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  • Boost bind with asio::placeholders::error

    - by Leandro
    Why it doesn't work? --- boost_bind.cc --- #include #include #include void func1 (const int& i) { } void func2 (const ::asio::error_code& e) { } int main () { ::boost::function f1 = ::boost::bind (&func1, 1); // it doesn't work! ::boost::function f2 = ::boost::bind (&func2, ::asio::placeholders::error); return 0; } This is the error: while_true@localhost:~ g++ -lpthread boost_bind.cc -o boost_bind In file included from boost_bind.cc:2: /usr/include/boost/bind.hpp: In member function ‘void boost::_bi::list1::operator()(boost::_bi::type, F&, A&, int) [with F = void (*)(const asio::error_code&), A = boost::_bi::list0, A1 = boost::arg (*)()]’: /usr/include/boost/bind/bind_template.hpp:20: instantiated from ‘typename boost::_bi::result_traits::type boost::_bi::bind_t::operator()() [with R = void, F = void (*)(const asio::error_code&), L = boost::_bi::list1 (*)()]’ /usr/include/boost/function/function_template.hpp:152: instantiated from ‘static void boost::detail::function::void_function_obj_invoker0::invoke(boost::detail::function::function_buffer&) [with FunctionObj = boost::_bi::bind_t (*)() , R = void]’ /usr/include/boost/function/function_template.hpp:904: instantiated from ‘void boost::function0::assign_to(Functor) [with Functor = boost::_bi::bind_t (*)() , R = void]’ /usr/include/boost/function/function_template.hpp:720: instantiated from ‘boost::function0::function0(Functor, typename boost::enable_if_c::type) [with Functor = boost::_bi::bind_t (*)() , R = void]’ /usr/include/boost/function/function_template.hpp:1040: instantiated from ‘boost::function::function(Functor, typename boost::enable_if_c::type) [with Functor = boost::_bi::bind_t (*)() , R = void]’ boost_bind.cc:14: instantiated from here /usr/include/boost/bind.hpp:232: error: no match for ‘operator[]’ in ‘a[boost::_bi::storage1 (*)()::a1_ [with int I = 1]]’ while_true@localhost:~

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  • Has Twisted changed its dependencies?

    - by cdecker
    Hi all, I'm currently working on a Python/Twisted project which is to be distributed and tested on Planetlab. For some reason my code was working on friday and now that I wanted to test a minor change it refuses to work at all: Traceback (most recent call last): File "acn_a4/src/node.py", line 6, in <module> from twisted.internet.protocol import DatagramProtocol File "/usr/lib/python2.5/site-packages/Twisted-10.0.0-py2.5-linux-i686.egg/twisted/__init__.py", line 18, in <module> from twisted.python import compat File "/usr/lib/python2.5/site-packages/Twisted-10.0.0-py2.5-linux-i686.egg/twisted/python/compat.py", line 146, in <module> import operator File "/home/cdecker/dev/acn/acn_a4/src/operator.py", line 7, in <module> File "/home/cdecker/acn_a4/src/node.py", line 6, in <module> from twisted.internet.protocol import DatagramProtocol File "/usr/lib/python2.5/site-packages/Twisted-10.0.0-py2.5-linux-i686.egg/twisted/internet/protocol.py", line 20, in <module> from twisted.python import log, failure, components File "/usr/lib/python2.5/site-packages/Twisted-10.0.0-py2.5-linux-i686.egg/twisted/python/log.py", line 19, in <module> from twisted.python import util, context, reflect File "/usr/lib/python2.5/site-packages/Twisted-10.0.0-py2.5-linux-i686.egg/twisted/python/util.py", line 5, in <module> import os, sys, hmac, errno, new, inspect, warnings File "/usr/lib/python2.5/inspect.py", line 32, in <module> from operator import attrgetter ImportError: cannot import name attrgetter And since I'm pretty new to python I have no idea what could have caused this problem. All suggestions are welcome :-)

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  • Using NHibernate's HQL to make a query with multiple inner joins

    - by Abu Dhabi
    The problem here consists of translating a statement written in LINQ to SQL syntax into the equivalent for NHibernate. The LINQ to SQL code looks like so: var whatevervar = from threads in context.THREADs join threadposts in context.THREADPOSTs on threads.thread_id equals threadposts.thread_id join posts1 in context.POSTs on threadposts.post_id equals posts1.post_id join users in context.USERs on posts1.user_id equals users.user_id orderby posts1.post_time where threads.thread_id == int.Parse(id) select new { threads.thread_topic, posts1.post_time, users.user_display_name, users.user_signature, users.user_avatar, posts1.post_body, posts1.post_topic }; It's essentially trying to grab a list of posts within a given forum thread. The best I've been able to come up with (with the help of the helpful users of this site) for NHibernate is: var whatevervar = session.CreateQuery("select t.Thread_topic, p.Post_time, " + "u.User_display_name, u.User_signature, " + "u.User_avatar, p.Post_body, p.Post_topic " + "from THREADPOST tp " + "inner join tp.Thread_ as t " + "inner join tp.Post_ as p " + "inner join p.User_ as u " + "where tp.Thread_ = :what") .SetParameter<THREAD>("what", threadid) .SetResultTransformer(Transformers.AliasToBean(typeof(MyDTO))) .List<MyDTO>(); But that doesn't parse well, complaining that the aliases for the joined tables are null references. MyDTO is a custom type for the output: public class MyDTO { public string thread_topic { get; set; } public DateTime post_time { get; set; } public string user_display_name { get; set; } public string user_signature { get; set; } public string user_avatar { get; set; } public string post_topic { get; set; } public string post_body { get; set; } } I'm out of ideas, and while doing this by direct SQL query is possible, I'd like to do it properly, without defeating the purpose of using an ORM. Thanks in advance!

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  • How to print a number with a space as thousand separator?

    - by dygi
    I've got a simple class Currency with overloaded operator<<. I don't know how can i separate the number with spaces every 3 digits, so it looks like: "1 234 567 ISK". #include <cstdlib> #include <iostream> using namespace std; class Currency { int val; char curr[4]; public: Currency(int _val, const char * _curr) { val = _val; strcpy(curr, _curr); } friend ostream & operator<< (ostream & out, const Currency & c); }; ostream & operator<< (ostream & out, const Currency & c) { out << c.val<< " " << c.curr; return out; } int main(int argc, char *argv[]) { Currency c(2354123, "ISK"); cout << c; } What interests me, is somehow the easiest solution for this particular situation.

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  • How do you save images to a Blackberry device via HttpConnection?

    - by Kai
    My script fetches xml via httpConnection and saves to persistent store. No problems there. Then I loop through the saved data to compose a list of image url's to fetch via queue. Each of these requests calls the httpConnection thread as so ... public synchronized void run() { HttpConnection connection = (HttpConnection)Connector.open("http://www.somedomain.com/image1.jpg"); connection.setRequestMethod("GET"); String contentType = connection.getHeaderField("Content-type"); InputStream responseData = connection.openInputStream(); connection.close(); outputFinal(responseData, contentType); } public synchronized void outputFinal(InputStream result, String contentType) throws SAXException, ParserConfigurationException, IOException { if(contentType.startsWith("text/")) { // bunch of xml save code that works fine } else if(contentType.equals("image/png") || contentType.equals("image/jpeg") || contentType.equals("image/gif")) { // how to save images here? } else { //default } } What I can't find any good documentation on is how one would take the response data and save it to an image stored on the device. Maybe I just overlooked something very obvious. Any help is very appreciated. Thanks

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  • Using a custom IList obtained through NHibernate

    - by Abu Dhabi
    Hi.I'm trying to write a web page in .NET, using C# and NHibernate 2.1. The pertinent code looks like this: var whatevervar = session.CreateSQLQuery("select thread_topic, post_time, user_display_name, user_signature, user_avatar, post_topic, post_body from THREAD, [USER], POST, THREADPOST where THREADPOST.thread_id=" + id + " and THREADPOST.thread_id=THREAD.thread_id and [USER].user_id=POST.user_id and POST.post_id=THREADPOST.post_id ORDER BY post_time;").List(); (I have tried to use joins in HQL, but then fell back on this query, due to HQL's unreadability.) The problem is that I'm getting a result that is incompatible with a repeater. When I try this: posts.DataSource = whatevervar.; posts.DataBind(); ...I get this: DataBinding: 'System.Object[]' does not contain a property with the name 'user_avatar'. In an earlier project, I used LINQ to SQL for this same purpose, and it looked like so: var whatevervar = from threads in context.THREADs join threadposts in context.THREADPOSTs on threads.thread_id equals threadposts.thread_id join posts1 in context.POSTs on threadposts.post_id equals posts1.post_id join users in context.USERs on posts1.user_id equals users.user_id orderby posts1.post_time where threads.thread_id == int.Parse(id) select new { threads.thread_topic, posts1.post_time, users.user_display_name, users.user_signature, users.user_avatar, posts1.post_body, posts1.post_topic }; That worked, and now I want to do the same with NHibernate. Unfortunately, I don't know how to make the repeater recognize the fields of the result of the query. Thanks in advance!

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  • video calling (center)

    - by rrejc
    We are starting to develop a new application and I'm searching for information/tips/guides on application architecture. Application should: read the data from an external (USB) device send the data to the remote server (through internet) receive the data from the remote server perform a video call with to the calling (support) center receive a video call call from the calling (support) center support touch screens In addition: some of the data should also be visible through the web page. So I was thinking about: On the server side: use the database (probably MS SQL) use ORM (nHibernate) to map the data from the DB to the domain objects create a layer with business logic in C# create a web (WCF) services (for client application) create an asp.net mvc application (for item 7.) to enable data view through the browser On the client side I would use WPF 4 application which will communicate with external device and the wcf services on the server. So far so good. Now the problem begins. I have no idea how to create a video call (outgoing or incoming) part of the application. I believe that there is no problem to communicate with microphone, speaker, camera with WPF/C#. But how to communicate with the call center? What protocol and encoding should be used? I think that I will need to create some kind of server which will: have a list of operators in the calling center and track which operator is occupied and which operator is free have a list of connected end users receive incoming calls from end users and delegate call to free operator delegate calls from calling center to the end user Any info, link, anything on where to start would be much appreciated. Many thanks!

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  • Quering XElements for children with children attributes.

    - by Arnej65
    Here is the XML outline: <Root> <Thing att="11"> <Child lang="e"> <record></record> <record></record> <record></record> </Child > <Child lang="f"> <record></record> <record></record> <record></record> </Child > </Thing> </Root> I have the following: TextReader reader = new StreamReader(Assembly.GetExecutingAssembly() .GetManifestResourceStream(FileName)); var data = XElement.Load(reader); foreach (XElement single in Data.Elements()) { // english records var EnglishSet = (from e in single.Elements("Child") where e.Attribute("lang").Equals("e") select e.Value).FirstOrDefault(); } But I'm getting back nothing. I want to be able to for Each "Thing" select the "Child" where the attribute "lang" equals a value. I have also tried this, which has not worked. var FrenchSet = single.Elements("Child") .Where(y => y.Attribute("lang").Equals("f")) .Select(x => x.Value).FirstOrDefault();

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  • Coredump in Multithreading Application in RHEL-5

    - by Chinnu
    I am working on multi-threading application it is dumping frequently.I could not able to analyaze the core.The core is showing like this Core was generated by 'thread-process'. Program terminated with signal 6, Aborted. #0 0x00000038f4e30045 in raise () from /lib64/libc.so.6 (gdb) where #0 0x00000038f4e30045 in raise () from /lib64/libc.so.6 #1 0x00000038f4e31ae0 in abort () from /lib64/libc.so.6 #2 0x00000038f4e681bb in __libc_message () from /lib64/libc.so.6 #3 0x00000038f4e72b96 in free () from /lib64/libc.so.6 #4 0x000000000046a137 in std::string::substr () #5 0x000000000042c549 in std::operator<< <char, std::char_traits<char>, std::allocator<char> > () #6 0x000000000042cc1d in std::operator<< <char, std::char_traits<char>, std::allocator<char> > () #7 0x000000000046b069 in std::string::substr () #8 0x000000000046c866 in std::string::substr () #9 0x0000000000431062 in std::operator<< <char, std::char_traits<char>, std::allocator<char> > () #10 0x00000038f5a062e7 in start_thread () from /lib64/libpthread.so.0 #11 0x00000038f4ece3bd in clone () from /lib64/libc.so.6

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  • Does NULL and nil are equal?

    - by monish
    Hi Guys, Actually my question here is does Null and nil are equal or not? I had an Example but I am confused when they are equal when they are not. NSNull *nullValue = [NSNull null]; NSArray *arrayWithNull = [NSArray arrayWithObject:nullValue]; NSLog(@"arrayWithNull: %@", arrayWithNull); id aValue = [arrayWithNull objectAtIndex:0]; if (aValue == nil) { NSLog(@"equals nil"); } else if (aValue == [NSNull null]) { NSLog(@"equals NSNull instance"); if ([aValue isEqual:nil]) { NSLog(@"isEqual:nil"); } } Here in the above case it shows that both Null and nil are not equal and it displays "equals NSNull instance" NSString *str=NULL; id str1=nil; if(str1 == str) { printf("\n IS EQUAL........"); } else { printf("\n NOT EQUAL........"); } And in the second case it shows both are equal and it displays "IS EQUAL". Anyone's help will be much appreciated. Thank you, Monish.

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  • IComparable not included when serializing in WCF

    - by djerry
    Hey guys, I have a list i'm filling at server side. It's a list of "User", which implements IComparable. Now when WCF is serializing the data, i guess it's not including the CompareTo method. This is my Object class : [DataContract] public class User : IComparable { private string e164, cn, h323; private int id; private DateTime lastActive; [DataMember] public DateTime LastActive { get { return lastActive; } set { laatstActief = value; } } [DataMember] public int Id { get { return id; } set { id = value; } } [DataMember] public string H323 { get { return h323; } set { h323 = value; } } [DataMember] public string Cn { get { return cn; } set { cn = value; } } [DataMember] public string E164 { get { return e164; } set { e164 = value; } } public User() { } public User(string e164, string cn, string h323, DateTime lastActive) { this.E164 = e164; this.Cn = cn; this.H323 = h323; this.LastActive= lastActive; } [DataMember] public string ToStringExtra { get { if (h323 != "/" && h323 != "") return h323 + " (" + e164 + ")"; return e164; } set { ;} } public override string ToString() { if (Cn.Equals("Trunk Line") || Cn.Equals("")) if (h323.Equals("")) return E164; else return h323; return Cn; } public int CompareTo(object obj) { User user = (User)obj; return user.LastActive.CompareTo(this.LastActive); } } Is it possible to get the CompareTo method to reach the client? Putting [DataMember] isn't the solution as i tried it ( i know...). Thanks in advance.

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  • rails: has_many :through validation?

    - by ramonrails
    Rails 2.1.0 (Cannot upgrade for now due to several constraints) I am trying to achieve this. Any hints? A project has many users through join model A user has many projects through join model Admin class inherits User class. It also has some Admin specific stuff. Admin like inheritance for Supervisor and Operator Project has one Admin, One supervisor and many operators. Now I want to 1. submit data for project, admin, supervisor and operator in a single project form 2. validate all and show errors on the project form. Project has_many :projects_users ; has_many :users, :through => :projects_users User has_many :projects_users ; has_many :projects, :through => :projects_users ProjectsUser = :id integer, :user_id :integer, :project_id :integer, :user_type :string ProjectUser belongs_to :project, belongs_to :user Admin < User # User has 'type:string' column for STI Supervisor < User Operator < User Is the approach correct? Any and all suggestions are welcome.

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  • More FP-correct way to create an update sql query

    - by James Black
    I am working on access a database using F# and my initial attempt at creating a function to create the update query is flawed. let BuildUserUpdateQuery (oldUser:UserType) (newUser:UserType) = let buf = new System.Text.StringBuilder("UPDATE users SET "); if (oldUser.FirstName.Equals(newUser.FirstName) = false) then buf.Append("SET first_name='").Append(newUser.FirstName).Append("'" ) |> ignore if (oldUser.LastName.Equals(newUser.LastName) = false) then buf.Append("SET last_name='").Append(newUser.LastName).Append("'" ) |> ignore if (oldUser.UserName.Equals(newUser.UserName) = false) then buf.Append("SET username='").Append(newUser.UserName).Append("'" ) |> ignore buf.Append(" WHERE id=").Append(newUser.Id).ToString() This doesn't properly put a , between any update parts after the first, for example: UPDATE users SET first_name='Firstname', last_name='lastname' WHERE id=... I could put in a mutable variable to keep track when the first part of the set clause is appended, but that seems wrong. I could just create an list of tuples, where each tuple is oldtext, newtext, columnname, so that I could then loop through the list and build up the query, but it seems that I should be passing in a StringBuilder to a recursive function, returning back a boolean which is then passed as a parameter to the recursive function. Does this seem to be the best approach, or is there a better one?

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  • How to pass multiple different records (not class due to delphi limitations) to a function?

    - by mingo
    Hi to all. I have a number of records I cannot convert to classes due to Delphi limitation (all of them uses class operators to implement comparisons). But I have to pass to store them in a class not knowing which record type I'm using. Something like this: type R1 = record begin x :Mytype; class operator Equal(a,b:R1) end; type R2 = record begin y :Mytype; class operator Equal(a,b:R2) end; type Rn = record begin z :Mytype; class operator Equal(a,b:Rn) end; type TC = class begin x : TObject; y : Mytype; function payload (n:TObject) end; function TC.payload(n:TObject) begin x := n; end; program: c : TC; x : R1; y : R2; ... c := TC.Create(): n:=TOBject(x); c.payload(n); Now, Delphi do not accept typecast from record to TObject, and I cannot make them classes due to Delphi limitation. Anyone knows a way to pass different records to a function and recognize their type when needed, as we do with class: if x is TMyClass then TMyClass(x) ... ???

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  • function objects versus function pointers

    - by kumar_m_kiran
    Hi All, I have two questions related to function objects and function pointers, Question : 1 When I read the different uses sort algorithm of STL, I see that the third parameter can be a function objects, below is an example class State { public: //... int population() const; float aveTempF() const; //... }; struct PopLess : public std::binary_function<State,State,bool> { bool operator ()( const State &a, const State &b ) const { return popLess( a, b ); } }; sort( union, union+50, PopLess() ); Question : Now, How does the statement, sort(union, union+50,PopLess()) work? PopLess() must be resolved into something like PopLess tempObject.operator() which would be same as executing the operator () function on a temporary object. I see this as, passing the return value of overloaded operation i.e bool (as in my example) to sort algorithm. So then, How does sort function resolve the third parameter in this case? Question : 2 Question Do we derive any particular advantage of using function objects versus function pointer? If we use below function pointer will it derive any disavantage? inline bool popLess( const State &a, const State &b ) { return a.population() < b.population(); } std::sort( union, union+50, popLess ); // sort by population PS : Both the above references(including example) are from book "C++ Common Knowledge: Essential Intermediate Programming" by "Stephen C. Dewhurst". I was unable to decode the topic content, thus have posted for help. Thanks in advance for your help.

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  • How `is_base_of` works?

    - by Alexey Malistov
    Why the following code works? typedef char (&yes)[1]; typedef char (&no)[2]; template <typename B, typename D> struct Host { operator B*() const; operator D*(); }; template <typename B, typename D> struct is_base_of { template <typename T> static yes check(D*, T); static no check(B*, int); static const bool value = sizeof(check(Host<B,D>(), int())) == sizeof(yes); }; //Test sample class Base {}; class Derived : private Base {}; //Exspression is true. int test[is_base_of<Base,Derived>::value && !is_base_of<Derived,Base>::value]; Note that B is private base. Note that operator B*() is const. How does this work? Why this works? Why static yes check(D*, T); is better than static yes check(B*, int); ?

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  • using switch in strings

    - by xtemer
    guys me trying to use switch in strings by first coverting string into char and then apply switch but still didnt done it....here is my code..help me out.. import javax.swing.*; import java.io.*; class HappyBirthday { public static void main(String[] args) throws IOException { String Month; char[] Months = Month.toCharArray(); BufferedReader dataIn= new BufferedReader(new InputStreamReader(System.in)); System.out.println("Please enter your month."); Month = JOptionPane.showInputDialog("enter month"); String month1={"January","feb"}; char[] month2 = month1.toCharArray(); // String s=month1.equals(Month); //System.out.print(month2Array[0]); switch (month2) { case 0: System.out.println("kool"); break; case 1: System.out.println("not kool"); break; default: }}} /** if (month1[1].equals(Month)) System.out.println("kool"); else if(month1[0].equals(Month)) System.out.println("kooooooooooooool"); else System.out.println("Big kooooool"); **/

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  • Does this language feature already exists?

    - by Pindatjuh
    I'm currently developing a new language for programming in a continuous environment (compare it to electrical engineering), and I've got some ideas on a certain language construction. Let me explain the feature by explanation and then by definition; x = a | b; Where x is a variable and a and b are other variables (or static values). if(x == a) { // all references to "x" are essentially references to "a". } if(x == b) { // same but with "b" } if(x != a) { // ... } if(x == a | b) { // guaranteed that "x" is '"a" | "b"'; interacting with "x" // will interact with both "a" and "b". } // etc. In the above, all code-blocks are executed, but the "scope" changes in each block how x is interpreted. In the first block, x is guaranteed to be a: thus interacting with x inside that block will interact on a. The second and the third code-block are only equal in this situation (because not b only remains a). The last block guarantees that x is at least a or b. Further more; | is not the "bitwise or operator", but I've called it the "and/or"-operator. It's definition is: "|" = "and" | "or" (On my blog, http://cplang.wordpress.com/2009/12/19/binop-and-or/, is more (mathematical) background information on this operator. It's loosely based on sets.) I do not know if this construction already exists, so that's my question: does this language feature already exists?

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  • Is there a better way to write this LINQ query?

    - by Raj Aththanayake
    Hi Is there a better simplified way to write this query. My logic is if collection contains customer ids and countrycodes, do the query ordey by customer id ascending. If there are no contain id in CustIDs then do the order by customer name. Is there a better way to write this query? I'm not really familiar with complex lambdas. var custIdResult = (from Customer c in CustomerCollection where (c.CustomerID.ToLower().Contains(param.ToLower()) && (countryCodeFilters.Any(item => item.Equals(c.CountryCode))) ) select c).ToList(); if (custIdResult.Count > 0) { return from Customer c in custIdResult where ( c.CustomerName.ToLower().Contains(param.ToLower()) && countryCodeFilters.Any(item => item.Equals(c.CountryCode))) orderby c.CustomerID ascending select c; } else { return from Customer c in CustomerCollection where (c.CustomerName.ToLower().Contains(param.ToLower()) && countryCodeFilters.Any(item => item.Equals(c.CountryCode))) orderby c.CustomerName descending select c; }

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  • FileNotFoundException Java

    - by Troels Hansen
    Hi, I'm trying to make a simple highscore system for a minesweeper game. However i keep getting a file not found exception, and i've tried to use the full path for the file aswell. package minesweeper; import java.io.*; import java.util.*; public class Highscore{ public static void submitHighscore(String difficulty) throws IOException{ int easy = 99999; int normal = 99999; int hard = 99999; //int newScore = (int) MinesweeperView.getTime(); int newScore = 10; File f = new File("Highscores.dat"); if (!f.exists()){ f.createNewFile(); } Scanner input = new Scanner(f); PrintStream output = new PrintStream(f); if (input.hasNextInt()){ easy = input.nextInt(); normal = input.nextInt(); hard = input.nextInt(); } output.flush(); if(difficulty.equals("easy")){ if (easy > newScore){ easy = newScore; } }else if (difficulty.equals("normal")){ if (normal > newScore){ normal = newScore; } }else if (difficulty.equals("hard")){ if (hard > newScore){ hard = newScore; } } output.println(easy); output.println(normal); output.println(hard); } //temporary main method used for debugging public static void main(String[] args) throws IOException { submitHighscore("easy"); } }

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  • How to create an AST with ANTLR from a hierarchical key-value syntax

    - by Brabster
    I've been looking at parsing a key-value data format with ANTLR. Pretty straightforward, but the keys represent a hierarchy. A simplified example of my input syntax: /a/b/c=2 /a/b/d/e=3 /a/b/d/f=4 In my mind, this represents a tree structured as follows: (a (b (= c 2) (d (= e 3) (= f 4)))) The nearest I can get is to use the following grammar: /* Parser Rules */ start: (component NEWLINE?)* EOF -> (component)*; component: FORWARD_SLASH ALPHA_STRING component -> ^(ALPHA_STRING component) | FORWARD_SLASH ALPHA_STRING EQUALS value -> ^(EQUALS ALPHA_STRING value); value: ALPHA_STRING; /* Lexer Rules */ NEWLINE : '\r'? '\n'; ALPHA_STRING : ('a'..'z'|'A'..'Z'|'0'..'9')+; EQUALS : '='; FORWARD_SLASH : '/'; Which produces: (a (b (= c 2))) (a (b (d (= e 3)))) (a (b (d (= f 4)))) I'm not sure whether I'm asking too much from a generic tool such as ANTLR here, and this is as close I can get with this approach. That is, from here I consume the parts of the tree and create the data structure I want by hand. So - can I produce the tree structure I want directly from a grammar? If so, how? If not, why not - is it a technical limitation in ANTLR or is it something more CS-y to do with the type of language involved?

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  • how to rotate around each record in linq and show that in view

    - by Sadegh
    Hi, I have four tables in my database and i want to join that's and return record's and show that into searchController! My query is this: public IQueryable PerformSearch(string query) { if (!string.IsNullOrEmpty(query)) { var results = from tbl1 in context.Table1 join tbl2 in context.Table2 on tbl1.Id equals tbl2.Id join tbl3 in context.Table3 on tbl2.Id equals tbl3.Id join tbl4 in context.Table4 on tbl3.Id equals tbl4.Id where tbl1.col2.Contains(query) orderby tbl1.Count descending select new { col1 = tbl1.Col1, col1 = tbl1.Col1, col1 = tbl1.Col1, . . . }; return results.AsQueryable(); } else return null; } And this method called in SearchController as below: public class SearchController : System.Web.Mvc.Controller { public System.Web.Mvc.ActionResult Search(System.String query) { var search = new Search(); ViewData["result"] = search.PerformSearch(query); return View("Search"); } } I don't know how i can rotate around each record (plus vs intellisense feature) returned by PeformSeach method and show that in view! Also is this a good way? thanks in advance

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  • How might I wrap the FindXFile-style APIs to the STL-style Iterator Pattern in C++?

    - by BillyONeal
    Hello everyone :) I'm working on wrapping up the ugly innards of the FindFirstFile/FindNextFile loop (though my question applies to other similar APIs, such as RegEnumKeyEx or RegEnumValue, etc.) inside iterators that work in a manner similar to the Standard Template Library's istream_iterators. I have two problems here. The first is with the termination condition of most "foreach" style loops. STL style iterators typically use operator!= inside the exit condition of the for, i.e. std::vector<int> test; for(std::vector<int>::iterator it = test.begin(); it != test.end(); it++) { //Do stuff } My problem is I'm unsure how to implement operator!= with such a directory enumeration, because I do not know when the enumeration is complete until I've actually finished with it. I have sort of a hack together solution in place now that enumerates the entire directory at once, where each iterator simply tracks a reference counted vector, but this seems like a kludge which can be done a better way. The second problem I have is that there are multiple pieces of data returned by the FindXFile APIs. For that reason, there's no obvious way to overload operator* as required for iterator semantics. When I overload that item, do I return the file name? The size? The modified date? How might I convey the multiple pieces of data to which such an iterator must refer to later in an ideomatic way? I've tried ripping off the C# style MoveNext design but I'm concerned about not following the standard idioms here. class SomeIterator { public: bool next(); //Advances the iterator and returns true if successful, false if the iterator is at the end. std::wstring fileName() const; //other kinds of data.... }; EDIT: And the caller would look like: SomeIterator x = ??; //Construct somehow while(x.next()) { //Do stuff } Thanks! Billy3

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  • Object equality in context of hibernate / webapp

    - by bert
    How do you handle object equality for java objects managed by hibernate? In the 'hibernate in action' book they say that one should favor business keys over surrogate keys. Most of the time, i do not have a business key. Think of addresses mapped to a person. The addresses are keeped in a Set and displayed in a Wicket RefreshingView (with a ReuseIfEquals strategy). I could either use the surrogate id or use all fields in the equals() and hashCode() functions. The problem is that those fields change during the lifetime ob the object. Either because the user entered some data or the id changes due to JPA merge() being called inside the OSIV (Open Session in View) filter. My understanding of the equals() and hashCode() contract is that those should not change during the lifetime of an object. What i have tried so far: equals() based on hashCode() which uses the database id (or super.hashCode() if id is null). Problem: new addresses start with an null id but get an id when attached to a person and this person gets merged() (re-attached) in the osiv-filter. lazy compute the hashcode when hashCode() is first called and make that hashcode @Transitional. Does not work, as merge() returns a new object and the hashcode does not get copied over. What i would need is an ID that gets assigned during object creation I think. What would be my options here? I don't want to introduce some additional persistent property. Is there a way to explicitly tell JPA to assign an ID to an object? Regards

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  • What noncluster index would be better to create on SQL Server?

    - by Junior Mayhé
    Here I am studying nonclustered indexes on SQL Server Management Studio. I've created a table with more than 1 million records. This table has a primary key. SELECT CustomerName FROM Customers Which leads the execution plan to show me: I/O cost = 3.45646 Operator cost = 4.57715 For the first attempt to improve performance, I've created a nonclustered index for this table: CREATE NONCLUSTERED INDEX [IX_CustomerID_CustomerName] ON [dbo].[Customers] ( [CustomerId] ASC, [CustomerName] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO With this first try, I've executed the select statement and the execution plan shows me: I/O cost = 2.79942 Operator cost = 3.92001 Now the second try, I've deleted this nonclustered index in order to create a new one. CREATE NONCLUSTERED INDEX [IX_CategoryName] ON [dbo].[Categories] ( [CategoryId] ASC ) INCLUDE ( [CategoryName]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO With this second try, I've executed the select statement and the execution plan shows me the same result: I/O cost = 2.79942 Operator cost = 3.92001 Am I doing something wrong or this is expected? Shall I use the first nonclustered index with two fields, or the second nonclustered with one field (CategoryID) including the second field (CategoryName)?

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