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  • How to Import a CSV file containing multiple sections into R?

    - by PaulHurleyuk
    I want to import the contents of a csv file into R, the csv file contains multiple sections of data vertically, seperated by blank lines and asterisks. For example ******************************************************** * SAMPLE DATA ****************************************** ******************************************************** Name, DOB, Sex Rod, 1/1/1970, M Jane, 5/7/1980, F Freddy, 9.12,1965, M ******************************************************* * Income Data **************************************** ******************************************************* Name, Income Rod, 10000 Jane, 15000 Freddy, 7500 I would like to import this into R as two seperate dataframes. Currently I'm manually cutting the csv file up into smaller files, but I think I could do it using read.csv and the skip and nrows settings of read.csv, If I could work out where the secion breaks are. This gives me a logical TRUE for every blank line ifelse(readLines("DATA.csv")=="",TRUE,FALSE) I'm hoping someone has already solved this problem.

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  • Is it possible to store pointers in shared memory without using offsets?

    - by Joseph Garvin
    When using shared memory, each process may mmap the shared region into a different area of their address space. This means that when storing pointers within the shared region, you need to store them as offsets of the start of the shared region. Unfortunately, this complicates use of atomic instructions (e.g. if you're trying to write a lock free algorithm). For example, say you have a bunch of reference counted nodes in shared memory, created by a single writer. The writer periodically atomically updates a pointer 'p' to point to a valid node with positive reference count. Readers want to atomically write to 'p' because it points to the beginning of a node (a struct) whose first element is a reference count. Since p always points to a valid node, incrementing the ref count is safe, and makes it safe to dereference 'p' and access other members. However, this all only works when everything is in the same address space. If the nodes and the 'p' pointer are stored in shared memory, then clients suffer a race condition: x = read p y = x + offset Increment refcount at y During step 2, p may change and x may no longer point to a valid node. The only workaround I can think of is somehow forcing all processes to agree on where to map the shared memory, so that real pointers rather than offsets can be stored in the mmap'd region. Is there any way to do that? I see MAP_FIXED in the mmap documentation, but I don't know how I could pick an address that would be safe.

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  • Android serialization: ImageView

    - by embo
    I have a simple class: public class Ball2 extends ImageView implements Serializable { public Ball2(Context context) { super(context); } } Serialization ok: private void saveState() throws IOException { ObjectOutputStream oos = new ObjectOutputStream(openFileOutput("data", MODE_PRIVATE)); try { Ball2 data = new Ball2(Game2.this); oos.writeObject(data); oos.flush(); } catch (Exception e) { Log.e("write error", e.getMessage(), e); } finally { oos.close(); } } But deserealization private void loadState() throws IOException { ObjectInputStream ois = new ObjectInputStream(openFileInput("data")); try { Ball2 data = (Ball2) ois.readObject(); } catch (Exception e) { Log.e("read error", e.getMessage(), e); } finally { ois.close(); } } fail with error: 03-24 21:52:43.305: ERROR/read error(1948): java.io.InvalidClassException: android.widget.ImageView; IllegalAccessException How deserialize object correctly?

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  • Should I commit or rollback a transaction that creates a temp table, reads, then deletes it?

    - by Triynko
    To select information related to a list of hundreds of IDs... rather than make a huge select statement, I create temp table, insert the ids into it, join it with a table to select the rows matching the IDs, then delete the temp table. So this is essentially a read operation, with no permanent changes made to any persistent database tables. I do this in a transaction, to ensure the temp table is deleted when I'm finished. My question is... what happens when I commit such a transaction vs. let it roll it back? Performance-wise... does the DB engine have to do more work to roll back the transaction vs committing it? Is there even a difference since the only modifications are done to a temp table? Related question here, but doesn't answer my specific case involving temp tables: http://stackoverflow.com/questions/309834/should-i-commit-or-rollback-a-read-transaction

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  • WebRequest using SSL

    - by pm_2
    I have the following code to retrieve a file using FTP (which works fine). FtpWebRequest request = (FtpWebRequest)WebRequest.Create(svrPath); request.KeepAlive = true; request.UsePassive = true; request.UseBinary = true; request.Method = WebRequestMethods.Ftp.DownloadFile; request.Credentials = new NetworkCredential(uname, passw); using (FtpWebResponse response = (FtpWebResponse)request.GetResponse()) using (Stream responseStream = response.GetResponseStream()) using (StreamReader reader = new StreamReader(responseStream)) using (StreamWriter destination = new StreamWriter(destinationFile)) { destination.Write(reader.ReadToEnd()); destination.Flush(); } However, when I try to do this using SSL, I am unable to access the file, as follows: FtpWebRequest request = (FtpWebRequest)WebRequest.Create(svrPath); request.KeepAlive = true; request.UsePassive = true; request.UseBinary = true; // The following line causes the download to fail request.EnableSsl = true; request.Method = WebRequestMethods.Ftp.DownloadFile; request.Credentials = new NetworkCredential(uname, passw); using (FtpWebResponse response = (FtpWebResponse)request.GetResponse()) using (Stream responseStream = response.GetResponseStream()) using (StreamReader reader = new StreamReader(responseStream)) using (StreamWriter destination = new StreamWriter(destinationFile)) { destination.Write(reader.ReadToEnd()); destination.Flush(); } Can anyone tell me why the latter would not work?

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  • Sensible unit test possible?

    - by nkr1pt
    Could a sensible unit test be written for this code which extracts a rar archive by delegating it to a capable tool on the host system if one exists? I can write a test case based on the fact that my machine runs linux and the unrar tool is installed, but if another developer who runs windows would check out the code the test would fail, although there would be nothing wrong with the extractor code. I need to find a way to write a meaningful test which is not binded to the system and unrar tool installed. How would you tackle this? public class Extractor { private EventBus eventBus; private ExtractCommand[] linuxExtractCommands = new ExtractCommand[]{new LinuxUnrarCommand()}; private ExtractCommand[] windowsExtractCommands = new ExtractCommand[]{}; private ExtractCommand[] macExtractCommands = new ExtractCommand[]{}; @Inject public Extractor(EventBus eventBus) { this.eventBus = eventBus; } public boolean extract(DownloadCandidate downloadCandidate) { for (ExtractCommand command : getSystemSpecificExtractCommands()) { if (command.extract(downloadCandidate)) { eventBus.fireEvent(this, new ExtractCompletedEvent()); return true; } } eventBus.fireEvent(this, new ExtractFailedEvent()); return false; } private ExtractCommand[] getSystemSpecificExtractCommands() { String os = System.getProperty("os.name"); if (Pattern.compile("linux", Pattern.CASE_INSENSITIVE).matcher(os).find()) { return linuxExtractCommands; } else if (Pattern.compile("windows", Pattern.CASE_INSENSITIVE).matcher(os).find()) { return windowsExtractCommands; } else if (Pattern.compile("mac os x", Pattern.CASE_INSENSITIVE).matcher(os).find()) { return macExtractCommands; } return null; } }

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  • Saving Blob data from SQLite database to a file

    - by Felipe
    Hello, I'm trying to save blob data from a SQLite database (Safari cache: Cache.db) to a file, but for some reason sqlite won't read the whole blob. I eventually would like to do this in ruby, but for now something that works directly in sqlite command prompt is fine. Also, I've read all of the entries that talk about this here on stackoverflow, but most of them only discuss the performance of saving images in blobs and the one entry that does show to save blobs to file is in C# which does not help me. Here is what I've tried: sqlite select * from cfurl_cache_response limit 1; 3501|0|945281827|0|http://www.gospelz.com/components/com_jomcomment/smilies/guest.gif|2010-02-24 16:20:07 sqlite select receiver_data from cfurl_cache_blob_data where entry_ID = 3501; GIF89a( A hexdump of the original (guest.gif) file shows that sqlite stops reading the blob after the first null value: $ hexdump -C guest.gif 00000000 47 49 46 38 39 61 28 00 28 00 f7 00 00 f1 f5 fd |GIF89a(.(.......| sqlite .output test.gif sqlite select receiver_data from cfurl_cache_blob_data where entry_ID = 3501; $ hexdump -C test.gif 00000000 47 49 46 38 39 61 28 0a |GIF89a(.|

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  • Using Application Settings and reading defaults from app.config

    - by Peter Goras
    Hi, I need to deploy a Windows Forms application using ClickOnce deployment. (VS2008, .NET 3.5) And I need to provide a configuration file for this app that any user can modify. For this reason, I am using Application Settings instead of standard appSetttings in app.config so I can separate the the user config from app config. see http://msdn.microsoft.com/en-us/library/ms228995(VS.80).aspx Creating a Settings.settings file using VS generated a class with hard-coded default values like this: [global::System.Configuration.DefaultSettingValueAttribute("blahblah")] public string MyProperty ... WTF? I want to read the default values from the app.config! So I created my own class deriving from ApplicationSettingsBase but I cannot get this to read values from the app.config. Any ideas?

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  • Creating an HTTP-Redirected Virtual Directopry in IIS 6.0 without specifying physical path & WMI/ADS

    - by Steve Johnson
    My question is : Is it possible to create a working IIS 6.0 Virtual Directory with providing Physical Path of the Virtual Directory.? I know that manually, it is not possible via IIS but programmatically such a virtual directory can be created. If an HTTPRedirect is set on that virtual directory but the site physical path is not specified, then will it work? Simply stated, how to create an HTTp-redirected Virtual Directory , directly without specifying any physical path to a folder or network share. Here is my code. Try If Directory.Exists(HomeDirectory) = False And Path.StartsWith("http://") = False Then Directory.CreateDirectory(HomeDirectory) End If Dim website As DirectoryEntry website = New DirectoryEntry("IIS://" & IISServer & "/W3SVC/" & WebsiteId & "/Root") Dim NewVDir As DirectoryEntry = website.Children.Add(VDirName, "IIsWebVirtualDir") If Path.StartsWith("http://") = False Then NewVDir.Properties("Path")(0) = Path NewVDir.Properties("HttpRedirect").Clear() Else NewVDir.Properties("HttpRedirect")(0) = Path End If If ((Perm And Permission.Read) = Permission.Read) Then NewVDir.Properties("AccessRead")(0) = True End If If ((Perm And Permission.Write) = Permission.Write) Then NewVDir.Properties("AccessWrite")(0) = True End If If ((Perm And Permission.DirBrowse) = Permission.DirBrowse) Then NewVDir.Properties("EnableDirBrowsing")(0) = True End If If ((Perm And Permission.CreatetApplication) = Permission.CreatetApplication) Then NewVDir.Invoke("AppCreate", True) End If If ((Perm And Permission.ScriptOnly) = Permission.ScriptOnly) Then NewVDir.Properties("AccessScript")(0) = True End If If ((Perm And Permission.ScriptNExecute) = Permission.ScriptNExecute) Then NewVDir.Properties("AccessExecute")(0) = True End If NewVDir.Properties("AuthAnonymous")(0) = True NewVDir.Properties("AuthNTLM")(0) = True NewVDir.Properties("AnonymousUserName")(0) = AnonUserName NewVDir.Properties("AnonymousUserPass")(0) = AnonPassword NewVDir.Properties("AppFriendlyName")(0) = AppFriendlyName NewVDir.CommitChanges() website.CommitChanges() NewVDir.Close() website.Close() Success = True Catch Err As Exception Throw New Exception("My Custom Exception Here: " & Err.Message) End Try

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  • Reading Windows ACLs from Java

    - by Matt Sheppard
    From within a Java program, I want to be able to list out the Windows users and groups who have permission to read a given file. Obviously Java has no built-in ability to read the Windows ACL information out, so I'm looking for other solutions. Are there any third party libraries available which can provide direct access to the ACL information for a Windows file? Failing that, maybe running cacls and capturing and then processing the output would be a reasonable temporary solution - Is the output format of cacls thoroughly documented anywhere, and is it likely to change between versions of Windows?

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  • passing in javascript values into iframe tag

    - by Cedar Jensen
    What's the best way to pass in the value held in a javascript variable into an iframe call on the same html page? I'm trying to improve my site's page response times by moving ad serving javascript code (the typical document.write('<script type="text/javascript" src="..") into a separate iframe. (Based on this posting) The request to the ad server typically require a seed variable declared once per site and incremented each time page is loaded by the client. What I want to do is pass in the seed variable into the document invoked by my iframe section. The seed variable is initialized in the 'head' tag of my main html document: <head> <script type="text/javascript"> <!-- custom_seed=1; //--> </script> </head> Later in the html document, I make the request through an iframe which returns the html necessary to invoke the ad server. <body> <!-- a bunch of html to display the page --> <iframe src="somepage.html" width="100%" height="100%"> <p>No support for iframe</p> </iframe> </body> The html returned in the 'somepage.html' has a script used to call the ad server and needs to use the earlier declared seed variable as a parameter: <script type="text/javascript"> document.write('<script type="text/javascript" src="http://ad.server.net/...seed='+ custom_seed +'?"></script>'); custom_seed++; </script> What's a good way to achieve this?

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  • Unit testing opaque structure based C API

    - by Nicolas Goy
    I have a library I wrote with API based on opaque structures. Using opaque structures has a lot of benefits and I am very happy with it. Now that my API are stable in term of specifications, I'd like to write a complete battery of unit test to ensure a solid base before releasing it. My concern is simple, how do you unit test API based on opaque structures where the main goal is to hide the internal logic? For example, let's take a very simple object, an array with a very simple test: WSArray a = WSArrayCreate(); int foo = 5; WSArrayAppendValue(a, &foo); int *bar = WSArrayGetValueAtIndex(a, 0); if(&foo != bar) printf("Eroneous value returned\n"); else printf("Good value returned\n"); WSRelease(a); Of course, this tests some facts, like the array actually acts as wanted with 1 value, but when I write unit tests, at least in C, I usualy compare the memory footprint of my datastructures with a known state. In my example, I don't know if some internal state of the array is broken. How would you handle that? I'd really like to avoid adding codes in the implementation files only for unit testings, I really emphasis loose coupling of modules, and injecting unit tests into the implementation would seem rather invasive to me. My first thought was to include the implementation file into my unit test, linking my unit test statically to my library. For example: #include <WS/WS.h> #include <WS/Collection/Array.c> static void TestArray(void) { WSArray a = WSArrayCreate(); /* Structure members are available because we included Array.c */ printf("%d\n", a->count); } Is that a good idea? Of course, the unit tests won't benefit from encapsulation, but they are here to ensure it's actually working.

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  • servlet resopnse data for autocomplete

    - by shams haque
    Hello experts, Following code is in php. i want to do same in java. Please tell me how do i generate this type of array or collection in java. I need this to response to json autocomplete. <?php $q = strtolower($_GET["q"]); if (!$q) return; $items = array( "Peter Pan"=>"[email protected]", "Molly"=>"[email protected]", "Forneria Marconi"=>"[email protected]", "Master Sync"=>"[email protected]", "Dr. Tech de Log"=>"[email protected]", "Don Corleone"=>"[email protected]", "Mc Chick"=>"[email protected]", "Donnie Darko"=>"[email protected]", "Quake The Net"=>"[email protected]", "Dr. Write"=>"[email protected]" ); $result = array(); foreach ($items as $key=>$value) { if (strpos(strtolower($key), $q) !== false) { array_push($result, array( "name" => $key, "to" => $value )); } } echo json_encode($result); ?>

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  • Getting Recognition for Open-Source Computer Language Projects

    - by Jon Purdy
    I like language a lot, so I write a lot of language-based solutions for programming, automation, and data definition. I'm very much a believer in open-source software, so lately I've started to push these projects to Sourceforge when I start them. I feel that these tools could be quite valuable in the right hands, and that they fill niches that otherwise go unfilled. The trouble, for me, is gaining recognition. No matter how useful the software I write, after a certain point I can no longer come up with anything to add or improve. Basically no one but me uses it, so it's not being attacked from enough angles to discover any new weaknesses. I cannot work on a project that doesn't have anything to do, but I won't have anything to do unless I gain recognition by working on it! This is greatly discouraging. It's like giving what you think is a really thoughtful gift to someone who just isn't paying attention. So I'm looking for advice on how to network and disseminate information about my projects so that they don't fizzle out like this. Are there any sites, newsgroups, or mailing lists that I've been completely missing?

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  • Creating a REST client API using Reactive Extensions (Rx)

    - by Jonas Follesø
    I'm trying to get my head around the right use cases for Reactive Extensions (Rx). The examples that keeps coming up are UI events (drag and drop, drawing), and suggestions that Rx is suitable for asynchronous applications/operations such as web service calls. I'm working on an application where I need to write a tiny client API for a REST service. I need to call four REST end-points, three to get some reference data (Airports, Airlines, and Statuses), and the fourth is the main service that will give you flight times for a given airport. I have created classes exposing the three reference data services, and the methods look something like this: public Observable<Airport> GetAirports() public Observable<Airline> GetAirlines() public Observable<Status> GetStatuses() public Observable<Flights> GetFlights(string airport) In my GetFlights method I want each Flight to hold a reference the Airport it's departing from, and the Airline operating the flight. To do that I need the data from GetAirports and GetAirlines to be available. My initial thinking was something like this: Write a Rx Query that will Subscribe on the three reference services (Airports, Airlines and Statuses) Add results into a Dictionary (airline code and Airline object) When all three GetAirports, GetAirlines and GetStatuses are complete, then return the GetFlights IObservable. Is this a reasonable scenario for Rx? I'm developing on the Windows Phone 7, so I'm not sure if there are major differences in the Rx implementations across the different platforms.

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  • Migrating C# code from Cassandra .5 to .6

    - by Jonathan
    I have some some simple code derived from an example that is meant to form a quick write to the Cassandra db, then loop back and read all current entries, everything worked fine. When .6 came out, i upgraded Cassandra and thrift, which threw errors in my code (www[dot]copypastecode[dot]com/26760/) - i was able to iron out the errors by converting the necessary types, however in the version that compiles now only seems to read one item back, im not sure if its not saving db changes or if its only reading back 1 entry. the "fixed" code is here: http://www.copypastecode.com/26752/. Any help would be greatly appreciated.

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  • How can I generate the Rowland prime sequence idiomatically in J?

    - by Gregory Higley
    If you're not familiar with the Rowland prime sequence, you can find out about it here. I've created an ugly, procedural monadic verb in J to generate the first n terms in this sequence, as follows: rowland =: monad define result =. 0 $ 0 t =. 1 $ 7 while. (# result) < y do. a =. {: t n =. 1 + # t t =. t , a + n +. a d =. | -/ _2 {. t if. d > 1 do. result =. ~. result , d end. end. result ) This works perfectly, and it indeed generates the first n terms in the sequence. (By n terms, I mean the first n distinct primes.) Here is the output of rowland 20: 5 3 11 23 47 101 7 13 233 467 941 1889 3779 7559 15131 53 30323 60647 121403 242807 My question is, how can I write this in more idiomatic J? I don't have a clue, although I did write the following function to find the differences between each successive number in a list of numbers, which is one of the required steps. Here it is, although it too could probably be refactored by a more experienced J programmer than I: diffs =: monad : '}: (|@({.-2&{.) , $:@}.) ^: (1 < #) y'

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  • Why do System.IO.Log SequenceNumbers have variable length?

    - by Doug McClean
    I'm trying to use the System.IO.Log features to build a recoverable transaction system. I understand it to be implemented on top of the Common Log File System. The usual ARIES approach to write-ahead logging involves persisting log record sequence numbers in places other than the log (for example, in the header of the database page modified by the logged action). Interestingly, the documentation for CLFS says that such sequence numbers are always 64-bit integers. Confusingly, however, the .Net wrapper around those SequenceNumbers can be constructed from a byte[] but not from a UInt64. It's value can also be read as a byte[], but not as a UInt64. Inspecting the implementation of SequenceNumber.GetBytes() reveals that it can in fact return arrays of either 8 or 16 bytes. This raises a few questions: Why do the .Net sequence numbers differ in size from the CLFS sequence numbers? Why are the .Net sequence numbers variable in length? Why would you need 128 bits to represent such a sequence number? It seems like you would truncate the log well before using up a 64-bit address space (16 exbibytes, or around 10^19 bytes, more if you address longer words)? If log sequence numbers are going to be represented as 128 bit integers, why not provide a way to serialize/deserialize them as pairs of UInt64s instead of rather-pointlessly incurring heap allocations for short-lived new byte[]s every time you need to write/read one? Alternatively, why bother making SequenceNumber a value type at all? It seems an odd tradeoff to double the storage overhead of log sequence numbers just so you can have an untruncated log longer than a million terabytes, so I feel like I'm missing something here, or maybe several things. I'd much appreciate it if someone in the know could set me straight.

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  • Asynchronous event loop design and issues.

    - by Artyom
    Hello, I'm designing event loop for asynchronous socket IO using epoll/devpoll/kqueue/poll/select (including windows-select). I have two options of performing, IO operation: Non-blocking mode, poll on EAGAIN Set socket to non-blocking mode. Read/Write to socket. If operation succeeds, post completion notification to event loop. If I get EAGAIN, add socket to "select list" and poll socket. Polling mode: poll and then execute Add socket to select list and poll it. Wait for notification that it is readable writable read/write Post completion notification to event loop of sucseeds To me it looks like first would require less system calls when using in normal mode, especially for writing to socket (buffers are quite big). Also it looks like that it would be possible to reduce the overhead over number of "select" executions, especially it is nice when you do not have something that scales well as epoll/devpoll/kqueue. Questions: Are there any advantages of the second approach? Are there any portability issues with non-blocking operations on sockets/file descriptors over numerous operating systems: Linux, FreeBSD, Solaris, MacOSX, Windows. Notes: Please do not suggest using existing event-loop/socket-api implementations

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  • Testing Finite State Machines

    - by Pondidum
    I have inherited a large and firaly complex state machine at work. It has 31 possbile states to be in. It has the following inputs: Enum: Current State (so 0 - 30) Enum: source (currently only 2 entries) Boolean: Request Boolean: type Enum: Status (3 states) Enum: Handling (3 states) Boolean: Completed The 31 States are really needed (big business process). Breaking into seperate state machines doesnt seem feasable - each state is distinct. I have written tests for one set of inputs (the most common set), with one test per input (all inputs constant, except for the State input): [Subject("Application Process States")] public class When_state_is_meeting2Requested : AppProcessBase { Establish context = () => { //Setup.... }; Because of = () => process.Load(jas, vac); It Current_node_should_be_meeting2Requested = () => process.CurrentNode.ShouldBeOfType<meetingRequestedNode>(); It Can_move_to_clientDeclined = () => Check(process, process.clientDeclined); It Can_move_to_meeting1Arranged = () => Check(process, process.meeting1Arranged); It Can_move_to_meeting2Arranged = () => Check(process, process.meeting2Arranged); It Can_move_to_Reject = () => Check(process, process.Reject); It Cannot_move_to_any_other_state = () => AllOthersFalse(process); } As no one is entirely sure on what the output should be for each state and set of inputs i have been starting to write tests for it, however on calculation i will need to write 4320 ( 30*2*2*2*3*3*2 ) tests for it. Does anyone have any suggestions on how i should go about testing this?

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  • sqlcipher command line not working

    - by Min Lin
    I have a encrypted sqlite db and its key. (Which is generated by an android program). However, when I open the db in command line I can not read the db. The command line tool is installed by: brew install sqlcipher I open the database by: sqlcipher EnDB.db >pragma key="6b74fcd"; >select * from bizinfo; It keeps telling me "Error: file is encrypted or is not a database" However, if I open the database file with gui app sqlite database browser (which is a windows program and I run it in wine). It pops up a window for me to enter the key, with 6b74fcd as the key it successfully read the database. As I want to automatically process the db in the future, I can not depend on the GUI. Do you know why the command line is not working?

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  • is it possible to do partial postback on web?

    - by carter-boater
    Hi all, I read some paragraphs in a book saying that it is not possible to do a partial postback for web, even AJAX is employed. Ajax will postback everything and update only ajaxfied controls. However, on pages I made using ajax, I used Fiddler to monitor the transportation. I found when the page initial load, it loaded everything include pictures .... However, when I click a button and do a ajax postback. I can only see the some data were loaded.... Looks like it doesn't need to reload the whole page again. I don't know if what I see is correct? Or the book I read is correct? Thank you guys.

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