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  • SQL inner join from field defined table?

    - by Wolftousen
    I have a, currently, a total of 6 tables that are part of this question. The primary table, tableA, contains columns that all the entries in the other 5 tables have in common. The other 5 tables have columns which define the entry in tableA in more detail. For example: TableA ID|Name|Volumn|Weight|Description 0 |T1 |0.4 |0.1 |Random text 1 |R1 |5.3 |25 |Random text TableB ID|Color|Shape 0 |Blue |Sphere TableC ID|Direction|Velocity 1 |North |3.4 (column names are just examples don't take them for what they mean...) The ID field in Table A is unique to all other tables (i.e. TableB will have 0, but TableC will not, nor any other Tables). What I would like to do is select all the fields from TableA and the corresponding (according to ID field) detail Table (TableB-F). What I have currently done and not tested is added a field to TableA so it looks like this: TableA ID|Name|Volumn|Weight|Description|Table 0 |T1 |0.4 |0.1 |Random text|TableB 1 |R1 |5.3 |25 |Random text|TableC I have a few questions about this: 1.Is it proper to do such a thing to TableA, as foreign keys wont work in this situation since they all need to link to different tables? 2.If this is proper, would the SQL query look like this (ID would be input by the user)? SELECT * FROM TableA AS a INNER JOIN a.Table AS t ON a.ID = ID; 3.Is there a better way to do this? Thanks for the help.

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  • Merging Three or More Images -- PHP

    - by bballer13sn
    Before I ask my question, I'd like to thank you all in advance for helping me with this. So here's the question: So, for my website, I've been trying to make it so people's characters (which are currently composed of several pictures that are moved by CSS) are merged into one image as to make my life easier. The chunk of code that currently doesn't work is as follows: $template = $charRow['template']; $gender = $charRow['gender']; $shirt = $charRow['shirt']; $pants = $charRow['pants']; $hat = $charRow['hat']; $templatePic = imagecreatefrompng("Templates/".$template); if (!empty($shirt)) { $shirtPic = imagecreatefrompng($shirt); imagecopy($templatePic,$shirtPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } if (!empty($pants)) { $pantsPic = imagecreatefrompng($pants); imagecopy($templatePic,$pantsPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } if (!empty($hat)) { $hatPic = imagecreatefrompng($hat); imagecopy($templatePic,$hatPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } imagePNG($templatePic, 'Images/'); //Problem line... This is the error PHP is giving me: Warning: imagepng() [function.imagepng]: Unable to open 'Images/' for writing: Is a directory in PathToParentFolderOfFollowingFile/testFile.php on line 139 What exactly does this error mean and how can it be fixed? NOTE: $charRow is not the problem. The query to get that is just not being displayed to all of you.

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  • Can't referr to my get method

    - by chility
    I have this amazing and good looking class: public class SayingsHolder extends Application{ ArrayList<String> SayingsList = new ArrayList<String>(){{ SayingsList.add("1"); SayingsList.add("2"); }}; public ArrayList<String> getSayingsList() { return SayingsList; } } Now I'm trying to call the getSayingsList method inside of my activity's FragmentStatePagerAdapter by: private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter { final SayingsHolder holder = (SayingsHolder).getApplication(); } Everything fine for now, but when I make my code like this: private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter { final SayingsHolder holder = (SayingsHolder).getApplication(); holder.getSayingsList(); } it says: Syntax error on token "getSayingsList", Identifier expected after this token The problem is that holder is not functional at all. What I mean is that when i type the this holder. the getSayingsList is not showing at all. What am I missing here? I know that it is an extremely small issue, but it seems that I can't spot it. My activity extends FragmentActivity if it's important It seems that I'm missing something here. I can't call my method anywhere in my activity. I'm starting a bounty, because I need an example.

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  • Scientific Data processing (Graph comparison and interpretation)

    - by pinkynobrain
    Hi stackoverflow friends, I'm trying to write a program to automate one of my more boring and repetitive work tasks. I have some programming experience but none with processing or interpreting large volumes of data so I am seeking your advice (both suggestions of techniques to try and also things to read to learn more about doing this stuff). I have a piece of equipment that monitors an experiment by taking repeated samples and displays the readings on its screen as a graph. The input of experiment can be altered and one of these changes should produce a change in a section of the graph which I currently identify by eye and is what I'm looking for in the experiment. I want to automate it so that a computer looks at a set of results and spots the experiment input that causes the change. I can already extract the results from the machine. Currently they results for a run are in the form of an integer array with the index being the sample number and the corresponding value being the measurement. The overall shape of the graph will be similar for each experiment run. The change I'm looking for will be roughly the same and will occur in approximately the same place every time for the correct experiment input. Unfortunately there are a few gotchas that make this problem more difficult. There is some noise in the measuring process which mean there is some random variation in the measured values between different runs. Although the overall shape of the graph remains the same. The time the experiment takes varies slightly each run causing two effects. First, the a whole graph may be shifted slightly on the x axis relative to another run's graph. Second, individual features may appear slightly wider or narrower in different runs. In both these cases the variation isn't particularly large and you can assume that the only non random variation is caused by the correct input being found. Thank you for your time, Pinky

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  • 2 basic but interesting questions about .NET

    - by b-gen-jack-o-neill
    Hi, when I first saw C#, I thought this must be some joke. I was starting with programming in C. But in C# you could just drag and drop objects, and just write event code to them. It was so simple. Now, I still like C the most, becouse I am very attracted to the basic low level operations, and C is just next level of assembler, with few basic routines, so I like it very much. Even more becouse I write little apps for microcontrollers. But yeasterday I wrote very simple control program for my microcontroller based LED cube in asm, and I needed some way to simply create animation sequences to the Cube. So, I remembered C#. I have practically NO C# skills, but still I created simple program to make animation sequences in about hour with GUI, just with help of google and help of the embeded function descriptions in C#. So, to get to the point, is there some other reason then top speed, to use any other language than C#? I mean, it is so effective. I know that Java is a bit of similiar, but I expect C# to be more Windows effective since its directly from Microsoft. The second question is, what is the advantage of compiling into CIL, and than run by CLR, than directly compile it into machine code? I know that portability is one, but since C# is mainly for Windows, wouldn´t it be more powerfull to just compile it directly? Thanks.

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  • Calling a constructor to reinitialize variables doesn't seem to work?

    - by Matt
    I wanted to run 1,000 iterations of a program, so set a counter for 1000 in main. I needed to reinitialize various variables after each iteration, and since the class constructor had all the initializations already written out - I decided to call that after each iteration, with the result of each iteration being stored in a variable in main. However, when I called the constructor, it had no effect...it took me a while to figure out - but it didn't reinitialize anything! I created a function exactly like the constructor - so the object would have its own version. When I called that, it reinitialized everything as I expected. int main() { Class MyClass() int counter = 0; while ( counter < 1000 ) { stuff happens } Class(); // This is how I tried to call the constructor initially. // After doing some reading here, I tried: // Class::Class(); // - but that didn't work either /* Later I used... MyClass.function_like_my_constructor; // this worked perfectly */ } ...Could someone try to explain why what I did was wrong, or didn't work, or was silly or what have you? I mean - mentally, I just figured - crap, I can call this constructor and have all this stuff reinitialized. Are constructors (ideally) ONLY called when an object is created?

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  • Questions about shifting from mysql to PDO

    - by Scarface
    Hey guys I have recently decided to switch all my current plain mysql queries performed with php mysql_query to PDO style queries to improve performance, portability and security. I just have some quick questions for any experts in this database interaction tool Will it prevent injection if all statements are prepared? (I noticed on php.net it wrote 'however, if other portions of the query are being built up with unescaped input, SQL injection is still possible' I was not exactly sure what this meant). Does this just mean that if all variables are run through a prepare function it is safe, and if some are directly inserted then it is not? Currently I have a connection at the top of my page and queries performed during the rest of the page. I took a look at PDO in more detail and noticed that there is a try and catch procedure for every query involving a connection and the closing of that connection. Is there a straightforward way to connecting and then reusing that connection without having to put everything in a try or constantly repeat the procedure by connecting, querying and closing? Can anyone briefly explain in layman's terms what purpose a set_exception_handler serves? I appreciate any advice from any more experienced individuals.

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  • Is there any trick to match two XML by one XSLT?

    - by brain_pusher
    Is there any trick to match two XML by one XSLT? I mean the way I can apply XSLT to a parameter passed. For example (I missed declarations to be short). XML1: XML to be transformed: <myData> <Collection> </Collection> </myData> XSLT need to be applied to the previous XML: <xsl:param name='items' /> <xsl:template match='Collection'> <!-- some transformation here --> </xsl:template> XML2: XML data passed as the parameter 'items': <newData> <Item>1</Item> <Item>2</Item> <Item>3</Item> </newData> And I need to create a set of nodes in the 'Collection' node in XML1 for each 'Item' element in XML2 using XSLT. And I do not know what XML2 contains exactly at design time. It is generated at runtime, so I can't place it inside XSLT, I know only its schema.

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  • How the clients (client sockets) are identified?

    - by Roman
    To my understanding by serverSocket = new ServerSocket(portNumber) we create an object which potentially can "listen" to the indicated port. By clientSocket = serverSocket.accept() we force the server socket to "listen" to its port and to "accept" a connection from any client which tries to connect to the server through the port associated with the server. When I say "client tries to connect to the server" I mean that client program executes "nameSocket = new Socket(serverIP,serverPort)". If client is trying to connect to the server, the server "accepts" this client (i.e. creates a "client socket" associated with this client). If a new client tries to connect to the server, the server creates another client socket (associated with the new client). But how the server knows if it is a "new" client or an "old" one which has already its socket? Or, in other words, how the clients are identified? By their IP? By their IP and port? By some "signatures"? What happens if an "old" client tries to use Socket(serverIP,serverIP) again? Will server create the second socket associated with this client?

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  • How to write this loop prettier?

    - by Tom
    I've just read this topic http://stackoverflow.com/questions/2930533/highlight-search-keywords-on-hover and actually I use pretty the same structure, but it looks awful. So can you give me an advice, how to write this loop prettier in one php file, I mean php and html at the same time? <table class="result"> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:15px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?>

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  • How to process more that one XML document in XSLT?

    - by brain_pusher
    Is there any trick to match two XML by one XSLT? I mean the way I can apply XSLT to a parameter passed. For example (I missed declarations to be short). XML1: XML to be transformed: <myData> <Collection> </Collection> </myData> XSLT need to be applied to the previous XML: <xsl:param name='items' /> <xsl:template match='Collection'> <!-- some transformation here --> </xsl:template> XML2: XML data passed as the parameter 'items': <newData> <Item>1</Item> <Item>2</Item> <Item>3</Item> </newData> And I need to create a set of nodes in the 'Collection' node in XML1 for each 'Item' element in XML2 using XSLT. And I do not know what XML2 contains exactly at design time. It is generated at runtime, so I can't place it inside XSLT, I know only its schema.

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  • Apache mod_rewrite : How to REWRITE (or whatever) child directories to parent?

    - by ????
    Actually i am trying to make a PHP MVC like application. A basic one. The current milestone i am reaching already includes: Basic RESTful Routing Means, if i type: www.example.com/items/book/8888 .. it properly just stays there as it is and i can already slice out the URL by slashes / and loads the responsible Controllers .... etc from the top single index.php file. I mean, so it is OK for the backend PHP. But the only problem is, it still CAN NOT process the REWRITES properly. For example, the CSS & JS are BROKEN as if i VIEW PAGE SOURCE of the page www.example.com/items/book/8888, the asset files are being called as: www.example.com/items/book/8888/css/main.css www.example.com/items/book/8888/js/jquery.js .. which really are PROBLEMS because in the code is like: <link type="text/css" rel="stylesheet" media="all" href="css/main.css"> <script type="text/javascript" src="js/jquery.js"></script> So the question is: How can i use Apache REWRITE (or whatever approach) to make sure every ASSET FILES to be correctly being called from the DOCROOT. For example, if i am in the URL: www.example.com/items/book/8888 My ASSET FILES should still be called as: www.example.com/css/main.css www.example.com/js/jquery.js Or is there any other methods i need to follow? Please kindly help suggest. Thank you.

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  • Is there any alternative way of writing this switch statement(C#3.0)

    - by Newbie
    Can it be done in a better way public static EnumFactorType GetFactorEnum(string str) { Standardization e = new Standardization(); switch (str.ToLower()) { case "beta": e.FactorType = EnumFactorType.BETA; break; case "bkp": e.FactorType = EnumFactorType.BOOK_TO_PRICE; break; case "yld": e.FactorType = EnumFactorType.DIVIDEND_YIELD; break; case "growth": e.FactorType = EnumFactorType.GROWTH; break; case "mean": e.FactorType = EnumFactorType.MARKET_CAP; break; case "momentum": e.FactorType = EnumFactorType.MOMENTUM; break; case "size": e.FactorType = EnumFactorType.SIZE; break; case "stat_fact1": e.FactorType = EnumFactorType.STAT_FACT_1; break; case "stat_fact2": e.FactorType = EnumFactorType.STAT_FACT_2; break; case "value": e.FactorType = EnumFactorType.VALUE; break; } return e.FactorType; } If I create a Static class(say Constatant) and declare variable like public static string BETA= "beta"; and then if I try to put that in the Case expression like Case Constants.BETA : e.FactorType = EnumFactorType.BETA; break; then the compiler will report error.(quite expected) So is there any other way?(I canot change the switch statement) Using C#3.0 Thanks

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  • Find existence of number in a sorted list in constant time? (Interview question)

    - by Rich
    I'm studying for upcoming interviews and have encountered this question several times (written verbatim) Find or determine non existence of a number in a sorted list of N numbers where the numbers range over M, M N and N large enough to span multiple disks. Algorithm to beat O(log n); bonus points for constant time algorithm. First of all, I'm not sure if this is a question with a real solution. My colleagues and I have mused over this problem for weeks and it seems ill formed (of course, just because we can't think of a solution doesn't mean there isn't one). A few questions I would have asked the interviewer are: Are there repeats in the sorted list? What's the relationship to the number of disks and N? One approach I considered was to binary search the min/max of each disk to determine the disk that should hold that number, if it exists, then binary search on the disk itself. Of course this is only an order of magnitude speedup if the number of disks is large and you also have a sorted list of disks. I think this would yield some sort of O(log log n) time. As for the M N hint, perhaps if you know how many numbers are on a disk and what the range is, you could use the pigeonhole principle to rule out some cases some of the time, but I can't figure out an order of magnitude improvement. Also, "bonus points for constant time algorithm" makes me a bit suspicious. Any thoughts, solutions, or relevant history of this problem?

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  • Allocating 32-bit integer arrays in 64-bit machines

    - by Shredderroy
    I have a 64-bit i7 machine. Suppose I allocate memory for n 32-bit integers. How many physical registers will actually be used in the allocation: n, or n/2? I tried to write the following simple programme to find out. #include <iostream> #include <cstdlib> using namespace std; int main (int argc, char *argv[]) { int a[4]; cout << &a[0] << "\t" << &a[3] << endl; cin.ignore (1); return 0; } // End main () The output is: 0018FA04 0018FA10 They seem further apart than they should be. Why aren't the addresses 04 and 07? And does this mean that the system is actually allocating four (or more) integers, instead of packing the four 32-bit integers into two 64-bit registers? Thanks in advance for your help.

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  • Rails 4 testing bug?

    - by Jamato
    Situation: if we add two identic line items into a cart, we update line item quantity instead of adding a duplicate.In browser everything works fine but in unit testing section something fails because of an empty cycle in code. Which I wanted to use to update all prices. Why? Is that a unit test engine bug? LineItem.all and cart.line_items in process of testing produce two DIFFERENT structures. #<LineItem id: 980190964, product_id: 1, cart_id: 999, created_at: "2014-06-01 00:21:28", updated_at: "2014-06-01 00:21:28", quantity: 2, price: #<BigDecimal:ba0fb544,'0.4E1',9(27)>> #<LineItem id: 980190964, product_id: 1, cart_id: 999, created_at: "2014-06-01 00:21:28", updated_at: "2014-06-01 00:21:28", quantity: 1, price: #<BigDecimal:ba0d1b04,'0.4E1',9(27)>> cart.line_items guy did not update quantity Code itself (produces LineItem which is then saved in line_item_controller which calls this method) class Cart < ActiveRecord::Base has_many :line_items, dependent: :destroy def add_product(product_id) # LOOK THIS CYCLE BREAKS UNIT TEST, SRSLY, I MEAN IT line_items.each do |item| end current_item = line_items.find_by(product_id: product_id) fresh_price = Product.find_by(id: product_id).price if current_item current_item.quantity += 1 else current_item = line_items.build(product_id: product_id, price: fresh_price) end return current_item end ... Unit test code test "non-unique item added" do cart = Cart.new(:id => 999) line_item0 = cart.add_product(2) line_item0.save line_item1 = cart.add_product(1) line_item1.save assert_equal 2, cart.line_items.size #success line_item2 = cart.add_product(1) line_item2.save assert_equal 2, cart.line_items.size, "what?" assert cart.total_price > 15 #fail, prices are not enough, quantity of product1 = 1 #we get total price from quantity, it's a simple method in model end And once again: IT DOES WORK in browser as it should. Even with cycle. I feel so dumb right now...

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  • Using data.table to aggregate

    - by dayne
    After multiple suggestions from SO users, I am finally trying to convert my code over to using data.tables. library(data.table) DT <- data.table(plate = paste0("plate",rep(1:2,each=5)), id = rep(c("CTRL","CTRL","ID1","ID2","ID3"),2), val = 1:10) > DT plate id val 1: plate1 CTRL 1 2: plate1 CTRL 2 3: plate1 ID1 3 4: plate1 ID2 4 5: plate1 ID3 5 6: plate2 CTRL 6 7: plate2 CTRL 7 8: plate2 ID1 8 9: plate2 ID2 9 10: plate2 ID3 10 What I would like to do is take the average of DT[,val] by plate when the id is "CTRL". I would normally aggregate the data frame, then use match to map the values back to a new column, 'ctrl'. Using the data.table package I can get: DT[id=="CTRL",ctrl:=mean(val),by=plate] > DT plate id val ctrl 1: plate1 CTRL 1 1.5 2: plate1 CTRL 2 1.5 3: plate1 ID1 3 NA 4: plate1 ID2 4 NA 5: plate1 ID3 5 NA 6: plate2 CTRL 6 6.5 7: plate2 CTRL 7 6.5 8: plate2 ID1 8 NA 9: plate2 ID2 9 NA 10: plate2 ID3 10 NA What I need is really: DT <- data.table(plate = paste0("plate",rep(1:2,each=5)), id = rep(c("CTRL","CTRL","ID1","ID2","ID3"),2), val = 1:10, ctrl = rep(c(1.5,6.5),each=5)) > DT plate id val ctrl 1: plate1 CTRL 1 1.5 2: plate1 CTRL 2 1.5 3: plate1 ID1 3 1.5 4: plate1 ID2 4 1.5 5: plate1 ID3 5 1.5 6: plate2 CTRL 6 6.5 7: plate2 CTRL 7 6.5 8: plate2 ID1 8 6.5 9: plate2 ID2 9 6.5 10: plate2 ID3 10 6.5 Eventually I would like to use much more complicated selections of the values, but I do not know how to select specific values, run some function, then map those values back to the appropriate row using data frames.

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  • AutoMapper strings to enum descriptions

    - by 6footunder
    Given the requirement: Take an object graph, set all enum type properties based on the processed value of a second string property. Convention dictates that the name of the source string property will be that of the enum property with a postfix of "Raw". By processed we mean we'll need to strip specified characters e.t.c. I've looked at custom formatters, value resolvers and type converters, none of which seems like a solution for this? We want to use AutoMapper as opposed to our own reflection routine for two reasons, a) it's used extensively throughout the rest of the project and b) it gives you recursive traversal ootb. -- Example -- Given the (simple) structure below, and this: var tmp = new SimpleClass { CountryRaw = "United States", Person = new Person { GenderRaw="Male" } }; var tmp2 = new SimpleClass(); Mapper.Map(tmp, tmp2); we'd expect tmp2's MappedCountry enum to be Country.UnitedStates and the Person property to have a gender of Gender.Male. public class SimpleClass1 { public string CountryRaw {get;set;} public Country MappedCountry {get;set;} public Person Person {get;set;} } public class Person { public string GenderRaw {get;set;} public Gender Gender {get;set;} public string Surname {get;set;} } public enum Country { UnitedStates = 1, NewZealand = 2 } public enum Gender { Male, Female, Unknown } Thanks

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  • when will come the new C++ standard? C++0x

    - by Oops
    Hi, when will the new C++ standard became official? C++ was standardized in 1998 and the standard is called C++98 the C++ standard was updated in 2003 and is called C++03 so the unofficial name "C++0x" lead us to the wrong conclusion that it will come within the first decade of the 20th century. Have u also mentioned that we all make the year 2000 bug again? Now we have 2010 so if you take the X as the latin sign for 10 it should come out this year. But no, also this would be wrong. The answer: The name of the language was always part of the language itself. As we all know the ++ operator means: one more But we have learned in some situations it would be better to write ++C so the other way around often is better. and what does the characters 0x mean in the C++ language? Right it's the prefix for a hexadecimal number. Now the question is easy to answer, it's meaning is: 0x++C int main(){ std::cout << "When will the new C++ standard come out? " << std::endl; int x0_ = 0x7D0, _0x = x0_, C = 0xC, Y1 = C+++_0x, Y2 = x0_+++C; std::cout << "it will be standardized between the Years: " << Y1 << " and " << Y2 << std::endl; char c; std::cin >> c; return 0; } do you agree? regards Oops

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  • What are some ways to accomplish a dynamic array?

    - by Ted
    I'm going to start working on a new game and one of the things I'd like to accomplish is a dynamic array sort of system that would hold map data. The game will be top-down 2d and made with XNA 4.0 and C#. You will begin in a randomized area which will essentially be tile based. As such a 2 dimensional array would be one way to accomplish this by holding numerical values which would correspond to a list of textures and that would be how it would draw this randomly created map. The problem is I would kind of only like to create the area around where you start and they could venture in which ever direction they wanted to. This would mean I'd have to populate the map array with more randomized data in the direction they go. I could make a really large array and use the center of it and the rest would be in anticipation of new content to be made, but that just seems very inefficient. I suppose when they start a new game I could have a one time map creation process that would go through and create a large randomly generated map array, but holding all of in memory at all times seems also inefficient. Perhaps if there was a way that I'd only hold parts of that map data in memory at one time and somehow not hold the rest in memory. In the end I only need to have a chunk of the map somewhat close to them in memory so perhaps some of you might have suggestions on good ways to approach this kind of randomized map and dynamic array problem. It wouldn't need to be a dynamic array type of thing if I made it so that it pulled in map data nearby that is needed and then once off the screen and not needed it could somehow get rid of that memory that way I wouldn't have a huge array taking up a bunch of memory.

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  • What's an effective way to reuse ArrayLists in a for loop?

    - by Patrick
    hi, I'm reusing the same ArrayList in a for loop, and I use for loop results = new ArrayList<Integer>(); experts = new ArrayList<Integer>(); output = new ArrayList<String>(); .... to create new ones. I guess this is wrong, because I'm allocating new memory. Is this correct ? If yes, how can I empty them ? Added: another example I'm creating new variables each time I call this method. Is this good practice ? I mean to create new precision, relevantFound.. etc ? Or should I declare them in my class, outside the method to not allocate more and more memory ? public static void computeMAP(ArrayList<Integer> results, ArrayList<Integer> experts) { //compute MAP double precision = 0; int relevantFound = 0; double sumprecision = 0; thanks

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  • Checking if a function has C-linkage at compile-time [unsolvable]

    - by scjohnno
    Is there any way to check if a given function is declared with C-linkage (that is, with extern "C") at compile-time? I am developing a plugin system. Each plugin can supply factory functions to the plugin-loading code. However, this has to be done via name (and subsequent use of GetProcAddress or dlsym). This requires that the functions be declared with C-linkage so as to prevent name-mangling. It would be nice to be able to throw a compiler error if the referred-to function is declared with C++-linkage (as opposed to finding out at runtime when a function with that name does not exist). Here's a simplified example of what I mean: extern "C" void my_func() { } void my_other_func() { } // Replace this struct with one that actually works template<typename T> struct is_c_linkage { static const bool value = true; }; template<typename T> void assertCLinkage(T *func) { static_assert(is_c_linkage<T>::value, "Supplied function does not have C-linkage"); } int main() { assertCLinkage(my_func); // Should compile assertCLinkage(my_other_func); // Should NOT compile } Is there a possible implementation of is_c_linkage that would throw a compiler error for the second function, but not the first? I'm not sure that it's possible (though it may exist as a compiler extension, which I'd still like to know of). Thanks.

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  • A good php framework in 2012

    - by Jormundir
    I've done a lot of googling around this, and practically all of the answers I find are pre 2011, and are answered in the usual, here are the 5 most popular frameworks... So I'd like to update this topic for 2012, I'm going to build a web application with a pretty complex back-end system driving it, and I'd like to use a framework so I don't have to reinvent the wheel. My application will be hugely user based, so I would appreciate a built in authentication/validation system. (When this is missing it takes me a good 2 weeks of intense and frivolous research to try to pick the "best" one (I don't want to roll my own, I don't think I'd do a better job than what's out there). I've looked into a tried a few, so I'll give you what I like and don't like, but I don't want to bias answers too much. I don't like: Frameworks that auto-generate bloated code. If they have the feature, fine, but if I have to use it, I get frustrated. Backwards compatibility with php4, eww. I don't need backwards compatibility at all. I like: Getting up and running quickly (but without all the auto-generation bogus), what I mean by this is that all the essentials are there, so I don't have to come to a grinding halt to research what the best 3rd party plugin is to get the feature I need. Thorough documentation, good tutorials. Good presentation of these materials. Please explain why your framework suggestion is good, don't just give the name of a framework without any justification. Thanks!

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  • C#:Getting all image files in folder

    - by Meko
    Hi all. I am trying to get all images from folder but ,this folder also include sub folders. like /photos/person1/ and /photos/person2/ .I can get photos in folder like path= System.IO.Directory.GetCurrentDirectory() + "/photo/" + groupNO + "/"; public List<String> GetImagesPath(String folderName) { DirectoryInfo Folder; FileInfo[] Images; Folder = new DirectoryInfo(folderName); Images = Folder.GetFiles(); List<String> imagesList = new List<String>(); for (int i = 0; i < Images.Length; i++) { imagesList.Add(String.Format(@"{0}/{1}", folderName, Images[i].Name)); // Console.WriteLine(String.Format(@"{0}/{1}", folderName, Images[i].Name)); } return imagesList; } But how can I get all photos in all sub folders? I mean I want to get all photos in /photo/ directory at once.

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  • Is there any good reason for private methods existence in C# (and OOP in general)?

    - by Piotr Lopusiewicz
    I don't mean to troll but I really don't get it. Why would language designers allow private methods instead of some naming convention (see __ in Python) ? I searched for the answer and usual arguments are: a) To make the implementation cleaner/avoid long vertical list of methods in IDE autocompletion b) To announce to the world which methods are public interface and which may change and are just for implementation purpose c) Readability Ok so now, all of those could be achieved by naming all private methods with __ prefix or by "private" keyword which doesn't have any implications other than be information for IDE (don't put those in autocompletion) and other programers (don't use it unless you really must). Hell, one could even require unsafe-like keyword to access private methods to really discourage this. I am asking this because I work with some c# code and I keep changing private methods to public for test purposes as many in-between private methods (like string generators for xml serialization) are very useful for debugging purposes (like writing some part of string to log file etc.). So my question is: Is there anything which is achieved by access restriction but couldn't be achieved by naming conventions without restricting the access ?

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