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  • How to get raw jpeg data (but no metatags / proprietary markers)

    - by CoolAJ86
    I want to get raw jpeg data - no metadata. I'm very confused looking at the jpeg "standards". How correct is my understanding of the marker "tree"? 0xFFD8 - Identifies the file as an image 0xFFE? - EXIF, JFIF, SPIFF, ICC, etc 0x???? - the length of the tag 0xFFD8 - Start of Image 0xFFE0 - should follow SOI as per spec, but often preceded by comments ??? 0x???? - Matrices, tags, random data ??? There are never other markers in-between these markers? Or these include the matrices and such? 0xFFDA - Start of Stream - This is what I want, yes? 0xXXXX - length of stream 0xFFD9 - End of Stream (EOI) 0x???? - Comment tags, extra exif, jfif info??? 0xFFD9 - End of Image 0xFF00 - escaped 0xFF, not to be confused with a marker This has been my reading material: http://en.wikipedia.org/wiki/JPEG http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html http://www.media.mit.edu/pia/Research/deepview/exif.html http://www.faqs.org/faqs/jpeg-faq/part1/section-15.html

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  • Binding a date string parameter in an MS Access PDO query

    - by harryg
    I've made a PDO database class which I use to run queries on an MS Access database. When querying using a date condition, as is common in SQL, dates are passed as a string. Access usually expects the date to be surrounded in hashes however. E.g. SELECT transactions.amount FROM transactions WHERE transactions.date = #2013-05-25#; If I where to run this query using PDO I might do the following. //instatiate pdo connection etc... resulting in a $db object $stmt = $db->prepare('SELECT transactions.amount FROM transactions WHERE transactions.date = #:mydate#;'); //prepare the query $stmt->bindValue('mydate', '2013-05-25', PDO::PARAM_STR); //bind the date as a string $stmt->execute(); //run it $result = $stmt->fetch(); //get the results As far as my understanding goes the statement that results from the above would look like this as binding a string results in it being surrounded by quotes: SELECT transactions.amount FROM transactions WHERE transactions.date = #'2013-05-25'#; This causes an error and prevents the statement from running. What's the best way to bind a date string in PDO without causing this error? I'm currently resorting to sprintf-ing the string which I'm sure is bad practise. Edit: if I pass the hash-surrounded date then I still get the error as below: Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[22018]: Invalid character value for cast specification: -3030 [Microsoft][ODBC Microsoft Access Driver] Data type mismatch in criteria expression. (SQLExecute[-3030] at ext\pdo_odbc\odbc_stmt.c:254)' in C:\xampp\htdocs\ips\php\classes.php:49 Stack trace: #0 C:\xampp\htdocs\ips\php\classes.php(49): PDOStatement-execute() #1 C:\xampp\htdocs\ips\php\classes.php(52): database-execute() #2 C:\xampp\htdocs\ips\try2.php(12): database-resultset() #3 {main} thrown in C:\xampp\htdocs\ips\php\classes.php on line 49

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  • Finding intersection of two spheres

    - by Onkar Deshpande
    Hi, Consider the following problem - I am given 2 links of length L0 and L1. P0 is the point that the first link starts at and P1 is the point that I want the end of second link to be at in 3-D space. I am supposed to write a function that should take in these 3-D points (P0 and P1) as inputs and should find all configurations of the links that put the second link's end point at P1. My understanding of how to go about it is - Each link L0 and L1 will create a sphere S0 and S1 around itself. I should find out the intersection of those two spheres (which will be a circle) and print all points that are on the circumference of that circle. I saw gmatt's first reply on the http://stackoverflow.com/questions/1406375/finding-intersection-points-between-3-spheres but could not understand it properly since the images did not show up. I also saw a formula for finding out the intersection at mathworld[dot]wolfram[dot]com/Sphere-SphereIntersection[dot]html . I could find the radius of intersection by the method given on mathworld. Also I can find the center of that circle and then use the parametric equation of circle to find the points. The only doubt that I have is will this method work for the points P0 and P1 mentioned above ? Please comment and let me know your thoughts.

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  • Getter and Setter vs. Builder strategy

    - by Extrakun
    I was reading a JavaWorld's article on Getter and Setter where the basic premise is that getters expose internal content of an object, hence tightening coupling, and go on to provide examples using builder objects. I was rather leery of abolishing getter/setter but on second reading of the article, see to quite like the idea. However, sometimes I just need one cruical element of an entity class, such as the user's id and writing one whole class just to extract that cruical element seems like overkill. It also implies that for different view, a different type of importer/exporter must be implemented (or the whole data of the class to be exported out, thus resulting in waste). Usually I tend towards filtering the result of a getter - for example, if I need to output the price of a product in different currency, I would code it as: return CurrencyOutput::convertTo($product->price(), 'USD'); This is with the understanding that the raw output of a getter is not necessary the final result to be pushed onto a screen or a database. Is getter/setter really as bad as it is protrayed to be? When should one adopt a builder strategy, or a 'get the result and filter it' approach? How do you avoid having a class needing to know about every other objects if you are not using getter/setter?

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  • Android Activity ClassNotFoundException - tried everything

    - by Matthew Rathbone
    I've just refactored an app into a framework library and an application, but now when I try and start the app in the emulator I get the following error stack trace: 06-02 18:22:35.529: E/AndroidRuntime(586): FATAL EXCEPTION: main 06-02 18:22:35.529: E/AndroidRuntime(586): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.matthewrathbone.eastersays/com.matthewrathbone.eastersays.EasterSimonSaysActivity}: java.lang.ClassNotFoundException: com.matthewrathbone.eastersays.EasterSimonSaysActivity in loader dalvik.system.PathClassLoader[/data/app/com.matthewrathbone.eastersays-1.apk] 06-02 18:22:35.529: E/AndroidRuntime(586): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585) 06-02 18:22:35.529: E/AndroidRuntime(586): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 06-02 18:22:35.529: E/AndroidRuntime(586): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 06-02 18:22:35.529: E/AndroidRuntime(586): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 06-02 18:22:35.529: E/AndroidRuntime(586): at android.os.Handler.dispatchMessage(Handler.java:99) 06-02 18:22:35.529: E/AndroidRuntime(586): at android.os.Looper.loop(Looper.java:123) 06-02 18:22:35.529: E/AndroidRuntime(586): at android.app.ActivityThread.main(ActivityThread.java:4627) 06-02 18:22:35.529: E/AndroidRuntime(586): at java.lang.reflect.Method.invokeNative(Native Method) 06-02 18:22:35.529: E/AndroidRuntime(586): at java.lang.reflect.Method.invoke(Method.java:521) 06-02 18:22:35.529: E/AndroidRuntime(586): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 06-02 18:22:35.529: E/AndroidRuntime(586): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 06-02 18:22:35.529: E/AndroidRuntime(586): at dalvik.system.NativeStart.main(Native Method) 06-02 18:22:35.529: E/AndroidRuntime(586): Caused by: java.lang.ClassNotFoundException: com.matthewrathbone.eastersays.EasterSimonSaysActivity in loader dalvik.system.PathClassLoader[/data/app/com.matthewrathbone.eastersays-1.apk] 06-02 18:22:35.529: E/AndroidRuntime(586): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243) 06-02 18:22:35.529: E/AndroidRuntime(586): at java.lang.ClassLoader.loadClass(ClassLoader.java:573) 06-02 18:22:35.529: E/AndroidRuntime(586): at java.lang.ClassLoader.loadClass(ClassLoader.java:532) 06-02 18:22:35.529: E/AndroidRuntime(586): at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 06-02 18:22:35.529: E/AndroidRuntime(586): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577) 06-02 18:22:35.529: E/AndroidRuntime(586): ... 11 more Usually this means that the manifest file is wrong in some way, but I've double checked everything I can think of. Here is my activity class: package com.matthewrathbone.eastersays; import android.os.Bundle; import com.rathboma.simonsays.Assets.Season; import com.rathboma.simonsays.SeasonPicker; import com.rathboma.simonsays.SimonSaysActivity; public class EasterSimonSaysActivity extends SimonSaysActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override protected void onDestroy() { // TODO Auto-generated method stub super.onDestroy(); } @Override public SeasonPicker getSeasonPicker() { return new SeasonPicker(){ @Override public Season getSeason() { // TODO Auto-generated method stub return Season.EASTER; } }; } } As you can see, it's listed correctly in the manifest: <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.matthewrathbone.eastersays" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="7" android:targetSdkVersion="15" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <activity android:name=".EasterSimonSaysActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest> I have no idea how to fix this, and would appreciate any help. I've scanned many similar questions on SO without seeing this particular behavior. More info: I've checked inside the generated APK and the class has an entry in the classes.dex file I've tried cleaning/building the project in eclipse I've tried using a totally new device image that doesn't have a copy of the APK on it already I've changed the library project into a regular java, then changed back into an android project, no difference

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  • UITableView and UITableCellView, how does this work with core plot ?

    - by Luc
    Hello, I'm very new to iPhone programming, and I'm currently following tutos to understand the whole thing. I've been able to do what I needed (retrive data from a JSON http server, parse them with YAJL and plot the data in core plot). I have done this in a "simple" view where I have added a UILayerHostingView as requested by core-plot. I am now trying to follow this tuto: http://blogs.remobjects.com/blogs/mh/2010/01/26/p973 but I am missing the first part regarding the views... My understanding is that I need to create a view with a UITableView first. Then add a UITableCellView to make the first cell be able to contain the graph ? Is this right ? Where does the method "(id)initWithStyle:(UITableViewCellStyle)style" come from ? For my needs, only the first cell needs to contain a graph, I will put some other info in the other cells. As for now, I have created a new GraphListViewController, in the corresponding view I have added a listview but I do not see any auto generated methods regading cell customisation ? Do I need to implements DataSource in this controller and manually add some customisation methods ? Do I need to add a UITagbleViewCell to this UITableViewTable within IB ? Hope I am not getting to confusing... Thanks a lot for your help, Best Regards, Luc

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  • How does this Switch statement know which case to execute? (PHP/MySQL)

    - by ggfan
    Here is a code form a PHP+MySQL book I am reading and I am having trouble understanding this code. This code is about checking a file uploaded into a database. (Please excuse any spelling errors if any, I was typing it in) Q1: How does it know which case to echo? In the whole code, there is no mention of each case. Q2: Why do they skip case 5?! Or does it not matter which numbers you use(so I can have case 1, case 18, case 2?) if($_FILES['userfile']['error']>0) { echo 'Problem: '; switch($_FILES['userfile']['error']) { case 1: echo 'File exceeded upload_max_filesize'; break; case 2: echo 'File exceeded max_file_size'; break; case 3: echo 'File only partially uploaded'; break; case 4: echo 'No file uploaded'; break; case 6: echo 'Cannot upload file: no temp directory specified'; break; case 7: echo 'Upload failed: Cannot write to disk'; break; } exit; }

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  • Problem while executing test case in VS2008 test project

    - by sukumar
    Hi all I have the situation as follows I have develpoed one test project in visual studio 2008 to test my target project. I was getting the following exception when i ran test case in my PC System.IO.FileNotFoundException: The specified module could not be found. (Exception from HRESULT: 0x8007007E) at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) at System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) at System.Reflection.Assembly.InternalLoadFrom(String assemblyFile, Evidence securityEvidence, Byte[] hashValue, AssemblyHashAlgorithm hashAlgorithm, Boolean forIntrospection, StackCrawlMark& stackMark) at System.Reflection.Assembly.LoadFrom(String assemblyFile) at Microsoft.VisualStudio.TestTools.TestTypes.Unit.UnitTestExecuter.GetType(UnitTestElement unitTest, String type) at Microsoft.VisualStudio.TestTools.TestTypes.Unit.UnitTestExecuter.ResolveMethods(). but the same project runs successfully in my colleague PC. as per my Understanding System.IO.FileNotFoundException will occur in case of missing out the dlls. i checked up with dependency walker to trace out the missed dll.dependency walke traced out the following dlls 1)MFC90D.dll 2)mSvcr90d.dll 3)msvcp90d.dll i copied this dlls to C:\windows\system32 from Microsoft visual studio 9.0 dir and again i ran the dependency walker.this time dependency walker is able to open the given testproject dll with 0 errors .even then the same exception comes up when i ran the test. i got fed up with this. can any one tell why it is behaving as PC dependent.is there any thing that i still missing? any suggestion can be helpfull Thakns in Advance Sukumar i

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  • Threads, Sockets, and Designing Low-Latency, High Concurrency Servers

    - by lazyconfabulator
    I've been thinking a lot lately about low-latency, high concurrency servers. Specifically, http servers. http servers (fast ones, anyway) can serve thousands of users simultaneously, with very little latency. So how do they do it? As near as I can tell, they all use events. Cherokee and Lighttpd use libevent. Nginx uses it's own event library performing much the same function of libevent, that is, picking a platform optimal strategy for polling events (like kqueue on *bsd, epoll on linux, /dev/poll on Solaris, etc). They all also seem to employ a strategy of multiprocess or multithread once the connection is made - using worker threads to handle the more cpu intensive tasks while another thread continues to listen and handle connections (via events). This is the extent of my understanding and ability to grok the thousand line sources of these applications. What I really want are finer details about how this all works. In examples of using events I've seen (and written) the events are handling both input and output. To this end, do the workers employ some sort of input/output queue to the event handling thread? Or are these worker threads handling their own input and output? I imagine a fixed amount of worker threads are spawned, and connections are lined up and served on demand, but how does the event thread feed these connections to the workers? I've read about FIFO queues and circular buffers, but I've yet to see any implementations to work from. Are there any? Do any use compare-and-swap instructions to avoid locking or is locking less detrimental to event polling than I think? Or have I misread the design entirely? Ultimately, I'd like to take enough away to improve some of my own event-driven network services. Bonus points to anyone providing solid implementation details (especially for stuff like low-latency queues) in C, as that's the language my network services are written in.

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  • CLR Stored Procedures

    - by Paul Hatcherian
    In an ASP.NET application, I have a small number of fairly complex, frequently used operations to execute against a database. In these operations, one or more of several tables needs updates or inserts based a logical evaluation of both input parameters and values of certain tables. I've maintained a separation of logic and data access, so the operation currently looks like this: Request received from client Business layer invokes data layer to retrieve data from database Business layer processes result and determines which operation to execute Business layer invokes appropriate data operation Response sent to client As you can see, the client is kept waiting while two separate requests are made to the database. In searching for a solution to this, I've found CLR Stored Procedures, but I'm not sure if I have the right idea about what they are useful for. I have written a replacement for the code above which especially places steps 2-4 in a CLR SP. My understanding is that the SP will be executed locally by SQL Server and result in only one call being made to the server. My initial benchmark tests show this is actually orders of magnitude slower than my original code, but I attribute that recompilation of the code I have not worked out yet and/or some flaw in my environment. My question is basically, is this the intended use of CLR SPs or am I missing something? I realize this is a bit of a compromise structurally, so if there's a better way to do it I'd love to hear it.

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  • Covariance and Contravariance inference in C# 4.0

    - by devoured elysium
    When we define our interfaces in C# 4.0, we are allowed to mark each of the generic parameters as in or out. If we try to set a generic parameter as out and that'd lead to a problem, the compiler raises an error, not allowing us to do that. Question: If the compiler has ways of inferring what are valid uses for both covariance (out) and contravariance(in), why do we have to mark interfaces as such? Wouldn't it be enough to just let us define the interfaces as we always did, and when we tried to use them in our client code, raise an error if we tried to use them in an un-safe way? Example: interface MyInterface<out T> { T abracadabra(); } //works OK interface MyInterface2<in T> { T abracadabra(); } //compiler raises an error. //This makes me think that the compiler is cappable //of understanding what situations might generate //run-time problems and then prohibits them. Also, isn't it what Java does in the same situation? From what I recall, you just do something like IMyInterface<? extends whatever> myInterface; //covariance IMyInterface<? super whatever> myInterface2; //contravariance Or am I mixing things? Thanks

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  • JQuery Deferred - Adding to the Deferred contract

    - by MgSam
    I'm trying to add another asynchronous call to the contract of an existing Deferred before its state is set to success. Rather than try and explain this in English, see the following pseudo-code: $.when( $.ajax({ url: someUrl, data: data, async: true, success: function (data, textStatus, jqXhr) { console.log('Call 1 done.') jqXhr.pipe( $.ajax({ url: someUrl, data: data, async: true, success: function (data, textStatus, jqXhr) { console.log('Call 2 done.'); }, }) ); }, }), $.ajax({ url: someUrl, data: data, async: true, success: function (data, textStatus, jqXhr) { console.log('Call 3 done.'); }, }) ).then(function(){ console.log('All done!'); }); Basically, Call 2 is dependent on the results of Call 1. I want Call 1 and Call 3 to be executed in parallel. Once all 3 calls are complete, I want the All Done code to execute. My understanding is that Deferred.pipe() is supposed to chain another asynchronous call to the given deferred, but in practice, I always get Call 2 completing after All Done. Does anyone know how to get jQuery's Deferred to do what I want? Hopefully the solution doesn't involve ripping the code apart into chunks any further. Thanks for any help.

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  • What would be the equivalent VB.NET code for this C# FluentNHibernate component mapping?

    - by Will Marcouiller
    I'm a C# programmer constrained to write VB.NET code. While exploring NHibernate further for my current client, I encountered FluentNHibernate, which I find real attractive. But now, I wonder how to "translate" this C# code for component mapping into VB.NET code: Component(x => x.Address, m => { m.Map(x => x.Number); m.Map(x => x.Street); m.Map(x => x.PostCode); }); I know from here: Component(Of Client)(Function(c) c.Address, ...) what I miss is how to continue with the brackets in VB.NET, since there's no Begin End keywords or so. EDIT 1: Following Mr. JaredPar instructions, I figured that his solution might work. If we take the time to read his answer, we may notice that we both don't know what the MType is within his solution. I might have found out that the MType is: FluentNHibernate.Mapping.ComponentPart(Of TComponent) Thus, TComponent is, from my understanding, an anonymous type that I shall parameter to use. From this point of view, since I wish to map the properties of my Address object, replacing TComponent in my help method signature seems not to work. Private Sub MapAdresseHelper(Of Adresse)(ByVal a As FluentNHibernate.Mapping.ComponentPart(Of Adresse)) a.Map(Function(m) m.Number) a.Map(Function(m) m.Street).Length(50) a.Map(Function(m) m.PostCode).Length(10) End Sub The error I get is that my Address class doesn't have a property member named Street, for instance. It sees my Address type, it recognizes it, but it seems buggy somehow. I guess VBNET is poorly designed for lambda expressions and is less evolved than C# (Sorry, a bit of frustration due to the constraint of working with it and not being capable of doing things VERY easily done in C#.) Thanks!

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  • Authenticating GTK app to run with root permissions

    - by Thomas Tempelmann
    I have a UI app (uses GTK) for Linux that requires to be run as root (it reads and writes /dev/disk*). Instead of requiring the user to open a root shell or use "sudo" manually every time when he launches my app, I wonder if the app can use some OS-provided API to ask the user to relaunch the app with root permissions. (Note: gtk app's can't use "setuid" mode, so that's not an option here.) The advantage here would be an easier workflow: The user could, from his default user account, double click my app from the desktop, and the app then would relaunch itself with root permission after been authenticated by the API/OS. I ask this because OS X offers exactly this: An app can ask the OS to launch an executable with root permissions - the OS (and not the app) then asks the user to input his credentials, verifies them and then launches the target as desired. I wonder if there's something similar for Linux (Ubuntu, e.g.) Update: The app is a remote operated disk repair tool for the unsavvy Linux user, and those Linux noobs won't have much understanding of using sudo or even changing their user's group memberships, especially if their disk just started acting up and they're freaking out. That's why I seek a solution that avoids technicalities like this.

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  • Neural Network with softmax activation

    - by Cambium
    This is more or less a research project for a course, and my understanding of NN is very/fairly limited, so please be patient :) ============== I am currently in the process of building a neural network that attempts to examine an input dataset and output the probability/likelihood of each classification (there are 5 different classifications). Naturally, the sum of all output nodes should add up to 1. Currently, I have two layers, and I set the hidden layer to contain 10 nodes. I came up with two different types of implementations 1) Logistic sigmoid for hidden layer activation, softmax for output activation 2) Softmax for both hidden layer and output activation I am using gradient descent to find local maximums in order to adjust the hidden nodes' weights and the output nodes' weights. I am certain in that I have this correct for sigmoid. I am less certain with softmax (or whether I can use gradient descent at all), after a bit of researching, I couldn't find the answer and decided to compute the derivative myself and obtained softmax'(x) = softmax(x) - softmax(x)^2 (this returns an column vector of size n). I have also looked into the MATLAB NN toolkit, the derivative of softmax provided by the toolkit returned a square matrix of size nxn, where the diagonal coincides with the softmax'(x) that I calculated by hand; and I am not sure how to interpret the output matrix. I ran each implementation with a learning rate of 0.001 and 1000 iterations of back propagation. However, my NN returns 0.2 (an even distribution) for all five output nodes, for any subset of the input dataset. My conclusions: o I am fairly certain that my gradient of descent is incorrectly done, but I have no idea how to fix this. o Perhaps I am not using enough hidden nodes o Perhaps I should increase the number of layers Any help would be greatly appreciated! The dataset I am working with can be found here (processed Cleveland): http://archive.ics.uci.edu/ml/datasets/Heart+Disease

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  • Why This Maintainability Index Increase?

    - by Timothy
    I would be appreciative if someone could explain to me the difference between the following two pieces of code in terms of Visual Studio's Code Metrics rules. Why does the Maintainability Index increase slightly if I don't encapsulate everything within using ( )? Sample 1 (MI score of 71) public static String Sha1(String plainText) { using (SHA1Managed sha1 = new SHA1Managed()) { Byte[] text = Encoding.Unicode.GetBytes(plainText); Byte[] hashBytes = sha1.ComputeHash(text); return Convert.ToBase64String(hashBytes); } } Sample 2 (MI score of 73) public static String Sha1(String plainText) { Byte[] text, hashBytes; using (SHA1Managed sha1 = new SHA1Managed()) { text = Encoding.Unicode.GetBytes(plainText); hashBytes = sha1.ComputeHash(text); } return Convert.ToBase64String(hashBytes); } I understand metrics are meaningless outside of a broader context and understanding, and programmers should exercise discretion. While I could boost the score up to 76 with return Convert.ToBase64String(sha1.ComputeHash(Encoding.Unicode.GetBytes(plainText))), I shouldn't. I would clearly be just playing with numbers and it isn't truly any more readable or maintainable at that point. I am curious though as to what the logic might be behind the increase in this case. It's obviously not line-count.

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  • WCF and streaming requests and responses

    - by Cheeso
    Is it correct that in WCF, I cannot have a service write to a stream that is received by the client? My understanding is that streaming is supported in WCF for requests, responses, or both. Is it true that in all cases, the receiver of the stream must invoke Read ? I would like to support a scenario where the receiver of the stream can Write on it. Is this supported? Let me show it this way. The simplest example of Streaming in WCF is the service returning a FileStream to a client. This is a streamed response. The server code is like this: [ServiceContract] public interface IStreamService { [OperationContract] Stream GetData(string fileName); } public class StreamService : IStreamService { public Stream GetData(string filename) { FileStream fs = new FileStream(filename, FileMode.Open) return fs; } } And the client code is like this: StreamDemo.StreamServiceClient client = new WcfStreamDemoClient.StreamDemo.StreamServiceClient(); Stream str = client.GetData(@"c:\path\to\myfile.dat"); do { b = str.ReadByte(); //read next byte from stream ... } while (b != -1); (example taken from http://blog.joachim.at/?p=33) Clear, right? The server returns the Stream to the client, and the client invokes Read on it. Is it possible for the client to provide a Stream, and the server to invoke Write on it? In other words, rather than a pull model - where the client pulls data from the server - it is a push model, where the client provides the "sink" stream and the server writes into it. Is this possible in WCF, and if so, how? What are the config settings required for the binding, interface, etc? The analogy is the Response.OutputStream from an ASP.NET request. In ASPNET, any page can invoke Write on the output stream, and the content is received by the client. Can I do something similar in WCF? Thanks.

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  • Obtaining touch location for a uiscrollview touch

    - by LOSnively
    I have a uiscrollview as an element of a uiscrollviewcontroller, along with other view objects. The image scrolls and zooms as expected, when the scrollView is the top subview. However, I also need to get the screen location of the touch, in particular when there is no scroll action. (I understand the location may change during a scroll, but that's not important.) I haven't found a way to do that. In the scrollviewcontroller implementation I have customized all of the standard methods that should do this: "touchesShouldBegin...", "touchesBegan:...", "touchesEnded:...", and so on. As far as I can tell, none of these are being called during a touch event when the scrollView is the top subview. I've tried setting the delayContentTouches property to both YES and NO, and that doesn't seem to make a difference. As an alternative, I've tried putting a UIView as the top subview and then tried passing the touches to the now underlying scrollView. In this configuration, the standard methods are called and I can get the touch location, but I haven't found a mechanism for the touches to be passed to the scrollView so scrolling occurs. Doing something like sending the touch messages to the specific scrollView, or to "super" or just sending them to nextResponder doesn't do it. It seems I can make the scroll work or find the location of the touch but not both, depending on what the "top" subview is. I suspect this is trivial, but after two weeks of struggling, it's time to eat my embarrassment for not being able to do this seemingly simplest of things. I've read all of the related questions here on stackoverflow, tried most if not all of the suggestions, and so far, nothing has worked. I've looked through the various links and references suggested by the answers, including Apple's documentation, but none have pointed out the gap in my understanding. Any ideas would be appreciated.

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  • getchar does not stop when using scanf

    - by Oz123
    I am have a difficulty understanding getchar(). In the following program getchar works as expected: #include <stdio.h> int main() { printf("Type Enter to continue..."); getchar(); return 0; } However, in the following program, getchar does not create a delay and the program ends: #include <stdio.h> int main() { char command[100]; scanf("%s", command ); printf("Type Enter to continue..."); getchar(); return 0; } I have the following weired workaround, which works, but I understand why: #include <stdio.h> int main() { char command[100]; int i; scanf("%s", command ); printf("Type Enter to continue..."); while ( getchar() != '\n') { i=0; } getchar(); return 0; } So my questions are: 1. What is scanf doing? Why does scanf do this ? 2. Why is my work around working? 3. What is a good way to emulate the following Python code: raw_input("Type Enter to continue")

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  • Is ASP.NET MVC is really MVC? Or how to separate model from controller?

    - by Andrey
    Hi all, This question is a bit rhetorical. At some point i got a feeling that ASP.NET MVC is not that authentic implementation of MVC pattern. Or i didn't understood it. Consider following domain: electric bulb, switch and motion detector. They are connected together and when you enter the room motion detector switches on the bulb. If i want to represent them as MVC: switch is model, because it holds the state and contains logic bulb is view, because it presents the state of model to human motion detector is controller, because it converts user actions to generic model commands Switch has one private field (On/Off) as a State and two methods (PressOn, PressOff). If you call PressOn when it is Off it goes to On, if you call it again state doesn't change. Bulb can be replaced with buzzer, motion detector with timer or button, but the model still represent the same logic. Eventually system will have same behavior. This is how i understand classical MVC decomposition, please correct me if i am wrong. Now let's decompose it in ASP.Net MVC way. Bulb is still a view Controller will be switch + motion detector Model is some object that will just pass state to bulb. So the logic that defines behavior moves to controller. Question 1: Is my understanding of MVC and ASP.NET MVC correct? Question 2: If yes, do you agree that ASP.NET MVC is not 100% accurate implementation? And back to life. The final question is how to separate model from controller in case of ASP.NET MVC. There can be two extremes. Controller does basic stuff and call model to do all the logic. Another is controller does all the logic and model is just something like class with properties that is mapped to DB. Question 3: Where should i draw the line between this extremes? How to balance? Thanks, Andrey

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  • Building a News-feed that comprises posts "created by user's connections" && "on the topics user is following"

    - by aklin81
    I am working on a project of Questions & Answers website that allows a user to follow questions on certain topics from his network. A user's news-feed wall comprises of only those questions that have been posted by his connections and tagged on the topics that he is following(his expertise topics). I am confused what database's datamodel would be most fitting for such an application. The project needs to consider the future provisions for scalability and high performance issues. I have been looking at Cassandra and MySQL solutions as of now. After my study of Cassandra I realized that Simple news-feed design that shows all the posts from network would be easy to design using Cassandra by executing fast writes to all followers of a user about the post from user. But for my kind of application where there is an additional filter of 'followed topics', (ie, the user receives posts "created by his network" && "on topics user is following"), I could not convince myself with a good schema design in Cassandra. I hope if I missed something because of my short understanding of cassandra, perhaps, can you please help me out with your suggestions of how this news-feed could be implemented in Cassandra ? Looking for a great project with Cassandra ! Edit: There are going to be maximum 5 tags allowed for tagging the question (ie, max 5 topics can be tagged on a question).

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  • how to push a string address to stack with assembly, machine code

    - by Yigit
    Hi all, I am changing minesweeper.exe in order to have an understanding of how code injection works. Simply, I want the minesweeper to show a message box before starting. So, I find a "cave" in the executable and then define the string to show in messagebox and call the messagebox. Additionally of course, I have to change the value at module entry point of the executable and first direct it to my additional code, then continue its own code. So at the cave what I do; "hello starbuck",0 push 0 //arg4 of MessageBoxW function push the address of my string //arg3, must be title push the address of my string //arg2, must be the message push 0 //arg1 call MessageBoxW ... Now since the memory addresses of codes in the executable change everytime it is loaded in the memory, for calling the MessageBoxW function, I give the offset of the address where MessageBoxW is defined in Import Address Table. For instance, if MessageBoxW is defined at address1 in the IAT and the instruction just after call MessageBoxW is at address2 instead of writing call MessageBoxW, I write call address2 - address1. So my question is, how do I do it for pushing the string's address to the stack? For example, if I do these changes via ollydbg, I give the immediate address of "hello starbuck" for pushing and it works. But after reloading the executable or starting it outside of ollydbg, it naturally fails, since the immediate addresses change. Thanks in advance, Yigit.

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  • DataTable to JSON

    - by Joel Coehoorn
    I recently needed to serialize a datatable to JSON. Where I'm at we're still on .Net 2.0, so I can't use the JSON serializer in .Net 3.5. I figured this must have been done before, so I went looking online and found a number of different options. Some of them depend on an additional library, which I would have a hard time pushing through here. Others require first converting to List<Dictionary<>>, which seemed a little awkward and needless. Another treated all values like a string. For one reason or another I couldn't really get behind any of them, so I decided to roll my own, which is posted below. As you can see from reading the //TODO comments, it's incomplete in a few places. This code is already in production here, so it does "work" in the basic sense. The places where it's incomplete are places where we know our production data won't currently hit it (no timespans or byte arrays in the db). The reason I'm posting here is that I feel like this can be a little better, and I'd like help finishing and improving this code. Any input welcome. public static class JSONHelper { public static string FromDataTable(DataTable dt) { string rowDelimiter = ""; StringBuilder result = new StringBuilder("["); foreach (DataRow row in dt.Rows) { result.Append(rowDelimiter); result.Append(FromDataRow(row)); rowDelimiter = ","; } result.Append("]"); return result.ToString(); } public static string FromDataRow(DataRow row) { DataColumnCollection cols = row.Table.Columns; string colDelimiter = ""; StringBuilder result = new StringBuilder("{"); for (int i = 0; i < cols.Count; i++) { // use index rather than foreach, so we can use the index for both the row and cols collection result.Append(colDelimiter).Append("\"") .Append(cols[i].ColumnName).Append("\":") .Append(JSONValueFromDataRowObject(row[i], cols[i].DataType)); colDelimiter = ","; } result.Append("}"); return result.ToString(); } // possible types: // http://msdn.microsoft.com/en-us/library/system.data.datacolumn.datatype(VS.80).aspx private static Type[] numeric = new Type[] {typeof(byte), typeof(decimal), typeof(double), typeof(Int16), typeof(Int32), typeof(SByte), typeof(Single), typeof(UInt16), typeof(UInt32), typeof(UInt64)}; // I don't want to rebuild this value for every date cell in the table private static long EpochTicks = new DateTime(1970, 1, 1).Ticks; private static string JSONValueFromDataRowObject(object value, Type DataType) { // null if (value == DBNull.Value) return "null"; // numeric if (Array.IndexOf(numeric, DataType) > -1) return value.ToString(); // TODO: eventually want to use a stricter format // boolean if (DataType == typeof(bool)) return ((bool)value) ? "true" : "false"; // date -- see http://weblogs.asp.net/bleroy/archive/2008/01/18/dates-and-json.aspx if (DataType == typeof(DateTime)) return "\"\\/Date(" + new TimeSpan(((DateTime)value).ToUniversalTime().Ticks - EpochTicks).TotalMilliseconds.ToString() + ")\\/\""; // TODO: add Timespan support // TODO: add Byte[] support //TODO: this would be _much_ faster with a state machine // string/char return "\"" + value.ToString().Replace(@"\", @"\\").Replace(Environment.NewLine, @"\n").Replace("\"", @"\""") + "\""; } }

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  • Flex/PHP/XML data issue

    - by reado
    I have built a simple application in Flex. When the application loads, a GET request is made to the xmlService.php file with parameters "fetchData=letters". This tells the PHP to return the XML code. In Flex Debug I can see the XML data being sent by the PHP to the flex client. What I need it to do is populate the first drop down box (id="letter") with this data, however nothing is being received by Flex. I added an Alert.show() to check what was being returned but when the application runs, the alert is blank. Can anyone help? Thanks in advance. Image: http://static.readescdn.com/misc/flex.gif // Flex <?xml version="1.0" encoding="utf-8"?> <s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/mx" width="300" height="300" creationComplete="windowedapplication1_creationCompleteHandler(event)"> <fx:Script> <![CDATA[ import mx.collections.ArrayCollection; import mx.controls.Alert; import mx.events.FlexEvent; import mx.rpc.events.FaultEvent; import mx.rpc.events.ResultEvent; import spark.events.IndexChangeEvent; protected function windowedapplication1_creationCompleteHandler(event:FlexEvent):void { var params:Object = {'fetchData':'letters'}; xmlService.send(params); } protected function xmlService_resultHandler(event:ResultEvent):void { var id:String = xmlService.lastResult.data.id.value; //Alert.show(xmlService.lastResult.data.id.value); if(id == 'letter') { letter.dataProvider = xmlService.lastResult.data.letter; letter.enabled = true; } else if(id == 'number') { number.dataProvider = xmlService.lastResult.data.number; number.enabled = true; submit.enabled = true; } else { submit.label = 'No Data!'; } } protected function xmlService_faultHandler(event:FaultEvent):void { Alert.show(event.fault.message); } protected function letter_changeHandler(event:IndexChangeEvent):void { var params:Object = {'fetchData':'numbers'}; xmlService.send(params); } ]]> </fx:Script> <fx:Declarations> <s:HTTPService id="xmlService" url="URL_GOES_HERE" method="POST" useProxy="false" resultFormat="e4x" result="xmlService_resultHandler(event)" fault="xmlService_faultHandler(event)"/> </fx:Declarations> <s:DropDownList x="94" y="10" id="letter" enabled="false" change="letter_changeHandler(event)" labelField="value"></s:DropDownList> <s:DropDownList x="94" y="39" id="number" enabled="false" labelField="value"></s:DropDownList> <s:Button x="115" y="68" label="Submit" id="submit" enabled="false"/> </s:WindowedApplication> // PHP <? if(isset($_POST['fetchData'])) { if($_POST['fetchData'] == 'letters') { $xml = '<data> <id value="letters"/> <letter label="Letter A" value="a"/> <letter label="Letter B" value="b"/> <letter label="Letter C" value="c"/> </data>'; } else if($_POST['fetchData'] == 'numbers') { $xml = '<data> <id value="letters"/> <number label="Number 1" value="1"/> <number label="Number 2" value="2"/> <number label="Number 3" value="3"/> </data>'; } else { $xml = '<data> <result value="'.$_POST['fetchData'].'"/> </data>'; } echo $xml; } else { echo '<data> <result value="NULL"/> </data>'; } ?>

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  • Serial.begin(speed, config) not compiling for Leonardo Board

    - by forgemo
    I would like to configure my serial communication to have no parity, 1 start- and 2 stop-bits. The documentation for Serial.begin(speed, config) states: (...) An optional second argument configures the data, parity, and stop bits. The default is 8 data bits, no parity, one stop bit. The documentation also lists the possible configuration-values. According to my (limited) understanding, I need SERIAL_7N2 or SERIAL_8N2 to meet my requirements. (I'm not sure how the data-bits relate to the the 1-start-bit that I need.) However, I can't even compile because I have no idea how to supply that config value to the begin method. (I don't have much Arduino/C++ experience) I've tried in my code the following two variants: Serial.begin(9600, SERIAL_8N2); Serial.begin(9600, "SERIAL_8N2"); Am I missing something? Additional Information: Serial.begin(speed, config) has been introduced with the latest Arduino 1.0.2 IDE version. The code defining/implementing the begin methods can be found here. HardwareSerial.h HardwareSerial.cpp Edit: According to the replies from PeterJ and borges, the following variant is correct. Serial.begin(9600, SERIAL_8N2); However, it's still not working. I found that the compile error doesn't occur if I change the configured board from my Arduino Leonardo to Arduino uno. Therefore, it could be a bug occurring only with a subset of boards ... or maybe it's not supported?!

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