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  • how to switch views according to command

    - by Veer
    I've a main view and many usercontrols. The main view contains a two column grid, with the first column filled with a listbox whose datatemplate consists of a usercontrol and the second column filled with another usercontrol. These two usercontrols have the same datacontext. MainView: <Grid> //Column defs ... <ListView Grid.Column="0" ItemSource="{Binding Foo}"> ... <DataTemplate> <Views: FooView1 /> </DataTemplate> </ListView> <TextBlock Text="{Binding Foo.Count}" /> <StackPanel Grid.Column="1"> <Views: FooView2 /> </StackPanel> <Grid> FooView1: <UserControl> <TextBlock Text="{Binding Foo.Title}"> </UserControl> FooView2: <UserControl> <TextBlock Text="{Binding Foo.Detail1}"> <TextBlock Text="{Binding Foo.Detail2}"> <TextBlock Text="{Binding Foo.Detail3}"> <TextBlock Text="{Binding Foo.Detail4}"> </UserControl> I've no IDE here. Excuse me if there is any syntax error When the user clicks on a button. These two usercontrols have to be replaced by another two usercontrols, so the datacontext changes, the main ui remaining the same. ie, FooView1 by BarView1 and FooView2 by BarView2 In short i want to bind this view changes in mainview to my command (command from Button) How can i do this? Also tell me if i could merge the usercontrol pairs, so that only one view exists for each viewmodel ie, FooView1 and FooView2 into FooView and so on...

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  • AutoMapper : Site wide usage of IValueFormatter for given types

    - by CRice
    It is my understanding I can configure AutoMapper in the following way and during mapping it should format all source model dates to the rules defined in the IValueFormatter and set the result to the mapped model. ForSourceType<DateTime>().AddFormatter<StandardDateFormatter>(); ForSourceType<DateTime?>().AddFormatter<StandardDateFormatter>(); I get no effect for my mapped class with this. It only works when I do the following: Mapper.CreateMap<Member, MemberForm>().ForMember(x => x.DateOfBirth, y => y.AddFormatter<StandardDateFormatter>()); I am mapping DateTime? Member.DateOfBirth to string MemberForm.DateOfBirth. The formatter basically creates a short date string from the date. Is there something I am missing when setting the default formatter for a given type? Thanks public class StandardDateFormatter : IValueFormatter { public string FormatValue(ResolutionContext context) { if (context.SourceValue == null) return null; if (!(context.SourceValue is DateTime)) return context.SourceValue.ToNullSafeString(); return ((DateTime)context.SourceValue).ToShortDateString(); } }

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  • Best implementation of Java Queue?

    - by Georges Oates Larsen
    I am working (In java) on a recursive image processing algorithm that recursively traverses the pixels of the image, outward from a center point. Unfortunately... That causes stack overflows, so I have decided to switch to a Queue-based algorithm. Now, this is all fine and dandy -- But considering the fact that its queue will be analyzing THOUSANDS of pixels in a very short amount of time, while constantly popping and pushing, WITHOUT maintaining a predictable state (It could be anywhere between length 100, and 20000); The queue implementation needs to have significantly fast popping and pushing abilities. A linked list seems attractive due to its ability to push elements unto its self without rearranging anything else in the list, but in order for it to be fast enough, it would need easy access to both its head, AND its tail (or second-to-last node if it were not doubly-linked). Sadly, though I cannot find any information related to the underlying implementation of linked lists in Java, so it's hard to say if a linked list is really the way to go... This brings me to my question... What would be the best implementation of the Queue interface in Java for what I intend to do? (I do not wish to edit or even access anything other than the head and tail of the queue -- I do not wish to do any sort of rearranging, or anything. On the flip side, I DO intend to do a lot of pushing and popping, and the queue will be changing size quite a bit, so preallocating would be inefficient)

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  • Heroku: Postgres type operator error after migrating DB from MySQL

    - by sevennineteen
    This is a follow-up to a question I'd asked earlier which phrased this as more of a programming problem than a database problem. http://stackoverflow.com/questions/2935985/postgres-error-with-sinatra-haml-datamapper-on-heroku I believe the problem has been isolated to the storage of the ID column in Heroku's Postgres database after running db:push. In short, my app runs properly on my original MySQL database, but throws Postgres errors on Heroku when executing any query on the ID column, which seems to have been stored in Postgres as TEXT even though it is stored as INT in MySQL. My question is why the ID column is being created as INT in Postgres on the data transfer to Heroku, and whether there's any way for me to prevent this. Here's the output from a heroku console session which demonstrates the issue: Ruby console for myapp.heroku.com >> Post.first.title => "Welcome to First!" >> Post.first.title.class => String >> Post.first.id => 1 >> Post.first.id.class => Fixnum >> Post[1] PostgresError: ERROR: operator does not exist: text = integer LINE 1: ...", "title", "created_at" FROM "posts" WHERE ("id" = 1) ORDER... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. Query: SELECT "id", "name", "email", "url", "title", "created_at" FROM "posts" WHERE ("id" = 1) ORDER BY "id" LIMIT 1 Thanks!

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  • encapsulation in python list (want to use " instead of ')

    - by Codehai
    I have a list of users users["pirates"] and they're stored in the format ['pirate1','pirate2']. If I hand the list over to a def and query for it in MongoDB, it returns data based on the first index (e.g. pirate1) only. If I hand over a list in the format ["pirate1","pirate"], it returns data based on all the elements in the list. So I think there's something wrong with the encapsulation of the elements in the list. My question: can I change the encapsulation from ' to " without replacing every ' on every element with a loop manually? Short Example: aList = list() # get pirate Stuff # users["pirates"] is a list returned by a former query # so e.g. users["pirates"][0] may be peter without any quotes for pirate in users["pirates"]: aList.append(pirate) aVar = pirateDef(aList) print(aVar) the definition: def pirateDef(inputList = list()): # prepare query col = mongoConnect().MYCOL # query for pirates Arrrr pirates = col.find({ "_id" : {"$in" : inputList}} ).sort("_id",1).limit(50) # loop over users userList = list() for person in pirates: # do stuff that has nothing to do with the problem # append user to userlist userList.append(person) return userList If the given list has ' encapsulation it returns: 'pirates': [{'pirate': 'Arrr', '_id': 'blabla'}] If capsulated with " it returns: 'pirates' : [{'_id': 'blabla', 'pirate' : 'Arrr'}, {'_id': 'blabla2', 'pirate' : 'cheers'}] EDIT: I tried figuring out, that the problem has to be in the MongoDB query. The list is handed over to the Def correctly, but after querying pirates only consists of 1 element... Thanks for helping me Codehai

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  • How to access widgets created within functions in later function calls in Qt

    - by Inanepenguin
    So currently I have code, in C++, that creates a few QLabels, a QLineEdit, and a QCheckBox when a selection is made from a QComboBox. However, I would like to be able to access the widgets I have created in a later function to destroy them if a new selection is made from the combo box. I am able to access the objects created from using the Designer by doing ui-Object but i am not able to do that with objects created by using my own code. Can I do that some how, because I know how to work with that. In short, I would like to be able to dynamically create/destroy QWidgets based on selections made by the user. Is there a reference I should know of to do this, or any documentation? Or am I just completely going about this the wrong way? Here is the code I presently have for creating the objects: if (eventType == QString::fromStdString("Birthday")) { QLabel *label1 = new QLabel ("Celebrant: "); QLabel *label2 = new QLabel ("Surprise: "); QLineEdit *lineEdit = new QLineEdit; QCheckBox *box = new QCheckBox; ui->gridLayout->addWidget(label1,3,0,1,1, 0); ui->gridLayout->addWidget(label2,4,0,1,1,0); ui->gridLayout->addWidget(lineEdit,3,1,1,1,0); ui->gridLayout->addWidget(box,4,1,1,2,0); }

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  • C# to unmanaged dll data structures interop

    - by Shane Powell
    I have a unmanaged DLL that exposes a function that takes a pointer to a data structure. I have C# code that creates the data structure and calls the dll function without any problem. At the point of the function call to the dll the pointer is correct. My problem is that the DLL keeps the pointer to the structure and uses the data structure pointer at a later point in time. When the DLL comes to use the pointer it has become invalid (I assume the .net runtime has moved the memory somewhere else). What are the possible solutions to this problem? The possible solutions I can think of are: Fix the memory location of the data structure somehow? I don't know how you would do this in C# or even if you can. Allocate memory manually so that I have control over it e.g. using Marshal.AllocHGlobal Change the DLL function contract to copy the structure data (this is what I'm currently doing as a short term change, but I don't want to change the dll at all if I can help it as it's not my code to begin with). Are there any other better solutions?

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  • Forwarding HTTP Request with Direct Server Return

    - by Daniel Crabtree
    I have servers spread across several data centers, each storing different files. I want users to be able to access the files on all servers through a single domain and have the individual servers return the files directly to the users. The following shows a simple example: 1) The user's browser requests http://www.example.com/files/file1.zip 2) Request goes to server A, based on the DNS A record for example.com. 3) Server A analyzes the request and works out that /files/file1.zip is stored on server B. 4) Server A forwards the request to server B. 5) Server B returns file1.zip directly to the user without going through server A. Note: steps 4 and 5 must be transparent to the user and cannot involve sending a redirect to the user as that would violate the requirement of a single domain. From my research, what I want to achieve is called "Direct Server Return" and it is a common setup for load balancing. It is also sometimes called a half reverse proxy. For step 4, it sounds like I need to do MAC Address Translation and then pass the request back onto the network and for servers outside the network of server A tunneling will be required. For step 5, I simply need to configure server B, as per the real servers in a load balancing setup. Namely, server B should have server A's IP address on the loopback interface and it should not answer any ARP requests for that IP address. My problem is how to actually achieve step 4? I have found plenty of hardware and software that can do this for simple load balancing at layer 4, but these solutions fall short and cannot handle the kind of custom routing I require. It seems like I will need to roll my own solution. Ideally, I would like to do the routing / forwarding at the web server level, i.e. in PHP or C# / ASP.net. However, I am open to doing it at a lower level such as Apache or IIS, or at an even lower level, i.e. a custom proxy service in front of everything.

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  • MySQL LIMIT 1 but query 15 rows?

    - by Ian
    Basically what I'm trying to do is compare the ID's of rows against 15 results in MySQL, eliminating all but 1 (using NOT IN) and then pull that result. Now normally this would be fine by itself, however the order of the 15 rows I'm doing the SQL query for are constantly changing based on a ranking, so there is a possibility that between the time the ranking updates, and the ajax request (which I submit the ID's for NOT IN) more than just one ID has changed, which would of course bring back more than one row which I do not want. So in short, is there a way in which I can query 15 rows, but only return one? Without having to run two separate queries. Any help is appreciated, thank you. EXAMPLE: Say I have 7 items in my database, and I'm displaying 5 on the page to the user. These are what are being displayed to the user: Apple Orange Kiwi Banana Grape But in the database I also have Peach Blackberry Now what I want to do is if the user deletes an item from their list, it will add another item (based on a ranking they have) Now the issue is, in order to know what they have on their list at the moment I send the remaining items to the database (say they deleted Kiwi, I would send Apple, Orange, Banana, and Grape) So now I select the highest ranked 5 items from are remaining six items, make sure they are not the ones already displayed on the page, and then add the new one to list (either Peach or Blackberry) All good and well, except that if both peach and blackberry now outrank grape, then I will be returning two results instead of just one. Because it would've searched... Apple Orange Banana Peach Blackberry and excluded... Apple Orange Banana Grape Which leaves us with both Peach and Blackberry, instead of just Peach or Blackberry

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  • QListWidget drag and drop items disappearing from list

    - by ppalasek
    Hello, I'm having trouble implementing a QListWidget with custom items that can be reordered by dragging and dropping. The problem is when I make a fast double click (a very short drag&drop) on an item, the item sometimes disappears from the QListWidget. This is the constructor for my Widget: ListPopisiDragDrop::ListPopisiDragDrop(QWidget *parent) : QListWidget(parent) { setSelectionMode(QAbstractItemView::SingleSelection); setDragEnabled(true); viewport()->setAcceptDrops(true); setDefaultDropAction(Qt::MoveAction); setDropIndicatorShown(true); setDragDropMode(QAbstractItemView::InternalMove); } also the drop event: void ListPopisiDragDrop::dropEvent(QDropEvent *event){ int startRow=currentIndex().row(); QListWidget::dropEvent(event); int endRow=currentIndex().row(); //more code... } Custom items are made by implementing paint() and sizeHint() functions from QAbstractItemDelegate. When the problem with disappearing items happens, the dropEvent isn't even called. I really don't know what is happening and if I'm doing something wrong. Any help is appreciated. Thanks! Edit: I'm running the application on a Symbian S60 5th edition phone. Edit2: If I add this line to the constructor: setDragDropOverwriteMode(true); the item in the list still disappears, but an empty row stays in it's place.

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  • hosting a high traffic facebook app (game)

    - by z3cko
    we are currently developing a high traffic facebook application. all the traffic will be within one month, where there are 500.000 to 1.000.000 expected users. after that month, the game is over and we have a winner - so the app will be archived. we are currently planning to develop the application with ruby on rails and searching for hosting options that can deal with the traffic. the problem is not so much the users, but the peak values: we will have around 500.000 requests coming daily within a short timeframe (lets say within 3 minutes in the worst case) we are expecting 500.000 to 1.000.000 users of the application, with peaks at 1:00pm (timezone GMT+1), where most (up to 80% of the users) will send most of the requests. the requests are from 11th of june to 11.july - after that, the app/game is closed/over. we are currently developing an aggressive caching mechanism - currently we are thinking about 2 or 3 small apps/webservices, that will handle the load. the load is distributed as follows: a) main application, cached data (11 screens, 200k each) b) voting: every day until 1:00pm (timezone GMT+1) - every user votes with about 10k data sent, high concurrent peak values! questions: is there any specific application setup that is recommendable? are there any hosting partners that can be recommended? thanks!

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  • figuring out which field to look for a value in with SQL and perl

    - by Micah
    I'm not too good with SQL and I know there's probably a much more efficient way to accomplish what I'm doing here, so any help would be much appreciated. Thanks in advance for your input! I'm writing a short program for the local school high school. At this school, juniors and seniors who have driver's licenses and cars can opt to drive to school rather than ride the bus. Each driver is assigned exactly one space, and their DLN is used as the primary key of the driver's table. Makes, models, and colors of cars are stored in a separate cars table, related to the drivers table by the License plate number field. My idea is to have a single search box on the main GUI of the program where the school secretary can type in who/what she's looking for and pull up a list of results. Thing is, she could be typing a license plate number, a car color, make, and model, someone driver's name, some student driver's DLN, or a space number. As the programmer, I don't know what exactly she's looking for, so a couple of options come to mind for me to build to be certain I check everywhere for a match: 1) preform a couple of SELECT * FROM [tablename] SQL statements, one per table and cram the results into arrays in my program, then search across the arrays one element at a time with regex, looking for a matched pattern similar to the search term, and if I find one, add the entire record that had a match in it to a results array to display on screen at the end of the search. 2) take whatever she's looking for into the program as a scaler and prepare multiple select statements around it, such as SELECT * FROM DRIVERS WHERE DLN = $Search_Variable SELECT * FROM DRIVERS WHERE First_Name = $Search_Variable SELECT * FROM CARS WHERE LICENSE = $Search_Variable and so on for each attribute of each table, sticking the results into a results array to show on screen when the search is done. Is there a cleaner way to go about this lookup without having to make her specify exactly what she's looking for? Possibly some kind of SQL statement I've never seen before?

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  • Safari and Chrome back button changes hidden and submit values in forms

    - by OverClocked
    The following problem happens on both Safari and Chrome, so probably a WebKit issue. Page A: a page that requires you to login to see, contains a form that has a type=submit button, with name=submit, and value=a Page B: some other page Page C: ask user to login page, contains a form with a type=submit button, with name=submit and value=c User visits page A, then page B. Then idles and the user's login session times out. User hits back button to go back to page A. Browser redirects user to page C. On Safari and Chrome, when C is rendered, the form on page C has the type=submit button, name=submit, but value shows up as "a". If you reload while on page C, "c" appears as the value of the name=submit button. The same problem appears with type=hidden input fields; when user hits back button, their values are also changed to some other value from some other form. Also, this problem also shows up w/o the redirect, with just submit then back. In this case the previous page renders with incorrect values for hidden and submit CGI variables. So far the only fix I can come up with is use Javascript to reset the type=hidden and type=submit variable values, after page C loads, to make sure the values are correct. But that's not clean and universally applicable. Short of WebKit fixing this error, has anyone ran into a better workaround? Thanks.

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  • Casting Type array to Generic array?

    - by George R
    The short version of the question - why can't I do this? I'm restricted to .NET 3.5. T[] genericArray; // Obviously T should be float! genericArray = new T[3]{ 1.0f, 2.0f, 0.0f }; // Can't do this either, why the hell not genericArray = new float[3]{ 1.0f, 2.0f, 0.0f }; Longer version - I'm working with the Unity engine here, although that's not important. What is - I'm trying to throw conversion between its fixed Vector2 (2 floats) and Vector3 (3 floats) and my generic Vector< class. I can't cast types directly to a generic array. using UnityEngine; public struct Vector { private readonly T[] _axes; #region Constructors public Vector(int axisCount) { this._axes = new T[axisCount]; } public Vector(T x, T y) { this._axes = new T[2] { x, y }; } public Vector(T x, T y, T z) { this._axes = new T[3]{x, y, z}; } public Vector(Vector2 vector2) { // This doesn't work this._axes = new T[2] { vector2.x, vector2.y }; } public Vector(Vector3 vector3) { // Nor does this this._axes = new T[3] { vector3.x, vector3.y, vector3.z }; } #endregion #region Properties public T this[int i] { get { return _axes[i]; } set { _axes[i] = value; } } public T X { get { return _axes[0];} set { _axes[0] = value; } } public T Y { get { return _axes[1]; } set { _axes[1] = value; } } public T Z { get { return this._axes.Length (Vector2 vector2) { Vector vector = new Vector(vector2); return vector; } public static explicit operator Vector(Vector3 vector3) { Vector vector = new Vector(vector3); return vector; } #endregion }

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  • Parsing: How to make error recovery in grammars like " a* b*"?

    - by Lavir the Whiolet
    Let we have a grammar like this: Program ::= a* b* where "*" is considered to be greedy. I usually implement "*" operator naively: Try to apply the expression under "*" to input one more time. If it has been applied successfully then we are still under current "*"-expression; try to apply the expression under "*" one more time. Otherwise we have reached next grammar expression; put characters parsed by expression under "*" back into input and proceed with next expression. But if there are errors in input in any of "a*" or "b*" part such a parser will "think" that in position of error both "a*" and "b*" have finished ("let's try "a"... Fail! OK, it looks like we have to proceed to "b*". Let's try "b"... Fail! OK, it looks like the string should have been finished...). For example, for string "daaaabbbbbbc" it will "say": "The string must end at position 1, delete superflous characters: daaaabbbbbbc". In short, greedy "*" operator becomes lazy if there are errors in input. How to make "*" operator to recover from errors nicely?

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  • How to intercept touch events globally?

    - by mystify
    I have an view which is sometimes covered by some other views. However, if the user slides the finger across the screen, I want to slide that underlying view across the screen, too. I could start making custom views for all those covering subviews and forward all kinds of touch events, but that's somewhat cumbersome. Maybe there's some kind of notification or another way that a UIView or UIControl subclass can be aware of touch events happening right now, no matter where they are. In short: I need an UIView subclass or UIControl subclass which knows about any touch events happening on the entire screen. Or at least if tht's not possible, knowing about any touch events happening above itself in the same underlying superview. Another description: There are 20 views, all reside inside the same superview. The first view is covered by 19 others. But if the user slides across the screen, that first view must slide too, so it must be aware of touch events. Is there any better solution that making all 19 views forward touch events? (yes, all 19 views respond to touch events in this example)

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  • Fastest way to perform subset test operation on a large collection of sets with same domain

    - by niktech
    Assume we have trillions of sets stored somewhere. The domain for each of these sets is the same. It is also finite and discrete. So each set may be stored as a bit field (eg: 0000100111...) of a relatively short length (eg: 1024). That is, bit X in the bitfield indicates whether item X (of 1024 possible items) is included in the given set or not. Now, I want to devise a storage structure and an algorithm to efficiently answer the query: what sets in the data store have set Y as a subset. Set Y itself is not present in the data store and is specified at run time. Now the simplest way to solve this would be to AND the bitfield for set Y with bit fields of every set in the data store one by one, picking the ones whose AND result matches Y's bitfield. How can I speed this up? Is there a tree structure (index) or some smart algorithm that would allow me to perform this query without having to AND every stored set's bitfield? Are there databases that already support such operations on large collections of sets?

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  • How to change the meaning of pointer access operator

    - by kumar_m_kiran
    Hi All, This may be very obvious question, pardon me if so. I have below code snippet out of my project, #include <stdio.h> class X { public: int i; X() : i(0) {}; }; int main(int argc,char *arv[]) { X *ptr = new X[10]; unsigned index = 5; cout<<ptr[index].i<<endl; return 0; } Question Can I change the meaning of the ptr[index] ? Because I need to return the value of ptr[a[index]] where a is an array for subindexing. I do not want to modify existing source code. Any new function added which can change the behavior is needed. Since the access to index operator is in too many places (536 to be precise) in my code, and has complex formulas inside the index subscript operator, I am not inclined to change the code in many locations. PS : 1. I tried operator overload and came to conclusion that it is not possible. 2. Also p[i] will be transformed into *(p+i). I cannot redefine the basic operator '+'. So just want to reconfirm my understanding and if there are any possible short-cuts to achieve. Else I need fix it by royal method of changing every line of code :) .

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  • C: socket connection timeout

    - by The.Anti.9
    I have a simple program to check if a port is open, but I want to shorten the timeout length on the socket connection because the default is far too long. I'm not sure how to do this though. Here's the code: #include <sys/socket.h> #include <sys/time.h> #include <sys/types.h> #include <arpa/inet.h> #include <netinet/in.h> #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <netdb.h> #include <stdlib.h> #include <string.h> #include <unistd.h> int main(int argc, char **argv) { u_short port; /* user specified port number */ char addr[1023]; /* will be a copy of the address entered by u */ struct sockaddr_in address; /* the libc network address data structure */ short int sock = -1; /* file descriptor for the network socket */ if (argc != 3) { fprintf(stderr, "Usage %s <port_num> <address>", argv[0]); return EXIT_FAILURE; } address.sin_addr.s_addr = inet_addr(argv[2]); /* assign the address */ address.sin_port = htons(atoi(argv[2])); /* translate int2port num */ sock = socket(AF_INET, SOCK_STREAM, 0); if (connect(sock,(struct sockaddr *)&address,sizeof(address)) == 0) { printf("%i is open\n", port); } close(sock); return 0; }

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  • Parse error: syntax error, unexpected T_STRING with index.php?

    - by janoChen
    It works perfectly in local host but when I upload it intothe server it has the following error: Parse error: syntax error, unexpected T_STRING in D:\Hosting\4923367\html\beta\index.php on line 4 index.php: <?php include_once 'localization.php'; ?> <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <!--Start Kampyle Exit-Popup Code--> <script type="text/javascript"> var k_push_vars = { "view_percentage": 10, "popup_font_color": "#000000", "popup_background": "#D4E2F0", "header": "Your feedback is important to us!", "question": "Would you be willing to give us a short (1 minute) feedback?", "footer": "Thank you for helping us improve our website", "yes": "Yes", "no": "No", "text_direction": "ltr", "images_dir": "http://cf.kampyle.com/", "yes_background": "#76AC78", "no_background": "#8D9B86", "site_code": 9662374 } </script> <script type="text/javascript" src="http://cf.kampyle.com/k_push.js"></script> <!--End Kampyle Exit-Popup Code--> <!-- Start Kampyle Css --> <link rel="stylesheet" type="text/css" media="screen" href="http://cf.kampyle.com/k_button.css" /> <!-- End Kampyle Css --> (continues)

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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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  • Variable length argument list - How to understand we retrieved the last argument?

    - by hkBattousai
    I have a Polynomial class which holds coefficients of a given polynomial. One of its overloaded constructors is supposed to receive these coefficients via variable argument list. template <class T> Polynomial<T>::Polynomial(T FirstCoefficient, ...) { va_list ArgumentPointer; va_start(ArgumentPointer, FirstCoefficient); T NextCoefficient = FirstCoefficient; std::vector<T> Coefficients; while (true) { Coefficients.push_back(NextCoefficient); NextCoefficient = va_arg(ArgumentPointer, T); if (/* did we retrieve all the arguments */) // How do I implement this? { break; } } m_Coefficients = Coefficients; } I know that we usually pass an extra parameter which tells the recipient method the total number of parameters, or we pass a sentimental ending parameter. But in order to keep thing short and clean, I don't prefer passing an extra parameter. Is there any way of doing this without modifying the method signature in the example?

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  • declarative_authorization permissions on roles

    - by William
    Hey all, I'm trying to add authorization to a rather large app that already exists, but I have to obfuscate the details a bit. Here's the background: In our app we have a number or roles that are hierarchical, roughly like this: BasicUser -> SuperUser -> Admin -> SuperAdmin For authorization each User model instance has an attribute 'role' which corresponds to the above. We have a RESTful controller "Users" that is namespaced under Backoffice. So in short it's Backoffice::UsersController. class Backoffice::UsersController < ApplicationController filter_access_to :all #... RESTful actions + some others end So here's the problem: We want users to be able to give permissions for users to edit users but ONLY if they have a 'smaller' role than they currently have. I've created the following in authorization_rules.rb authorization do role :basic_user do has_permission_on :backoffice_users, :to => :index end role :super_user do includes :basic_user has_permission_on :backoffice_users, :to => :edit do if_attribute :role => is_in { %w(basic_user) } end end role :admin do includes :super_user end role :super_admin do includes :admin end end And unfortunately that's as far as I got, the rule doesn't seem to get applied. If I comment the rule out, nobody can edit If I leave the rule in you can edit everybody I've also tried a couple of variations on the if_attribute: if_attribute :role => is { 'basic_user' } if_attribute :role => 'basic_user' and they get the same effect. Does anybody have any suggestions?

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  • Cannot Find Symbol Method?

    - by Aaron
    In my driver program, This line gives me cannot find symbol error and I don't know why, the method is clearly defined in the SavingsAccount class, and I can refer to all other methods in my driver program but just not that one, I tried changing the type to double, and etc but still not working. Refer to ** Account acct2 = new SavingsAccount (name); acct2.calculateBalance(); SavingsAccount Class Inherited from Account Class: public class SavingsAccount extends Account { private final short minBalance = 0; private double overdraftFee; private double yearlyInterestRate = 0.02; private double interestAmount; public SavingsAccount (String name) { super(name); } public double withdraw (double amount) { if (accountBalance - amount >= minBalance) { accountBalance -= amount; System.out.print ("Withdraw Successful"); } else { accountBalance -= amount; overdraftFee = accountBalance * (0.10); accountBalance += overdraftFee; System.out.print ("Withdraw Succesful, however overdraft fee of 10% has been applied to your account"); } return accountBalance; } **public void calculateBalance () { interestAmount = (accountBalance * yearlyInterestRate); accountBalance += interestAmount; }** public String toString() { return super.toString() + " Interest Received: " + interestAmount; } } Account class, if needed import java.util.Random; import java.text.NumberFormat; public abstract class Account { protected double accountBalance; protected long accountNumber; protected String accountHolder; public Account (String name) { accountHolder = name; accountBalance = 0; Random accountNo = new Random(); accountNumber = accountNo.nextInt(100000); } public double deposit (double amount) { accountBalance += amount; return accountBalance; } public String toString() { NumberFormat accountBal = NumberFormat.getCurrencyInstance(); return "Account Balance: " + accountBal.format(accountBalance) + "\nAccount Number: " + accountNumber; } public String getAccountHolder() { return accountHolder; } public double getAccountBalance() { return accountBalance; } public abstract double withdraw (double amount); }

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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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