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• How does OfType<T>() Work?

  - by TheCloudlessSky

  How does OfType() Work? I read this link about what's going on but how exactly does the LINQ provider know how to get all objects matching the specified type. I know the IQueryable<T> "chains" up requests and then evaluates when GetEnumerator() is called (right?). Specifically I want to know how does the framework quickly do type comparison? I wrote a method in a .NET 2.0 project that went like this (since 2.0 doesn't support these kind of features): public IEnumerable<TResult> OfType<TResult>() where TResult : class { foreach (TItem item in this.InnerList) { TResult matchItem = item as TResult; if (matchItem != null) { yield return matchItem; } } } Is this the best implementation?

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• Only strip commas surrounded by numbers in a string

  - by overlook77

  I am using StreamReader to read each line of a CSV file into a string. As I am processing each line, I need to strip out any commas that ONLY are surrounded by other numbers. For example, if the string was: "textfield1", "textfield2", "100.00", "1,070.00" I would need to only take the comma out of "1,070.00" from this entire string, resulting in: "textfield1", "textfield2", "100.00", "1070.00" Each string read from the CSV file can differ in number of fields, length, etc., so I need to use something (Regular Expressions maybe?) that looks at the entire string without hardcoding a location or blanket removal of all commas. Here is the approach I have been trying: StreamReader sr = new StreamReader(strInputFile); string nextLine = sr.ReadLine(); try { while ((nextLine = sr.ReadLine()) != null) { string rawtext = nextLine.Replace("[0-9]"+","+"[0-9]" , "[0-9]"+"[0-9]"); // ....rest of code } } This obviously doesn't work because I don't understand how to do this :) I am new at C# and inexperienced in Regex, so hopefully this is relatively simple.

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• How to use .DefaultListCellRenderer

  - by loddn

  First, i'm new at Java-programming and my native lang is not english, but still i hope to get some help from you all. What I try to do is a simple java-interface with a jComboBox and a jList. I want to poplate to jComboBox with Object-names and when the user select one of the names get the object-id which i will use to populate the jList. It's probably simple but i have bin stuck with this problem all day. private void loadComboBox() { biz.Object object = new biz.Object(); try { ArrayList<biz.Object> arrayOfObjects= object.getAllObjects();// ArrayList of objects for (biz.Object o:arrayOfObjects) { if (o != null) cbm.addElement(o); //`toString-method } cb.setModel(cbm); //JComboBox

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• Why StringWriter.ToString return `System.Byte[]` and not the data?

  - by theateist

  UnZipFile method writes the data from inputStream to outputWriter. Why sr.ToString() returns System.Byte[] and not the data? using (var sr = new StringWriter()) { UnZipFile(response.GetResponseStream(), sr); var content = sr.ToString(); } public static void UnZipFile(Stream inputStream, TextWriter outputWriter) { using (var zipStream = new ZipInputStream(inputStream)) { ZipEntry currentEntry; if ((currentEntry = zipStream.GetNextEntry()) != null) { var size = 2048; var data = new byte[size]; while (true) { size = zipStream.Read(data, 0, size); if (size > 0) { outputWriter.Write(data); } else { break; } } } } }

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• Form Closing help

  - by Michael Quiles

  How can I call the button1_Click event in the form closing event so I don't have to copy and paste the code from button1_Click? public void button1_Click(object sender, EventArgs e) { //Yes or no message box to exit the application DialogResult Response; Response = MessageBox.Show("Are you sure you want to Exit?", "Exit", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2); if (Response == DialogResult.Yes) // Exits the application Application.Exit(); } public void xGameThemeComboBox_SelectedIndexChanged(object sender, EventArgs e) { string folder = Application.StartupPath; string theme = (string)xGameThemeComboBox.Items[xGameThemeComboBox.SelectedIndex]; string path = System.IO.Path.Combine(folder, theme + ".jpg"); Image newImage = new Bitmap(path); if (this.BackgroundImage != null) this.BackgroundImage.Dispose(); { this.BackgroundImage = newImage; } } private void xGameForm_FormClosing(object sender, FormClosingEventArgs e) { // call button1_Click here }

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• SQL Outer joins

  - by dsquaredtech

  Three tables courses,registration,students columns in students firstname,lastname,studentid,major,admitdate,graddate,gender,dob columns in registration courseid,studentid columns in courses coursenumber,coursename,credits select statement I need to modify select lastname as 'Last Name',sum(credits) as 'Credits Registered For' from students as s inner join registration as r on s.studentid = r.studentid inner join courses as c on c.coursenumber = c.courseid group by last name; the question on the lab is... Modify the previous query to show all students, even if they have not registered for a class. You should have 14 rows. Students who are not registered will show NULL in output. I know this requires outer join of some sort but I'm not fully grasping these joins i've read multiple posts on here and other sites but can't seem figure it out.

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• Exception for java Swing application?

  - by Rich Fluckiger

  For some reason this is locking up the java application. Did I handle the exception correctly? private void submitButtonActionPerformed(java.awt.event.ActionEvent evt) { double amount, interest,rateCalc, a, b, c, payment; int years, months; while (true){ try{ amount = Double.valueOf(loanAmount.getText()); interest = Double.valueOf(interestRate.getText()); years = Integer.valueOf(loanYears.getText()); rateCalc = (interest/12); months = (years*12); a = Math.pow((1+rateCalc),months); b = (a*rateCalc); c = (a-1); payment = (amount *(b/c)); monthlyPayment.setText("Mortgage Payment $ = " + payment); } catch (NumberFormatException nfe){ javax.swing.JOptionPane.showMessageDialog(null, "Please enter numbers and not letters"); return; } } } monthlyPayment returns to the java app.

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• finding character in string C language

  - by iSight

  Hi, I am searching a character at first occurence in string using the following code. But, it is taking some time when the character is too long or the character that i am searching is at far extend, which makes delay in other operations. How could i tackle with this problem. The code is below here. Note: attrPtr is a char* which holds a reference to a string containing '"' character at far extend. int position = 0; char qolon = '"';//character to search while (*(attrPtr + position++) != qolon); char* attrValue = NULL; attrValue = (char*)malloc(position * sizeof(char)); strncpy(attrValue, attrPtr, position-1);

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• error message fix

  - by user1722654

  for (int i = 0; i < dataGridView1.Rows.Count; i++) { //bool sleected = false; if (dataGridView1.Rows[i].Cells[3].Value != null) { selected.Add(i); } } //string donew = ""; // line off error textBox1.Text = ((String)dataGridView1.Rows[1].Cells[2].Value); /* for (int i = 0; i < selected.Count; i++) { textAdded.Add((String)dataGridView1.Rows[0].Cells[2].Value); // donew += (String)dataGridView1.Rows[selected[i]].Cells[2].Value; }*/ I keep getting the error Unable to cast object of type 'System.Double' to type 'System.String' What can I do to overcome this?

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• Implicit type conversion in DB/2 inserts?

  - by IronGoofy

  We're using SQL Inserts to insert some data via a script into DB/2 tables, e.g. CREATE TABLE TICKETS (TICKETID VARCHAR(10) NOT NULL); On my home installation, this statement works fine (note that I'm using an integer which is autoatically cast into a VarChar): INSERT INTO TICKETS (TICKETID) VALUES (1); while at my customer's site I get a type error. My question(s): Is this behavior version dependent? (I use a DB2 Express V9.7, while the customer has an Enterprise V9.5) Is there a config option to change the behavior? (I would like my home install to behave as close as possible as the production environment is going to be.)

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• Windows Azure Mobil Services first connection in Android

  - by egente

  my application based windows azure mobil services. Application connecting time is well normally but when login to application first time azure mobile services connection is very slow like 10 second, after connection speed is normally. how can i solve this problem? my codes; private MobileServiceClient mClient; private MobileServiceTable<products> mProductsTable; mClient = new MobileServiceClient( "https://example.azure-mobile.net/", "aaaaaaaaaaaaaaaaaaaaaaaa", this).withFilter(new ProgressFilter());; mProductsTable = mClient.getTable(products.class); mProductsTable.where() .execute(new TableQueryCallback<products>() { public void onCompleted(List<products> result, int count, Exception exception, ServiceFilterResponse response) { if (exception == null) { } else{ Toast.makeText(Product.this, "Ops!!! Error.", 1000).show(); }} });

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• iqueryable select/where not working

  - by Steve

  I have two tables Boxer and Prospect. Boxers has general stuff like name and and dob etc and a BoxerId While Prospect contains only one value (at the moment) which is a boxerId. If a boxer is a prospect(up and coming boxer) there Id will be in the prospect table. This works fine but now I want to select all boxers that are prospects public static IQueryable<Boxer> IsProspect(this IQueryable<Boxer> query) { //this does not filter down to only prospects!!! return query.Where(x => x.Prospect != null); } This is the function I call using: var repository = GetRepository<Boxer>(); var boxers = repository.Query().IsProspect(); I would hope this would filter my collection of all boxers down to just boxers that are prospects! Oddly it doesnt filter it but if i hover over my boxers object and look at each boxer during debugging I can see "IsProspect" true or false correctly

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• python array.array with strings as data type

  - by Gladius

  Is there an object that acts like array.array, yet can handle strings (or character arrays) as its data type? It should be able to convert the string array to binary and back again, preferably with null terminated strings, however fixed length strings would be acceptable. >>> my_array = stringarray(['foo', 'bar']) >>> my_array.tostring() 'foo\0bar\0' >>> re_read = stringarray('foo\0bar\0') >>> re_read[:] ['foo', 'bar'] I will be using it with arrays that contain a couple million strings.

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• Silverlight 4 Binding to ConverterParameter

  - by FrEEzE2046

  Hello everybody, I have a ValueConverter which needs to be called with a dynamic parameter, depending on a property. I can't see a way to do this ... Width="{Binding ActualWidthValue, Source={StaticResource VisibleSize}, Converter={StaticResource Fraction}}" The "Fraction" converter get's (or should get) a parameter of type System.Size, which contains a numerator and denumerator. This value (should) depend on a ItemCollection.Count. Resetting the ItemCollection should reinvoke the Converter with the new values. My first idea was to manually change the ConverterParameter in CodeBehind on the PropertyChanged event of my ItemCollection DependencyProperty. But, as I know now, Silverlight has no GetBinding() method. I heard about GetBindingExpression and tried to do. But MyGrid.GetBindingExpression(Grid.ActualHeightProperty) is always returning null, although the Binding is already established. So, what can I do to reach my target?

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• Can't figure out what's wrong with my php/sql statement

  - by Olegious

  So this is probably a dumb beginner question, but I've been looking at it and can't figure it out. A bit of background: just practicing making a web app, a form on page 1 takes in some values from the user, posts them to the next page which contains the code to connect to the DB and populate the relevant tables. I establish the DB connection successfully, here's the code that contains the query: $conn->query("SET NAMES 'utf9'"); $query_str = "INSERT INTO 'qa'.'users' ('id', 'user_name','password' ,'email' ,'dob' ,'sx') VALUES (NULL, $username, $password, $email, $dob, $sx);"; $result = @$conn->query($query_str); Here's the error that is returned:Insert query failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''qa'.'users' ('id', 'user_name' ,'password' ,'email' ,'dob' ,'s' at line 1 Thanks in advance!

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• "And" condition in C#/LINQ Query

  - by user1213055

  partial void PrintDocLetter1_CanExecute(ref bool result) { if (this.PatientsMasterItem.DoctorsMasterItem != null) { var Doctor = PatientsMasterItem.DoctorsMasterItem; var PatientList = Doctor.PatientsMasterItem; var Letters = PatientsMasterItem.LettersSentItem; if ((PatientList.Count() > 1) && (Letters.Any(i => i.LetterType == "DoctorLetter1"))) { result = false; } else { result = true; } } } I think something is wrong with my second condition. I'm trying to find two things. 1) Doctors with more than 1 patient. 2) Among those patients whether a lettertype called "DoctorLetter1" has been sent or not. The above code is working good for that particular record but not working other patients with same doctors where patient1 has already been sent with DoctorLetter1.

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• Add list type to association

  - by teucer

  Hi All, I am using the eUML2 (Free version) plugin to draw a UML class diagram. Now, let's assume I have a class Person and a class Car. I want the class Person to have a member cars which is a List<Car>, i.e. private List<Car> cars = null. My question is how do I include this information in the class diagram? To be more precise, how do I include the type information for the List in the eUML2 association? Regards

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• C# Add class instance with internal timer to a static List, is it safe?

  - by CodeMongo

  My program has a static list of type classA. ClassA implements a threading timer that executes a task. The list may contain as many instances of classA as desired. Is this technique causing threading issues where the class instances can block each other? It that is the case how can I solve the that problem. ex: static List<MyClassType> list=null; void static Main() { list = new List<MyClassType>(); var a = new MyClassType(); var b = new MyClassType(); list.Add(a); list.Add(b); Console.ReadKey(); } a and b will execute theire internal task based on the timer.Is it s bsd technique? Why?

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• Using popen() to invoke a shell command?

  - by Anvar

  When running the following code through xcode I get inconsistent behavior. Sometimes it prints the git version correctly, other times it doesn't print anything. The return code from the shell command is always 0 though. Any ideas on why this might be? What am I doing wrong? #define BUFFER_SIZE 256 int main (int argc, const char * argv[]) { FILE *fpipe; char *command="/opt/local/bin/git --version"; char line[BUFFER_SIZE]; if ( !(fpipe = (FILE*)popen(command, "r")) ) { // If fpipe is NULL perror("Problems with pipe"); exit(1); } while ( fgets( line, sizeof(char) * BUFFER_SIZE, fpipe)) { // Inconsistent (happens sometimes) printf("READING LINE"); printf("%s", line); } int status = pclose(fpipe); if (status != 0) { // Never happens printf("Strange error code: %d", status); } return 0; }

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• any way to simplify this with a form of dynamic class instantiation?

  - by gnychis

  I have several child classes that extend a parent class, forced to have a uniform constructor. I have a queue which keeps a list of these classes, which must extend MergeHeuristic. The code that I currently have looks like the following: Class<? extends MergeHeuristic> heuristicRequest = _heuristicQueue.pop(); MergeHeuristic heuristic = null; if(heuristicRequest == AdjacentMACs.class) heuristic = new AdjacentMACs(_parent); if(heuristicRequest == SimilarInterfaceNames.class) heuristic = new SimilarInterfaceNames(_parent); if(heuristicRequest == SameMAC.class) heuristic = new SameMAC(_parent); Is there any way to simplify that to dynamically instantiate the class, something along the lines of: heuristic = new heuristicRequest.somethingSpecial(); That would flatten that block of if statements.

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• Can't pass and retrieve CharSequence to another activity using intent.getExtras() method.

  - by vt

  Activity 1: Intent i = new Intent(this, Activity2.class); CharSequence btText = btButton.getText(); i.putExtra(BUTTON_TEXT, btText); startActivityForResult(i, ACTIVITY_SETTINGS); Activity 2: in onCreate: Bundle extras = getIntent().getExtras(); if (extras != null) { mButtonText = extras.getCharSequence(Activity1.BUTTON_TEXT); } The resulting CharSequence is not what was passed, it's something like "(id=830066506776)" instead. This works: CharSequence test2 = getIntent().getCharSequenceExtra(Activity1.BUTTON_TEXT); What is wrong with getExtras approach? This is what they used in Notepadv3 example. This is for Android 2.1. Thank you.

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• problem in playing next song in the avaudioplayer

  - by Rajashekar

  Hello friends my delegate method looks like this. after the first song is played it goes into this method and plays the second song , however when the second song is done playing it stops. it does not go into the delegate method.i need to play all the songs continuously. i am not sure, why. can someone help me. (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)p successfully:(BOOL)flag { if (flag == NO) NSLog(@"Playback finished unsuccessfully"); else { //[player stop]; index++; NSLog(@"%d",index); path=[[NSBundle mainBundle] pathForResource:[songlist objectAtIndex:index] ofType:@"mp3"]; [player initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL]; [songlabel2 setTitle:[songlist objectAtIndex:index]]; [endtime setText:[NSString stringWithFormat:@"%.2f",[player duration]/100]]; [player play]; } }

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• how to print not mapped value

  - by IcanMakeIt

  I am using complicated SQL queries, i have to use SqlQuery ... in simple way: MODEL: public class C { public int ID { get; set; } [NotMapped] public float Value { get; set; } } CONTROLLER: IEnumerable<C> results = db.C.SqlQuery(@"SELECT ID, ATAN(-45.01) as Value from C); return View(results.ToList()); VIEW: @model IEnumerable<C> @foreach (var item in Model) { @Html.DisplayFor(modelItem => item.Value) } and the result for item.Value is NULL. So my question is , how can i print the computed value from SQL Query ? Thank you for help.

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• Creating a json obj from a string when working without a net connection?

  - by user246114

  Hi, I have a json object returned from a third party api, it looks like: {"version":"1.0","encoding":"UTF-8"} I'm going to be working on my project without a network connection, so I have to do everything locally. How can I create an instance of a json object locally for testing? Say I copy the above string, can I do something like: var json = null; if (debugging_locally) { json = new jsonObj('{"version":"1.0","encoding":"UTF-8"}'); } else { json = doAjaxCall(); } doStuffWithJsonObj(json); so I just want to create a json object from a stored string if debugging locally - how can I do that? Thanks

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• Any idea why this query always returns duplicate items?

  - by Kardo

  I want to get all Images not used by current ItemID. The this subquery but it also always returns duplicate Images: EDITED select Images.ImageID, Images.ItemStatus, Images.UserName, Images.Url, Image_Item.ItemID, Image_Item.ItemID from Images left join (select ImageID, ItemID, MAX(DateCreated) x from Image_Item where ItemID != '5a0077fe-cf86-434d-9f3b-7ff3030a1b6e' group by ImageID, ItemID having count(*) = 1) image_item on Images.imageid = image_item.imageid where ItemID is not null I guess the problem is with the subquery which I can't avoid duplicate rows: select ImageID, ItemID, MAX(DateCreated) x from Image_Item where ItemID != '5a0077fe-cf86-434d-9f3b-7ff3030a1b6e' group by ImageID, ItemID having count(*) = 1 Result: F2EECBDC-963D-42A7-90B1-4F82F89A64C7 0578AC61-3C32-4A1D-812C-60A09A661E71 F2EECBDC-963D-42A7-90B1-4F82F89A64C7 9A4EC913-5AD6-4F9E-AF6D-CF4455D81C10 42BC8B1A-7430-4915-9CDA-C907CBC76D6A CB298EB9-A105-4797-985E-A370013B684F 16371C34-B861-477C-9A7C-DEB27C8F333D 44E6349B-7EBF-4C7E-B3B0-1C6E2F19992C Table: Images ImageID uniqueidentifier UserName nvarchar(100) DateCreated smalldatetime Url nvarchar(250) ItemStatus char(1) Table: Image_Item ImageID uniqueidentifier ItemID uniqueidentifier UserName nvarchar(100) ItemStatus char(1) DateCreated smalldatetime Any kind help is highly appreciated.

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