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• xerces-c: Xml parsing multiple files

  - by user459811

  I'm atempting to learn xerces-c and was following this tutorial online. http://www.yolinux.com/TUTORIALS/XML-Xerces-C.html I was able to get the tutorial to compile and run through a memory checker (valgrind) with no problems however when I made alterations to the program slightly, the memory checker returned some potential leak bytes. I only added a few extra lines to main to allow the program to read two files instead of one. int main() { string configFile="sample.xml"; // stat file. Get ambigious segfault otherwise. GetConfig appConfig; appConfig.readConfigFile(configFile); cout << "Application option A=" << appConfig.getOptionA() << endl; cout << "Application option B=" << appConfig.getOptionB() << endl; // Added code configFile = "sample1.xml"; appConfig.readConfigFile(configFile); cout << "Application option A=" << appConfig.getOptionA() << endl; cout << "Application option B=" << appConfig.getOptionB() << endl; return 0; } I was wondering why is it when I added the extra lines of code to read in another xml file, it would result in the following output? ==776== Using Valgrind-3.6.0 and LibVEX; rerun with -h for copyright info ==776== Command: ./a.out ==776== Application option A=10 Application option B=24 Application option A=30 Application option B=40 ==776== ==776== HEAP SUMMARY: ==776== in use at exit: 6 bytes in 2 blocks ==776== total heap usage: 4,031 allocs, 4,029 frees, 1,092,045 bytes allocated ==776== ==776== 3 bytes in 1 blocks are definitely lost in loss record 1 of 2 ==776== at 0x4C28B8C: operator new(unsigned long) (vg_replace_malloc.c:261) ==776== by 0x5225E9B: xercesc_3_1::MemoryManagerImpl::allocate(unsigned long) (MemoryManagerImpl.cpp:40) ==776== by 0x53006C8: xercesc_3_1::IconvGNULCPTranscoder::transcode(unsigned short const*, xercesc_3_1::MemoryManager*) (IconvGNUTransService.cpp:751) ==776== by 0x4038E7: GetConfig::readConfigFile(std::string&) (in /home/bonniehan/workspace/test/a.out) ==776== by 0x403B13: main (in /home/bonniehan/workspace/test/a.out) ==776== ==776== 3 bytes in 1 blocks are definitely lost in loss record 2 of 2 ==776== at 0x4C28B8C: operator new(unsigned long) (vg_replace_malloc.c:261) ==776== by 0x5225E9B: xercesc_3_1::MemoryManagerImpl::allocate(unsigned long) (MemoryManagerImpl.cpp:40) ==776== by 0x53006C8: xercesc_3_1::IconvGNULCPTranscoder::transcode(unsigned short const*, xercesc_3_1::MemoryManager*) (IconvGNUTransService.cpp:751) ==776== by 0x40393F: GetConfig::readConfigFile(std::string&) (in /home/bonniehan/workspace/test/a.out) ==776== by 0x403B13: main (in /home/bonniehan/workspace/test/a.out) ==776== ==776== LEAK SUMMARY: ==776== definitely lost: 6 bytes in 2 blocks ==776== indirectly lost: 0 bytes in 0 blocks ==776== possibly lost: 0 bytes in 0 blocks ==776== still reachable: 0 bytes in 0 blocks ==776== suppressed: 0 bytes in 0 blocks ==776== ==776== For counts of detected and suppressed errors, rerun with: -v ==776== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 2 from 2)

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• programmatically creating property list from json to include an array

  - by Michael Robinson

  [{"memberid":"18", "useridFK":"30", "loginName":"Johnson", "name":"Frank", "age":"23", "place":"School", },] Someone else posted a similar question but without the fact that it was coming from a JSON deserialization. Quinn had some suggestions but it was confused about where to place/replace the following code (if it's correct): NSDictionary *item1 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@" member",[NSNumber numberWithInt:3],nil] forKeys:[NSArray arrayWithObjects:@"Title",@"View",nil]]; into this: NSData *jsonData = [jsonreturn dataUsingEncoding:NSUTF32BigEndianStringEncoding]; NSError *error = nil; NSDictionary * dict = [[CJSONDeserializer deserializer] deserializeAsDictionary:jsonData error:&error]; if (dict) { rowsArray = [dict objectForKey:@"member"]; [rowsArray retain]; } My Array.plist needs to look like the following: Root: Dictionary V Rows: Array V Item 0: Dictionary Title: String 18 V Children Array V Item 0 Dictionary Title String 30 etc. Thanks in advance. Every tutorial on JSON only shows a simple array being returned, never a 2-D..It's driving me crazy trying to figure this out.

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• What is wrong with this null check for data reader

  - by Phil

  c.Open() r = x.ExecuteReader If Not r("filename").IsDbnull Then imagepath = "<img src='images/'" & getimage(r("filename")) & " border='0' align='absmiddle'" End If c.Close() r.Close() I have also tried; If r("filename") Is DBNull.Value Then imagepath = String.Empty Else imagepath = "<img src='images/'" & getimage(r("filename")) & " border='0' align='absmiddle'" End If c.Close() r.Close() The error is: Invalid attempt to read when no data is present. The idea of my code is to build an img src string only when data is available. Help greatly appreciated. Thanks

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• Authorization in a more purely OOP style...

  - by noblethrasher

  I've never seen this done but I had an idea of doing authorization in a more purely OO way. For each method that requires authorization we associate a delegate. During initialization of the class we wire up the delegates so that they point to the appropriate method (based on the user's rights). For example: class User { private deleteMemberDelegate deleteMember; public StatusMessage DeleteMember(Member member) { if(deleteMember != null) { deleteMember(member); } } //other methods defined similarly... User(string name, string password) //cstor. { //wire up delegates based on user's rights. //Thus we handle authentication and authorization in the same method. } } This way the client code never has to explictly check whether or not a user is in a role, it just calls the method. Of course each method should return a status message so that we know if and why it failed. Thoughts?

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• Find number of differences in 2 strings

  - by Pirate for Profit

  int n = string.numDifferences("noob", "newb"); // 2 ??

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• iphone: accessing the preferences localization file from code

  - by phonecoddy

  I was just facing the following problem and couldn't find a solution for it. Hopefully someone could help. The app I am working on has some preferences, which are using a localization file. Now I want to use labels in my app, which display the exact names, which are used in the localization file for the preferences. But I couldn't find a way to access the information which is stored in Settings.bundle - en.lproj - localizationfile.strings. to make this clear: If you open your preferences for your app, the display shows the localized string of the title and the value of the setting. I need to access the localized string of the title of each preference from my code. Does any know how to do this?

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• Why can I not add a set accessor to an overriden property?

  - by Svish

  In a base class I have this property: public virtual string Text { get { return text; } } I want to override that and return a different text, but I would also like to be able to set the text, so I did this: public override string Text { get { return differentText; } set { differentText = value; } } This however does not work. I get a red squiggly under set saying that I can not override because it does not have a set accessor. Why is this aproblem? What should I do?

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• Issue with 'selected' value within form

  - by JM4

  I currently have a form built in which after validation, if errors exist, the data stays on screen for the consumer to correct. An example of how this works for say the 'Year of Birth' is: <select name="DOB3"> <option value="">Year</option> <?php for ($i=date('Y'); $i>=1900; $i--) { echo "<option value='$i'"; if ($fields["DOB3"] == $i) echo " selected"; echo ">$i</option>"; } ?> </select> If an error is found, the year of birth value returns the year previously entered. I am able to have this work on all field with the exception of my 'State' field. I build the array and function for the drop down with the following code: <?php $states_arr = array('AL'=>"Alabama",'AK'=>"Alaska",'AZ'=>"Arizona",'AR'=>"Arkansas",'CA'=>"California",'CO'=>"Colorado",'CT'=>"Connecticut",'DE'=>"Delaware",'DC'=>"District Of Columbia",'FL'=>"Florida",'GA'=>"Georgia",'HI'=>"Hawaii",'ID'=>"Idaho",'IL'=>"Illinois", 'IN'=>"Indiana", 'IA'=>"Iowa", 'KS'=>"Kansas",'KY'=>"Kentucky",'LA'=>"Louisiana",'ME'=>"Maine",'MD'=>"Maryland", 'MA'=>"Massachusetts",'MI'=>"Michigan",'MN'=>"Minnesota",'MS'=>"Mississippi",'MO'=>"Missouri",'MT'=>"Montana",'NE'=>"Nebraska",'NV'=>"Nevada",'NH'=>"New Hampshire",'NJ'=>"New Jersey",'NM'=>"New Mexico",'NY'=>"New York",'NC'=>"North Carolina",'ND'=>"North Dakota",'OH'=>"Ohio",'OK'=>"Oklahoma", 'OR'=>"Oregon",'PA'=>"Pennsylvania",'RI'=>"Rhode Island",'SC'=>"South Carolina",'SD'=>"South Dakota",'TN'=>"Tennessee",'TX'=>"Texas",'UT'=>"Utah",'VT'=>"Vermont",'VA'=>"Virginia",'WA'=>"Washington",'WV'=>"West Virginia",'WI'=>"Wisconsin",'WY'=>"Wyoming"); function showOptionsDrop($array, $active, $echo=true){ $string = ''; foreach($array as $k => $v){ $s = ($active == $k)? ' selected="selected"' : ''; $string .= '<option value="'.$k.'"'.$s.'>'.$v.'</option>'."\n"; } if($echo) { echo $string;} else { return $string;} } ?> I then call the function from within the form using: <td><select name="State"><option value="">Choose a State</option><?php showOptionsDrop($states_arr, null, true); ?></select></td> Not sure what I'm missing but would love any assistance if somebody sees the error in my code. Thanks!

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• programming question

  - by shivam

  using System; using System.Data; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Data.SqlClient; namespace datasynchronization { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { string connectString = @"Data Source=MOON\SQL2005;Initial Catalog=databaseA;Integrated Security=True"; using (var srcCon = new SqlConnection(connectString)) //connection to source table { srcCon.Open();//source table connection open SqlCommand cmd = new SqlCommand();// sqlobject for source table cmd.Connection = srcCon; string connectionString = @"Data Source=MOON\SQL2005;Initial Catalog=databaseB;Integrated Security=True"; using (var tgtCon = new SqlConnection(connectionString)) //connection to target table { tgtCon.Open(); //target table connection open SqlCommand objcmd1 = new SqlCommand();//sqlobject for target table objcmd1.Connection = tgtCon; objcmd1.CommandText = "SELECT MAX(date) FROM Table_2"; //query to findout the max date from target table var maxdate = objcmd1.ExecuteScalar(); // store the value of max date into the variable maxdate cmd.CommandText = string.Format("SELECT id,date,name,city,salary,region FROM Table_1 where date >'{0}'", maxdate); //select query to fetch rows from source table using (var reader = cmd.ExecuteReader()) { SqlCommand objcmd = new SqlCommand(); objcmd.Connection = tgtCon; objcmd.CommandText = "INSERT INTO Table_2(id,date,name,city,salary,region)VALUES(@id,@date,@name,@city,@salary,@region)"; objcmd.Parameters.Add("@id", SqlDbType.Int); objcmd.Parameters.Add("@date", SqlDbType.DateTime); objcmd.Parameters.Add("@name", SqlDbType.NVarChar); objcmd.Parameters.Add("@city", SqlDbType.NVarChar); objcmd.Parameters.Add("@salary", SqlDbType.Int); objcmd.Parameters.Add("@region", SqlDbType.Char); while (reader.Read()) { var order1 = reader[0].ToString(); var order2 = reader[1].ToString(); var order3 = reader[2].ToString(); var order4 = reader[3].ToString(); var order5 = reader[4].ToString(); var order6 = reader[5].ToString(); objcmd.Parameters["@id"].Value = order1; objcmd.Parameters["@date"].Value = order2; objcmd.Parameters["@name"].Value = order3; objcmd.Parameters["@city"].Value = order4; objcmd.Parameters["@salary"].Value = order5; objcmd.Parameters["@region"].Value = order6; objcmd.ExecuteNonQuery(); } } tgtCon.Close(); } srcCon.Close(); } } } } how can i organize the above written code in an efficient way?

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• Understanding WebRequest

  - by Nai

  I found this snippet of code here that allows you to log into a website and get the response from the logged in page. However, I'm having trouble understanding all the part of the code. I've tried my best to fill in whatever I understand so far. Hope you guys can fill in the blanks for me. Thanks string nick = "mrbean"; string password = "12345"; //this is the query data that is getting posted by the website. //the query parameters 'nick' and 'password' must match the //name of the form you're trying to log into. you can find the input names //by using firebug and inspecting the text field string postData = "nick=" + nick + "&password=" + password; // this puts the postData in a byte Array with a specific encoding //Why must the data be in a byte array? byte[] data = Encoding.ASCII.GetBytes(postData); // this basically creates the login page of the site you want to log into WebRequest request = WebRequest.Create("http://www.mrbeanandme.com/login/"); // im guessing these parameters need to be set but i dont why? request.Method = "POST"; request.ContentType = "application/x-www-form-urlencoded"; request.ContentLength = data.Length; // this opens a stream for writing the post variables. // im not sure what a stream class does. need to do some reading into this. Stream stream = request.GetRequestStream(); // you write the postData to the website and then close the connection? stream.Write(data, 0, data.Length); stream.Close(); // this receives the response after the log in WebResponse response = request.GetResponse(); stream = response.GetResponseStream(); // i guess you need a stream reader to read a stream? StreamReader sr = new StreamReader(stream); // this outputs the code to console and terminates the program Console.WriteLine(sr.ReadToEnd()); Console.ReadLine();

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• How can I edit an entity in MVC4 with EF5 which has a unique constraint?

  - by Yoeri

  [HttpPost] public ActionResult Edit(Car car) { if (ModelState.IsValid) { db.Entry(car).State = EntityState.Modified; db.SaveChanges(); return RedirectToAction("Index"); } return View(car); } This is a controller method scaffolded by MCV 4 My "car" entity has a unique field: LicensePlate. I have custom validation on my Entity: Validation: public partial class Car { partial void ValidateObject(ref List<ValidationResult> validationResults) { using (var db = new GarageIncEntities()) { if (db.Cars.Any(c => c.LicensePlate.Equals(this.LicensePlate))) { validationResults.Add( new ValidationResult("This licenseplate already exists.", new string[]{"LicensePlate"})); } } } } should it be usefull, my car entity: public partial class Car:IValidatableObject { public int Id { get; set; } public string Color { get; set; } public int Weight { get; set; } public decimal Price { get; set; } public string LicensePlate { get; set; } public System.DateTime DateOfSale { get; set; } public int Type_Id { get; set; } public int Fuel_Id { get; set; } public virtual CarType Type { get; set; } public virtual Fuel Fuel { get; set; } public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) { var result = new List<ValidationResult>(); ValidateObject(ref result); return result; } partial void ValidateObject(ref List<ValidationResult> validationResults); } QUESTION: Everytime I edit a car, it raises an error: Validation failed for one or more entities. See 'EntityValidationErrors' property for more details. The error is the one raised by my validation, saying it can't edit because there is already a car with that license plate. If anyone could point me in the right direction to fix this, that would be great! I searched but couldn't find anything, so even related posts are welcome!

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• How do partialviews work in asp.net MVC when passing parameters back?

  - by Rob Ellis

  I have a page with a partialview on it which is a list of items. I have a button on it which shows the next 5 items. This is done via ajax:- using (Ajax.BeginForm("ShowUpdates", new AjaxOptions() { UpdateTargetId = "statusUpdateContainer", InsertionMode = InsertionMode.InsertAfter })) { <input type="submit" class="formbutton" value="Show More" style="width:100%;"/> } My partial view controller: [HttpPost] public ActionResult ShowUpdates(string page, string pagesize) { //get data code hidden here return PartialView("_statusUpdates"); } My question is that I need the 'page' variable to increment each time someone presses the form button which is contained within the partialview. How do I keep track of that variable?

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• Differences between query using LINQ and IQueryable interface directly?

  - by JohnMetta

  Using Entity Framework 4, and given: ObjectSet<Thing> AllThings = Context.CreateObjectSet<Thing>; public IQueryable<Thing> ByNameA(String name) { IQueryable<Thing> query = from o in AllThings where o.Name == name select o; return query; } public IQueryable<Thing> ByNameB(String name) { return AllThings.Where((o) => o.Name == name); } Both return IQueryable< instances, and thus the query doesn't hit the server until something like ToList() is called, right? Is it purely readability that is the difference, or are the using fundamentally different technologies on the back-end?

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• C++/CLI: CA2123: Requires SecurityCriticalAttribute?

  - by TomTom

  I am a little lost on erros like that: Warning 7 CA2123 : Microsoft.Security : Add the following security attribute to 'RithmicConnector::Connect(String^)' in order to match a LinkDemand on base method 'IConnector::Connect(String^)': 'SecurityCriticalAttribute'. c:\work\nettecture\tradex\source\tradex.connectivity.rithmic\rithmicconnector.cpp 52 Tradex.Connectivity.Rithmic Where do I add the SecurityCriticalAttribute? I tried on the header file - but the error does not disappear. I have one of those pretty much on every exposed method of a (managed C++) interface DLL. And I want CA to run through. How do I fix those? Regards

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• How to access a field's value via reflection (Scala 2.8)

  - by soc

  Consider the following code: class Foo(var name: String = "bar") Now i try to get the value and the correct type of it via reflection: val foo = new Foo val field = foo.getDeclaredField("name") field.setAccessible(true) //This is where it doesn't work val value = field.get(????) I tried things like field.get(foo), but that just returns an java.lang.Object but no String. Basically I need the correct type, because I want to invoke a method on it (e. g. toCharArray). What is the suggested way to do that?

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• XSL: Parsing XML to HTML - How do I use value-of an element data as an html attribute?

  - by AtomR

  <input src="LOGO.JPG" type="image" name="imagem"> I have an xml element that contains the image path that needs to be displayed in HTML after the parse. <xsl:value-of select="image"/> returns the string that is stored in the image element but how can I use it to make that string be the src atribute value in an html tag? I tried <input src="<xsl:value-of select="image"/>" type="image" name="imagem"> but obviously that doesn't work so how can it be done? I hope I was clear in my question. Please help!

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• Is it possible to have regexp that matches all valid regular expressions?

  - by Juha Syrjälä

  Is it possible to detect if a given string is valid regular expression, using just regular expressions? Say I have some strings, that may or may not be a valid regular expressions. I'd like to have a regular expression matches those string that correspond to valid regular expression. Is that possible? Or do I have use some higher level grammar (i.e. context free language) to detect this? Does it affect if I am using some extended version of regexps like Perl regexps? If that is possible, what the regexp matching regexp is?

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• Loading a XML, but for asp.net 2.0

  - by Blankman

  I need to load an XML document into my Dictionary<string,string> object. XML looks like: <nodes> <node id="123"> <text>text goes here</text> </node> </nodes> How can I do this using XmlDocument? I want readability over performance, and I find XmlReader to be hard to read b/c you have to keep checking the node type.

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• sampling integers uniformly efficiently in python using numpy/scipy

  - by user248237

  I have a problem where depending on the result of a random coin flip, I have to sample a random starting position from a string. If the sampling of this random position is uniform over the string, I thought of two approaches to do it: one using multinomial from numpy.random, the other using the simple randint function of Python standard lib. I tested this as follows: from numpy import * from numpy.random import multinomial from random import randint import time def use_multinomial(length, num_points): probs = ones(length)/float(length) for n in range(num_points): result = multinomial(1, probs) def use_rand(length, num_points): for n in range(num_points): rand(1, length) def main(): length = 1700 num_points = 50000 t1 = time.time() use_multinomial(length, num_points) t2 = time.time() print "Multinomial took: %s seconds" %(t2 - t1) t1 = time.time() use_rand(length, num_points) t2 = time.time() print "Rand took: %s seconds" %(t2 - t1) if __name__ == '__main__': main() The output is: Multinomial took: 6.58072400093 seconds Rand took: 2.35189199448 seconds it seems like randint is faster, but it still seems very slow to me. Is there a vectorized way to get this to be much faster, using numpy or scipy? thanks.

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• Can i Automap a tree heirarchy with fluent nhibernate?

  - by NakChak

  Is it possible to auto map a simple nested object structure? Something like this public class Employee : Entity { public Employee() { this.Manages = new List<Employee>(); } public virtual string FirstName { get; set; } public virtual string LastName { get; set; } public virtual bool IsLineManager { get; set; } public virtual Employee Manager { get; set; } public virtual IList<Employee> Manages { get; set; } } Causes the following error at run time: Repeated column in mapping for collection: SharpKtulu.Core.Employee.Manages column: EmployeeFk Is it possible to automap this sort of structure, or do i have over ride the auto mapper for this sort of structure?

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• What does these FindBug messages show?

  - by Hans Klock

  Not every description from from http://findbugs.sourceforge.net/bugDescriptions.html is clear to me. Sure, I can study the implementation but if somebody is more experienced then me, some explanation and examples would be great. Do you have some examples for UI_INHERITANCE_UNSAFE_GETRESOURCE when this is getting a problem? In BX_UNBOXED_AND_COERCED_FOR_TERNARY_OPERATOR I don't see the problem either. If one type is "bigger" then the other, for example int and float, then the result is float. If its Integer and Float its the wrapper Float too. That's what I expect. Does the GC_UNRELATED_TYPES really help to find errors? Isn't it the job of the compiler to check, if--taking the given example--Foo can't go into a Collection<String>. Does HE_SIGNATURE_DECLARES_HASHING_OF_UNHASHABLE_CLASS mean something like bla(Foo f){hashtable.put(f);}, where ´Foo´ is not hashable? Does FingBugs "see" the subclasses too? NP_GUARANTEED_DEREF_ON_EXCEPTION_PATH is stronger "wrong" then NP_ALWAYS_NULL_EXCEPTION? Why two error cases and with NP_NULL_ON_SOME_PATH_EXCEPTION even one more? Sounds very similar to me. What is an example of SIO_SUPERFLUOUS_INSTANCEOF? Something like foo(String s){if (s intenceof String) .... This does a null check too, but this is not the test here... NN_NAKED_NOTIFY. I my opinion the description is not clear. A change of the state is not necessary. If I use new Object() to wait and notify on I don't change the object state. Or is state the lock-state? I don't get it. SP_SPIN_ON_FIELD. Can this really happen that a compiler will move this outside from a loop? This doesn't make sense to me because from outside a Thread can always change the values. And if the variable is volatile the JVM can't cache the value. So what's the meaning? That is the difference between STCAL_STATIC_CALENDAR_INSTANCE and STCAL_INVOKE_ON_STATIC_CALENDAR_INSTANCE or STCAL_INVOKE_ON_STATIC_DATE_FORMAT_INSTANCE/STCAL_STATIC_SIMPLE_DATE_FORMAT_INSTANCE? Why is XXXX.class in WL_USING_GETCLASS_RATHER_THAN_CLASS_LITERAL better then getClass()? A getClass() in a superclass called from the subclass will always return the Class object from the subclass which is good I think. What exactly does EQ_UNUSUAL do? It should check that the argument is of the same type of the class itself but it does't? Did you ever had problems with breaks? Is there real value with SF_SWITCH_FALLTHROUGH? Sounds to strong for me. No idea what TQ_EXPLICIT_UNKNOWN_SOURCE_VALUE_REACHES_ALWAYS_SINK and TQ_EXPLICIT_UNKNOWN_SOURCE_VALUE_REACHES_NEVER_SINK could be.

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• Reading a text file in c++

  - by Yavuz Karacabey

  string numbers; string fileName = "text.txt"; ifstream inputFile; inputFile.open(fileName.c_str(),ios_base::in); inputFile >> numbers; inputFile.close(); cout << numbers; And my text.txt file is: 1 2 3 4 5 basically a set of integers separated by tabs. The problem is the program only reads the first integer in the text.txt file and ignores the rest for some reason. If I remove the tabs between the integers it works fine, but with tabs between them, it won't work. What causes this? As far as I know it should ignore any white space characters or am I mistaken? If so is there a better way to get each of these numbers from the text file?

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• Ruby on Rails: attr_accessor for submodels

  - by williamjones

  I'm working with some models where a lot of a given model's key attributes are actually stored in a submodel. Example: class WikiArticle has_many :revisions has_one :current_revision, :class_name => "Revision", :order => "created_at DESC" end class Revision has_one :wiki_article end The Revision class has a ton of database fields, and the WikiArticle has very few. However, I often have to access a Revision's fields from the context of a WikiArticle. The most important case of this is probably on creating an article. I've been doing that with lots of methods that look like this, one for each field: def description if @description @description elsif current_revision current_revision.description else "" end end def description=(string) @description = string end And then on my save, I save @description into a new revision. This whole thing reminds me a lot of attr_accessor, only it doesn't seem like I can get attr_accessor to do what I need. How can I define an attr_submodel_accessor such that I could just give field names and have it automatically create all those methods the way attr_accessor does?

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• Interoperability between two AES algorithms

  - by lpfavreau

  Hello, I'm new to cryptography and I'm building some test applications to try and understand the basics of it. I'm not trying to build the algorithms from scratch but I'm trying to make two different AES-256 implementation talk to each other. I've got a database that was populated with this Javascript implementation stored in Base64. Now, I'm trying to get an Objective-C method to decrypt its content but I'm a little lost as to where the differences in the implementations are. I'm able to encrypt/decrypt in Javascript and I'm able to encrypt/decrypt in Cocoa but cannot make a string encrypted in Javascript decrypted in Cocoa or vice-versa. I'm guessing it's related to the initialization vector, nonce, counter mode of operation or all of these, which quite frankly, doesn't speak to me at the moment. Here's what I'm using in Objective-C, adapted mainly from this and this: @implementation NSString (Crypto) - (NSString *)encryptAES256:(NSString *)key { NSData *input = [self dataUsingEncoding: NSUTF8StringEncoding]; NSData *output = [NSString cryptoAES256:input key:key doEncrypt:TRUE]; return [Base64 encode:output]; } - (NSString *)decryptAES256:(NSString *)key { NSData *input = [Base64 decode:self]; NSData *output = [NSString cryptoAES256:input key:key doEncrypt:FALSE]; return [[[NSString alloc] initWithData:output encoding:NSUTF8StringEncoding] autorelease]; } + (NSData *)cryptoAES256:(NSData *)input key:(NSString *)key doEncrypt:(BOOL)doEncrypt { // 'key' should be 32 bytes for AES256, will be null-padded otherwise char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused) bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding) // fetch key data [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding]; NSUInteger dataLength = [input length]; // See the doc: For block ciphers, the output size will always be less than or // equal to the input size plus the size of one block. // That's why we need to add the size of one block here size_t bufferSize = dataLength + kCCBlockSizeAES128; void* buffer = malloc(bufferSize); size_t numBytesCrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(doEncrypt ? kCCEncrypt : kCCDecrypt, kCCAlgorithmAES128, kCCOptionECBMode | kCCOptionPKCS7Padding, keyPtr, kCCKeySizeAES256, nil, // initialization vector (optional) [input bytes], dataLength, // input buffer, bufferSize, // output &numBytesCrypted ); if (cryptStatus == kCCSuccess) { // the returned NSData takes ownership of the buffer and will free it on deallocation return [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted]; } free(buffer); // free the buffer; return nil; } @end Of course, the input is Base64 decoded beforehand. I see that each encryption with the same key and same content in Javascript gives a different encrypted string, which is not the case with the Objective-C implementation that always give the same encrypted string. I've read the answers of this post and it makes me believe I'm right about something along the lines of vector initialization but I'd need your help to pinpoint what's going on exactly. Thank you!

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• Insane CPU usage in QT 5.0

  - by GravityScore

  I'm having trouble using the QT framework, particularly with the paintEvent of QWidget. I have a QWidget set up, and am overriding the paintEvent of it. I need to render a bunch of rectangles (grid system), 51 by 19, leading to 969 rectangles being drawn. This is done in a for loop. Then I also need to draw an image on each on of these grids. The QWidget is added to a QMainWindow, which is shown. This works nicely, but it's using up 47% of CPU per window open! And I want to allow the user to open multiple windows like this, likey having 3-4 open at a time, which puts the CPU close to 150%. Why does this happen? Here is the paintEvent contents. The JNI calls don't cause the CPU usage, commenting them out doesn't lower it, but commenting out the p.fillRect and Renderer::renderString (which draws the image) lowers the CPU to about 5%. // Background QPainter p(this); p.fillRect(0, 0, this->width(), this->height(), QBrush(QColor(0, 0, 0))); // Lines for (int y = 0; y < Global::terminalHeight; y++) { // Line and color method ID jmethodID lineid = Manager::jenv->GetMethodID(this->javaClass, "getLine", "(I)Ljava/lang/String;"); error(); jmethodID colorid = Manager::jenv->GetMethodID(this->javaClass, "getColorLine", "(I)Ljava/lang/String;"); error(); // Values jstring jl = (jstring) Manager::jenv->CallObjectMethod(this->javaObject, lineid, jint(y)); error(); jstring cjl = (jstring) Manager::jenv->CallObjectMethod(this->javaObject, colorid, jint(y)); error(); // Convert to C values const char *l = Manager::jenv->GetStringUTFChars(jl, 0); const char *cl = Manager::jenv->GetStringUTFChars(cjl, 0); QString line = QString(l); QString color = QString(cl); // Render line for (int x = 0; x < Global::terminalWidth; x++) { QColor bg = Renderer::colorForHex(color.mid(x + color.length() / 2, 1)); // Cell location on widget int cellx = x * Global::cellWidth + Global::xoffset; int celly = y * Global::cellHeight + Global::yoffset; // Background p.fillRect(cellx, celly, Global::cellWidth, Global::cellHeight, QBrush(bg)); // String // Renders the image to the grid Renderer::renderString(p, tc, text, cellx, celly); } // Release Manager::jenv->ReleaseStringUTFChars(jl, l); Manager::jenv->ReleaseStringUTFChars(cjl, cl); }

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