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• filling colors on a map - PHP

  - by jeremy

  I am trying to determine how to fill colors onto a map - such as the "Risk" board game map. I've done this before with HTML tables, by pulling an HTML color code from a SQL table and then just using it to fill the cell the color I want it. But for a non-square map, I'm not sure where to look. I have created a very simple two color map - its white with black borders. My desired result is having the 'regions' on the map shaded with a color, based on data in a sql table (just like the "fill" button in Paint). This looks like what I need: http://php.net/manual/en/function.imagefilltoborder.php and now.. how to define the borders... At the moment I have tried nothing, because the question was: how do I have PHP fill parts of an image? I have tried making an image in Paint, and then scratching my head wondering how to fill parts of it. Having stumbled upon a link, let me focus this a bit more: It appears that with imagefilltoborder that I can put an image on my server, perhaps one that looks like a black and white version of the RISK map - black borders and white everything else. Some questions: Is it correct that the 'border' variable should use the color of my border (whatever value black is) so that the code can "see" where the border is? Is it correct that I'll just need to figure out X,Y coords to begin the fill? Does this work if I have 10 different spots to fill on the map? Can I use varying colors from code or pulled from SQL to assign different colors to those 10 spots, and use 10 different X,Y coords to get them all?

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• How can I build a generic dataset-handling Perl library?

  - by Pep.

  Hello, I want to build a generic Perl module for handling and analysing biomedical character separated datasets and which can, most certain, be used on any kind of datasets that contain a mixture of categorical (A,B,C,..) and continuous (1.2,3,881..) and identifier (XXX1,XXX2...). The plan is to have people initialize the module and then use some arguments to point to the data file(s), the place were the analysis reports should be placed and the structure of the data. By structure of data I mean which variable is in which place and its name/type. And this is where I need some enlightenment. I am baffled how to do this in a clean way. Obviously, having people create a simple schema file, be it XML or some other format would be the cleanest but maybe not all people enjoy doing something like this. The solutions I can think of are: Create a configuration file in XML or similar and with a prespecified format. Pass the information during initialization of the module. Use the first row of the data as headers and try to guess types (ouch) Surely there must be a "canonical" way of doing this that is also usable and efficient. Thanks p.

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• Unpacking varargin to individual variables

  - by Richie Cotton

  I'm writing a wrapper to a function that takes varargin as its inputs. I want to preserve the function signature in the wrapper, but nesting varargin causes all the variable to be lumped together. function inner(varargin) %#ok<VANUS> % An existing function disp(nargin) end function outer(varargin) % My wrapper inner(varargin); end outer('foo', 1:3, {}) % Uh-oh, this is 1 I need a way to unpack varargin in the outer function, so that I have a list of individual variables. There is a really nasty way to do this by constructing a string of the names of the variables to pass the inner, and calling eval. function outer2(varargin) %#ok<VANUS> % My wrapper, second attempt inputstr = ''; for i = 1:nargin inputstr = [inputstr 'varargin{' num2str(i) '}']; %#ok<AGROW> if i < nargin inputstr = [inputstr ', ']; %#ok<AGROW> end end eval(['inner(' inputstr ')']); end outer2('foo', 1:3, {}) % 3, as it should be Can anyone think of a less hideous way of doing things, please?

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• Instrumenting a string

  - by George Polevoy

  Somewhere in C++ era i have crafted a library, which enabled string representation of the computation history. Having a math expression like: TScalar Compute(TScalar a, TScalar b, TScalar c) { return ( a + b ) * c; } I could render it's string representation: r = Compute(VerbalScalar("a", 1), VerbalScalar("b", 2), VerbalScalar("c", 3)); Assert.AreEqual(9, r.Value); Assert.AreEqual("(a+b)*c==(1+2)*3", r.History ); C++ operator overloading allowed for substitution of a simple type with a complex self-tracking entity with an internal tree representation of everything happening with the objects. Now i would like to have the same possibility for NET strings, only instead of variable names i would like to see a stack traces of all the places in code which affected a string. And i want it to work with existing code, and existing compiled assemblies. Also i want all this to hook into visual studio debugger, so i could set a breakpoint, and see everything that happened with a string. Which technology would allow this kind of things? I know it sound like an utopia, but I think visual studio code coverage tools actually do the same kind of job while instrumenting the assemblies.

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• User will input some filter criteria -- how can I turn it into a regular expression for String.match

  - by envinyater

  I have a program where the user will enter a string such as PropertyA = "abc_*" and I need to have the asterisk match any character. In my code, I'm grabbing the property value and replacing PropertyA with the actual value. For instance, it could be abc_123. I also pull out the equality symbol into a variable. It should be able to cover this type of criteria PropertyB = 'cba' PropertyC != '*-this' valueFromHeader is the lefthand side and value is the righthand side. if (equality.equals("=")) { result = valueFromHeader.matches(value); } else if (equality.equals("!=")) { result = !valueFromHeader.matches(value); } EDIT: The existing code had this type of replacement for regular expressions final String ESC = "\\$1"; final String NON_ALPHA = "([^A-Za-z0-9@])"; final String WILD = "*"; final String WILD_RE_TEMP = "@"; final String WILD_RE = ".*"; value = value.replace(WILD, WILD_RE_TEMP); value = value.replaceAll(NON_ALPHA,ESC); value = value.replace(WILD_RE_TEMP, WILD_RE); It doesn't like the underscore here... abcSite_123 != abcSite_123 (evaluates to true) abcSite_123$1.matches("abcSite$1123") It doesn't like the underscore...

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• parsing of mathematical expressions

  - by gcc

  (in c90) (linux) input: sqrt(2 - sin(3*A/B)^2.5) + 0.5*(C*~(D) + 3.11 +B) a b /*there are values for a,b,c,d */ c d input: cos(2 - asin(3*A/B)^2.5) +cos(0.5*(C*~(D)) + 3.11 +B) a b /*there are values for a,b,c,d */ c d input: sqrt(2 - sin(3*A/B)^2.5)/(0.5*(C*~(D)) + sin(3.11) +ln(B)) /*max lenght of formula is 250 characters*/ a b /*there are values for a,b,c,d */ c /*each variable with set of floating numbers*/ d As you can see infix formula in the input depends on user. My program will take a formula and n-tuples value. Then it calculate the results for each value of a,b,c and d. If you wonder I am saying ;outcome of program is graph. /sometimes,I think i will take input and store in string. then another idea is arise " I should store formula in the struct" but i don't know how I can construct the code on the base of structure./ really, I don't know way how to store the formula in program code so that I can do my job. can you show me? /* a,b,c,d is letters cos,sin,sqrt,ln is function*/

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• Issue changing innodb_log_file_size

  - by savageguy

  I haven't done much tweaking in the past so this might be relatively easy however I am running into issues. This is what I do: Stop MySQL Edit my.cnf (changing innodb_log_file_size) Remove ib_logfile0/1 Start MySQL Starts fine however all InnoDB tables have the .frm file is invalid error, the status shows InnoDB engine is disabled so I obviously go back, remove the change and everything works again. I was able to change every other variable I've tried but I can't seem to find out why InnoDB fails to start even after removing the log files. Am I missing something? Thanks. Edit: Pasting of the log below - looks like it still seems to find the log file even though they are not there? Shutdown: 090813 10:00:14 InnoDB: Starting shutdown... 090813 10:00:17 InnoDB: Shutdown completed; log sequence number 0 739268981 090813 10:00:17 [Note] /usr/sbin/mysqld: Shutdown complete Startup after making the changes: InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes InnoDB: than specified in the .cnf file 0 268435456 bytes! 090813 11:00:18 [Warning] 'user' entry '[email protected]' ignored in --skip-name-resolve mode. 090813 11:00:18 [Note] /usr/sbin/mysqld: ready for connections. Version: '5.0.81-community-log' socket: '/var/lib/mysql/mysql.sock' port: 3306 MySQL Community Edition (GPL) 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' Its just a spam of the same error until I correct it When it did start after it recreated the log files so it must be looking in the same spot I am.

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• Using static variables for Strings

  - by Vivart

  below content is taken from Best practice: Writing efficient code but i didn't understand why private static String x = "example"; faster than private static final String x ="example"; Can anybody explain this. Using static variables for Strings When you define static fields (also called class fields) of type String, you can increase application speed by using static variables (not final) instead of constants (final). The opposite is true for primitive data types, such as int. For example, you might create a String object as follows: private static final String x = "example"; For this static constant (denoted by the final keyword), each time that you use the constant, a temporary String instance is created. The compiler eliminates "x" and replaces it with the string "example" in the bytecode, so that the BlackBerry® Java® Virtual Machine performs a hash table lookup each time that you reference "x". In contrast, for a static variable (no final keyword), the String is created once. The BlackBerry JVM performs the hash table lookup only when it initializes "x", so access is faster. private static String x = "example"; You can use public constants (that is, final fields), but you must mark variables as private.

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• iPhone inputting NSUserDefaults into a UITextField

  - by Rob

  I am writing a program where I where the first time a user runs it - they will have to fill out about 10 different UITextFields. I am trying to save the fields so that on subsequent runs of the program that whatever they previously put will already be displayed in those UITextFields so the wont have to re-input it in - unless they want to edit something in which case they still have that option. I think that I have figured out a good way to save the strings using NSUserDefaults but now I am trying to figure out how to have those fields populate a UITextField - it doesnt seem as easy as if they were UILabels. This is the route I am attempting: // in the viewDidLoad portion. NSUserDefaults *userData = [NSUserDefaults standardUserDefaults]; //Hooks. NSString *placeHolderName = [userData stringForKey:@"name"]; txtName.text = @"%@", placeHolderName; When I do this, it simply displays the '%@' in the textfields. I want whatever variable being held by placeHolderName to be automatically put into that UITextField. Is this possible?

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• Can I use drawRect to refresh a UIView subclass?

  - by Timbo

  I've created a subclass of UIView called Status which is designed to display a rectangle of a certain size (within a view) depending on the value of a variable. // Interface #import <Foundation/Foundation.h> #import <QuartzCore/QuartzCore.h> @interface Status: UIView { NSString* name; int someVariable; } @property int someVariable; @property (assign) NSString *name; - (void) createStatus: (NSString*)withName; - (void) drawRect:(CGRect)rect; @end // Implementation #import "Status.h" @implementation Status @synthesize name, someVariable; - (void) createStatus: (NSString*)withName { name = withName; someVariable = 10000; } - (void) drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); //Draw Status CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1); // fill CGContextFillRect(context, CGRectMake(0.0, 0.0, someVariable, 40.0)); } //// myviewcontroller implementation - (void) viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; myStatus = [[Status alloc] initWithFrame:CGRectMake(8,8,200,56)]; myStatus.backgroundColor = [UIColor grayColor]; [self.view addSubview:myStatus]; } How do I set this up so I can repeatedly call a refresh of the status bar? I'll probably call the refresh 4 times per second using a NSTimer, I'm just not sure what to call or if I should move this rectangle drawing to a separate function or something... Thanks in advance for your help :)

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• Accessing the calling object into ajax response... (not the ajax call)

  - by Nishchay Sharma

  I have an object of type Application (defined by me). Whenever an object of this type is created, it automatically loads a php file say "start.php" using jquery ajax and assign the response to a div say "Respo". Now what i want is to access the Application object from that Respo div. Unfortunately, i have no clue how to do this... in my ajax call: function Application(options) { ....... var appObj=this; $.ajax({ url:appObj.location, //Already defined success:function(data) { $("#respo").html(data); } }); } Now in my Respo division i want to access that Application object... I tried: alert(this) but it resulted in an object of DOMWindow... i tried editing success function as: function Application(options) { ....... var appObj=this; $.ajax({ url:appObj.location, //Already defined success:function(data) { $("#respo").html("<script type='text/javascript'>var Self="+appObj+"</script>"); $("#respo").html(data); } }); } But i ended nowhere. :( Although if i assign "var Self='nishchay';" then alerting Self from start.php gives nishchay but i am not able to assign the calling object of Application type to the Self variable. It is the only way I cud think of. :\ Please help me... actually my object has some editing functions to control itself - its look and feel and some other options. I want the code loaded by object to control the object itself. Please help me.. Thanks in advance. Nishchay

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• How do I use the Enum value from a class in another part of code?

  - by ChiggenWingz

  Coming from a C# background from a night course at a local college, I've sort of started my way in C++. Having a lot pain getting use to the syntax. I'm also still very green when it comes to coding techniques. From my WinMain function, I want to be able to access a variable which is using an enum I declared in another class. (inside core.h) class Core { public: enum GAME_MODE { INIT, MENUS, GAMEPLAY }; GAME_MODE gameMode; Core(); ~Core(); ...OtherFunctions(); }; (inside main.cpp) Core core; int WINAPI WinMain(...) { ... startup code here... core.gameMode = Core.GAME_MODE.INIT; ...etc... } Basically I want to set that gameMode to the enum value of Init or something like that from my WinMain function. I want to also be able to read it from other areas. I get the error... expected primary-expression before '.' token If I try to use core.gameMode = Core::GAME_MODE.INIT;, then I get the same error. I'm not fussed about best practices, as I'm just trying to get the basic understanding of passing around variables in C++ between files. I'll be making sure variables are protected and neatly tucked away later on once I am use to the flexibility of the syntax. If I remember correctly, C# allowed me to use Enums from other classes, and all I had to do was something like Core.ENUMNAME.ENUMVALUE. I hope what I'm wanting to do is clear :\ As I have no idea what a lot of the correct terminology is.

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• perl - converting a date into a string

  - by Jason

  I need to convert a date to a string, the date is entered as 07/04/2010 and should then read July 4th 2010. It should also be able to be entered using singe digits instead of double (7 instead of 07, and it needs to add the 20 to the year if the user enters only /10) This is what I have so far - #!/usr/bin/perl use CGI qw(:standard); use strict; #declare variables my ($date, $month, $day, $year); my @months = ("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"); #assign input item to variable $date = param('Date'); #break date apart $date =~ /([0-9]{1,2})\/([0-9]{1,2})\/([0-9]{2,2}|20[0-9]{2,2})/; $month = $1; $day = $2; $year = $3; unless($year =~ /20[0-9]{2,2}/){ $year = "20".$year; } $date = $months[int($1)]." ".$day.", ".$year; #display date print "<HTML><HEAD><TITLE>The Date</TITLE></HEAD>\n"; print "<BODY>\n"; print "The date is: $date\n"; print "</BODY></HTML>\n"; However I keep getting errors Use of uninitialized value in pattern match (m//) at c08ex6.cgi line 14. Use of uninitialized value in pattern match (m//) at c08ex6.cgi line 18. Use of uninitialized value in concatenation (.) or string at c08ex6.cgi line 19. Use of uninitialized value in int at c08ex6.cgi line 21. Use of uninitialized value in concatenation (.) or string at c08ex6.cgi line 21.

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• Why is PLINQ slower than LINQ for this code?

  - by Rob Packwood

  First off, I am running this on a dual core 2.66Ghz processor machine. I am not sure if I have the .AsParallel() call in the correct spot. I tried it directly on the range variable too and that was still slower. I don't understand why... Here are my results: Process non-parallel 1000 took 146 milliseconds Process parallel 1000 took 156 milliseconds Process non-parallel 5000 took 5187 milliseconds Process parallel 5000 took 5300 milliseconds using System; using System.Collections.Generic; using System.Diagnostics; using System.Linq; namespace DemoConsoleApp { internal class Program { private static void Main() { ReportOnTimedProcess( () => GetIntegerCombinations(), "non-parallel 1000"); ReportOnTimedProcess( () => GetIntegerCombinations(runAsParallel: true), "parallel 1000"); ReportOnTimedProcess( () => GetIntegerCombinations(5000), "non-parallel 5000"); ReportOnTimedProcess( () => GetIntegerCombinations(5000, true), "parallel 5000"); Console.Read(); } private static List<Tuple<int, int>> GetIntegerCombinations( int iterationCount = 1000, bool runAsParallel = false) { IEnumerable<int> range = Enumerable.Range(1, iterationCount); IEnumerable<Tuple<int, int>> integerCombinations = from x in range from y in range select new Tuple<int, int>(x, y); return runAsParallel ? integerCombinations.AsParallel().ToList() : integerCombinations.ToList(); } private static void ReportOnTimedProcess( Action process, string processName) { var stopwatch = new Stopwatch(); stopwatch.Start(); process(); stopwatch.Stop(); Console.WriteLine("Process {0} took {1} milliseconds", processName, stopwatch.ElapsedMilliseconds); } } }

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• Issues regarding playing audio files in a JME midlet.

  - by Northernen

  I am making a midlet which is to be used to play out local audio files. It is obviously not working. I am getting a null reference on the "is" variable, in the code snippet shown below. 1. try{ 2. System.out.println("path: " + this.getClass()); 3. InputStream is = this.getClass().getResourceAsStream("res/01Track.wav"); 4. p1=Manager.createPlayer(is, "audio"); 5. p1.realize(); 6. p1.prefetch(); 7. p1.start(); 8. } 9. catch(Exception e){ 10. System.out.println(e.getMessage()); 11. } I assume there is something wrong with the "this.getClass().getResourceAsStream("res/01Track.wav")" bit, but I can not for the life of me figure out why, and I have tried referring to the file in 20 different ways. If I printline "this.getClass()" it gives me "path: class Mp3spiller". The absolute path to "01Track.wav" is "E:\Mine dokumenter\Dokumenter\workspace_mobiljava\Mp3spiller\res\01Track.wav". Am I completely wrong in thinking that I should refer relatively to "E:\Mine dokumenter\Dokumenter\workspace_mobiljava\Mp3spiller"? If anyone could point out what I am doing wrong, I would be grateful. I have basically stolen the code from a tutorial I found online, so I would have thought it would be working.

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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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• Entity framework with Linq to Entities performance

  - by mare

  If I have a static method like this public static string GetTicClassificationTitle(string classI, string classII, string classIII) { using (TicDatabaseEntities ticdb = new TicDatabaseEntities()) { var result = from classes in ticdb.Classifications where classes.ClassI == classI where classes.ClassII == classII where classes.ClassIII == classIII select classes.Description; return result.FirstOrDefault(); } } and use this method in various places in foreach loops or just plain calling it numerous times, does it create and open new connection every time? If so, how can I tackle this? Should I cache the results somewhere, like in this case, I would cache the entire Classifications table in Memory Cache? And then do queries vs this cached object? Or should I make TicDatabaseEntities variable static and initialize it at class level? Should my class be static if it contains only static methods? Because right now it is not.. Also I've noticed that if I return result.First() instead of FirstOrDefault() and the query does not find a match, it will issue an exception (with FirstOrDefault() there is no exception, it returns null). Thank you for clarification.

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• Bad idea to have the same object, have a different side effect after method call.

  - by Nathan W

  Hi all, I'm having a bit of a gesign issue(again). Say I have this Buttonpad object: now this object is a wrapper object over one in a com object. At the moment it has a method on it called CreateInto(IComObject). Now to make a new button pad in the Com Object. You do: ButtonPad pad = new ButtonPad(); pad.Title = "Hello"; // Set some more properties. pad.CreateInto(Cominstance); The createinfo method will excute the right commands to buid the button pad in the com object. After it has been created it any calls against it are foward to the underlying object for change so: pad.Title = "New title"; will call the com object to set the title and also set the internal title variable. Basically any calls before the CreateInfo method only affect the .NET object anything after has the side effect of calling the com object also. I'm not very good at sequence diagrams but here is my attempt to explain whats going on: This doesn't feel good to me, it feels like I'm lying to the user about what the button pad does. I was going to have a object called WrappedButtonPad, which is returned from CreateInto and the user could make calls against that to make changes to the Com Object, but I feel having two objects that almost do the same thing but only differ by names might be even worse. Are these valid designs, or am I right to be worried? How else would you handle a object the can create and query a com object?

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• Why doesn't this PHP execute?

  - by cam

  I copied the code from this site exactly: http://davidwalsh.name/web-service-php-mysql-xml-json as follows, /* require the user as the parameter */ if(isset($_GET['user']) && intval($_GET['user'])) { /* soak in the passed variable or set our own */ $number_of_posts = isset($_GET['num']) ? intval($_GET['num']) : 10; //10 is the default $format = strtolower($_GET['format']) == 'json' ? 'json' : 'xml'; //xml is the default $user_id = intval($_GET['user']); //no default /* connect to the db */ $link = mysql_connect('localhost','username','password') or die('Cannot connect to the DB'); mysql_select_db('db_name',$link) or die('Cannot select the DB'); /* grab the posts from the db */ $query = "SELECT post_title, guid FROM wp_posts WHERE post_author = $user_id AND post_status = 'publish' ORDER BY ID DESC LIMIT $number_of_posts"; $result = mysql_query($query,$link) or die('Errant query: '.$query); /* create one master array of the records */ $posts = array(); if(mysql_num_rows($result)) { while($post = mysql_fetch_assoc($result)) { $posts[] = array('post'=>$post); } } /* output in necessary format */ if($format == 'json') { header('Content-type: application/json'); echo json_encode(array('posts'=>$posts)); } else { header('Content-type: text/xml'); echo '<posts>'; foreach($posts as $index => $post) { if(is_array($post)) { foreach($post as $key => $value) { echo '<',$key,'>'; if(is_array($value)) { foreach($value as $tag => $val) { echo '<',$tag,'>',htmlentities($val),'</',$tag,'>'; } } echo '</',$key,'>'; } } } echo '</posts>'; } /* disconnect from the db */ @mysql_close($link); } And the php doesn't execute, it just displays as plain text. What's the dealio? The host supports PHP, I use it to run a Wordpress blog and other things.

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• sum of square of each elements in the vector using for_each

  - by pierr

  Hi, As the function accepted by for_each take only one parameter (the element of the vector), I have to define a static int sum = 0 somewhere so that It can be accessed after calling the for_each . I think this is awkward. Any better way to do this (still use for_each) ? #include <algorithm> #include <vector> #include <iostream> using namespace std; static int sum = 0; void add_f(int i ) { sum += i * i; } void test_using_for_each() { int arr[] = {1,2,3,4}; vector<int> a (arr ,arr + sizeof(arr)/sizeof(arr[0])); for_each( a.begin(),a.end(), add_f); cout << "sum of the square of the element is " << sum << endl; } In Ruby, We can do it this way: sum = 0 [1,2,3,4].each { |i| sum += i*i} #local variable can be used in the callback function puts sum #=> 30 Would you please show more examples how for_each is typically used in practical programming (not just print out each element)? Is it possible use for_each simulate 'programming pattern' like map and inject in Ruby (or map /fold in Haskell). #map in ruby >> [1,2,3,4].map {|i| i*i} => [1, 4, 9, 16] #inject in ruby [1, 4, 9, 16].inject(0) {|aac ,i| aac +=i} #=> 30 EDIT: Thank you all. I have learned so much from your replies. We have so many ways to do the same single thing in C++ , which makes it a little bit difficult to learn. But it's interesting :)

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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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• reading a file of unknown length with a function

  - by Faken

  I'm trying to write a short function that will let me quickly read in a file of unknown size and return pointer to the array of data and the length of that array but it seems my code isn't working. What am i doing wrong? int readIn(int* pointer, param parameters, string description) { string fileName = parameters.fileName + " " + description + ".bin"; ifstream readFile; readFile.open(fileName.c_str(), ios::in|ios::binary|ios::ate); int size = readFile.tellg(); int length = size / 4; int* output = new int [length]; readFile.seekg (0, ios::beg); readFile.read(reinterpret_cast<char*>(output), (size)); readFile.close(); pointer = output; // link new array with the pointer return length; } and in the main function: int* testList; int numEntries = readIn(testList, parameters, "test"); I end up with an error saying that my testList variable was used and not initialized. What am i doing wrong?

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• Accessing program information that gdb sees in C++

  - by anon

  I have a program written in C++, on Linux, compiled with -g. When I run it under gdb, I can 1) set breakpoints 2) at those breakpoints, print out variables 3) see the stackframe 4) given a variable that's a structure, print out parts of the structure (i.e. how ddd displays information). Now, given that my program is compiled with "-g" -- is there anyway that I can access this power within my program itself? I.e. given that my program is compiled with "-g", is there some std::vector<string> getStackFrame(); function I can call to get the current stackframe at the current point of execution? Given a pointer to an object and it's type ... can I do std::vector getClassMember(class_name); ? I realize the default answer is "no, C++ doesn't support that level of introspection" -- however, recall I'm on linux, my program is compiled with "-g", and gdb can do it, so clearly the inforamtion is there. Question is: is there some API for accessing it? EDIT: PS Naysers, I'd love to see a reason for closing this question.

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• "Function object is unsubscriptable" in basic integer to string mapping function

  - by IanWhalen

  I'm trying to write a function to return the word string of any number less than 1000. Everytime I run my code at the interactive prompt it appears to work without issue but when I try to import wordify and run it with a test number higher than 20 it fails as "TypeError: 'function' object is unsubscriptable". Based on the error message, it seems the issue is when it tries to index numString (for example trying to extract the number 4 out of the test case of n = 24) and the compiler thinks numString is a function instead of a string. since the first line of the function is me defining numString as a string of the variable n, I'm not really sure why that is. Any help in getting around this error, or even just help in explaining why I'm seeing it, would be awesome. def wordify(n): # Convert n to a string to parse out ones, tens and hundreds later. numString = str(n) # N less than 20 is hard-coded. if n < 21: return numToWordMap(n) # N between 21 and 99 parses ones and tens then concatenates. elif n < 100: onesNum = numString[-1] ones = numToWordMap(int(onesNum)) tensNum = numString[-2] tens = numToWordMap(int(tensNum)*10) return tens+ones else: # TODO pass def numToWordMap(num): mapping = { 0:"", 1:"one", 2:"two", 3:"three", 4:"four", 5:"five", 6:"six", 7:"seven", 8:"eight", 9:"nine", 10:"ten", 11:"eleven", 12:"twelve", 13:"thirteen", 14:"fourteen", 15:"fifteen", 16:"sixteen", 17:"seventeen", 18:"eighteen", 19:"nineteen", 20:"twenty", 30:"thirty", 40:"fourty", 50:"fifty", 60:"sixty", 70:"seventy", 80:"eighty", 90:"ninety", 100:"onehundred", 200:"twohundred", 300:"threehundred", 400:"fourhundred", 500:"fivehundred", 600:"sixhundred", 700:"sevenhundred", 800:"eighthundred", 900:"ninehundred", } return mapping[num] if __name__ == '__main__': pass

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• Beginner PHP: I can't insert data into MYSQL database

  - by Victor

  I'm learning PHP right now and I'm trying to insert data into a MySQL database called "pumpl2" The table is set up like this. create table product ( productid int unsigned not null auto_increment primary key, price int(9) not null, value int(9) not null, description text ); I have a form and want to insert the fields from the form in the database. Here is what the php file looks like. <?php // create short variable names $price = $_POST['price']; $value = $_POST['value']; $description = $_POST['description']; if (!$price || !$value || !$description) { echo "You have not entered all the required details.<br />" ."Please go back and try again."; exit; } @ $db = new mysqli('localhost', 'pumpl', '********', 'pumpl2'); if (mysqli_connect_errno()) { echo "Error: Could not connect to database. Please try again later."; exit; } $query = "insert into pumpl2 values ('".$price."', '".$value."', '".$description."')"; $result = $db->query($query); if ($result) { echo $db->affected_rows." product inserted into database."; } else { echo "An error has occurred. The item was not added."; } $db->close(); ?> When I submit the form, I get an error message "An error has occurred. The item was not added." Does anyone know what the problem is? Thank you!

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