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• Android: Defined array resource not found ?!

  - by David

  Hi, i have a strange (?) error in my android application. I have defined some arrays in values/arrays.xml the following way: <?xml version="1.0" encoding="utf-8"?> <resources> <array name="perimeter"> <item>10 miles</item> <item>20 miles</item> <item>30 miles</item> </array> <array name="regvalues"> <item>1</item> <item>2</item> <item>3</item> </array> </resources> Now I want to use them in a ListPreference for a PreferenceActivity (defined by an xml file). So i set android:entries="@array/perimeter" android:entryValues="@array/regvalues" for this ListPreference. When I try to use this on my device the app crashes. (NullPointer in Dialog.close()) If I try to use the regvalues-items as Entries for the ListPreference i get a NullPointer in ArrayAdapter.createViewFromResource(int, View, ViewGroup, int) line: 355 So there seems to be sth wrong with the regvalues array. But what ?!? Eclipse shows me no errors at compile time. So everything in the xml-file and java-code is written correctly and there are no typos. Where is the problem?!?

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• why does cx_oracle execute() not like my string now?

  - by Frank Stallone

  I've downloaded cx_oracle some time ago and wrote a script to convert data to XML. I've had to reisntall my OS and grabbed the latest version of cx_Oracle (5.0.3) and all of the sudden my code is broken. The first thing was that cx_Oracle.connect wanted unicode rather string for the username and password, that was very easy to fix. But now it keeps failing on the cursor.execute and tells me my string is not a string even when type() tells me it is a string. Here is a test script I initally used ages ago and worked fine on my old version but does not work on cx_Oracle now. import cx_Oracle ip = 'url.to.oracle' port = 1521 SID = 'mysid' dsn_tns = cx_Oracle.makedsn(ip, port, SID) connection = cx_Oracle.connect(u'name', u'pass', dsn_tns) cursor = connection.cursor() cursor.arraysize = 50 sql = "select isbn, title_code from core_isbn where rownum<=20" print type(sql) cursor.execute(sql) for isbn, title_code in cursor.fetchall(): print "Values from DB:", isbn, title_code cursor.close() connection.close() When I run that I get: Traceback (most recent call last): File "C:\NetBeansProjects\Python\src\db_temp.py", line 48, in cursor.execute(sql) TypeError: expecting None or a string Does anyone know what I may be doing wrong?

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• Defining default value in combobox in CakePHP

  - by Keyur

  <?php echo $form->create('admin_merchant_form', array('action' => '#')); echo $form->input('company_name', array('label' => 'Company Name')); echo $form->input('ac_owner', array('label' => 'Account Owner', 'options' => array('a','b','b'), 'default' => $merchant_select)); echo $form->end('Update'); ?> This is CakePHP code to generate a form with one combobox containing the values "a,b,c" and assigning the default value as $merchant_select which is numerical data. Now the problem is when I assign like 'default'=1 it returns 'b' in the combobox as default value but when writing 'default' = $merchant_select the combobox shows only the first value which is 'a'. The $merchant_select variable is assigned a numeric value equal to merchant's id which 1,2 or 3 when I select any row in the grid. And I also have JavaScript code which alerts with the merchant value when I select any row in the grid so the numeric data is definitely assigned to the $merchant_select variable.

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• Implemeting web-based autocomplete for structured input

  - by ravigad

  I am looking to implement web-based autocomplete for structured commands. So, for example, suppose I was trying to implement a web-based Windows command line with autocomplete, in such a case I would want to suggest all the available commands, then, once a user selects a command, all the options for that command, then if a user enters a switch (say '-' dash or '/' slash) then offer all the switches for that command and all the relevant values that can follow, and so on. All from the same text input box. If you have used version 4.0 of JIRA, I am thinking of something similar to the JQL search input box that they have implemented. I have not managed to find any tutorials that look at this scenario end-to-end (which is a shame, because it would be great to see more applications that do this). What I am looking for is some guidance on the steps needed to implement this solution: Do you have any experience implementing such a solution and if so what components did you use? Would you use a framework such as ANTLR to provide the available options to the end user? If not what would do? Sorry for raising such a general question, but my main problem is working out how the pieces fit together as opposed to, say, how to do autocomplete or how to parse/tokenize an input command...

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• How can I timeout Client-scoped variables in Coldfusion?

  - by Joshua Carmody

  I apologize if this is a "duh" question. It seems like the answer should be easily googleable, but I haven't found it yet. I am working on a large Coldfusion application that stores a large amount of session/user data in the Client scope (ie <cfset Client.UserName = "JoshuaC"> ). I did not write this application, and I don't have the luxury of significantly refactoring it. I've been given the task of setting the Client variables to time out after 72 hours. I'm not entirely sure how to do this. If I had written the application, I would have stored the variables in the Session scope, and then changed the sessiontimeout attribute of the CFAPPLICATION tag. As it is though, I'm not sure if that timeout affects the Client variables, or what their level of persistence is. The way the application works now, the Client variables never time out, and only clearing the user's cookies, or visiting a logout page which sets all the Client-scoped application variables to "", will clear the values. Of course, I could create some kind of timestamp variable like Client.LastAccessDateTime, and put something in the Application.cfm to clear the client variables if that datetime is more than 72 hours prior to Now(). But there's got to be a better way, right?

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• overwrite parameters passed by querystring

  - by opensas

  I have the following problem I have a web framework built with classic asp that saves the page state in hidden textboxes, and then issues a submit to itself. Before submitting, we have a javascript functions that saves the action in a hidden "action" input, and then performs the submit. The page loads the state from those hidden texts, reads the action issued, reads extra parameters, like the id of the record to edit, and then builds the page accordingly. I'd like to make a url link to automatically start the page with "edit" action on a "x" id. So I was thinking about building the following url, for example http://myapp/user?action=edit&id=23 the problem is that when the page auto-submits, que url string keeps the parameters. I'd like to achieve the following: when the user clicks on http://myapp/user?action=edit&id=23 my page should receive the posted values action=edit and id=23 but the url should be just http://myapp/user and both parameters should be kept in the hidden texts... (I wonder if I make myself clear...) thanks a lot saludos sas ps: I have a couple of ideas about how to solve it, but I'll post them as answers...

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• Building "isolated" and "automatically updated" caches (java.util.List) in Java.

  - by Aidos

  Hi Guys, I am trying to write a framework which contains a lot of short-lived caches created from a long-living cache. These short-lived caches need to be able to return their entier contents, which is a clone from the original long-living cache. Effectively what I am trying to build is a level of transaction isolation for the short-lived caches. The user should be able to modify the contents of the short-lived cache, but changes to the long-living cache should not be propogated through (there is also a case where the changes should be pushed through, depending on the Cache type). I will do my best to try and explain: master-cache contains: [A,B,C,D,E,F] temporary-cache created with state [A,B,C,D,E,F] 1) temporary-cache adds item G: [A,B,C,D,E,F] 2) temporary-cache removes item B: [A,C,D,E,F] master-cache contains: [A,B,C,D,E,F] 3) master-cache adds items [X,Y,Z]: [A,B,C,D,E,F,X,Y,Z] temporary-cache contains: [A,C,D,E,F] Things get even harder when the values in the items can change and shouldn't always be updated (so I can't even share the underlying object instances, I need to use clones). I have implemented the simple approach of just creating a new instance of the List using the standard Collection constructor on ArrayList, however when you get out to about 200,000 items the system just runs out of memory. I know the value of 200,000 is excessive to iterate, but I am trying to stress my code a bit. I had thought that it might be able to somehow "proxy" the list, so the temporary-cache uses the master-cache, and stores all of it's changes (effectively a Memento for the change), however that quickly becomes a nightmare when you want to iterate the temporary-cache, or retrieve an item at a specific index. Also given that I want some modifications to the contents of the list to come through (depending on the type of the temporary-cache, whether it is "auto-update" or not) and I get completly out of my depth. Any pointers to techniques or data-structures or just general concepts to try and research will be greatly appreciated. Cheers, Aidos

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• Facebook Tagging friends to the picture

  - by Rajesh Dante

  Below code tag only first uid then then its shows Fatal error: Uncaught OAuthException: (#100) Invalid parameter and can i use exact location for tagging.. as in below code x and y values are in pixel $facebook = new Facebook ( array ( 'appId' => FBAPPID, 'secret' => FBSECRETID ) ); $facebook->setFileUploadSupport ( true ); if (isset ( $_POST ['image'] ) && isset ( $_POST ['tname'] )) { $path_to_image = encrypt::instance ()->decode ( $_POST ['image'] ); $tags = (array)encrypt::instance ()->decode ( $_POST ['tname'] ); /* * Output $tags = array ( 0 => '[{"tag_uid":"100001083191675","x":100,"y":100},{"tag_uid":"100001713817872","x":100,"y":230},{"tag_uid":"100000949945144","x":100,"y":360},{"tag_uid":"100001427144227","x":230,"y":100},{"tag_uid":"100000643504257","x":230,"y":230},{"tag_uid":"100001155130231","x":230,"y":360}]' ); */ $args = array ( 'message' => 'Von ', 'source' => '@' . $path_to_image, 'access_token' => $this->user->fbtoken ) ; $photo = $facebook->api ( $this->user->data->fbid . '/photos', 'post', $args ); // upload works but not tags if (is_array ( $photo ) && ! empty ( $photo ['id'] )) { echo 'Photo uploaded. Check it on Graph API Explorer. ID: ' . $photo ['id']; foreach ( $tags as $key => $t ) { $tagRe = json_encode ( $t ); $args = array ( 'tags' => $tagRe, 'access_token' => $this->user->fbtoken ); $facebook->api ( '/' . $photo ['id'] . '/tags', 'post', $args ); } } }

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• Javascript Recursion

  - by rpophessagr

  I have an ajax call and would like to recall it once I finish parsing and animating the result into the page. And that's where I'm getting stuck. I was able to recall the function, but it seems to not take into account the delays in the animation. i.e. The console keeps outputting the values at a wild pace. I thought setInterval might help with the interval being the sum of the length of my delays, but I can't get that to work... function loadEm(){ var result=new Array(); $.getJSON("jsonCall.php",function(results){ $.each(results, function(i, res){ rand = (Math.floor(Math.random()*11)*1000)+2000; fullRand += rand; console.log(fullRand); $("tr:first").delay(rand).queue(function(next) { doStuff(res); next(); }); }); var int=self.setInterval("loadEm()",fullRand); }); } });

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• Java queue and multi-dimention array question? [Beginner level]

  - by javaLearner.java

  First of all, this is my code (just started learning java): Queue<String> qe = new LinkedList<String>(); qe.add("b"); qe.add("a"); qe.add("c"); qe.add("d"); qe.add("e"); My question: Is it possible to add element to the queue with two values, like: qe.add("a","1"); // where 1 is integer So, that I know element "a" have value 1. If I want to add a number let say "2" to element a, I will have like a = 3. If this cant be done, what else in java classes that can handle this? I tried to use multi-dimention array, but its kinda hard to do the queue, like pop, push etc. (Maybe I am wrong) How to call specific element in the queue? Like, call element a, to check its value. [Note] Please don't give me links that ask me to read java docs. I was reading, and I still dont get it. The reason why I ask here is because, I know I can find the answer faster and easier.

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• Whose fault is a NullReferenceException?

  - by stefan.at.wpf

  I'm currently working on a class which exposes an internal List through a property. The List shall and can be modified. The problem is, entries in the internal list could be set to null from outside the class. My code actually looks like this: class ClassWithList { List<object> _list = new List<object>(); // get accessor, which however returns the reference to the list, // therefore the list can be modified (this is intended) public List<object> Data { get { return _list; } } private void doSomeWorkWithTheList() { foreach(object obj in _list) // do some work with the objects in the list without checking for null. } } So now in the doSomeWorkWithTheList() I could always check whether the current list entry is null or I could just asume that the person using this class doesn't have the great idea to set entries to null. So finally the questions end up in: Whose fault is a NullReferenceException in this case? Is it the fault of the class developer not checking everything for null (which would make code generally - not only in this class - more complex) or is it the fault of the user of this class, as setting a List entry to null doesn't really make sense? I'd tend to generally not check values for null except in some really special cases. Is this a bad style or de facto standard / standard in praxis? I know there's probably no ultimate answer for this, I'm just missing enough experience for such thing and therefore wondering what other developers think about such cases and want to hear what's done in reality about checking null (or not).

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• std::vector elements initializing

  - by Chameleon

  std::vector<int> v1(1000); std::vector<std::vector<int>> v2(1000); std::vector<std::vector<int>::const_iterator> v3(1000); How elements of these 3 vectors initialized? About int, I test it and I saw that all elements become 0. Is this standard? I believed that primitives remain undefined. I create a vector with 300000000 elements, give non-zero values, delete it and recreate it, to avoid OS memory clear for data safety. Elements of recreated vector were 0 too. What about iterator? Is there a initial value (0) for default constructor or initial value remains undefined? When I check this, iterators point to 0, but this can be OS When I create a special object to track constructors, I saw that for first object, vector run the default constructor and for all others it run the copy constructor. Is this standard? Is there a way to completely avoid initialization of elements? Or I must create my own vector? (Oh my God, I always say NOT ANOTHER VECTOR IMPLEMENTATION) I ask because I use ultra huge sparse matrices with parallel processing, so I cannot use push_back() and of course I don't want useless initialization, when later I will change the value.

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• build SQL query string using user input

  - by user175084

  i have to make a string by using the values which the user selects on the webpage suppose i need to display files for multiple machines with differnt search criteria.. i currently use this code: DataTable dt = new DataTable(); SqlConnection connection = new SqlConnection(); connection.ConnectionString = ConfigurationManager.ConnectionStrings["DBConnectionString"].ConnectionString; connection.Open(); SqlCommand sqlCmd = new SqlCommand("SELECT FileID FROM Files WHERE MachineID=@machineID and date= @date", connection); SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd); sqlCmd.Parameters.AddWithValue("@machineID", machineID); sqlCmd.Parameters.AddWithValue("@date", date); sqlDa.Fill(dt); now this is fixed query where the user just has one machine and just selects one date... i want to make a query in which the user has multiple search options like type or size if he wants depending on what he selects also if he can select multiple machines.. SELECT FileID FROM Files WHERE (MachineID=@machineID1 or MachineID = @machineID2...) and (date= @date and size=@size and type=@type... ) all of this happens in runtime... other wise i have to create a for loop to put multiple machines one by one... and have multiple queries depending on the case the user selected... this is quiet interesting and i could use some help... thanks

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• Why are changes to classes ignored after dom changes?

  - by Lg102

  I have a price grid that uses relative positioning to move a field around, beneath a box with: overflow: hidden;. In this is field, there are absolute-positioned boxes containing prices. When this box is hovered, the matching values above and left of the will change color. In order to achieve this, a class is toggled using jQuery. This initially works. However, after the grid is moved, the class change doesn't affect the block above the grid anymore. In the Chrome console, i can see the class being added, but it's css-styling isn't applied. No other styles for the element have changed. I am 100% sure there is no other style-rule influencing the element, it just stops responding to the change in class after the DOM has been altered. Can i 'refresh' the DOM somehow? Edit: I've tried to get the relevant code only: Adding the cell in the first place: $("#price_dates_cells").append("<div id='"+weekday[theBeginDate.getDay()]+"-"+theBeginDate.getDate()+"-"+(theBeginDate.getMonth()-1)+"' class='datecell' style='left: "+( Math.floor( difference / ( 3600 * 24 * 1000) ) * ( cellwidth ) )+"px'>"+weekday[theBeginDate.getDay()]+"<br>"+theBeginDate.getDate()+" "+yearmonth[theBeginDate.getMonth()]+"</div>"); Toggle the class: var str_element = "#"+weekday[Bdate.getDay()]+"-"+Bdate.getDate()+"-"+(Bdate.getMonth()-1); $(str_element).toggleClass("red"); and the movement that seems to cause the problem: $('#price_grid').animate({"top": (( ( horizontalMovement ) * cellheight)) }, 'fast', 'linear');

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• How to convert Big Endian and how to flip the highest bit?

  - by Robert Frank

  I am using a TStream to read binary data (thanks to this post: http://stackoverflow.com/questions/2878180/how-to-use-a-tfilestream-to-read-2d-matrices-into-dynamic-array). My next problem is that the data is Big Endian. From my reading, the Swap() method is seemingly deprecated. How would I swap the types below? 16-bit two's complement binary integer 32-bit two's complement binary integer 64-bit two's complement binary integer IEEE single precision floating-point - Are IEEE affected by Big Endian? And, finally, since the data is unsigned, the creators of this dataset have stored the unsigned values as signed integers (excluding the IEEE). They instruct that one need only add an offset (2^15, 2^31, and 2^63) to recover the unsigned data. But, they note that flipping the most significant bit is the fastest way to do that. How does one efficiently flip the most significant bit of a 16, 32, or 64-bit integer? So, if the data on disk (16-bit) is "85 FB" - the desired result after reading the data and swapping and bit flipping would be 1531. Is there a way to accomplish the swapping and bit flipping with generics so it fits into the generic answer at the link above? Yes, kids, THIS is how scientific astronomical data is stored by NASA, ESO, and all professional astronomers. This FITS standard is considered by some to be one of the most successful standards ever created in its proliferation and flexibility!

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• PHP GET issue - it aint workin!

  - by benhowdle89

  I have a simple PHP form which displays inputs with values from a mysql DB and send the form results to another page which updates a db table based on the GET results: echo "<form method='get' action='updateprojects.php'>"; echo "<table>"; echo "<tr>"; echo " <th>Project No</th> <th>Customer Name</th> <th>Description</th> </tr>"; while($row = mysql_fetch_array($result)) { echo "<tr>"; echo "<td><input value=" . $row['project_no'] . "></input></td>"; echo "<td><input value='" . $row['cust_name'] . "'></input></td>"; echo "<td><input value='" . $row['description'] . "'></input></td>"; echo "</tr>"; } echo "</table>"; echo "<input type='submit' value='Update' />"; echo "</form>"; on updateprojects.php i have set up the GET variable and even echoed them to check but nothing comes through! Cannot see why!? This is the start of updateprojects.php: echo $_GET['project_no'].$_GET['cust_name'].$_GET['description'];

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• Oracle User definied aggregate function for varray of varchar

  - by baju

  I am trying to write some aggregate function for the varray and I get this error code when I'm trying to use it with data from the DB: ORA-00600 internal error code, arguments: [kodpunp1], [], [], [], [], [], [], [], [], [], [], [] [koxsihread1], [0], [3989], [45778], [], [], [], [], [], [], [], [] Code of the function is really simple(in fact it does nothing ): create or replace TYPE "TEST_VECTOR" as varray(10) of varchar(20) ALTER TYPE "TEST_VECTOR" MODIFY LIMIT 4000 CASCADE create or replace type Test as object( lastVector TEST_VECTOR, STATIC FUNCTION ODCIAggregateInitialize(sctx in out Test) return number, MEMBER FUNCTION ODCIAggregateIterate(self in out Test, value in TEST_VECTOR) return number, MEMBER FUNCTION ODCIAggregateMerge(self IN OUT Test, ctx2 IN Test) return number, MEMBER FUNCTION ODCIAggregateTerminate(self IN Test, returnValue OUT TEST_VECTOR, flags IN number) return number ); create or replace type body Test is STATIC FUNCTION ODCIAggregateInitialize(sctx in out Test) return number is begin sctx := Test(TEST_VECTOR()); return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateIterate(self in out Test, value in TEST_VECTOR) return number is begin self.lastVector := value; return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateMerge(self IN OUT Test, ctx2 IN Test) return number is begin return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateTerminate(self IN Test, returnValue OUT TEST_VECTOR, flags IN number) return number is begin returnValue := self.lastVector; return ODCIConst.Success; end; end; create or replace FUNCTION test_fn (input TEST_VECTOR) RETURN TEST_VECTOR PARALLEL_ENABLE AGGREGATE USING Test; Next I create some test data: create table t1_test_table( t1_id number not null, t1_value TEST_VECTOR not null, Constraint PRIMARY_KEY_1 PRIMARY KEY (t1_id) ) Next step is to put some data to the table insert into t1_test_table (t1_id,t1_value) values (1,TEST_VECTOR('x','y','z')) Now everything is prepared to perform queries: Select test_fn(TEST_VECTOR('y','x')) from dual Query above work well Select test_fn(t1_value) from t1_test_table where t1_id = 1 Version of Oracle DBMS I use: 11.2.0.3.0 Does anyone tried do such a thing? What can be the reason that it does not work? How to solve it? Thanks in advance for help.

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• T-SQL: Dynamic Query by Selected Column in ASP.NET GridView

  - by jp2code

  I'm trying to modify a stored procedure used in an ASP.NET page. By default, the stored procedure returns all of the data, which can be overwhelming for employees in the plant. I want to add a drop down menu item for the column name and a text box for a value to allow our employees to search the data for their specific items. What I would like to add is the ability to pass in a Column Name and Column Value to search, similar to the following: DECLARE @colName nVarChar(50), @colValue nVarChar(50) SET @colName='EmployeeID' SET @colValue='007135' SELECT Column1, Column2, Column3, Column4, Column5, Column6, Column7 FROM viewNum1 WHERE ((@colName IS NULL) OR (@colValue IS NULL) OR ('['+@colName+']'=@colValue)) If all values passed in (@colValue and @colName), all records return; however, if I try specifying that @colName=EmployeeID and @colValue='007135' (a value that does exist in the database), no records are returned. Next is the problem that I am running an old SQL Server 2000 database that does not allow the stored procedure to access the table column names, and the whole technique looks prone to SQL Injection. Finally, I don't see how to bind my GridView control to this and still have the ability to display all records. How would I write such a filtering stored procedure?

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• Input questions mysql php html

  - by Marcelo

  (Q1)Hi I'm using textbox in my project and I can't receive the values that are typed <textarea rows="5" cols="60"> Type your suggestion </textarea> <br> <input type="submit" name="sugestao" value="Submit" /> Sorry I don't know how to 'kill' html code, that's why < is missing. All I'm getting in the column of the database from this text box is "Submit", I'd like to receive whatever is written in the text area. How can I make the value equal whaterever is typed? (Q2) How can I make sure that I'll only store the same type(int,varchar,text) that I setted,declared in the database. For example: age(int), but if someone types "abc" in the input it will be stored in my database as the value 0 . How can I forbid this, and only save the age when it's just int and all the other fields(like name, email) are filled ?. And if is still possible warn the user that he is typing something wrong, don't need to say where. Sorry for any mistake in English and Thanks for the attention.

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• Qt/C++ - confused about caller/callee, object ownership

  - by Isabel

  I am creating a GUI to manipulate a robot arm. The location of the arm can be described by 6 floats (describing the positions of the various arm joints. The interface consists of a QGraphicsView with a diagram of the arm (which can be clicked to change the arm position - adjusting the 6 floats). The interface also has 6 lineEdit boxes, to also adjust those values separately. When the graphics view is clicked, and when the line edit boxes are changed, I'd like the line edit boxes / graphics view to stay in synchronisation. This brings me to confusion about how to store the 6 floats, and trigger events when they're updated. My current idea is this: The robot arm's location should be represented by a class, RobotArmLocation. Objects of this class then have methods such as obj.ShoulderRotation() and obj.SetShoulderRotation(). The MainWindow has a single instance of RobotArmLocation. Next is the bit I'm more confused about, how to join everything up. I am thinking: The MainWindow has a ArmLocationChanged slot. This is signalled whenever the location object is changed. The diagram class will have a SetRobotArmLocation(RobotArmLocation &loc). When the diagram is changed, it's free to change the location object, and fire a signal to the ArmLocationChanged slot. Likewise, changing any of the text boxes will fire a signal to that ArmLocationChanged slot. The slot then has code to synchronise all the elements. This kind of seems like a mess to me, does anyone have any other suggestions? I've also thought of the following, does it have any merrit? The RobotArmLocation class has a ValueChanged slot, the diagram and textboxes can use that directly, and bypass the MainWindow directly (seems cleaner?) thanks for any wisdom!

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• Boost threading/mutexs, why does this work?

  - by Flamewires

  Code: #include <iostream> #include "stdafx.h" #include <boost/thread.hpp> #include <boost/thread/mutex.hpp> using namespace std; boost::mutex mut; double results[10]; void doubler(int x) { //boost::mutex::scoped_lock lck(mut); results[x] = x*2; } int _tmain(int argc, _TCHAR* argv[]) { boost::thread_group thds; for (int x = 10; x>0; x--) { boost::thread *Thread = new boost::thread(&doubler, x); thds.add_thread(Thread); } thds.join_all(); for (int x = 0; x<10; x++) { cout << results[x] << endl; } return 0; } Output: 0 2 4 6 8 10 12 14 16 18 Press any key to continue . . . So...my question is why does this work(as far as i can tell, i ran it about 20 times), producing the above output, even with the locking commented out? I thought the general idea was: in each thread: calculate 2*x copy results to CPU register(s) store calculation in correct part of array copy results back to main(shared) memory I would think that under all but perfect conditions this would result in some part of the results array having 0 values. Is it only copying the required double of the array to a cpu register? Or is it just too short of a calculation to get preempted before it writes the result back to ram? Thanks.

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• Segmentation Fault?

  - by user336808

  Hello, when I run this program while inputting a number greater than 46348, I get a segmentation fault. For any values below it, the program works perfectly. I am using CodeBlocks 8.02 on Ubuntu 10.04 64-bit. The code is as follows: int main() { int number = 46348; vector<bool> sieve(number+1,false); vector<int> primes; sieve[0] = true; sieve[1] = true; for(int i = 2; i <= number; i++) { if(sieve[i]==false) { primes.push_back(i); int temp = i*i; while(temp <= number) { sieve[temp] = true; temp = temp + i; } } } for(int i = 0; i < primes.size(); i++) cout << primes[i] << " "; return 0; }

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• calculating the index of an array C#

  - by Kerry G

  I want to display a list of the answers a student entered incorrectly. How do I identify the index of these questions? I am hoping to change the contents of a textbox to a list of the questions answered incorrectly, which would require calculating the index of each incorrect question. using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; namespace WindowsFormsApplication5 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } //return a pass/fail //return number of correct answers //return number of incorrect answers //return index figures of incorrect values public void examResults () { string[] correctAnswers = {B,D,A,A,C,A,B,A,C,D,B,C,D,A,D,C,C,B,D,A}; string[] studentResults = File.ReadAllLines("studentResults.txt"); var c = correctAnswers.Where((x, i) => x.Equals(studentResults[i])).Count(); if ( c <= 14) passFailBox.Text = "Student has failed the exam"; else passFailBox.Text = "Student has passed the exam"; numberCorrectBox.Text = "Student has answered" + c + "answers correctly"; int f; f= 21-c; numberIncorrectBox.Text = "Student has answered" + f + "answers incorrectly"; } } }

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• Why do I get errors when using unsigned integers in an expression with C++?

  - by neuviemeporte

  Given the following piece of (pseudo-C++) code: float x=100, a=0.1; unsigned int height = 63, width = 63; unsigned int hw=31; for (int row=0; row < height; ++row) { for (int col=0; col < width; ++col) { float foo = x + col - hw + a * (col - hw); cout << foo << " "; } cout << endl; } The values of foo are screwed up for half of the array, in places where (col - hw) is negative. I figured because col is int and comes first, that this part of the expression is converted to int and becomes negative. Unfortunately, apparently it doesn't, I get an overflow of an unsigned value and I've no idea why. How should I resolve this problem? Use casts for the whole or part of the expression? What type of casts (C-style or static_cast<...)? Is there any overhead to using casts (I need this to work fast!)? EDIT: I changed all my unsigned ints to regular ones, but I'm still wondering why I got that overflow in this situation.

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• Threads are blocked in malloc and free, virtual size

  - by Albert Wang

  Hi, I'm running a 64-bit multi-threaded program on the windows server 2003 server (X64), It run into a case that some of the threads seem to be blocked in the malloc or free function forever. The stack trace is like follows: ntdll.dll!NtWaitForSingleObject() + 0xa bytes ntdll.dll!RtlpWaitOnCriticalSection() - 0x1aa bytes ntdll.dll!RtlEnterCriticalSection() + 0xb040 bytes ntdll.dll!RtlpDebugPageHeapAllocate() + 0x2f6 bytes ntdll.dll!RtlDebugAllocateHeap() + 0x40 bytes ntdll.dll!RtlAllocateHeapSlowly() + 0x5e898 bytes ntdll.dll!RtlAllocateHeap() - 0x1711a bytes MyProg.exe!malloc(unsigned __int64 size=0) Line 168 C MyProg.exe!operator new(unsigned __int64 size=1) Line 59 + 0x5 bytes C++ ntdll.dll!NtWaitForSingleObject() ntdll.dll!RtlpWaitOnCriticalSection() ntdll.dll!RtlEnterCriticalSection() ntdll.dll!RtlpDebugPageHeapFree() ntdll.dll!RtlDebugFreeHeap() ntdll.dll!RtlFreeHeapSlowly() ntdll.dll!RtlFreeHeap() MyProg.exe!free(void * pBlock=0x000000007e8e4fe0) C BTW, the param values passed to the new operator is not correct here maybe due to optimization. Also, at the same time, I found in the process Explorer, the virtual size of this program is 10GB, but the private bytes and working set is very small (<2GB). We did have some threads using virtualalloc but in a way that commit the memory in the call, and these threads are not blocked. m_pBuf = VirtualAlloc(NULL, m_size, MEM_COMMIT, PAGE_READWRITE); ...... VirtualFree(m_pBuf, 0, MEM_RELEASE); This looks strange to me, seems a lot of virtual space is reserved but not committed, and malloc/free is blocked by lock. I'm guessing if there's any corruptions in the memory/object, so plan to turn on gflag with pageheap to troubleshoot this. Does anyone has similar experience on this before? Could you share with me so I may get more hints? Thanks a lot!

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