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• Using fonts that aren't on iPhone

  - by 4thSpace

  I'd like to use some fonts that aren't part of the iPhone OS. I've seen games that use non standard fonts. I can install the fonts, create images for each one in Photoshop and then use those images in the iPhone app. However, I don't think that is a practical way to go. If the color or tint needs to be adjusted (because of background) or size, I'll have to redesign every font I'm using. Is there a better way to do this? I read this http://stackoverflow.com/questions/360751/can-i-embed-a-custom-font-in-an-iphone-application and downloaded the open source font label app. However, it crashes most of the time when I try using particular fonts. In regards to the last comment about using UIFont with the fontWithName:size, that certainly doesn't work. Your font variable will be nil. Listing all available fonts reveals why - none of the custom fonts are in the list. I've also read http://stackoverflow.com/questions/566054/how-do-i-include-a-font-with-my-iphone-application, which definitely does not work. Same as last comment in above link.

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• C/C++ macro/template blackmagic to generate unique name.

  - by anon

  Macros are fine. Templates are fine. Pretty much whatever it works is fine. The example is OpenGL; but the technique is C++ specific and relies on no knowledge of OpenGL. Precise problem: I want an expression E; where I do not have to specify a unique name; such that a constructor is called where E is defined, and a destructor is called where the block E is in ends. For example, consider: class GlTranslate { GLTranslate(float x, float y, float z); { glPushMatrix(); glTranslatef(x, y, z); } ~GlTranslate() { glPopMatrix(); } }; Manual solution: { GlTranslate foo(1.0, 0.0, 0.0); // I had ti give it a name ..... } // auto popmatrix Now, I have this not only for glTranslate, but lots of other PushAttrib/PopAttrib calls too. I would prefer not to have to come up with a unique name for each var. Is there some trick involving macros templates ... or something else that will automatically create a variable who's constructor is called at point of definition; and destructor called at end of block? Thanks!

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• c++ floating point precision loss: 3015/0.00025298219406977296

  - by SigTerm

  The problem. Microsoft Visual C++ 2005 compiler, 32bit windows xp sp3, amd 64 x2 cpu. Code: double a = 3015.0; double b = 0.00025298219406977296; //*((unsigned __int64*)(&a)) == 0x40a78e0000000000 //*((unsigned __int64*)(&b)) == 0x3f30945640000000 double f = a/b;//3015/0.00025298219406977296; the result of calculation (i.e. "f") is 11917835.000000000 (*((unsigned __int64*)(&f)) == 0x4166bb4160000000) although it should be 11917834.814763514 (i.e. *((unsigned __int64*)(&f)) == 0x4166bb415a128aef). I.e. fractional part is lost. Unfortunately, I need fractional part to be correct. Questions: 1) Why does this happen? 2) How can I fix the problem? Additional info: 0) The result is taken directly from "watch" window (it wasn't printed, and I didn't forget to set printing precision). I also provided hex dump of floating point variable, so I'm absolutely sure about calculation result. 1) The disassembly of f = a/b is: fld qword ptr [a] fdiv qword ptr [b] fstp qword ptr [f] 2) f = 3015/0.00025298219406977296; yields correct result (f == 11917834.814763514 , *((unsigned __int64*)(&f)) == 0x4166bb415a128aef ), but it looks like in this case result is simply calculated during compile-time: fld qword ptr [__real@4166bb415a128aef (828EA0h)] fstp qword ptr [f] So, how can I fix this problem? P.S. I've found a temporary workaround (i need only fractional part of division, so I simply use f = fmod(a/b)/b at the moment), but I still would like to know how to fix this problem properly - double precision is supposed to be 16 decimal digits, so such calculation isn't supposed to cause problems.

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• AngularJS not validating email field in form

  - by idipous

  I have the html below where I have a form that I want to submit to the AngularJS Controller. <div class="newsletter color-1" id="subscribe" data-ng-controller="RegisterController"> <form name="registerForm"> <div class="col-md-6"> <input type="email" placeholder="[email protected]" data-ng-model="userEmail" required class="subscribe"> </div> <div class="col-md-2"> <button data-ng-click="register()" class="btn btn-primary pull-right btn-block">Subsbcribe</button> </div> </form> </div> And the controller is below app.controller('RegisterController', function ($scope,dataFactory) { $scope.users = dataFactory.getUsers(); $scope.register = function () { var userEmail = $scope.userEmail; dataFactory.insertUser(userEmail); $scope.userEmail = null; $scope.ThankYou = "Thank You!"; } }); The problem is that no validation is taking place when I click the button. It is always routed to the controller although I do not supply a correct email. So every time I click the button I get the {{ThankYou}} variable displayed. Maybe I do not understand something.

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• Scanning, Checking, Converting, Copying values ... How to ? -- C --

  - by ZaZu

  Hi there, Its been a while now and im still trying to get a certain code to work. I asked some question about different commands etc. before, but now I hope this is the final one (combining all questions in one code). I basically want to : *Scan an input (should be character ? ) *Check if its a number *If not, return error *Convert that character into a float number *Copy the value to another variable ( I called it imp here) Here is what I came up with : #include<stdio.h> #include<stdlib.h> #include<ctype.h> main(){ int digits; float imp=0; int alpha; do{ printf("Enter input\n\n"); scanf("\n%c",&alpha); digits=isdigit(alpha); if(digits==0){ printf("error\n\n"); } imp=atof(alpha); }while(digits==0); } The problem is this code does not work at all ... It gives me that atof must be of a const char and whenever I try changing it around, it just keeps failing. I am frustrated and forced to ask here, because I believe I have tried alot and I keep failing, but I wont be relieved until I get it to work xD So I really need your help guys. Please tell me why isnt this code working, what am I doing wrong ? I am still learning C and really appreciate your help :)

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• What's the best way to communicate the purpose of a string parameter in a public API?

  - by Dave

  According to the guidance published in New Recommendations for Using Strings in Microsoft .NET 2.0, the data in a string may exhibit one of the following types of behavior: A non-linguistic identifier, where bytes match exactly. A non-linguistic identifier, where case is irrelevant, especially a piece of data stored in most Microsoft Windows system services. Culturally-agnostic data, which still is linguistically relevant. Data that requires local linguistic customs. Given that, I'd like to know the best way to communicate which behavior is expected of a string parameter in a public API. I wasn't able to find an answer in the Framework Design Guidelines. Consider the following methods: f(string this_is_a_linguistic_string) g(string this_is_a_symbolic_identifier_so_use_ordinal_compares) Is variable naming and XML documentation the best I can do? Could I use attributes in some way to mark the requirements of the string? Now consider the following case: h(Dictionary<string, object> dictionary) Note that the dictionary instance is created by the caller. How do I communicate that the callee expects the IEqualityComparer<string> object held by the dictionary to perform, for example, a case-insensitive ordinal comparison?

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• javascript array/object issue

  - by FlyingCat

  I am trying to push elements to an array. for (a=0; a < test.length; a++){ if(this.testnumber != test[a].number){ //it will only loop 8 times under conditional statement group = { title: test.Title , ID: test.ID, contents: [] }; this.company.push(group); this.testnumber = test.number[a]; } //outside of if conditional statement.. it will loop 15 times //i want every test[a].conetents get pushed to group.contents array. //this.company is the final variable I need for this function... group.contents.push(test[a].contents); } However, when I do console.log(this.company); I see 8 elmements with only 1 element in each group.contents array The ideal situation is to have 8 elements with 2 to 3 elements in the group.contents array I hope I explain my situation well. Any idea how to solve my issue? Thanks a lot!

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• Join with Three Tables

  - by John

  Hello, In MySQL, I am using the following three tables (their fields are listed after their titles): comment: commentid loginid submissionid comment datecommented login: loginid username password email actcode disabled activated created points submission: submissionid loginid title url displayurl datesubmitted I would like to display "datecommented" and "comment" for a given "username," where "username" equals a variable called $profile. I would also like to make the "comment" a hyperlink to http://www...com/.../comments/index.php?submission='.$rowc["title"].'&submissionid='.$rowc["submissionid"].'&url='.$rowc["url"].'&countcomments='.$rowc["countComments"].'&submittor='.$rowc["username"].'&submissiondate='.$rowc["datesubmitted"].'&dispurl='.$rowc["displayurl"].' where countComments equals COUNT(c.commentid) and $rowc is part of the query listed below. I tried using the code below to do what I want, but it didn't work. How could I change it to make it do what I want? Thanks in advance, John $sqlStrc = "SELECT s.loginid ,s.title ,s.url ,s.displayurl ,s.datesubmitted ,l.username ,l.loginid ,s.title ,s.submissionid ,c.comment ,c.datecommented ,COUNT(c.commentid) countComments FROM submission s INNER JOIN login l ON s.loginid = l.loginid LEFT OUTER JOIN comment c ON c.loginid = l.loginid WHERE l.username = '$profile' GROUP BY c.loginid ORDER BY s.datecommented DESC LIMIT 10"; $resultc = mysql_query($sqlStrc); $arrc = array(); echo "<table class=\"samplesrec1c\">"; while ($rowc = mysql_fetch_array($resultc)) { $dtc = new DateTime($rowc["datecommented"], $tzFromc); $dtc->setTimezone($tzToc); echo '<tr>'; echo '<td class="sitename3c">'.$dtc->format('F j, Y &\nb\sp &\nb\sp g:i a').'</a></td>'; echo '<td class="sitename1c"><a href="http://www...com/.../comments/index.php?submission='.$rowc["title"].'&submissionid='.$rowc["submissionid"].'&url='.$rowc["url"].'&countcomments='.$rowc["countComments"].'&submittor='.$rowc["username"].'&submissiondate='.$rowc["datesubmitted"].'&dispurl='.$rowc["displayurl"].'">'.stripslashes($rowc["comment"]).'</a></td>'; echo '</tr>'; } echo "</table>";

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• Modifying bundled properties from visitor

  - by ravenspoint

  How should I modify the bundled properties of a vertex from inside a visitor? I would like to use the simple method of sub-scripting the graph, but the graph parameter passed into the visitor is const, so compiler disallows changes. I can store a reference to the graph in the visitor, but this seems weird. /** A visitor which identifies vertices as leafs or trees */ class bfs_vis_leaf_finder:public default_bfs_visitor { public: /** Constructor @param[in] total reference to int variable to store total number of leaves @param[in] g reference to graph ( used to modify bundled properties ) */ bfs_vis_leaf_finder( int& total, graph_t& g ) : myTotal( total ), myGraph( g ) { myTotal = 0; } /** Called when the search finds a new vertex If the vertex has no children, it is a leaf and the total leaf count is incremented */ template <typename Vertex, typename Graph> void discover_vertex( Vertex u, Graph& g) { if( out_edges( u, g ).first == out_edges( u, g ).second ) { myTotal++; //g[u].myLevel = s3d::cV::leaf; myGraph[u].myLevel = s3d::cV::leaf; } else { //g[u].myLevel = s3d::cV::tree; myGraph[u].myLevel = s3d::cV::tree; } } int& myTotal; graph_t& myGraph; };

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• typedef a functions prototype

  - by bitmask

  I have a series of functions with the same prototype, say int func1(int a, int b) { // ... } int func2(int a, int b) { // ... } // ... Now, I want to simplify their definition and declaration. Of course I could use a macro like that: #define SP_FUNC(name) int name(int a, int b) But I'd like to keep it in C, so I tried to use the storage specifier typedef for this: typedef int SpFunc(int a, int b); This seems to work fine for the declaration: SpFunc func1; // compiles but not for the definition: SpFunc func1 { // ... } which gives me the following error: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token Is there a way to do this correctly or is it impossible? To my understanding of C this should work, but it doesn't. Why? Note, gcc understands what I am trying to do, because, if I write SpFunc func1 = { /* ... */ } it tells me error: function 'func1' is initialized like a variable Which means that gcc understands that SpFunc is a function type.

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• How to call stored procedure by hibernate?

  - by user367097

  Hi I have an oracle stored procedure GET_VENDOR_STATUS_COUNT(DOCUMENT_ID IN NUMBER , NOT_INVITED OUT NUMBER,INVITE_WITHDRAWN OUT NUMBER,... rest all parameters are OUT parameters. In hbm file I have written - <sql-query name="getVendorStatus" callable="true"> <return-scalar column="NOT_INVITED" type="string"/> <return-scalar column="INVITE_WITHDRAWN" type="string"/> <return-scalar column="INVITED" type="string"/> <return-scalar column="DISQUALIFIED" type="string"/> <return-scalar column="RESPONSE_AWAITED" type="string"/> <return-scalar column="RESPONSE_IN_PROGRESS" type="string"/> <return-scalar column="RESPONSE_RECEIVED" type="string"/> { call GET_VENDOR_STATUS_COUNT(:DOCUMENT_ID , :NOT_INVITED ,:INVITE_WITHDRAWN ,:INVITED ,:DISQUALIFIED ,:RESPONSE_AWAITED ,:RESPONSE_IN_PROGRESS ,:RESPONSE_RECEIVED ) } </sql-query> In java I have written - session.getNamedQuery("getVendorStatus").setParameter("DOCUMENT_ID", "DOCUMENT_ID").setParameter("NOT_INVITED", "NOT_INVITED") ... continue till all the parametes . I am getting the sql exception 18:29:33,056 WARN [JDBCExceptionReporter] SQL Error: 1006, SQLState: 72000 18:29:33,056 ERROR [JDBCExceptionReporter] ORA-01006: bind variable does not exist Please let me know what is the exact process of calling a stored procedure from hibernate. I do not want to use JDBC callable statement.

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• Trouble tunneling my local Wordpress install to the mysql database on appfog

  - by alanmoo

  I've set up a wordpress install on appfog (using rackspace), and cloned the install to my local machine for development. I know the install works (using MAMP) because I created a local mysql database and changed wp-config.php to point to it. However, I want to develop without having to change wp-config.php every time I commit. After doing some research, it seems like the Appfog service Caldecott lets me tunnel into the mysql database on the server, using af tunnel. Unfortunately, I'm having issues with getting it working. Even if I change my MAMP mysql port to something like 8889, and tunnel mysql through port 3306, it looks like it's connected but I still get "Error establishing a database connection" when loading my localhost Wordpress. When I quit the mysql monitor (using ctrl+x, ctrl+c), I get a message stating "Error: 'mysql' execution failed; is it in your $PATH?'. Originally, no, it wasn't, but I've fixed my PATH variable on my local machine so that when I go to Terminal and just type mysql, it loads up. So I guess my question is 2 parts: 1.)Am I going with the right approach for Wordpress development on my local machine and 2.)If so, why is the tunnel not working?

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• Wordpress paths issue

  - by Martin

  I have set a crawler up in wordpress which grabs stocks data and writes to file which when a user enters a symbol/ticker the variable is read and if it matches the data of a previous crawl for that particular companies data will echo the text file on page, if no data is found the crawler then sets off grabs it and writes to file to save for the next time that symbol is used. The problem im having is that everything works groovey apart from one thing, when the content is written to file it saves it in the WP root and not inside a subfolder of the theme, basicaly this means that root becomes untidy very quickly and also should the theme be used on another site then its not practical as some important info is missing. I have tried bloginfo and absolute both return the same failure. This is the code i am using to write to file, like i say it works apart from writing the file into root. <?php $CompDetails = "http://www.devserverurl.com/mattv1/wp-content/themes/stocks/tools/modules/Stock_Quote/company_details/$Symbol.txt"; if (file_exists($CompDetails)) {} else { include ('crawler_file.php'); $html = file_get_html("http://targeturl.com/research/stocks/snapshot/snapshot.asp?ticker=$Symbol:US"); $es = $html->find('div[class="detailsDataContainerLt"]'); $tickerdetails = ("$es[0]"); $FileHandle2 = fopen($CompDetails, 'w') or die("can't open file"); fwrite($FileHandle2, $tickerdetails); fclose($FileHandle2); } ?> edit below, have also tried this and the same happens as above <?php if (file_exists($_SERVER['DOCUMENT_ROOT'] . "/wp-content/themes/stocks/tools/modules/Stock_Quote/company_details/$Symbol.txt")) {} else { include ('crawler_file.php'); $html = file_get_html("http://targeturl.com/research/stocks/snapshot/snapshot.asp?ticker=$Symbol:US"); $es = $html->find('div[class="detailsDataContainerLt"]'); $tickerdetails = ("$es[0]"); $FileHandle2 = fopen($_SERVER['DOCUMENT_ROOT'] . "/wp-content/themes/stocks/tools/modules/Stock_Quote/company_details/$Symbol.txt", 'w') or die("can't open file"); fwrite($FileHandle2, $tickerdetails); fclose($FileHandle2); } ?>

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• PHP Object Access Syntax Question with the $

  - by ImperialLion

  I've been having trouble searching for this answer because I am not quite sure how to phrase it. I am new to PHP and still getting my feet on the ground. I was writing a page with a class in it that had the property name. When I originally wrote the page there was no class so I just had a variable called $name. When I went to encapsulate it in a class I accidental changed it to be $myClass->$name. It tool me a while to realize that the syntax I needed was $myClass->name. The reason it took so long was the error I kept getting was "Attempt to access a null property" or something along those lines. The error lead me to believe it was a data population error. My question is does $myClass->$name have a valid meaning? In other words is there a time you would use this and a reason why it doesn't create a syntax error? If so what is the semantic meaning of that code? When would I use it if it is valid? If its not valid, is there a reason that it doesn't create a syntax error?

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• Looking for the log file on iPhone

  - by zp26

  Hi, I have a problem. I have the code below for save a data on file. I build my app on the device, and run. The result variable is TRUE, but i don't find the file on the my iPhone device. Can you help me? Thank and sorry for my english XP -(void)saveXML:(NSString*)name:(float)x:(float)y:(float)z{ NSMutableData *data = [NSMutableData data]; NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]; [archiver setOutputFormat:NSPropertyListXMLFormat_v1_0]; [archiver encodeFloat:x forKey:@"x"]; [archiver encodeFloat:y forKey:@"y"]; [archiver encodeFloat:z forKey:@"z"]; [archiver encodeObject:name forKey:@"name"]; [archiver finishEncoding]; NSString* filePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"XML Position"]; BOOL result = [data writeToFile:filePath atomically:YES]; if(result) [self updateTextView:@"success"]; [archiver release]; }

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• Cannot compute equation, always gives zero

  - by user1738391

  Did i miss something? The variable percentage_ always equals 0. I've checked nTimes and winnings, they give the correct values as what is being input. Even when I test out a simple equation like, percentage_=1+1, percentage_ will give 0. Can someone help? #pragma once #include <iostream> #include <string> #include <cstdlib> #include <iomanip> using namespace std; class GuessMachine { private: int nTimes; int winnings; string nM[6]; public: GuessMachine(); void displayPrizes(); void displayMenu(); int getInput(); void checkNumber(); void checkPrize(); }; void GuessMachine::checkPrize() { MagicNumber mn; int prize_=mn.generateNumber(); float percentage_; percentage_ = float (winnings/nTimes*100); //<--On this line percentage is always 0 no matter what winnings and nTimes are cout<<"Percentage is "<<percentage_<<endl; if(percentage_ >= 50) { cout<<"You have scored "<<percentage_<<"% and won "<<nM[prize_]; } else { cout<<"You have scored "<<percentage_<<"%. You lose!!"; } cin.ignore(); cin.ignore(); }

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• Why is it that an int in C++ that isnt initialized (then used) doesn't return an error?

  - by omizzle

  I am new to C++ (just starting). I come from a Java background and I was trying out the following piece of code that would sum the numbers between 1 and 10 (inclusive) and then print out the sum: /* * File: main.cpp * Author: omarestrella * * Created on June 7, 2010, 8:02 PM */ #include <cstdlib> #include <iostream> using namespace std; int main() { int sum; for(int x = 1; x <= 10; x++) { sum += x; } cout << "The sum is: " << sum << endl; return 0; } When I ran it it kept printing 32822 for the sum. I knew the answer was supposed to be 55 and realized that its print the max value for a short (32767) plus 55. Changing int sum; to int sum = 0; would work (as it should, since the variable needs to be initialized!). Why does this behavior happen, though? Why doesnt the compiler warn you about something like this? I know Java screams at you when something isnt initialized. Thank you.

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• objective-c having issues with an NSDictioary object

  - by Mark

  I have a simple iPhone app that Im learning and I want to have an instance variable called urlLists which is an NSDictionary I have declared it like so: @interface MyViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>{ IBOutlet UIPickerView *pickerView; NSMutableArray *categories; NSDictionary *urlLists; } @property(retain) NSDictionary *urlLists; @end and in the implementation: @implementation MyViewController @synthesize urlLists; ... - (void)viewDidLoad { [super viewDidLoad]; categories = [[NSMutableArray alloc] init]; [categories addObject:@"Sport"]; [categories addObject:@"Entertainment"]; [categories addObject:@"Technology"]; [categories addObject:@"Political"]; NSArray *objects = [NSArray arrayWithObjects:@"value1", @"value2", @"value3", @"value4", nil]; urlLists = [NSDictionary dictionaryWithObjects:objects forKeys:categories]; for (id key in urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } ... @end And, this all works up to here. I have added a UIPicker to my app, and when I select one of the items, I want to Log the one picked and its related entry in my dictionary. -(void) pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger) component { for (id key in self.urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } but I get the old EXC_BAD_ACCESS error... I know Im missing something small, but what? Thanks

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• Returning a reference from a Class member?

  - by nebukadnezzar

  Hi, I've a class that basically looks like this: class App { public function newTemplate($filename, $vars=array()) { $smarty = new Smarty; $smarty->compile_dir = $this->template_compile_path; if(count($vars) > 0) { foreach($vars as $v_key => $v_name) { $smarty->assign($v_key, $v_name); } } return $smarty; } } However, when I create a Instance of 'App', the reference to $smarty seems broken, as every call to the membermethods don't seem to do anything: $app = new App; $tpl = $app->newTemplate("index.tmpl"); $tpl->assign("foo", "bar"); // {$foo} does not appear with "bar" in the template Now I wonder why? Of course I tried to use references: ... public function &newTemplate() ... ... But that doesn't work. Variable references don't seem to work either: ... $tpl = &$app->newTemplate("index.tmpl"); ... What is causing PHP here not to return a proper reference? Help is very appreciated!

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• CSS positioning div above another div when not in that order in the HTML

  - by devmode

  Given a template where the HTML cannot be modified because of other requirements, how is it possible to display a div above another div when they are not in that order in the HTML and both divs contain data that could produce a varying height and width. HTML: <div id="wrapper"     <div id="firstDiv"         Content to be below in this situation     </div     <div id="secondDiv"         Content to be above in this situation     </div </div Other elements Hopefully it is obvious that the desired result is: Content to be above in this situation Content to be below in this situation Other elements When the dimensions are fixed it easy to position them where needed, but I need some ideas for when the content is variable. For the sake of this scenario, please just consider the width to be 100% on both. Edit: A CSS solution is the most ideal solution. Thank you for the Javascript options mentioned. Without getting too wordy about what or why (or who) ... I am specifically looking for a CSS only solution (and it will probably have to be met with other solutions if that doesn't pan out). One more ... there are other elements following this. A good suggestion was mentioned given the limited scenario I demonstrated -- given that it might be the best answer, but I am looking to also make sure elements following this aren't impacted.

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• numpy array assignment problem

  - by Sujan

  Hi All: I have a strange problem in Python 2.6.5 with Numpy. I assign a numpy array, then equate a new variable to it. When I perform any operation to the new array, the original's values also change. Why is that? Please see the example below. Kindly enlighten me, as I'm fairly new to Python, and programming in general. -Sujan >>> import numpy as np >>> a = np.array([[1,2],[3,4]]) >>> b = a >>> b array([[1, 2], [3, 4]]) >>> c = a >>> c array([[1, 2], [3, 4]]) >>> c[:,1] = c[:,1] + 5 >>> c array([[1, 7], [3, 9]]) >>> b array([[1, 7], [3, 9]]) >>> a array([[1, 7], [3, 9]])

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• Best (Java) book for understanding 'under the bonnet' for programming?

  - by Ben

  What would you say is the best book to buy to understand exactly how programming works under the hood in order to increase performance? I've coded in assembly at university, I studied computer architecture and I obviously did high level programming, but what I really dont understand is things like: -what is happening when I perform a cast -whats the difference in performance if I declare something global as opposed to local? -How does the memory layout for an ArrayList compare with a Vector or LinkedList? -Whats the overhead with pointers? -Are locks more efficient than using synchronized? -Would creating my own array using int[] be faster than using ArrayList -Advantages/disadvantages of declaring a variable volatile I have got a copy of Java Performance Tuning but it doesnt go down very low and it contains rather obvious things like suggesting a hashmap instead of using an ArrayList as you can map the keys to memory addresses etc. I want something a bit more Computer Sciencey, linking the programming language to what happens with the assembler/hardware. The reason im asking is that I have an interview coming up for a job in High Frequency Trading and everything has to be as efficient as possible, yet I cant remember every single possible efficiency saving so i'd just like to learn the fundamentals. Thanks in advance

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• How do I set up the python/c library correctly?

  - by Bartvbl

  I have been trying to get the python/c library to like my mingW compiler. The python online doncumentation; http://docs.python.org/c-api/intro.html#include-files only mentions that I need to import the python.h file. I grabbed it from the installation directory (as is required on the windows platform), and tested it by compiling the script: #include "Python.h". This compiled fine. Next, I tried out the snippet of code shown a bit lower on the python/c API page: PyObject *t; t = PyTuple_New(3); PyTuple_SetItem(t, 0, PyInt_FromLong(1L)); PyTuple_SetItem(t, 1, PyInt_FromLong(2L)); PyTuple_SetItem(t, 2, PyString_FromString("three")); For some reason, the compiler would compile the code if I'd remove the last 4 lines (so that only the pyObject variable definition would be left), yet calling the actual constructor of the tuple returned errors. I am probably missing something completely obvious here, given I am very new to C, but does anyone know what it is?

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• How to call a generic method with an anonymous type involving generics?

  - by Alex Black

  I've got this code that works: def testTypeSpecialization = { class Foo[T] def add[T](obj: Foo[T]): Foo[T] = obj def addInt[X <% Foo[Int]](obj: X): X = { add(obj) obj } val foo = addInt(new Foo[Int] { def someMethod: String = "Hello world" }) assert(true) } But, I'd like to write it like this: def testTypeSpecialization = { class Foo[T] def add[X, T <% Foo[X](obj: T): T = obj val foo = add(new Foo[Int] { def someMethod: String = "Hello world" }) assert(true) } This second one fails to compile: no implicit argument matching parameter type (Foo[Int]{ ... }) = Foo[Nothing] was found. Basically: I'd like to create a new anonymous class/instance on the fly (e.g. new Foo[Int] { ... } ), and pass it into an "add" method which will add it to a list, and then return it The key thing here is that the variable from "val foo = " I'd like its type to be the anonymous class, not Foo[Int], since it adds methods (someMethod in this example) Any ideas? I think the 2nd one fails because the type Int is being erased. I can apparently 'hint' the compiler like this: def testTypeSpecialization = { class Foo[T] def add[X, T <% Foo[X]](dummy: X, obj: T): T = obj val foo = add(2, new Foo[Int] { def someMethod: String = "Hello world" }) assert(true) }

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• Matlab GUI: How to Save the Results of Functions (states of application)

  - by niko

  Hi, I would like to create an animation which enables the user to go backward and forward through the steps of simulation. An animation has to simulate the iterative process of channel decoding (a receiver receives a block of bits, performs an operation and then checks if the block corresponds to parity rules. If the block doesn't correspond the operation is performed again and the process finally ends when the code corresponds to a given rules). I have written the functions which perform the decoding process and return a m x n x i matrix where m x n is the block of data and i is the iteration index. So if it takes 3 iterations to decode the data the function returns a m x n x 3 matrix with each step is stired. In the GUI (.fig file) I put a "decode" button which runs the method for decoding and there are buttons "back" and "forward" which have to enable the user to switch between the data of recorded steps. I have stored the "decodedData" matrix and currentStep value as a global variable so by clicking "forward" and "next" buttons the indices have to change and point to appropriate step states. When I tried to debug the application the method returned the decoded data but when I tried to click "back" and "next" the decoded data appeared not to be declared. Does anyone know how is it possible to access (or store) the results of the functions in order to enable the described logic which I want to implement in Matlab GUI?

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