won't be a problem because if it gets to the catch the program will exit... But the compiler doesn't know that and so doesn't allow this code. If I try to add a dummy assignment to the catch, I get - "The final field FILE_NAME may already have been assigned." I clearly can't assign a default value before the try-catch because I can only assign to it once. Any ideas...?

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  • Installer downloads wrong version of sql server compact edition

    - by MartinStettner
    I have a Visual Studio setup project which defines SQL Server 3.5 as prerequisite. I also set it up to download the required files from the source (i.e. Microsoft). My project uses Sql Server 3.5 SP1. If I create the installer on my development machine, everything works fine. When the installer is built on the build machine, it downloads the "old" 3.5 version (without SP1) which makes my application crash. (If I install SP1 on the test system manually, the application just works find...) I installed both Visual Studio 2008 SP1 and Sql Server 3.5 SP1 on the build machine. This seems to be some issue with the prerequisite packages but they look the same on the development and the build machines. Any idea what goes wrong here? EDIT Ok, I rechecked it and the package descriptions are'nt the sames. Oddly enough, the .msi file is the right one on the build machine but the old one on the development machine, so I guess if I tried to build an installer which includes the prerequisites, I'd get the wrong result on the dev machine and the right one on the build machine. Extended question: How are the prerequesite packages (under C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bootstrapper\Packages\SQL Server Compact Edition) meant to be updated to SP1? Is the SQL Server CE SP1 installer responsible for this?

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  • Javascript/PHP popup page problem

    - by Suezy
    I have a program in PHP that allows user to pop in a message, for confirmation from user. As seen below is the link i used. From inbox.php: echo "<a href='inbox.php' onclick=\"popup('acknowledge.php?id=$id')\"><font size=1px color=maroon>acknowledge</font></a></td>"; From acknowledge.php: if ($_POST['no']) { header("location: inbox.php"); } ?> <body bgcolor=skyblue> <center><form name=form1 method=post> <b><u> Acknowledge Message </u></b><br><br> Are you sure yout want to acknowledge this message?<br><br> <input type=button name=yes value="Yes"> &nbsp; <input type=submit name="no" value="No" onSubmit="window.close()"> </form> </center> </body> The problem is, everytime i click "no", to go back from previous page. It sets the page size the same as the popup page. It becomes smaller too. What's the problem? Answers are very much appreciated.

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  • Newbie C# Question about float/int/text type formatting

    - by user563501
    Hey everybody, I'm a total C# newb with a light (first year CS) background in Python. I wrote a console program in Python for doing marathon pace running calculations and I'm trying to figure out the syntax for this in C# using Visual Studio 2010. Here's a chunk of what I've got so far: string total_seconds = ((float.Parse(textBox_Hours.Text) * 60 * 60) + (float.Parse(textBox_Minutes.Text) * 60) + float.Parse(textBox_Seconds.Text)).ToString(); float secs_per_unit = ((float)(total_seconds) / (float)(textBox_Distance.Text)); float mins_per_unit = (secs_per_unit / 60); string pace_mins = (int)mins_per_unit.ToString(); string pace_secs = (float.Parse(mins_per_unit) - int.Parse(mins_per_unit) * 60).ToString(); textBox_Final_Mins.Text = pace_mins; textBox_Final_Secs.Text = pace_mins; Imagine you have a running pace of 8 minutes and 30 seconds per mile. secs_per_unit would be 510, mins_per_unit would be 8.5. pace_mins would simply be 8 and pace_secs would be 30. In Python I'd just convert variables from a float to a string to get 8 instead of 8.5, for example; hopefully the rest of the code gives you an idea of what I've been doing. Any input would be appreciated.

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  • C# / XNA - Load objects to the memory - how it works?

    - by carl
    Hello I'm starting with C# and XNA. In the "Update" method of the "Game" class I have this code: t = Texture2D.FromFile( [...] ); //t is a 'Texture2D t;' which loads small image. "Update" method is working like a loop, so this code is called many times in a second. Now, when I run my game, it takes 95MB of RAM and it goes slowly to about 130MB (due to the code I've posted, without this code it remains at 95MB), then goes immediately to about 100MB (garbare colletion?) and again goes slowly to 130MB, then immediately to 100MB and so on. So my first question: Can You explain why (how) it works like that? I've found, that if I change the code to: t.Dispose() t = Texture2D.FromFile( [...] ); it works like that: first it takes 95MB and then goes slowly to about 101MB (due to the code) and remains at this level. I don't understand why it takes this 6MB (101-95)... ? I want to make it works like that: load image, release from memory, load image, release from memory and so on, so the program should always takes 95MB (it takes 95MB when image is loaded only once in previous method). Whats instructions should I use? If it is important, the size of the image is about 10KB. Thank You!

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  • What's the best way to resolve this scope problem?

    - by Peter Stewart
    I'm writing a program in python that uses genetic techniques to optimize expressions. Constructing and evaluating the expression tree is the time consumer as it can happen billions of times per run. So I thought I'd learn enough c++ to write it and then incorporate it in python using cython or ctypes. I've done some searching on stackoverflow and learned a lot. This code compiles, but leaves the pointers dangling. I tried 'this_node = new Node(...' . It didn't seem to work. And I'm not at all sure how I'd delete all the references as there would be hundreds. I'd like to use variables that stay in scope, but maybe that's not the c++ way. What is the c++ way? class Node { public: char *cargo; int depth; Node *left; Node *right; } Node make_tree(int depth) { depth--; if(depth <= 0) { Node tthis_node("value",depth,NULL,NULL); return tthis_node; } else { Node this_node("operator" depth, &make_tree(depth), &make_tree(depth)); return this_node; } };

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  • Error Message-The source attachment does not contain the source for the file ListView.class

    - by user603695
    Hello, new to Android. I get the following message in the debugger perspective: The source attachment does not contain the source for the file ListView.class You can change the source attachment by clicking the change attached Source Below Needless to say the app errors. I've tried to change the source attachment to the location path: C:/Program Files/Android/android-sdk-windows/platforms/android-8/android.jar However, this did not work. Any thoughts would be much appreciated. Code is: import android.app.ListActivity; import android.os.Bundle; import android.view.*; import android.widget.*; public class HelloListView extends ListActivity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setListAdapter(new ArrayAdapter<String>(this, R.layout.main, COUNTRIES)); ListView lv = getListView(); lv.setTextFilterEnabled(true); lv.setOnItemClickListener(new AdapterView.OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View view, int position, long id) { // When clicked, show a toast with the TextView text Toast.makeText(getApplicationContext(), ((TextView) view).getText(), Toast.LENGTH_SHORT).show(); } }); } static final String[] COUNTRIES = new String[] { "Afghanistan", "Albania", "Algeria", "American Samoa... Thanks!

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  • Why is F# member not found when used in subclass

    - by James Black
    I have a base type that I want to inherit from, for all my DAO objects, but this member gets the error further down about not being defined: type BaseDAO() = member v.ExecNonQuery2(conn)(sqlStr) = let comm = new MySqlCommand(sqlStr, conn, CommandTimeout = 10) comm.ExecuteNonQuery |> ignore comm.Dispose |> ignore I inherit in this type: type CreateDatabase() = inherit BaseDAO() member private self.createDatabase(conn) = self.ExecNonQuery2 conn "DROP DATABASE IF EXISTS restaurant" This is what I see when my script runs in the interactive shell: --> Referenced 'C:\Program Files\MySQL\MySQL Connector Net 6.2.3\Assemblies\MySql.Data.dll' [Loading C:\Users\jblack\Documents\Visual Studio 2010\Projects\RestaurantService\RestaurantDAO\BaseDAO.fs] namespace FSI_0106.RestaurantServiceDAO type BaseDAO = class new : unit -> BaseDAO member ExecNonQuery2 : conn:MySql.Data.MySqlClient.MySqlConnection -> sqlStr:string -> unit member execNonQuery : sqlStr:string -> unit member execQuery : sqlStr:string * selectFunc:(MySql.Data.MySqlClient.MySqlDataReader -> 'a list) -> 'a list member f : x:obj -> string member Conn : MySql.Data.MySqlClient.MySqlConnection end [Loading C:\Users\jblack\Documents\Visual Studio 2010\Projects\RestaurantService\RestaurantDAO\CreateDatabase.fs] C:\Users\jblack\Documents\Visual Studio 2010\Projects\RestaurantService\RestaurantDAO\CreateDatabase.fs(56,14): error FS0039: The field, constructor or member 'ExecNonQuery2' is not defined I am curious what I am doing wrong. I have tried not inheriting, and just instantiating the BaseDAO type in the function, but I get the same error. I started on this path because I had a property that had the same error, so it seems there may be a problem with how I am defining my BaseDAO type, but it compiles with no error, which further confuses me about this problem.

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  • How to set up django-admin.py on windows vista?

    - by shin
    I manage to install Django after some struggles by using setup.py install on Windows Vista Now I tried to use django-admin.py but it is not working. According to this document, http://docs.djangoproject.com/en/dev/ref/django-admin/ The django-admin.py script should be on your system path if you installed Django via its setup.py utility. If it’s not on your path, ... For Windows users, who do not have symlinking functionality available, you can copy django-admin.py to a location on your existing path or edit the PATH settings (under Settings - Control Panel - System - Advanced - Environment...) to point to its installed location. I checked ComputerpropertiesEnvironment Variables, but path to django-admin.py is not in anywhere. So I added C:\Python25\Lib\site-packages\django\bin which is the folder of django-admin.py in User variables for shin Variable PATH, Value C:\Program Files\Google\google_appengine\;C:\Python25\Lib\site-packages\django\bin\ Am I supposed to add to System variables?? But it still does not work. Could anyone tell me how to add the Path in Environment Variables please? Thanks in advance.

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  • Highlighting correctly in an emacs major mode

    - by Paul Nathan
    Hi, I am developing an emacs major mode for a language (aka mydsl). However, using the techniques on xahlee's site doesn't seem to be working for some reason (possibly older emacs dialect..) The key issues I am fighting with are (1) highlighting comments is not working and (2), the use of regexp-opt lines is not working. I've reviewed the GNU manual and looked over cc-mode and elisp mode... those are significantly more complicated than I need. ;;;Standard # to newline comment ;;;Eventually should also have %% to %% multiline block comments (defun mydsl-comment-dwim (arg) "comment or uncomment" (interactive "*P") (require 'newcomment) (let ((deactivate-mark nil) (comment-start "#") (comment-end "") comment-dwim arg))) (defvar mydsl-events '("reservedword1" "reservedword2")) (defvar mydsl-keywords '("other-keyword" "another-keyword")) ;;Highlight various elements (setq mydsl-hilite '( ; stuff between " ("\"\\.\\*\\?" . font-lock-string-face) ; : , ; { } => @ $ = are all special elements (":\\|,\\|;\\|{\\|}\\|=>\\|@\\|$\\|=" . font-lock-keyword-face) ( ,(regexp-opt mydsl-keywords 'words) . font-lock-builtin-face) ( ,(regexp-opt mydsl-events 'words) . font-lock-constant-face) )) (defvar mydsl-tab-width nil "Width of a tab for MYDSL mode") (define-derived-mode mydsl-mode fundamental-mode "MYDSL mode is a major mode for editing MYDSL files" ;Recommended by manual (kill-all-local-variables) (setq mode-name "MYDSL script") (setq font-lock-defaults '((mydsl-hilite))) (if (null mydsl-tab-width) (setq tab-width mydsl-tab-width) (setq tab-width default-tab-width) ) ;Comment definitions (define-key mydsl-mode-map [remap comment-dwim] 'mydsl-comment-dwim) (modify-syntax-entry ?# "< b" mydsl-mode-syntax-table) (modify-syntax-entry ?\n "> b" mydsl-mode-syntax-table) ;;A gnu-correct program will have some sort of hook call here. ) (provide 'mydsl-mode)

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  • C++ ofstream cannot write to file....

    - by user69514
    Hey I am trying to write some numbers to a file, but when I open the file it is empty. Can you help me out here? Thanks. /** main function **/ int main(){ /** variables **/ RandGen* random_generator = new RandGen; int random_numbers; string file_name; /** ask user for quantity of random number to produce **/ cout << "How many random number would you like to create?" << endl; cin >> random_numbers; /** ask user for the name of the file to store the numbers **/ cout << "Enter name of file to store random number" << endl; cin >> file_name; /** now create array to store the number **/ int random_array [random_numbers]; /** file the array with random integers **/ for(int i=0; i<random_numbers; i++){ random_array[i] = random_generator -> randInt(-20, 20); cout << random_array[i] << endl; } /** open file and write contents of random array **/ const char* file = file_name.c_str(); ofstream File(file); /** write contents to the file **/ for(int i=0; i<random_numbers; i++){ File << random_array[i] << endl; } /** close the file **/ File.close(); return 0; /** END OF PROGRAM **/ }

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  • Cannot access Class methods from previous windows form - C#

    - by George
    I am writing an app, still, where I need to test some devices every minute for 30 minutes. It made sense to use a timer set to kick off every 60 secs and do whats required in the event handler. However, I need the app to wait for the 30 mins until I have finished with the timer since the following code alters the state of the devices I am trying to monitor. I obviously don't want to use any form of loop to do this. I thought of using another windows form, since I also display the progress, which will simply kick off the timer and wait until its complete. The problem I am having with this is that I use a device Class and cant seem to get access to the methods in the device class from the 2nd (3rd actually - see below) windows form. I have an initial windows form where I get input from the user, then call the 2nd windows form where it work out which tests need to be done and which device classes need to be used, and then I want to call the 3rd windows form to handle the timer. I will have up to 6-7 device classes and so wanted to only instantiate them when actually requiring them, from the 2nd form. Should I have put this logic into the 1st windows form (program class ??) ? Would I not still have the problem of not being able to access device class methods from there too ? Anyway, perhaps someone knows of a better way to do the checks every minute without the rest of the code executing (and changing the status of the devices) or how I should be accessing the methods in the app ?? Well that's the problem, I cant get that part of it to work correctly. Here is the definition for the calling form including the device class - namespace NdtStart { public partial class fclsNDTCalib : Form { NDTClass NDT = new NDTClass(); public fclsNDTCalib() (new fclsNDTTicker(NDT)).ShowDialog(); Here is the class def for the called form - namespace NdtStart { public partial class fclsNDTTicker : Form { public fclsNDTTicker() I tried lots but couldn't get the arguments to work.

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  • Calculate the retrieved rows in database Visual C#

    - by Tanya Lertwichaiworawit
    I am new in Visual C# and would want to know how to calculate the retrieved data from a database. Using the above GUI, when "Calculate" is click, the program will display the number of students in textBox1, and the average GPA of all students in textBox2. Here is my database table "Students": I was able to display the number of students but I'm still confused to how I can calculate the average GPA Here's my code: private void button1_Click(object sender, EventArgs e) { string connection = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Database1.accdb"; OleDbConnection connect = new OleDbConnection(connection); string sql = "SELECT * FROM Students"; connect.Open(); OleDbCommand command = new OleDbCommand(sql, connect); DataSet data = new DataSet(); OleDbDataAdapter adapter = new OleDbDataAdapter(command); adapter.Fill(data, "Students"); textBox1.Text = data.Tables["Students"].Rows.Count.ToString(); double gpa; for (int i = 0; i < data.Tables["Students"].Rows.Count; i++) { gpa = Convert.ToDouble(data.Tables["Students"].Rows[i][2]); } connect.Close(); }

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  • The new operator in C# isn't overriding base class member

    - by Dominic Zukiewicz
    I am confused as to why the new operator isn't working as I expected it to. Note: All classes below are defined in the same namespace, and in the same file. This class allows you to prefix any content written to the console with some provided text. public class ConsoleWriter { private string prefix; public ConsoleWriter(string prefix) { this.prefix = prefix; } public void Write(string text) { Console.WriteLine(String.Concat(prefix,text)); } } Here is a base class: public class BaseClass { protected static ConsoleWriter consoleWriter = new ConsoleWriter(""); public static void Write(string text) { consoleWriter.Write(text); } } Here is an implemented class: public class NewClass : BaseClass { protected new static ConsoleWriter consoleWriter = new ConsoleWriter("> "); } Now here's the code to execute this: class Program { static void Main(string[] args) { BaseClass.Write("Hello World!"); NewClass.Write("Hello World!"); Console.Read(); } } So I would expect the output to be Hello World! > Hello World! But the output is Hello World Hello World I do not understand why this is happening. Here is my thought process as to what is happening: The CLR calls the BaseClass.Write() method The CLR initialises the BaseClass.consoleWriter member. The method is called and executed with the BaseClass.consoleWriter variable Then The CLR calls the NewClass.Write() The CLR initialises the NewClass.consoleWriter object. The CLR sees that the implementation lies in BaseClass, but the method is inherited through The CLR executes the method locally (in NewClass) using the NewClass.consoleWriter variable I thought this is how the inheritance structure works? Please can someone help me understand why this is not working?

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  • Requirements for connecting to Oracle with JDBC?

    - by Lord Torgamus
    I'm a newbie to Java-related web development, and I can't seem to get a simple program with JDBC working. I'm using off-the-shelf Oracle 10g XE and the Eclipse EE IDE. From the books and web pages I've checked so far, I've narrowed the problem down to either an incorrectly written database URL or a missing JAR file. I'm getting the following error: java.sql.SQLException: No suitable driver found for jdbc:oracle://127.0.0.1:8080 with the following code: import java.sql.*; public class DatabaseTestOne { public static void main(String[] args) { String url = "jdbc:oracle://127.0.0.1:8080"; String username = "HR"; String password = "samplepass"; String sql = "SELECT EMPLOYEE_ID FROM EMPLOYEES WHERE LAST_NAME='King'"; Connection connection; try { connection = DriverManager.getConnection(url, username, password); Statement statement = connection.createStatement(); System.out.println(statement.execute(sql)); connection.close(); } catch (SQLException e) { System.err.println(e); } } } What is the proper format for a database URL, anyways? They're mentioned a lot but I haven't been able to find a description. Thanks! EDIT (the answer): Based on duffymo's answer, I got ojdbc14.jar from http://www.oracle.com/technology/software/tech/java/sqlj_jdbc/htdocs/jdbc_10201.html and dropped it in the Eclipse project's Referenced Libraries. Then I changed the start of the code to ... try { Class.forName("oracle.jdbc.driver.OracleDriver"); } catch (ClassNotFoundException e) { System.err.println(e); } // jdbc:oracle:thin:@<hostname>:<port>:<sid> String url = "jdbc:oracle:thin:@GalacticAC:1521:xe"; ... and it worked.

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  • VSC++, virtual method at bad adress, curious bug

    - by antoon.groenewoud
    Hello, This guy: virtual phTreeClass* GetTreeClass() const { return (phTreeClass*)m_entity_class; } When called, crashed the program with an access violation, even after a full recompile. All member functions and virtual member functions had correct memory adresses (I hovered mouse over the methods in debug mode), but this function had a bad memory adress: 0xfffffffc. Everything looked okay: the 'this' pointer, and everything works fine up until this function call. This function is also pretty old and I didn't change it for a long time. The problem just suddenly popped up after some work, which I commented all out to see what was doing it, without any success. So I removed the virtual, compiled, and it works fine. I add virtual, compiled, and it still works fine! I basically changed nothing, and remember that I did do a full recompile earlier, and still had the error back then. I wasn't able to reproduce the problem. But now it is back. I didn't change anything. Removing virtual fixes the problem. Sincerely, Antoon

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  • After interruption, delayed audio route change notifications when recording

    - by Frank Shearar
    My iPhone application requires that I know when a user has/has not plugged in her headphones. That's easy. AudioSessionAddPropertyListener with a callback listening to kAudioSessionProperty_AudioRouteChange. I write logs with NSLog as things happen. User plugs the headphones in? Get a notification, and a line in the gdb console. User unplugs the headphones? Ditto. At the same time I'm sensing the noise level of the environment by starting a recording audio queue. This, too, works great: I can get the mic noise level and listen for audio route changes just fine. What I find is that after an interruption, and I've reactivated the audio session and restored the audio category to kAudioSessionCategory_RecordAudio, the audio route notifications go a bit haywire. When I plug in the headphones, I see no notification. When I unplug the headphones I see BOTH the "plugged in" notification AND the "unplugged" notification, in rapid succession. It's like the "plugged in" notification's delayed and, when the "unplugged" notification arrives, the queue of pending notifications is flushed. What am I doing wrong? How do I correctly restore the audio session to get timeous notifications? EDIT: iPhone OS 3.1.2, running on an iPhone 3G. I'm running a program compiled with the 3.0 SDK (from within XCode 3.1.2).

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  • Parallel.Foreach loop creating multiple db connections throws connection errors?

    - by shawn.mek
    Login failed. The login is from an untrusted domain and cannot be used with Windows authentication I wanted to get my code running in parallel, so I changed my foreach loop to a parallel foreach loop. It seemed simple enough. Each loop connects to the database, looks up some stuff, performs some logic, adds some stuff, closes the connection. But I get the above error? I'm using my local sql server and entity framework (each loop uses it's own context). Is there some problem with connecting multiple times using the same local login or something? How did I get around this? I have (before trying to covert to a parallel.foreach loop) split my list of objects that I am foreach looping through into four groups (separate csv files) and run four concurrent instances of my program (which ran faster overall than just one, thus the idea for parallel). So it seems connecting to the db shouldn't be a problem? Any ideas? EDIT: Here's before var gtgGenerator = new CustomGtgGenerator(); var connectionString = ConfigurationManager.ConnectionStrings["BioEntities"].ConnectionString; var allAccessionsFromObs = _GetAccessionListFromDataFiles(collectionId); ForEach(cloneIdAndAccessions in allAccessionsFromObs) DoWork(gtgGenerator, taxonId, organismId, cloneIdAndAccessions, connectionString)); after var gtgGenerator = new CustomGtgGenerator(); var connectionString = ConfigurationManager.ConnectionStrings["BioEntities"].ConnectionString; var allAccessionsFromObs = _GetAccessionListFromDataFiles(collectionId); Parallel.ForEach(allAccessionsFromObs, cloneIdAndAccessions => DoWork(gtgGenerator, taxonId, organismId, cloneIdAndAccessions, connectionString)); Inside the DoWork I use the BioEntities using (var bioEntities = new BioEntities(connectionString)) {...}

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  • SWT Drag and Drop support for Text widget

    - by bryantsai
    I've written an application recently using SWT. In one of its dialog box, I have a few widgets, one of which is Text, which is designed to support DND with other widgets. I've first added DND support for the 2 Tree widgets on the same dialog box (both drag source and drop target). Before I added DND support for that Text widget, I noticed that on Linux platform (gtk), SWT Text widget automatically get drag and drop support. That is, I can already drag from the other Tree widgets and drop on this Text (at any position to inserted there), as well as selecting and dragging any text from this Text to other Tree or Text widget. However, this is only working on Linux platform but not on Windows. The same program, if running on Windows, will not have any DND support for that Text widget (Tree widgets of course have DND support since I specifically write for them). So here's what I want to achieve on Windows as well: drop text at any position in Text widget. before dropping and while hovering, able to see the caret position clearly where the intended position to drop. caret position should move along with the mouse cursor. support multi-line in Text widget SOLUTION: DropTarget target = new DropTarget(sytledText, DND.DROP_MOVE | DND.DROP_COPY); target.setTransfer(new Transfer[] { TextTransfer.getInstance() }); target.addDropListener(new StyleTextDropTargetEffect(sytledText)); Use StyledText instead of Text widget Use StyledTextDropTargetEffect (or extend it) and add it as dr op listener

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