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• Does a site's bounce rate influence Google rankings?

  - by Joel Spolsky

  Does Google consider bounce rate or something similar in ranking sites? Background: here at Stack Exchange we noticed that the latest Google algorithm changes resulted in about a 20% dip in traffic to Server Fault (and a much smaller dip in traffic to Super User). Stack Overflow traffic was not affected. There was an article on WebProNews which hypothesized that bounce rate might be a ranking signal in Google's latest Panda update. According to Google Analytics, these are our bounce rates over the last month: Site Bounce Rate Avg Time on Site ------------- ----------- ---------------- SuperUser 84.67% 01:16 ServerFault 83.76% 00:53 Stack Overflow 63.63% 04:12 Now, technically, Google has no way to know the bounce rate. If you go to Google, search for something, and click on the first result, Google can't tell the difference between: a user who turns off their computer a user who goes to a completely different web site a user who spends hours clicking around on the website they landed on What Google does know is how long it takes the user to come back to Google and do another search. According to the book In The Plex (page 47), Google distinguishes between what they call "short clicks" and "long clicks": A short click is a search where the user quickly comes back to Google and does another search. Google interprets this as a signal that the first search results were unsatisfactory. A long click is a search where the user doesn't search again for a long time. The book says that Google uses this information internally, to judge the quality of their own algorithms. It also said that short click data in which someone retypes a slight variation of the search is used to fuel the "Did you mean...?" spell checking algorithm. So, my hypothesis is that Google has recently decided to use long click rates as a signal of a high quality site. Does anyone have any evidence of this? Have you seen any high-bounce-rate sites which lost traffic (or vice-versa)?

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• EXCEL VBA STUDENTS DATABASE [on hold]

  - by BENTET

  I AM DEVELOPING AN EXCEL DATABASE TO RECORD STUDENTS DETAILS. THE HEADINGS OF THE TABLE ARE DATE,YEAR, PAYMENT SLIP NO.,STUDENT NUMBER,NAME,FEES,AMOUNT PAID, BALANCE AND PREVIOUS BALANCE. I HAVE BEEN ABLE TO PUT UP SOME CODE WHICH IS WORKING, BUT THERE ARE SOME SETBACKS THAT I WANT TO BE ADDRESSED.I ACTUALLY DEVELOPED A USERFORM FOR EACH PROGRAMME OF THE INSTITUTION AND ASSIGNED EACH TO A SPECIFIC SHEET BUT WHENEVER I ADD A RECORD, IT DOES NOT GO TO THE ASSIGNED SHEET BUT GOES TO THE ACTIVE SHEET.ALSO I WANT TO HIDE ALL SHEETS AND BE WORKING ONLY ON THE USERFORMS WHEN THE WORKBOOK IS OPENED.ONE PROBLEM AM ALSO FACING IS THE UPDATE CODE.WHENEVER I UPDATE A RECORD ON A SPECIFIC ROW, IT RATHER EDIT THE RECORD ON THE FIRST ROW NOT THE RECORD EDITED.THIS IS THE CODE I HAVE BUILT SO FAR.I AM VIRTUALLY A NOVICE IN PROGRAMMING. Private Sub cmdAdd_Click() Dim lastrow As Long lastrow = Sheets("Sheet4").Range("A" & Rows.Count).End(xlUp).Row Cells(lastrow + 1, "A").Value = txtDate.Text Cells(lastrow + 1, "B").Value = ComBox1.Text Cells(lastrow + 1, "C").Value = txtSlipNo.Text Cells(lastrow + 1, "D").Value = txtStudentNum.Text Cells(lastrow + 1, "E").Value = txtName.Text Cells(lastrow + 1, "F").Value = txtFees.Text Cells(lastrow + 1, "G").Value = txtAmountPaid.Text txtDate.Text = "" ComBox1.Text = "" txtSlipNo.Text = "" txtStudentNum.Text = "" txtName.Text = "" txtFees.Text = "" txtAmountPaid.Text = "" End Sub Private Sub cmdClear_Click() txtDate.Text = "" ComBox1.Text = "" txtSlipNo.Text = "" txtStudentNum.Text = "" txtName.Text = "" txtFees.Text = "" txtAmountPaid.Text = "" txtBalance.Text = "" End Sub Private Sub cmdClearD_Click() txtDate.Text = "" ComBox1.Text = "" txtSlipNo.Text = "" txtStudentNum.Text = "" txtName.Text = "" txtFees.Text = "" txtAmountPaid.Text = "" txtBalance.Text = "" End Sub Private Sub cmdClose_Click() Unload Me End Sub Private Sub cmdDelete_Click() 'declare the variables Dim findvalue As Range Dim cDelete As VbMsgBoxResult 'check for values If txtStudentNum.Value = "" Or txtName.Value = "" Or txtDate.Text = "" Or ComBox1.Text = "" Or txtSlipNo.Text = "" Or txtFees.Text = "" Or txtAmountPaid.Text = "" Or txtBalance.Text = "" Then MsgBox "There is not data to delete" Exit Sub End If 'give the user a chance to change their mind cDelete = MsgBox("Are you sure that you want to delete this student", vbYesNo + vbDefaultButton2, "Are you sure????") If cDelete = vbYes Then 'delete the row Set findvalue = Sheet4.Range("D:D").Find(What:=txtStudentNum, LookIn:=xlValues) findvalue.EntireRow.Delete End If 'clear the controls txtDate.Text = "" ComBox1.Text = "" txtSlipNo.Text = "" txtStudentNum.Text = "" txtName.Text = "" 'txtFees.Text = "" txtAmountPaid.Text = "" txtBalance.Text = "" End Sub Private Sub cmdSearch_Click() Dim lastrow As Long Dim currentrow As Long Dim studentnum As String lastrow = Sheets("Sheet4").Range("A" & Rows.Count).End(xlUp).Row studentnum = txtStudentNum.Text For currentrow = 2 To lastrow If Cells(currentrow, 4).Text = studentnum Then txtDate.Text = Cells(currentrow, 1) ComBox1.Text = Cells(currentrow, 2) txtSlipNo.Text = Cells(currentrow, 3) txtStudentNum.Text = Cells(currentrow, 4).Text txtName.Text = Cells(currentrow, 5) txtFees.Text = Cells(currentrow, 6) txtAmountPaid.Text = Cells(currentrow, 7) txtBalance.Text = Cells(currentrow, 8) End If Next currentrow txtStudentNum.SetFocus End Sub Private Sub cmdSearchName_Click() Dim lastrow As Long Dim currentrow As Long Dim studentname As String lastrow = Sheets("Sheet4").Range("A" & Rows.Count).End(xlUp).Row studentname = txtName.Text For currentrow = 2 To lastrow If Cells(currentrow, 5).Text = studentname Then txtDate.Text = Cells(currentrow, 1) ComBox1.Text = Cells(currentrow, 2) txtSlipNo.Text = Cells(currentrow, 3) txtStudentNum.Text = Cells(currentrow, 4) txtName.Text = Cells(currentrow, 5).Text txtFees.Text = Cells(currentrow, 6) txtAmountPaid.Text = Cells(currentrow, 7) txtBalance.Text = Cells(currentrow, 8) End If Next currentrow txtName.SetFocus End Sub Private Sub cmdUpdate_Click() Dim tdate As String Dim tlevel As String Dim tslipno As String Dim tstudentnum As String Dim tname As String Dim tfees As String Dim tamountpaid As String Dim currentrow As Long Dim lastrow As Long 'If Cells(currentrow, 5).Text = studentname Then 'txtDate.Text = Cells(currentrow, 1) lastrow = Sheets("Sheet4").Range("A" & Columns.Count).End(xlUp).Offset(0, 1).Column For currentrow = 2 To lastrow tdate = txtDate.Text Cells(currentrow, 1).Value = tdate txtDate.Text = Cells(currentrow, 1) tlevel = ComBox1.Text Cells(currentrow, 2).Value = tlevel ComBox1.Text = Cells(currentrow, 2) tslipno = txtSlipNo.Text Cells(currentrow, 3).Value = tslipno txtSlipNo = Cells(currentrow, 3) tstudentnum = txtStudentNum.Text Cells(currentrow, 4).Value = tstudentnum txtStudentNum.Text = Cells(currentrow, 4) tname = txtName.Text Cells(currentrow, 5).Value = tname txtName.Text = Cells(currentrow, 5) tfees = txtFees.Text Cells(currentrow, 6).Value = tfees txtFees.Text = Cells(currentrow, 6) tamountpaid = txtAmountPaid.Text Cells(currentrow, 7).Value = tamountpaid txtAmountPaid.Text = Cells(currentrow, 7) Next currentrow txtDate.SetFocus ComBox1.SetFocus txtSlipNo.SetFocus txtStudentNum.SetFocus txtName.SetFocus txtFees.SetFocus txtAmountPaid.SetFocus txtBalance.SetFocus End Sub PLEASE I WAS THINKING IF I CAN DEVELOP SOMETHING THAT WILL USE ONLY ONE USERFORM TO SEND DATA TO DIFFERENT SHEETS IN THE WORKBOOK.

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• Fastest pathfinding for static node matrix

  - by Sean Martin

  I'm programming a route finding routine in VB.NET for an online game I play, and I'm searching for the fastest route finding algorithm for my map type. The game takes place in space, with thousands of solar systems connected by jump gates. The game devs have provided a DB dump containing a list of every system and the systems it can jump to. The map isn't quite a node tree, since some branches can jump to other branches - more of a matrix. What I need is a fast pathfinding algorithm. I have already implemented an A* routine and a Dijkstra's, both find the best path but are too slow for my purposes - a search that considers about 5000 nodes takes over 20 seconds to compute. A similar program on a website can do the same search in less than a second. This website claims to use D*, which I have looked into. That algorithm seems more appropriate for dynamic maps rather than one that does not change - unless I misunderstand it's premise. So is there something faster I can use for a map that is not your typical tile/polygon base? GBFS? Perhaps a DFS? Or have I likely got some problem with my A* - maybe poorly chosen heuristics or movement cost? Currently my movement cost is the length of the jump (the DB dump has solar system coordinates as well), and the heuristic is a quick euclidean calculation from the node to the goal. In case anyone has some optimizations for my A*, here is the routine that consumes about 60% of my processing time, according to my profiler. The coordinateData table contains a list of every system's coordinates, and neighborNode.distance is the distance of the jump. Private Function findDistance(ByVal startSystem As Integer, ByVal endSystem As Integer) As Integer 'hCount += 1 'If hCount Mod 0 = 0 Then 'Return hCache 'End If 'Initialize variables to be filled Dim x1, x2, y1, y2, z1, z2 As Integer 'LINQ queries for solar system data Dim systemFromData = From result In jumpDataDB.coordinateDatas Where result.systemId = startSystem Select result.x, result.y, result.z Dim systemToData = From result In jumpDataDB.coordinateDatas Where result.systemId = endSystem Select result.x, result.y, result.z 'LINQ execute 'Fill variables with solar system data for from and to system For Each solarSystem In systemFromData x1 = (solarSystem.x) y1 = (solarSystem.y) z1 = (solarSystem.z) Next For Each solarSystem In systemToData x2 = (solarSystem.x) y2 = (solarSystem.y) z2 = (solarSystem.z) Next Dim x3 = Math.Abs(x1 - x2) Dim y3 = Math.Abs(y1 - y2) Dim z3 = Math.Abs(z1 - z2) 'Calculate distance and round 'Dim distance = Math.Round(Math.Sqrt(Math.Abs((x1 - x2) ^ 2) + Math.Abs((y1 - y2) ^ 2) + Math.Abs((z1 - z2) ^ 2))) Dim distance = firstConstant * Math.Min(secondConstant * (x3 + y3 + z3), Math.Max(x3, Math.Max(y3, z3))) 'Dim distance = Math.Abs(x1 - x2) + Math.Abs(z1 - z2) + Math.Abs(y1 - y2) 'hCache = distance Return distance End Function And the main loop, the other 30% 'Begin search While openList.Count() != 0 'Set current system and move node to closed currentNode = lowestF() move(currentNode.id) For Each neighborNode In neighborNodes If Not onList(neighborNode.toSystem, 0) Then If Not onList(neighborNode.toSystem, 1) Then Dim newNode As New nodeData() newNode.id = neighborNode.toSystem newNode.parent = currentNode.id newNode.g = currentNode.g + neighborNode.distance newNode.h = findDistance(newNode.id, endSystem) newNode.f = newNode.g + newNode.h newNode.security = neighborNode.security openList.Add(newNode) shortOpenList(OLindex) = newNode.id OLindex += 1 Else Dim proposedG As Integer = currentNode.g + neighborNode.distance If proposedG < gValue(neighborNode.toSystem) Then changeParent(neighborNode.toSystem, currentNode.id, proposedG) End If End If End If Next 'Check to see if done If currentNode.id = endSystem Then Exit While End If End While If clarification is needed on my spaghetti code, I'll try to explain.

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• Indexed view deadlocking

  - by Dave Ballantyne

  Deadlocks can be a really tricky thing to track down the root cause of.  There are lots of articles on the subject of tracking down deadlocks, but seldom do I find that in a production system that the cause is as straightforward.  That being said,  deadlocks are always caused by process A needs a resource that process B has locked and process B has a resource that process A needs.  There may be a longer chain of processes involved, but that is the basic premise. Here is one such (much simplified) scenario that was at first non-obvious to its cause: The system has two tables,  Products and Stock.  The Products table holds the description and prices of a product whilst Stock records the current stock level. USE tempdb GO CREATE TABLE Product ( ProductID INTEGER IDENTITY PRIMARY KEY, ProductName VARCHAR(255) NOT NULL, Price MONEY NOT NULL ) GO CREATE TABLE Stock ( ProductId INTEGER PRIMARY KEY, StockLevel INTEGER NOT NULL ) GO INSERT INTO Product SELECT TOP(1000) CAST(NEWID() AS VARCHAR(255)), ABS(CAST(CAST(NEWID() AS VARBINARY(255)) AS INTEGER))%100 FROM sys.columns a CROSS JOIN sys.columns b GO INSERT INTO Stock SELECT ProductID,ABS(CAST(CAST(NEWID() AS VARBINARY(255)) AS INTEGER))%100 FROM Product There is a single stored procedure of GetStock: Create Procedure GetStock as SELECT Product.ProductID,Product.ProductName FROM dbo.Product join dbo.Stock on Stock.ProductId = Product.ProductID where Stock.StockLevel <> 0 Analysis of the system showed that this procedure was causing a performance overhead and as reads of this data was many times more than writes,  an indexed view was created to lower the overhead. CREATE VIEW vwActiveStock With schemabinding AS SELECT Product.ProductID,Product.ProductName FROM dbo.Product join dbo.Stock on Stock.ProductId = Product.ProductID where Stock.StockLevel <> 0 go CREATE UNIQUE CLUSTERED INDEX PKvwActiveStock on vwActiveStock(ProductID) This worked perfectly, performance was improved, the team name was cheered to the rafters and beers all round.  Then, after a while, something else happened… The system updating the data changed,  The update pattern of both the Stock update and the Product update used to be: BEGIN TRAN UPDATE... COMMIT BEGIN TRAN UPDATE... COMMIT BEGIN TRAN UPDATE... COMMIT It changed to: BEGIN TRAN UPDATE... UPDATE... UPDATE... COMMIT Nothing that would raise an eyebrow in even the closest of code reviews.  But after this change we saw deadlocks occuring. You can reproduce this by opening two sessions. In session 1 begin transaction Update Product set ProductName ='Test' where ProductID = 998 Then in session 2 begin transaction Update Stock set Stocklevel = 5 where ProductID = 999 Update Stock set Stocklevel = 5 where ProductID = 998 Hop back to session 1 and.. Update Product set ProductName ='Test' where ProductID = 999 Looking at the deadlock graphs we could see the contention was between two processes, one updating stock and the other updating product, but we knew that all the processes do to the tables is update them.  Period.  There are separate processes that handle the update of stock and product and never the twain shall meet, no reason why one should be requiring data from the other.  Then it struck us,  AH the indexed view. Naturally, when you make an update to any table involved in a indexed view, the view has to be updated.  When this happens, the data in all the tables have to be read, so that explains our deadlocks.  The data from stock is read when you update product and vice-versa. The fix, once you understand the problem fully, is pretty simple, the apps did not guarantee the order in which data was updated.  Luckily it was a relatively simple fix to order the updates and deadlocks went away.  Note, that there is still a *slight* risk of a deadlock occurring, if both a stock update and product update occur at *exactly* the same time.

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• Drawing Flowchart for function calculate a number in the Fibonacci Series

  - by truongvan

  I'm trying make Flowchart for function calculate a number in the Fibonacci Series. But It looks like not right. I don't how draw the recursive function. Please help me how to fix it. My flowchart: DIA This is my code: #include <iostream> using namespace std; long long Fibonacci(int input); int main() { cout << "Input Fibonacci Index number: "; int Index = 0; cin >> Index; cout << Fibonacci(i) << endl; return 0; } long long Fibonacci(int input) { if (input < 2) return input; else { return Fibonacci(input - 1) + Fibonacci(input - 2); } }

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• Speakers, Please Check Your Time

  - by AjarnMark

  Woodrow Wilson was once asked how long it would take him to prepare for a 10 minute speech. He replied "Two weeks". He was then asked how long it would take for a 1 hour speech. "One week", he replied. 2 hour speech? "I'm ready right now," he replied.  Whether that is a true story or an urban legend, I don’t really know, but either way, it is a poignant reminder for all speakers, and particularly apropos this week leading up to the PASS Community Summit. (Cross-posted to the PASS Professional Development Virtual Chapter blog #PASSProfDev.) What’s the point of that story?  Simply this…if you have plenty of time to do your presentation, you don’t need to prepare much because it is easy to throw in more and more material to stretch out to your allotted time.  But if you are on a tight time constraint, then it will take significant preparation to distill your talk down to only the essential points. I have attended seven of the last eight North American Summit events, and every one of them has been fantastic.  The speakers are great, the material is timely and relevant, and the networking opportunities are awesome.  And every year, there is one little thing that just bugs me…speakers going over their allotted time.  Why does it bother me so?  Well, if you look at a typical schedule for a Summit, you’ll see that there are six or more sessions going on at the same time, and only 15 minutes to move from one to another.  If you’re trying to maximize your training dollar by attending something during every session time slot, and you don’t want to be the last guy trying to squeeze into the middle of the row, then those 15 minutes can be critical.  All the more so if you need to stop and use the bathroom or if you have to hike to the opposite end of the convention center.  It is really a bad position to find yourself having to choose between learning the last key points of Speaker A who is going over time, and getting over to Speaker B on time so you don’t miss her key opening remarks. And frankly, I think it is just rude.  Yes, the speakers are the function, after all they are bringing the content that the rest of us are paying to learn.  But it is also an honor to be given the opportunity to speak at a conference like this, and no one speaker is so important that the conference would be a disaster without him.  Speakers know when they submit their abstract, long before the conference, how much time they will have.  It has been the same pattern at the Summit for at least the last eight years.  Program Sessions are 75 minutes long.  Some speakers who have a good track record, and meet other qualifying criteria, are extended an invitation to present a Spotlight Session which is 90 minutes (a 20% increase).  So there really is no excuse.  It’s not like you were promised a 2-hour segment and then discovered when you got here that it was only 75 minutes.  In fact, it’s not like PASS advertised 90-minute sessions for everyone and then a select few were cut back to only 75.  As a speaker, you know well before you get here which type of session you are doing and how long it is, so as a professional, you should plan accordingly. Now you might think that this only happens to rookies, but I’ll tell you that some of the worst offenders are big-name veterans who draw huge attendance numbers for their sessions.  Some attendees blow this off as, “Hey, it’s so-and-so, and I’d stay here for hours and listen to him/her talk.”  To which I would reply, “Then they should have submitted for a pre- or post-conference day-long seminar instead, but don’t try to squeeze your day-long talk into a 90-minute session.”  Now I don’t really believe that these speakers are being malicious or just selfishly trying to extend their time in the spotlight.  I think that most of them are merely being undisciplined and did not trim their presentation sufficiently, or allowed themselves to get off-track (often in a generous attempt to help someone in the audience with a question or problem that really should have been noted for further discussion after the session). So here is my recommendation…my plea, even.  TRIM THE FAT!  Now.  Before it’s too late.  Before you even get on the airplane, take a long, hard look at your presentation and eliminate some of the points that you originally thought you had to make, but in reality are not truly crucial to your main topic.  Delete a few slides.  Test your demos and have them already scripted rather than typing them during your talk.  It is better to cut out too much and end up with plenty of time at the end for Questions & Answers.  And you can always keep some notes on the stuff that you cut out so that you could fill it back in at the end as bonus material if you really do end up with a whole bunch of time on your hands.  But I don’t think you will.  And if you do, that will look even better to the audience as it will look like you’re giving them something extra that not every audience gets.  And they will thank you for that.

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• When will java change to 64bit addressing and how can we get there faster?

  - by Ido Tamir

  Having to work with large files now, I would like to know when the java libraries will start switching to long for indexing in their methods. From Inputstreams read(byte[] b, int off, int len) - funnily there is long skip(long) also - to MappedByteBuffer to the basic indexing of arrays and lists, everything is adressed as int. Is there an official plan for enhancment of the libraries? Do initiatives exist to pressure oracle into enhancing the libraries, if there is no official plan yet?

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• Encrypt images before uploading to Dropbox [migrated]

  - by Cherry

  I want to encrypt a file first before the file will be uploaded to the dropbox. So i have implement the encryption inside the uploading of the codes. However, there is an error after i integrate the codes together. Where did my mistake go wrong? Error at putFileOverwriteRequest and it says The method putFileOverwriteRequest(String, InputStream, long, ProgressListener) in the type DropboxAPI is not applicable for the arguments (String, FileOutputStream, long, new ProgressListener(){}) Another problem is that this FileOutputStream fis = new FileOutputStream(new File("dont know what to put in this field")); i do not know where to put the file so that after i read the file, it will call the path and then upload to the Dropbox. Anyone is kind to help me in this? As time is running out for me and i still cant solve the problem. Thank you in advance. The full code is as below. public class UploadPicture extends AsyncTask<Void, Long, Boolean> { private DropboxAPI<?> mApi; private String mPath; private File mFile; private long mFileLen; private UploadRequest mRequest; private Context mContext; private final ProgressDialog mDialog; private String mErrorMsg; public UploadPicture(Context context, DropboxAPI<?> api, String dropboxPath, File file) { // We set the context this way so we don't accidentally leak activities mContext = context.getApplicationContext(); mFileLen = file.length(); mApi = api; mPath = dropboxPath; mFile = file; mDialog = new ProgressDialog(context); mDialog.setMax(100); mDialog.setMessage("Uploading " + file.getName()); mDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); mDialog.setProgress(0); mDialog.setButton("Cancel", new OnClickListener() { public void onClick(DialogInterface dialog, int which) { // This will cancel the putFile operation mRequest.abort(); } }); mDialog.show(); } @Override protected Boolean doInBackground(Void... params) { try { KeyGenerator keygen = KeyGenerator.getInstance("DES"); SecretKey key = keygen.generateKey(); //generate key //encrypt file here first byte[] plainData; byte[] encryptedData; Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding"); cipher.init(Cipher.ENCRYPT_MODE, key); //File f = new File(mFile); //read file FileInputStream in = new FileInputStream(mFile); //obtains input bytes from a file plainData = new byte[(int)mFile.length()]; in.read(plainData); //Read bytes of data into an array of bytes encryptedData = cipher.doFinal(plainData); //encrypt data FileOutputStream fis = new FileOutputStream(new File("dont know what to put in this field")); //upload to a path first then call the path so that it can be uploaded up to the dropbox //save encrypted file to dropbox // By creating a request, we get a handle to the putFile operation, // so we can cancel it later if we want to //FileInputStream fis = new FileInputStream(mFile); String path = mPath + mFile.getName(); mRequest = mApi.putFileOverwriteRequest(path, fis, mFile.length(), new ProgressListener() { @Override public long progressInterval() { // Update the progress bar every half-second or so return 500; } @Override public void onProgress(long bytes, long total) { publishProgress(bytes); } }); if (mRequest != null) { mRequest.upload(); return true; } } catch (DropboxUnlinkedException e) { // This session wasn't authenticated properly or user unlinked mErrorMsg = "This app wasn't authenticated properly."; } catch (DropboxFileSizeException e) { // File size too big to upload via the API mErrorMsg = "This file is too big to upload"; } catch (DropboxPartialFileException e) { // We canceled the operation mErrorMsg = "Upload canceled"; } catch (DropboxServerException e) { // Server-side exception. These are examples of what could happen, // but we don't do anything special with them here. if (e.error == DropboxServerException._401_UNAUTHORIZED) { // Unauthorized, so we should unlink them. You may want to // automatically log the user out in this case. } else if (e.error == DropboxServerException._403_FORBIDDEN) { // Not allowed to access this } else if (e.error == DropboxServerException._404_NOT_FOUND) { // path not found (or if it was the thumbnail, can't be // thumbnailed) } else if (e.error == DropboxServerException._507_INSUFFICIENT_STORAGE) { // user is over quota } else { // Something else } // This gets the Dropbox error, translated into the user's language mErrorMsg = e.body.userError; if (mErrorMsg == null) { mErrorMsg = e.body.error; } } catch (DropboxIOException e) { // Happens all the time, probably want to retry automatically. mErrorMsg = "Network error. Try again."; } catch (DropboxParseException e) { // Probably due to Dropbox server restarting, should retry mErrorMsg = "Dropbox error. Try again."; } catch (DropboxException e) { // Unknown error mErrorMsg = "Unknown error. Try again."; } catch (FileNotFoundException e) { } return false; } @Override protected void onProgressUpdate(Long... progress) { int percent = (int)(100.0*(double)progress[0]/mFileLen + 0.5); mDialog.setProgress(percent); } @Override protected void onPostExecute(Boolean result) { mDialog.dismiss(); if (result) { showToast("Image successfully uploaded"); } else { showToast(mErrorMsg); } } private void showToast(String msg) { Toast error = Toast.makeText(mContext, msg, Toast.LENGTH_LONG); error.show(); } }

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• How do I configure upstart to run a script on shutdown when the process takes longer than 10secs?

  - by Tiris

  I am running ubuntu 11.10 in a virtual machine (VirtualBox) to learn more about development in linux. I am using a git repository to save my work and have written a script to bundle my work up and save it to the shared folder for use while the virtual machine is not running. I would like to automatically run this script before shutdown so that my work is always available if the vm is off (currently I have to manually run the script). I don't know if upstart is the best way to accomplish this, but this is the config that I wrote as a test: description "test script to run at shutdown" start on runlevel [056] task script touch /media/sf_LinuxEducation/start sleep 15 touch /media/sf_LinuxEducation/start-long end script pre-start script touch /media/sf_LinuxEducation/pre-start sleep 15 touch /media/sf_LinuxEducation/pre-start-long end script post-start script touch /media/sf_LinuxEducation/post-start sleep 15 touch /media/sf_LinuxEducation/post-start-long end script pre-stop script touch /media/sf_LinuxEducation/pre-stop sleep 15 touch /media/sf_LinuxEducation/pre-stop-long end script post-stop script touch /media/sf_LinuxEducation/post-stop sleep 15 touch /media/sf_LinuxEducation/post-stop-long end script The result is that only one touch is accomplished (the first touch in pre-start). What do I need to change to see one of the touches after the sleep to work? Or Is there an easier way to get this accomplished? Thanks in advance.

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• Getting timing consistency in Linux

  - by Jim Hunziker

  I can't seem to get a simple program (with lots of memory access) to achieve consistent timing in Linux. I'm using a 2.6 kernel, and the program is being run on a dual-core processor with realtime priority. I'm trying to disable cache effects by declaring the memory arrays as volatile. Below are the results and the program. What are some possible sources of the outliers? Results: Number of trials: 100 Range: 0.021732s to 0.085596s Average Time: 0.058094s Standard Deviation: 0.006944s Extreme Outliers (2 SDs away from mean): 7 Average Time, excluding extreme outliers: 0.059273s Program: #include <stdio.h> #include <stdlib.h> #include <math.h> #include <sched.h> #include <sys/time.h> #define NUM_POINTS 5000000 #define REPS 100 unsigned long long getTimestamp() { unsigned long long usecCount; struct timeval timeVal; gettimeofday(&timeVal, 0); usecCount = timeVal.tv_sec * (unsigned long long) 1000000; usecCount += timeVal.tv_usec; return (usecCount); } double convertTimestampToSecs(unsigned long long timestamp) { return (timestamp / (double) 1000000); } int main(int argc, char* argv[]) { unsigned long long start, stop; double times[REPS]; double sum = 0; double scale, avg, newavg, median; double stddev = 0; double maxval = -1.0, minval = 1000000.0; int i, j, freq, count; int outliers = 0; struct sched_param sparam; sched_getparam(getpid(), &sparam); sparam.sched_priority = sched_get_priority_max(SCHED_FIFO); sched_setscheduler(getpid(), SCHED_FIFO, &sparam); volatile float* data; volatile float* results; data = calloc(NUM_POINTS, sizeof(float)); results = calloc(NUM_POINTS, sizeof(float)); for (i = 0; i < REPS; ++i) { start = getTimestamp(); for (j = 0; j < NUM_POINTS; ++j) { results[j] = data[j]; } stop = getTimestamp(); times[i] = convertTimestampToSecs(stop-start); } free(data); free(results); for (i = 0; i < REPS; i++) { sum += times[i]; if (times[i] > maxval) maxval = times[i]; if (times[i] < minval) minval = times[i]; } avg = sum/REPS; for (i = 0; i < REPS; i++) stddev += (times[i] - avg)*(times[i] - avg); stddev /= REPS; stddev = sqrt(stddev); for (i = 0; i < REPS; i++) { if (times[i] > avg + 2*stddev || times[i] < avg - 2*stddev) { sum -= times[i]; outliers++; } } newavg = sum/(REPS-outliers); printf("Number of trials: %d\n", REPS); printf("Range: %fs to %fs\n", minval, maxval); printf("Average Time: %fs\n", avg); printf("Standard Deviation: %fs\n", stddev); printf("Extreme Outliers (2 SDs away from mean): %d\n", outliers); printf("Average Time, excluding extreme outliers: %fs\n", newavg); return 0; }

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• Hibernate Exception, what wrong ? [[Exception in thread "main" org.hibernate.InvalidMappingException

  - by user195970

  I use netbean 6.7.1 to write "hello world" witch hibernate, but I get some errors, plz help me, thank you very much. my exception init: deps-module-jar: deps-ear-jar: deps-jar: Copying 1 file to F:\Documents and Settings\My Dropbox\DropboxNetBeanProjects\loginspring\build\web\WEB-INF\classes compile-single: run-main: Oct 25, 2009 2:44:05 AM org.hibernate.cfg.Environment <clinit> INFO: Hibernate 3.2.5 Oct 25, 2009 2:44:05 AM org.hibernate.cfg.Environment <clinit> INFO: hibernate.properties not found Oct 25, 2009 2:44:05 AM org.hibernate.cfg.Environment buildBytecodeProvider INFO: Bytecode provider name : cglib Oct 25, 2009 2:44:05 AM org.hibernate.cfg.Environment <clinit> INFO: using JDK 1.4 java.sql.Timestamp handling Oct 25, 2009 2:44:05 AM org.hibernate.cfg.Configuration configure INFO: configuring from resource: /hibernate.cfg.xml Oct 25, 2009 2:44:05 AM org.hibernate.cfg.Configuration getConfigurationInputStream INFO: Configuration resource: /hibernate.cfg.xml Oct 25, 2009 2:44:06 AM org.hibernate.cfg.Configuration addResource INFO: Reading mappings from resource : hibernate/Tbluser.hbm.xml Oct 25, 2009 2:44:06 AM org.hibernate.util.XMLHelper$ErrorLogger error SEVERE: Error parsing XML: XML InputStream(1) Document is invalid: no grammar found. Oct 25, 2009 2:44:06 AM org.hibernate.util.XMLHelper$ErrorLogger error SEVERE: Error parsing XML: XML InputStream(1) Document root element "hibernate-mapping", must match DOCTYPE root "null". Exception in thread "main" org.hibernate.InvalidMappingException: Could not parse mapping document from resource hibernate/Tbluser.hbm.xml at org.hibernate.cfg.Configuration.addResource(Configuration.java:569) at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:1587) at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:1555) at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1534) at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1508) at org.hibernate.cfg.Configuration.configure(Configuration.java:1428) at org.hibernate.cfg.Configuration.configure(Configuration.java:1414) at hibernate.CreateTest.main(CreateTest.java:22) Caused by: org.hibernate.InvalidMappingException: Could not parse mapping document from invalid mapping at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:502) at org.hibernate.cfg.Configuration.addResource(Configuration.java:566) ... 7 more Caused by: org.xml.sax.SAXParseException: Document is invalid: no grammar found. at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:195) at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:131) at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:384) at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:318) at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:250) at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl$NSContentDriver.scanRootElementHook(XMLNSDocumentScannerImpl.java:626) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:3095) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:921) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648) at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:140) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205) at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522) at org.dom4j.io.SAXReader.read(SAXReader.java:465) at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:499) ... 8 more Java Result: 1 BUILD SUCCESSFUL (total time: 1 second) hibernate.cfg.xml <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate</property> <property name="hibernate.connection.username">root</property> </session-factory> </hibernate-configuration> Tbluser.hbm.xml <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Oct 25, 2009 2:37:30 AM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="hibernate.Tbluser" table="tbluser" catalog="hibernate"> <id name="userId" type="java.lang.Integer"> <column name="userID" /> <generator class="identity" /> </id> <property name="username" type="string"> <column name="username" length="50" /> </property> <property name="password" type="string"> <column name="password" length="50" /> </property> <property name="email" type="string"> <column name="email" length="50" /> </property> <property name="phone" type="string"> <column name="phone" length="50" /> </property> <property name="groupId" type="java.lang.Integer"> <column name="groupID" /> </property> </class> </hibernate-mapping> Tbluser.java package hibernate; // Generated Oct 25, 2009 2:37:30 AM by Hibernate Tools 3.2.1.GA /** * Tbluser generated by hbm2java */ public class Tbluser implements java.io.Serializable { private Integer userId; private String username; private String password; private String email; private String phone; private Integer groupId; public Tbluser() { } public Tbluser(String username, String password, String email, String phone, Integer groupId) { this.username = username; this.password = password; this.email = email; this.phone = phone; this.groupId = groupId; } public Integer getUserId() { return this.userId; } public void setUserId(Integer userId) { this.userId = userId; } public String getUsername() { return this.username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return this.password; } public void setPassword(String password) { this.password = password; } public String getEmail() { return this.email; } public void setEmail(String email) { this.email = email; } public String getPhone() { return this.phone; } public void setPhone(String phone) { this.phone = phone; } public Integer getGroupId() { return this.groupId; } public void setGroupId(Integer groupId) { this.groupId = groupId; } }

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• Java: immutable Stack?

  - by HH

  I chose to use Stacks and Tables before knowing Collections has immutable empty things only for Set, Map and List. Because the size of table does not change after its init: Integer[] table = new Intger[0] I can use the zero-witdh table as an empty table. But I cannot use final or empty Stack to get immutable Stack: No immutability to Stack with Final import java.io.*; import java.util.*; public class TestStack{ public static void main(String[] args) { final Stack<Integer> test = new Stack<Integer>(); Stack<Integer> test2 = new Stack<Integer>(); test.push(37707); test2.push(80437707); //WHY is there not an error to remove an elment // from FINAL stack? System.out.println(test.pop()); System.out.println(test2.pop()); } } Java Api 5 for list interface shows that Stack is an implementing class for list and arraylist, here. The java.coccurrent pkg does not have any immutable Stack data structure. From Stack to some immutable data structure How to get immutable Stack data structure? Can I box it with list? Should I switch my current implementatios from stacks to Lists to get immutable? Which immutable data structure is Very fast with about similar exec time as Stack?

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• unable to get "ItemValue" of selected item using f:selectitems tag in ace:autocompleteEntry

  - by user1641976

  i want to get the Value of selectItem (ItemValue which is an Integer and the Item Label is String) in my backing bean using autocompleteentry tag of icefaces 3.1.0 but i get error: here is the code: <tr> <td>Current City</td> <td> <ace:autoCompleteEntry value="#{service.cityId}" styleClass="select-field" rows="10" width="400" filterMatchMode="" > <f:selectItems value="#{service.cities}" ></f:selectItems> </ace:autoCompleteEntry> </td> </tr> Bean is : public class Service{ private Integer cityId; public Integer getCityId() { return cityId; } public void setCityId(Integer cityId) { this.cityId= cityId; } private <SelectItem> cities; public List<SelectItem> getCities() { return cities=Dao.getCityList(); } public void setCities(List<SelectItem> cities) { this.cities= cities; } } the cities has itemvalue as a number and itemLabel as String stored in it. I do get autocomplete fine and shows list of matches if i store value in some String property of backing bean but if storing in integer property of bean, gives this error as soon i write something in autocomplete. INFO: WARNING: FacesMessage(s) have been enqueued, but may not have been displayed. sourceId=frmmaster:j_idt205:txtcity[severity=(ERROR 2), summary=(frmmaster:j_idt205:txtcity: 'a' must be a number consisting of one or more digits.), detail=(frmmaster:j_idt205:txtcity: 'a' must be a number between -2147483648 and 2147483647 Example: 9346)] Kindly reply any person i need to solve this issue as soon as possible.

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• ASP.NET Membership with two providers cant use GetAllUsers method

  - by Bayonian

  Hi, I'm using two membership providers. When I declared a following statement Dim allUsers As MembershipUserCollection = Membership.Providers("CustomSqlRoleManager").GetAllUsers Then, it gave me this error message. Argument not specified for paramenter 'totalRecords' of 'Public MustOverride Function GetAllUsers(pageIndex as Integer, pageSize as Integer, ByRef totalRecords as Integer) As System.Web.Security.MembershipUserCollection' Then, I added what it asked for like this : Dim allUsers As MembershipUserCollection = Membership.Providers("CustomSqlRoleManager").GetAllUsers(1, 50, 100) I don't get anything in return. I debugged it and allUsers = Nothing. What's wrong the declaration above? Do I really have to provider the paramenters when calling Membership.Providers("CustomSqlRoleManager").GetAllUsers? Update 1 If, I used the statement below: Dim allUsers As MembershipUserCollection = Membership.Providers("MembershipRoleManager").GetAllUsers(0, 0, totalUser) I got this error message: The pageSize must be greater than zero. Parameter name: pageSize. [ArgumentException: The pageSize must be greater than zero. Parameter name: pageSize] System.Web.Security.SqlMembershipProvider.GetAllUsers(Int32 pageIndex, Int32 pageSize, Int32& totalRecords) +1848357 But it works if I provied the pageSize param: Dim pageSize As Integer = GetTotalNumberOfUser() Dim allUsers As MembershipUserCollection = Membership.Providers("MembershipRoleManager").GetAllUsers(0, pageSize, totalUser) This statment Dim pageSize As Integer = GetTotalNumberOfUser() returns the total counted record, it's already round trip to database, just to get the total number of users, because I need to provide the pageSize param value.

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• Unicode Collations problem ?

  - by Bayonian

  (.NET 3.5 SP1, VS 2008, VB.NET, MSSQL Server 2008) I'm writing a small web app to test the Khmer Unicode and Lao Unicode. I have a table that store text in Khmer Unicode with the following structure : [t_id] [int] IDENTITY(1,1) NOT NULL [t_chid] [int] NOT NULL [t_vn] [int] NOT NULL [t_v] [nvarchar](max) NOT NULL I can use Linq to SQL to do CRUD normally. The text display properly on the web page, even though I didn't change the default collation of MSSQL Server 2008. When it comes to search the column [t_v], the page will take a very long time to load and in fact, it loads every row of that column. It never compares with the "key word" criteria that I use for the search. Here's my query for the search : Public Shared Function SearchTestingKhmerTable(ByVal keyword As String) As DataTable Dim db As New BibleDataClassesDataContext() Dim query = From b In db.khmer_books _ From ch In db.khmer_chapters _ From v In db.testing_khmers _ Where v.t_v.Contains(keyword) And ch.kh_book_id = b.kh_b_id And v.t_chid = ch.kh_ch_id _ Select b.kh_b_id, b.kh_b_title, ch.kh_ch_id, ch.kh_ch_number, v.t_id, v.t_vn, v.t_v Dim dtDataTableOne = New DataTable("dtOne") dtDataTableOne.Columns.Add("bid", GetType(Integer)) dtDataTableOne.Columns.Add("btitle", GetType(String)) dtDataTableOne.Columns.Add("chid", GetType(Integer)) dtDataTableOne.Columns.Add("chn", GetType(Integer)) dtDataTableOne.Columns.Add("vid", GetType(Integer)) dtDataTableOne.Columns.Add("vn", GetType(Integer)) dtDataTableOne.Columns.Add("verse", GetType(String)) For Each r In query dtDataTableOne.Rows.Add(New Object() {r.kh_b_id, r.kh_b_title, r.kh_ch_id, r.kh_ch_number, r.t_id, r.t_vn, r.t_v}) Next Return dtDataTableOne End Function Please note that I use the exact same code and database design with Lao Unicode and it works just fine. I get the returned query as expected for the search. I can't figure out what the problem with searching for query in Khmer table.

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• Tiff Analyzer

  - by Kevin

  I am writing a program to convert some data, mainly a bunch of Tiff images. Some of the Tiffs seems to have a minor problem with them. They show up fine in some viewers (Irfanview, client's old system) but not in others (Client's new system, Window's picture and fax viewer). I have manually looked at the binary data and all the tags seem ok. Can anyone recommend an app that can analyze it and tell me what, if anything, is wrong with it? Also, for clarity sake, I'm only converting the data about the images which is stored seperately in a database and copying the images, I'm not editting the images myself, so I'm pretty sure I'm not messing them up. UDPATE: For anyone interested, here are the tags from a good and bad file: BAD Tag Type Length Value 256 Image Width SHORT 1 1652 257 Image Length SHORT 1 704 258 Bits Per Sample SHORT 1 1 259 Compression SHORT 1 4 262 Photometric SHORT 1 0 266 Fill Order SHORT 1 1 273 Strip Offsets LONG 1 210 (d2 Hex) 274 Orientation SHORT 1 3 277 Samples Per Pixel SHORT 1 1 278 Rows Per Strip SHORT 1 450 279 Strip Byte Counts LONG 1 7264 (1c60 Hex) 282 X Resolution RATIONAL 1 <194 200 / 1 = 200.000 283 Y Resolution RATIONAL 1 <202 200 / 1 = 200.000 284 Planar Configuration SHORT 1 1 296 Resolution Unit SHORT 1 2 Good Tag Type Length Value 254 New Subfile Type LONG 1 0 (0 Hex) 256 Image Width SHORT 1 1193 257 Image Length SHORT 1 788 258 Bits Per Sample SHORT 1 1 259 Compression SHORT 1 4 262 Photometric SHORT 1 0 266 Fill Order SHORT 1 1 270 Image Description ASCII 45 256 273 Strip Offsets LONG 1 1118 (45e Hex) 274 Orientation SHORT 1 1 277 Samples Per Pixel SHORT 1 1 278 Rows Per Strip LONG 1 788 (314 Hex) 279 Strip Byte Counts LONG 1 496 (1f0 Hex) 280 Min Sample Value SHORT 1 0 281 Max Sample Value SHORT 1 1 282 X Resolution RATIONAL 1 <301 200 / 1 = 200.000 283 Y Resolution RATIONAL 1 <309 200 / 1 = 200.000 284 Planar Configuration SHORT 1 1 293 Group 4 Options LONG 1 0 (0 Hex) 296 Resolution Unit SHORT 1 2

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• Delphi: Using Enumerators to filter TList<T: class> by class type?

  - by afrazier

  Okay, this might be confusing. What I'm trying to do is use an enumerator to only return certain items in a generic list based on class type. Given the following hierarchy: type TShapeClass = class of TShape; TShape = class(TObject) private FId: Integer; public function ToString: string; override; property Id: Integer read FId write FId; end; TCircle = class(TShape) private FDiameter: Integer; public property Diameter: Integer read FDiameter write FDiameter; end; TSquare = class(TShape) private FSideLength: Integer; public property SideLength: Integer read FSideLength write FSideLength; end; TShapeList = class(TObjectList<TShape>) end; How can I extend TShapeList such that I can do something similar to the following: procedure Foo; var ShapeList: TShapeList; Shape: TShape; Circle: TCircle; Square: TSquare; begin // Create ShapeList and fill with TCircles and TSquares for Circle in ShapeList<TCircle> do begin // do something with each TCircle in ShapeList end; for Square in ShapeList<TSquare> do begin // do something with each TSquare in ShapeList end; for Shape in ShapeList<TShape> do begin // do something with every object in TShapeList end; end; I've tried extending TShapeList using an adapted version of Primoz Gabrijelcic's bit on Parameterized Enumerators using a factory record as follows: type TShapeList = class(TObjectList<TShape>) public type TShapeFilterEnumerator<T: TShape> = record private FShapeList: TShapeList; FClass: TShapeClass; FIndex: Integer; function GetCurrent: T; public constructor Create(ShapeList: TShapeList); function MoveNext: Boolean; property Current: T read GetCurrent; end; TShapeFilterFactory<T: TShape> = record private FShapeList: TShapeList; public constructor Create(ShapeList: TShapeList); function GetEnumerator: TShapeFilterEnumerator<T>; end; function FilteredEnumerator<T: TShape>: TShapeFilterFactory<T>; end; Then I modified Foo to be: procedure Foo; var ShapeList: TShapeList; Shape: TShape; Circle: TCircle; Square: TSquare; begin // Create ShapeList and fill with TCircles and TSquares for Circle in ShapeList.FilteredEnumerator<TCircle> do begin // do something with each TCircle in ShapeList end; for Square in ShapeList.FilteredEnumerator<TSquare> do begin // do something with each TSquare in ShapeList end; for Shape in ShapeList.FilteredEnumerator<TShape> do begin // do something with every object in TShapeList end; end; However, Delphi 2010 is throwing an error when I try to compile Foo about Incompatible types: TCircle and TShape. If I comment out the TCircle loop, then I get a similar error about TSquare. If I comment the TSquare loop out as well, the code compiles and works. Well, it works in the sense that it enumerates every object since they all descend from TShape. The strange thing is that the line number that the compiler indicates is 2 lines beyond the end of my file. In my demo project, it indicated line 177, but there's only 175 lines. Is there any way to make this work? I'd like to be able to assign to Circle directly without going through any typecasts or checking in my for loop itself.

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• Constant NSDictionary/NSArray for class methods.

  - by Jeff B

  I am trying to code a global lookup table of sorts. I have game data that is stored in character/string format in a plist, but which needs to be in integer/id format when it is loaded. For instance, in the level data file, a "p" means player. In the game code a player is represented as the integer 1. This let's me do some bitwise operations, etc. I am simplifying greatly here, but trying to get the point across. Also, there is a conversion to coordinates for the sprite on a sprite sheet. Right now this string-integer, integer-string, integer-coordinate, etc. conversion is taking place in several places in code using a case statement. This stinks, of course, and I would rather do it with a dictionary lookup. I created a class called levelInfo, and want to define the dictionary for this conversion, and then class methods to call when I need to do a conversion, or otherwise deal with level data. NSString *levelObjects = @"empty,player,object,thing,doohickey"; int levelIDs[] = [0,1,2,4,8]; // etc etc @implementation LevelInfo +(int) crateIDfromChar: (char) crateChar { int idx = [[crateTypes componentsSeparatedByString:@","] indexOfObject: crateChar]; return levelIDs[idx]; } +(NSString *) crateStringFromID: (int) crateID { return [[crateTypes componentsSeparatedByString:@","] objectAtIndex: crateID]; } @end Is there a better way to do this? It feels wrong to basically build these temporary arrays, or dictionaries, or whatever for each call to do this translation. And I don't know of a way to declare a constant NSArray or NSDictionary. Please, tell me a better way....

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• VBA-Sorting the data in a listbox, sort works but data in listbox not changed

  - by Mike Clemens

  A listbox is passed, the data placed in an array, the array is sort and then the data is placed back in the listbox. The part that does work is putting the data back in the listbox. Its like the listbox is being passed by value instead of by ref. Here's the sub that does the sort and the line of code that calls the sort sub. Private Sub SortListBox(ByRef LB As MSForms.ListBox) Dim First As Integer Dim Last As Integer Dim NumItems As Integer Dim i As Integer Dim j As Integer Dim Temp As String Dim TempArray() As Variant ReDim TempArray(LB.ListCount) First = LBound(TempArray) ' this works correctly Last = UBound(TempArray) - 1 ' this works correctly For i = First To Last TempArray(i) = LB.List(i) ' this works correctly Next i For i = First To Last For j = i + 1 To Last If TempArray(i) > TempArray(j) Then Temp = TempArray(j) TempArray(j) = TempArray(i) TempArray(i) = Temp End If Next j Next i ! data is now sorted LB.Clear ! this doesn't clear the items in the listbox For i = First To Last LB.AddItem TempArray(i) ! this doesn't work either Next i End Sub Private Sub InitializeForm() ' There's code here to put data in the list box Call SortListBox(FieldSelect.CompleteList) End Sub Thanks for your help.

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• Why does fprintf start printing out of order or not at all?

  - by Steve Melvin

  This code should take an integer, create pipes, spawn two children, wait until they are dead, and start all over again. However, around the third time around the loop I lose my prompt to enter a number and it no longer prints the number I've entered. Any ideas? #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #define WRITE 1 #define READ 0 int main (int argc, const char * argv[]) { //Pipe file-descriptor array unsigned int isChildA = 0; int pipeA[2]; int pipeB[2]; int num = 0; while(1){ fprintf(stderr,"Enter an integer: "); scanf("%i", &num); if(num == 0){ fprintf(stderr,"You entered zero, exiting...\n"); exit(0); } //Open Pipes if(pipe(pipeA) < 0){ fprintf(stderr,"Could not create pipe A.\n"); exit(1); } if(pipe(pipeB) < 0){ fprintf(stderr,"Could not create pipe B.\n"); exit(1); } fprintf(stderr,"Value read: %i \n", num); fprintf(stderr,"Parent PID: %i\n", getpid()); pid_t procID = fork(); switch (procID) { case -1: fprintf(stderr,"Fork error, quitting...\n"); exit(1); break; case 0: isChildA = 1; break; default: procID = fork(); if (procID<0) { fprintf(stderr,"Fork error, quitting...\n"); exit(1); } else if(procID == 0){ isChildA = 0; } else { write(pipeA[WRITE], &num, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); pid_t pid; while (pid = waitpid(-1, NULL, 0)) { if (errno == ECHILD) { break; } } } break; } if (procID == 0) { //We're a child, do kid-stuff. ssize_t bytesRead = 0; int response; while (1) { while (bytesRead == 0) { bytesRead = read((isChildA?pipeA[READ]:pipeB[READ]), &response, sizeof(int)); } if (response < 2) { //Kill other child and self fprintf(stderr, "Terminating PROCID: %i\n", getpid()); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); return 0; } else if(!(response%2)){ //Even response/=2; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } else { //Odd response*=3; response++; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } } } } return 0; } This is the output I am getting... bash-3.00$ ./proj2 Enter an integer: 101 Value read: 101 Parent PID: 9379 PROCID: 9380, VALUE: 304 PROCID: 9381, VALUE: 152 PROCID: 9380, VALUE: 76 PROCID: 9381, VALUE: 38 PROCID: 9380, VALUE: 19 PROCID: 9381, VALUE: 58 PROCID: 9380, VALUE: 29 PROCID: 9381, VALUE: 88 PROCID: 9380, VALUE: 44 PROCID: 9381, VALUE: 22 PROCID: 9380, VALUE: 11 PROCID: 9381, VALUE: 34 PROCID: 9380, VALUE: 17 PROCID: 9381, VALUE: 52 PROCID: 9380, VALUE: 26 PROCID: 9381, VALUE: 13 PROCID: 9380, VALUE: 40 PROCID: 9381, VALUE: 20 PROCID: 9380, VALUE: 10 PROCID: 9381, VALUE: 5 PROCID: 9380, VALUE: 16 PROCID: 9381, VALUE: 8 PROCID: 9380, VALUE: 4 PROCID: 9381, VALUE: 2 PROCID: 9380, VALUE: 1 Terminating PROCID: 9381 Terminating PROCID: 9380 Enter an integer: 102 Value read: 102 Parent PID: 9379 PROCID: 9386, VALUE: 51 PROCID: 9387, VALUE: 154 PROCID: 9386, VALUE: 77 PROCID: 9387, VALUE: 232 PROCID: 9386, VALUE: 116 PROCID: 9387, VALUE: 58 PROCID: 9386, VALUE: 29 PROCID: 9387, VALUE: 88 PROCID: 9386, VALUE: 44 PROCID: 9387, VALUE: 22 PROCID: 9386, VALUE: 11 PROCID: 9387, VALUE: 34 PROCID: 9386, VALUE: 17 PROCID: 9387, VALUE: 52 PROCID: 9386, VALUE: 26 PROCID: 9387, VALUE: 13 PROCID: 9386, VALUE: 40 PROCID: 9387, VALUE: 20 PROCID: 9386, VALUE: 10 PROCID: 9387, VALUE: 5 PROCID: 9386, VALUE: 16 PROCID: 9387, VALUE: 8 PROCID: 9386, VALUE: 4 PROCID: 9387, VALUE: 2 PROCID: 9386, VALUE: 1 Terminating PROCID: 9387 Terminating PROCID: 9386 Enter an integer: 104 Value read: 104 Parent PID: 9379 Enter an integer: PROCID: 9388, VALUE: 52 PROCID: 9389, VALUE: 26 PROCID: 9388, VALUE: 13 PROCID: 9389, VALUE: 40 PROCID: 9388, VALUE: 20 PROCID: 9389, VALUE: 10 PROCID: 9388, VALUE: 5 PROCID: 9389, VALUE: 16 PROCID: 9388, VALUE: 8 PROCID: 9389, VALUE: 4 PROCID: 9388, VALUE: 2 PROCID: 9389, VALUE: 1 Terminating PROCID: 9388 Terminating PROCID: 9389 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9395, VALUE: 316 PROCID: 9396, VALUE: 158 PROCID: 9395, VALUE: 79 PROCID: 9396, VALUE: 238 PROCID: 9395, VALUE: 119 PROCID: 9396, VALUE: 358 PROCID: 9395, VALUE: 179 PROCID: 9396, VALUE: 538 PROCID: 9395, VALUE: 269 PROCID: 9396, VALUE: 808 PROCID: 9395, VALUE: 404 PROCID: 9396, VALUE: 202 PROCID: 9395, VALUE: 101 PROCID: 9396, VALUE: 304 PROCID: 9395, VALUE: 152 PROCID: 9396, VALUE: 76 PROCID: 9395, VALUE: 38 PROCID: 9396, VALUE: 19 PROCID: 9395, VALUE: 58 PROCID: 9396, VALUE: 29 PROCID: 9395, VALUE: 88 PROCID: 9396, VALUE: 44 PROCID: 9395, VALUE: 22 PROCID: 9396, VALUE: 11 PROCID: 9395, VALUE: 34 PROCID: 9396, VALUE: 17 PROCID: 9395, VALUE: 52 PROCID: 9396, VALUE: 26 PROCID: 9395, VALUE: 13 PROCID: 9396, VALUE: 40 PROCID: 9395, VALUE: 20 PROCID: 9396, VALUE: 10 PROCID: 9395, VALUE: 5 PROCID: 9396, VALUE: 16 PROCID: 9395, VALUE: 8 PROCID: 9396, VALUE: 4 PROCID: 9395, VALUE: 2 PROCID: 9396, VALUE: 1 Terminating PROCID: 9395 Terminating PROCID: 9396 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9397, VALUE: 316 PROCID: 9398, VALUE: 158 PROCID: 9397, VALUE: 79 PROCID: 9398, VALUE: 238 PROCID: 9397, VALUE: 119 PROCID: 9398, VALUE: 358 PROCID: 9397, VALUE: 179 PROCID: 9398, VALUE: 538 PROCID: 9397, VALUE: 269 PROCID: 9398, VALUE: 808 PROCID: 9397, VALUE: 404 PROCID: 9398, VALUE: 202 PROCID: 9397, VALUE: 101 PROCID: 9398, VALUE: 304 PROCID: 9397, VALUE: 152 PROCID: 9398, VALUE: 76 PROCID: 9397, VALUE: 38 PROCID: 9398, VALUE: 19 PROCID: 9397, VALUE: 58 PROCID: 9398, VALUE: 29 PROCID: 9397, VALUE: 88 PROCID: 9398, VALUE: 44 PROCID: 9397, VALUE: 22 PROCID: 9398, VALUE: 11 PROCID: 9397, VALUE: 34 PROCID: 9398, VALUE: 17 PROCID: 9397, VALUE: 52 PROCID: 9398, VALUE: 26 PROCID: 9397, VALUE: 13 PROCID: 9398, VALUE: 40 PROCID: 9397, VALUE: 20 PROCID: 9398, VALUE: 10 PROCID: 9397, VALUE: 5 PROCID: 9398, VALUE: 16 PROCID: 9397, VALUE: 8 PROCID: 9398, VALUE: 4 PROCID: 9397, VALUE: 2 PROCID: 9398, VALUE: 1 Terminating PROCID: 9397 Terminating PROCID: 9398 106 Value read: 106 Parent PID: 9379 Enter an integer: PROCID: 9399, VALUE: 53 PROCID: 9400, VALUE: 160 PROCID: 9399, VALUE: 80 PROCID: 9400, VALUE: 40 PROCID: 9399, VALUE: 20 PROCID: 9400, VALUE: 10 PROCID: 9399, VALUE: 5 PROCID: 9400, VALUE: 16 PROCID: 9399, VALUE: 8 PROCID: 9400, VALUE: 4 PROCID: 9399, VALUE: 2 PROCID: 9400, VALUE: 1 Terminating PROCID: 9399 Terminating PROCID: 9400 ^C Another thing that's strange, when ran from within XCode it behaves normally. However, when ran from bash on Solaris or OSX it acts up.

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• Passing to service custom class instance in WCF

  - by hgulyan

  Hi, I have my custom class Customer with its properties. I added DataContract mark above the class and DataMember to properties and it was working fine, but I'm calling a service class's function, passing customer instance as parameter and some of my properties get 0 values. While debugging I can see my properties values and after it gets to the function, some properties' values are 0. Why it can be so? There's no code between this two actions. DataContract mark workes fine, everything's ok. Any suggestions on this issue? I tried to change ByRef to ByVal, but it doesn't change anything. Why it would pass other values right and some of integer types just 0? Maybe the answer is simple, but I can't figure it out. Thank You. _ Public Class Customer Private Type_of_clientField As Integer = -1 _ Public Property type_of_client() As Integer Get Return Type_of_clientField End Get Set(ByVal value As Integer) Type_of_clientField = value End Set End Property End Class _ _

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• Compass - Lucene Full text search. Structure and Best Practice.

  - by Rob

  Hi, I have played about with the tutorial and Compass itself for a bit now. I have just started to ramp up the use of it and have found that the performance slows drastically. I am certain that this is due to my mappings and the relationships that I have between entities and was looking for suggestions about how this should be best done. Also as a side question I wanted to know if a variable is in an @searchableComponent but is not defined as @searchable when the component object is pulled out of Compass results will you be able to access that variable? I have 3 main classes that I want to search on - Provider, Location and Activity. They are all inter-related - a Provider can have many locations and activites and has an address; A Location has 1 provider, many activities and an address; An activity has 1 provider and many locations. I have a join table between activity and Location called ActivityLocation that can later provider additional information about the relationship. My classes are mapped to compass as shown below for provider location activity and address. This works but gives a huge index and searches on it are comparatively slow, any advice would be great. Cheers, Rob @Searchable public class AbstractActivity extends LightEntity implements Serializable { /** * Serialisation ID */ private static final long serialVersionUID = 3445339493203407152L; @SearchableId (name="actID") private Integer activityId =-1; @SearchableComponent() private Provider provider; @SearchableComponent(prefix = "activity") private Category category; private String status; @SearchableProperty (name = "activityName") @SearchableMetaData (name = "activityshortactivityName") private String activityName; @SearchableProperty (name = "shortDescription") @SearchableMetaData (name = "activityshortDescription") private String shortDescription; @SearchableProperty (name = "abRating") @SearchableMetaData (name = "activityabRating") private Integer abRating; private String contactName; private String phoneNumber; private String faxNumber; private String email; private String url; @SearchableProperty (name = "completed") @SearchableMetaData (name = "activitycompleted") private Boolean completed= false; @SearchableProperty (name = "isprivate") @SearchableMetaData (name = "activityisprivate") private Boolean isprivate= false; private Boolean subs= false; private Boolean newsfeed= true; private Set news = new HashSet(0); private Set ActivitySession = new HashSet(0); private Set payments = new HashSet(0); private Set userclub = new HashSet(0); private Set ActivityOpeningTimes = new HashSet(0); private Set Events = new HashSet(0); private User creator; private Set userInterested = new HashSet(0); boolean freeEdit = false; private Integer activityType =0; @SearchableComponent (maxDepth=2) private Set activityLocations = new HashSet(0); private Double userRating = -1.00; Getters and Setters .... @Searchable public class AbstractLocation extends LightEntity implements Serializable { /** * Serialisation ID */ private static final long serialVersionUID = 3445339493203407152L; @SearchableId (name="locationID") private Integer locationId; @SearchableComponent (prefix = "location") private Category category; @SearchableComponent (maxDepth=1) private Provider provider; @SearchableProperty (name = "status") @SearchableMetaData (name = "locationstatus") private String status; @SearchableProperty private String locationName; @SearchableProperty (name = "shortDescription") @SearchableMetaData (name = "locationshortDescription") private String shortDescription; @SearchableProperty (name = "abRating") @SearchableMetaData (name = "locationabRating") private Integer abRating; private Integer boolUseProviderDetails; @SearchableProperty (name = "contactName") @SearchableMetaData (name = "locationcontactName") private String contactName; @SearchableComponent private Address address; @SearchableProperty (name = "phoneNumber") @SearchableMetaData (name = "locationphoneNumber") private String phoneNumber; @SearchableProperty (name = "faxNumber") @SearchableMetaData (name = "locationfaxNumber") private String faxNumber; @SearchableProperty (name = "email") @SearchableMetaData (name = "locationemail") private String email; @SearchableProperty (name = "url") @SearchableMetaData (name = "locationurl") private String url; @SearchableProperty (name = "completed") @SearchableMetaData (name = "locationcompleted") private Boolean completed= false; @SearchableProperty (name = "isprivate") @SearchableMetaData (name = "locationisprivate") private Boolean isprivate= false; @SearchableComponent private Set activityLocations = new HashSet(0); private Set LocationOpeningTimes = new HashSet(0); private Set events = new HashSet(0); @SearchableProperty (name = "adult_cost") @SearchableMetaData (name = "locationadult_cost") private String adult_cost =""; @SearchableProperty (name = "child_cost") @SearchableMetaData (name = "locationchild_cost") private String child_cost =""; @SearchableProperty (name = "family_cost") @SearchableMetaData (name = "locationfamily_cost") private String family_cost =""; private Double userRating = -1.00; private Set costs = new HashSet(0); private String cost_caveats =""; Getters and Setters .... @Searchable public class AbstractActivitylocations implements java.io.Serializable { /** * */ private static final long serialVersionUID = 1365110541466870626L; @SearchableId (name="id") private Integer id; @SearchableComponent private Activity activity; @SearchableComponent private Location location; Getters and Setters..... @Searchable public class AbstractProvider extends LightEntity implements Serializable { private static final long serialVersionUID = 3060354043429663058L; @SearchableId private Integer providerId = -1; @SearchableComponent (prefix = "provider") private Category category; @SearchableProperty (name = "businessName") @SearchableMetaData (name = "providerbusinessName") private String businessName; @SearchableProperty (name = "contactName") @SearchableMetaData (name = "providercontactName") private String contactName; @SearchableComponent private Address address; @SearchableProperty (name = "phoneNumber") @SearchableMetaData (name = "providerphoneNumber") private String phoneNumber; @SearchableProperty (name = "faxNumber") @SearchableMetaData (name = "providerfaxNumber") private String faxNumber; @SearchableProperty (name = "email") @SearchableMetaData (name = "provideremail") private String email; @SearchableProperty (name = "url") @SearchableMetaData (name = "providerurl") private String url; @SearchableProperty (name = "status") @SearchableMetaData (name = "providerstatus") private String status; @SearchableProperty (name = "notes") @SearchableMetaData (name = "providernotes") private String notes; @SearchableProperty (name = "shortDescription") @SearchableMetaData (name = "providershortDescription") private String shortDescription; private Boolean completed = false; private Boolean isprivate = false; private Double userRating = -1.00; private Integer ABRating = 1; @SearchableComponent private Set locations = new HashSet(0); @SearchableComponent private Set activities = new HashSet(0); private Set ProviderOpeningTimes = new HashSet(0); private User creator; boolean freeEdit = false; Getters and Setters... Thanks for reading!! Rob

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• Visual Studio Conversion Suite

  - by KingPop

  I have this as my conversion program for the "Length", how can I do it the simpliest way instead of keeping the if, elseif, else too much, i do not have much experience and trying to improve my programming skills on visual studio 2008. Basically, I get annoyed with the formulas because I don't know if it is right, I use google but doesn't help because i don't know how to get it right when the program converts from type to type. Public Class Form2 Dim Metres As Integer Dim Centimetres As Integer Dim Inches As Integer Dim Feet As Integer Dim Total As Integer Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load ErrorMsg.Hide() End Sub Private Sub btnConvert_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConvert.Click Metres = 1 Centimetres = 0.01 Inches = 0.0254 Feet = 0.3048 txtTo.Text = 0 If txtFrom.Text <> "" Then If IsNumeric(txtFrom.Text) And IsNumeric(txtTo.Text) Then If cbFrom.Text = "Metres" And cbTo.Text = "Centimetres" Then Total = txtFrom.Text * Metres txtTo.Text = Total ElseIf cbFrom.Text = "Metres" And cbTo.Text = "Inches" Then Total = txtFrom.Text * 100 txtTo.Text = Total ElseIf cbFrom.Text = "Metres" And cbTo.Text = "Feet" Then ElseIf cbFrom.Text = "Centimetres" And cbTo.Text = "Metres" Then ElseIf cbFrom.Text = "Centimetres" And cbTo.Text = "Inches" Then ElseIf cbFrom.Text = "Centimetres" And cbTo.Text = "Feet" Then ElseIf cbFrom.Text = "Inches" And cbTo.Text = "Metres" Then ElseIf cbFrom.Text = "Inches" And cbTo.Text = "Centimetres" Then ElseIf cbFrom.Text = "Inches" And cbTo.Text = "Feet" Then ElseIf cbFrom.Text = "Feet" And cbTo.Text = "Metres" Then ElseIf cbFrom.Text = "Feet" And cbTo.Text = "Centimetres" Then ElseIf cbFrom.Text = "Feet" And cbTo.Text = "Inches" Then End If End If End If End Sub End Class This is the source for what I have done at the moment.

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• JAVA image transfer problem

  - by user579098

  Hi, I have a school assignment, to send a jpg image,split it into groups of 100 bytes, corrupt it, use a CRC check to locate the errors and re-transmit until it eventually is built back into its original form. It's practically ready, however when I check out the new images, they appear with errors.. I would really appreciate if someone could look at my code below and maybe locate this logical mistake as I can't understand what the problem is because everything looks ok :S For the file with all the data needed including photos and error patterns one could download it from this link:http://rapidshare.com/#!download|932tl2|443122762|Data.zip|739 Thanks in advance, Stefan p.s dont forget to change the paths in the code for the image and error files package networks; import java.io.*; // for file reader import java.util.zip.CRC32; // CRC32 IEEE (Ethernet) public class Main { /** * Reads a whole file into an array of bytes. * @param file The file in question. * @return Array of bytes containing file data. * @throws IOException Message contains why it failed. */ public static byte[] readFileArray(File file) throws IOException { InputStream is = new FileInputStream(file); byte[] data=new byte[(int)file.length()]; is.read(data); is.close(); return data; } /** * Writes (or overwrites if exists) a file with data from an array of bytes. * @param file The file in question. * @param data Array of bytes containing the new file data. * @throws IOException Message contains why it failed. */ public static void writeFileArray(File file, byte[] data) throws IOException { OutputStream os = new FileOutputStream(file,false); os.write(data); os.close(); } /** * Converts a long value to an array of bytes. * @param data The target variable. * @return Byte array conversion of data. * @see http://www.daniweb.com/code/snippet216874.html */ public static byte[] toByta(long data) { return new byte[] { (byte)((data >> 56) & 0xff), (byte)((data >> 48) & 0xff), (byte)((data >> 40) & 0xff), (byte)((data >> 32) & 0xff), (byte)((data >> 24) & 0xff), (byte)((data >> 16) & 0xff), (byte)((data >> 8) & 0xff), (byte)((data >> 0) & 0xff), }; } /** * Converts a an array of bytes to long value. * @param data The target variable. * @return Long value conversion of data. * @see http://www.daniweb.com/code/snippet216874.html */ public static long toLong(byte[] data) { if (data == null || data.length != 8) return 0x0; return (long)( // (Below) convert to longs before shift because digits // are lost with ints beyond the 32-bit limit (long)(0xff & data[0]) << 56 | (long)(0xff & data[1]) << 48 | (long)(0xff & data[2]) << 40 | (long)(0xff & data[3]) << 32 | (long)(0xff & data[4]) << 24 | (long)(0xff & data[5]) << 16 | (long)(0xff & data[6]) << 8 | (long)(0xff & data[7]) << 0 ); } public static byte[] nextNoise(){ byte[] result=new byte[100]; // copy a frame's worth of data (or remaining data if it is less than frame length) int read=Math.min(err_data.length-err_pstn, 100); System.arraycopy(err_data, err_pstn, result, 0, read); // if read data is less than frame length, reset position and add remaining data if(read<100){ err_pstn=100-read; System.arraycopy(err_data, 0, result, read, err_pstn); }else // otherwise, increase position err_pstn+=100; // return noise segment return result; } /** * Given some original data, it is purposefully corrupted according to a * second data array (which is read from a file). In pseudocode: * corrupt = original xor corruptor * @param data The original data. * @return The new (corrupted) data. */ public static byte[] corruptData(byte[] data){ // get the next noise sequence byte[] noise = nextNoise(); // finally, xor data with noise and return result for(int i=0; i<100; i++)data[i]^=noise[i]; return data; } /** * Given an array of data, a packet is created. In pseudocode: * frame = corrupt(data) + crc(data) * @param data The original frame data. * @return The resulting frame data. */ public static byte[] buildFrame(byte[] data){ // pack = [data]+crc32([data]) byte[] hash = new byte[8]; // calculate crc32 of data and copy it to byte array CRC32 crc = new CRC32(); crc.update(data); hash=toByta(crc.getValue()); // create a byte array holding the final packet byte[] pack = new byte[data.length+hash.length]; // create the corrupted data byte[] crpt = new byte[data.length]; crpt = corruptData(data); // copy corrupted data into pack System.arraycopy(crpt, 0, pack, 0, crpt.length); // copy hash into pack System.arraycopy(hash, 0, pack, data.length, hash.length); // return pack return pack; } /** * Verifies frame contents. * @param frame The frame data (data+crc32). * @return True if frame is valid, false otherwise. */ public static boolean verifyFrame(byte[] frame){ // allocate hash and data variables byte[] hash=new byte[8]; byte[] data=new byte[frame.length-hash.length]; // read frame into hash and data variables System.arraycopy(frame, frame.length-hash.length, hash, 0, hash.length); System.arraycopy(frame, 0, data, 0, frame.length-hash.length); // get crc32 of data CRC32 crc = new CRC32(); crc.update(data); // compare crc32 of data with crc32 of frame return crc.getValue()==toLong(hash); } /** * Transfers a file through a channel in frames and reconstructs it into a new file. * @param jpg_file File name of target file to transfer. * @param err_file The channel noise file used to simulate corruption. * @param out_file The name of the newly-created file. * @throws IOException */ public static void transferFile(String jpg_file, String err_file, String out_file) throws IOException { // read file data into global variables jpg_data = readFileArray(new File(jpg_file)); err_data = readFileArray(new File(err_file)); err_pstn = 0; // variable that will hold the final (transfered) data byte[] out_data = new byte[jpg_data.length]; // holds the current frame data byte[] frame_orig = new byte[100]; byte[] frame_sent = new byte[100]; // send file in chunks (frames) of 100 bytes for(int i=0; i<Math.ceil(jpg_data.length/100); i++){ // copy jpg data into frame and init first-time switch System.arraycopy(jpg_data, i*100, frame_orig, 0, 100); boolean not_first=false; System.out.print("Packet #"+i+": "); // repeat getting same frame until frame crc matches with frame content do { if(not_first)System.out.print("F"); frame_sent=buildFrame(frame_orig); not_first=true; }while(!verifyFrame(frame_sent)); // usually, you'd constrain this by time to prevent infinite loops (in // case the channel is so wacked up it doesn't get a single packet right) // copy frame to image file System.out.println("S"); System.arraycopy(frame_sent, 0, out_data, i*100, 100); } System.out.println("\nDone."); writeFileArray(new File(out_file),out_data); } // global variables for file data and pointer public static byte[] jpg_data; public static byte[] err_data; public static int err_pstn=0; public static void main(String[] args) throws IOException { // list of jpg files String[] jpg_file={ "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo1.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo2.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo3.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo4.jpg" }; // list of error patterns String[] err_file={ "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 1.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 2.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 3.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 4.DAT" }; // loop through all jpg/channel combinations and run tests for(int x=0; x<jpg_file.length; x++){ for(int y=0; y<err_file.length; y++){ System.out.println("Transfering photo"+(x+1)+".jpg using Pattern "+(y+1)+"..."); transferFile(jpg_file[x],err_file[y],jpg_file[x].replace("photo","CH#"+y+"_photo")); } } } }

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• Shift count negative or too big error - correct solution?

  - by PeterK

  I have the following function for reading a big-endian quadword (in a abstract base file I/O class): unsigned long long CGenFile::readBEq(){ unsigned long long qT = 0; qT |= readb() << 56; qT |= readb() << 48; qT |= readb() << 40; qT |= readb() << 32; qT |= readb() << 24; qT |= readb() << 16; qT |= readb() << 8; qT |= readb() << 0; return qT; } The readb() functions reads a BYTE. Here are the typedefs used: typedef unsigned char BYTE; typedef unsigned short WORD; typedef unsigned long DWORD; The thing is that i get 4 compiler warnings on the first four lines with the shift operation: warning C4293: '<<' : shift count negative or too big, undefined behavior I understand why this warning occurs, but i can't seem to figure out how to get rid of it correctly. I could do something like: qT |= (unsigned long long)readb() << 56; This removes the warning, but isn't there any other problem, will the BYTE be correctly extended all the time? Maybe i'm just thinking about it too much and the solution is that simple. Can you guys help me out here? Thanks.

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