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• How to call a bool function...

  - by Gerri

  Hello, I did not see anything that address my particular code problem. I have a bool function in a class; the bool function is named: bool Triplet::operator ==(const Triplet& operand)const And I am trying to call it in Main but having problems just getting the call right. Apparently if I leave out any thing in the wording it gives an error that I have too few aruguments and if I try to use the entire wording of the function, I get the error that I need a semi-colon, but I already have a semi-colon at the end of the call, so I know that something else is wrong and I simply cannot figure out what is wrong! Any help would be appreciated! Thanks in advance.

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• Purpose of boost::checked_delete

  - by Channel72

  I don't understand the purpose of boost::checked_delete. The documentation says: The C++ Standard allows, in 5.3.5/5, pointers to incomplete class types to be deleted with a delete-expression. When the class has a non-trivial destructor, or a class-specific operator delete, the behavior is undefined. Some compilers issue a warning when an incomplete type is deleted, but unfortunately, not all do, and programmers sometimes ignore or disable warnings. The supplied function and class templates can be used to prevent these problems, as they require a complete type, and cause a compilation error otherwise. So the C++ standard allows you to delete incomplete types, which causes undefined behavior if the type has a non-trivial destructor. What? How can an incomplete type have any destructor at all? Isn't an incomplete type just a prototype?

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• casting between sibling classes, AS3

  - by felix-gasca

  I have two classes, derivedClassA and derivedClassB which both extend parentClass I'm declaring var o:parentClass and then, depending on what's going on, I want to cast o as either being of type derivedClassA or derivedClassB. Essentially, this: var o:parentClass ... if(shouldUseA) o = new derivedClassA(); else o = new derivedClassB(); o.doSomething(); But it's not working, I'm getting all sorts of errors. Isn't this how class inheritance works? I feel like I'm missing something really fundamental, but I can't figure out what. Am I supposed to be using interfaces instead? Is there another way of doing what I want?

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• On Memory Allocation and C++

  - by Arpan

  And I quote from MSDN http://msdn.microsoft.com/en-us/library/aa366533(VS.85).aspx: The malloc function has the disadvantage of being run-time dependent. The new operator has the disadvantage of being compiler dependent and language dependent. Now the questions folks: a) What do we mean that malloc is run-time dependent? What kind of dynamic memory allocation functions can be independent of run-time? This statement sounds real strange. b) new is language dependent? Of course it should be right? Are HeapAlloc, LocalAlloc etc language independent? c) From a pure performance perspective are the MSVC provided routines preferable? Arpan

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• Double Inner Join generates unexpected error

  - by Itamar Marom

  In my database I have three tables: Users: UserID (Auto Numbering), UserName, UserPassword and a few other unimportant fields. PrivateMessages: MessageID (Auto Numbering), SenderID and a few other fields defining the message content. MessageStatus: MessageID, ReceiverID, MessageWasRead (Boolean) What I need is a query to which I input a user's id and I get all the private messages he has received. In addition, I also need to receive each message's sender UserName. For this I wrote the following query: SELECT Users.*, PrivateMessages.*, MessageStatus.* FROM PrivateMessages INNER JOIN Users ON PrivateMessages.SenderID = Users.UserID INNER JOIN MessageStatus ON PrivateMessages.MessageID = MessageStatus.MessageID WHERE MessageStatus.ReceiverID=[@userid]; But for some reason when I try saving it in my Access database, I get the following error (translated to English by me, since my office is in a different language): Syntax error (missing operator) at expression: "PrivateMessages.SenderID = Users.UserID INNER JOIN MessageStatus ON PrivateMessages.MessageID = MessageStatus.MessageI". Any ideas what could cause this? Thanks.

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• has_many conditions or proc on foreign key

  - by ere

  I have a has_many association between two models using a date as both the foreign and primary key for each model. It works perfectly one way but not the other. Works has_one :quiz_log, :primary_key => :start_at, :foreign_key => :start_at Doesn't work has_many :event_logs, :primary_key => :start_at, :foreign_key => :start_at The reason being (i think) because the start_at on QuizLog is a date and the start_at on EventLog is a datetime. So it returns nil trying to match the exact datetime on a simple date. How can I cast the foreign_key start_at on the second statement to convert it first from datetime to simply date so it will match the second model?

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• Accessing subclass members from a superclass pointer C++

  - by Dr. Monkey

  I have an array of custom class Student objects. CourseStudent and ResearchStudent both inherit from Student, and all the instances of Student are one or the other of these. I have a function to go through the array, determine the subtype of each Student, then call subtype-specific member functions on them. The problem is, because these functions are not overloaded, they are not found in Student, so the compiler kicks up a fuss. If I have a pointer to Student, is there a way to get a pointer to the subtype of that Student? Would I need to make some sort of fake cast here to get around the compile-time error?

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• Casting to global variable from LPVOID - C

  - by Jamie Keeling

  I am trying to cast data to a struct from a parameter passed into my method, I need the data to be passed to a global variable as it is needed elsewhere in my application. I have tried the following but I get errors saying that diceResult is an undeclared identifier Here is the code itself: //Structure to hold dice data typedef struct diceData { int dice1; int dice2; }; struct diceResult; DWORD WINAPI UnpackDiceData(LPVOID sentData) { //Unpack data struct diceData unpackedData = *((struct diceData*)sentData); diceResult.dice1 = unpackedData.dice1; diceResult.dice2 = unpackedData.dice2; } I don't understand why it won't recognise it being there when it's clearly global.

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• C++ refactor common code with one different statement

  - by user231536

  I have two methods f(vector<int>& x, ....) and g(DBConn& x, ....) where the (....) parameters are all identical. The code inside the two methods are completely identical except for one statement where we do different actions based on the type of x: in f(): we do x.push_back(i) in g(): we do x.DeleteRow(i) What is the simplest way to extract the common code into one method and yet have the two different statements? I am thinking of having a templated functor that overloads operator () (int a) but that seems overkill.

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• Bit conversion operations in PHP

  - by Goro

  Hello, I find myself in need of performing bit-level conversion on variables in PHP. In more detail, I have a bit stream that is read as an integer by hardware, and I need to do some operations on the bits to make it into what its actually supposed to be (a float). I have to do this a few times for different formats, and the functionality I need is Being able to select and move individual bits in a variable Being able to cast statically one type of variable to the other (ie. int to float) I know php natively supports bitwise AND, OR, etc, and shift operations, but I was wondering if: there may already be a library in php that does this sort of thing I would be better off with delegating the calculations to some other language Thanks,

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• Enumerable.Range in and Expression and Entity Framework

  - by eka808

  I'm currently developping an expression method (used in linq to entity queries) who has to give me a daycount for a given period (start date and end date) decrementing this daycount if specials days are in the period. My idea was the following : Generate an enumerable with all the dates (and with Enumerable.Range) Make a .Where on this enumerable to remove the specials dates Like a MyEnumerable.Where(a = a != "20120101") After that, return a MyEnumerable.Count() I come with this code : return (p) => Enumerable .Range(1, 4) .Where(a => a != 20120101) .AsQueryable() .Count() I tried to cast as a list, as a queryable, both (like the example) and no way ! it doesn't work ! I always get this error : LINQ to Entities does not recognize the method 'System.Collections.Generic.IEnumerable`1[System.Int32] Range(Int32, Int32)' method, and this method cannot be translated into a store expression. Have you got an idea about that ? Using an enumerable is of course not mandatory, any working solutions is good ^^ Thank's by advance !

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• Updating files with a Perforce trigger before submit [migrated]

  - by phantom-99w

  I understand that this question has, in essence, already been asked, but that question did not have an unequivocal answer, so please bear with me. Background: In my company, we use Perforce submission numbers as part of our versioning. Regardless of whether this is a correct method or not, that is how things are. Currently, many developers do separate submissions for code and documentation: first the code and then the documentation to update the client-facing docs with what the new version numbers should be. I would like to streamline this process. My thoughts are as follows: create a Perforce trigger (which runs on the server side) which scans the submitted documentation files (such as .txt) for a unique term (such as #####PERFORCE##CHANGELIST##NUMBER###ROFL###LOL###WHATEVER#####) and then replaces it with the value of what the change list would be when submitted. I already know how to determine this value. What I cannot figure out, is how or where to update the files. I have already determined that using the change-content trigger (whether possible or not), which "fire[s] after changelist creation and file transfer, but prior to committing the submit to the database", is the way to go. At this point the files need to exist somewhere on the server. How do I determine the (temporary?) location of these files from within, say, a Python script so that I can update or sed to replace the placeholder value with the intended value? The online documentation for Perforce which I have found so far have not been very explicit on whether this is possible or how the mechanics of a submission at this stage would work.

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• How to test Text Search accuracy and efficiency?

  - by DEN

  I have created a web application. One of the feature is text search which perform the boolean operator ( NOT, AND, OR) as well. However, I have no idea on calculating the search's accuracy and efficiency. For example: 1 . Probe identification system for a measurement instrument 2 . Pulse-based impedance measurement instrument 3 . Millimeter with filtered measurement mode when the user key in will return the result as below input :measurement instrument Result: 1,2 input : measurement OR instrument NOT milimeter Result: 1,2,3 so, i have no idea on what issue and what algorithm to calculate on the accuracy and efficiency of the text search.. anyone have any idea on that?

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• Filter objects within two seconds of one another using SQLAlchemy

  - by Arrieta

  Hello: I have two tables with a column 'date'. One holds (name, date) and the other holds (date, p1, p2). Given a name, I want to use the date in table 1 to query p1 and p2 from table two; the match should happen if date in table one is within two seconds of date in table two. How can you accomplish this using SQLAlchemy? I've tried (unsuccessfully) to use the between operator and with a clause like: td = datetime.timedelta(seconds=2) q = session.query(table1, table2).filter(table1.name=='my_name').\ filter(between(table1.date, table2.date - td, table2.date + td)) Any thoughts?

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• Possible to fire asp.net validation from jQuery?

  - by Abe Miessler

  I have a form with several text boxes on it. I only want to accept floats, but it is likely that users will enter a dollar sign. I'm using the following code to remove dollar signs and validate the content: jQuery: $("#<%= tb.ClientID %>").change(function() { var ctrl = $("#<%= tb.ClientID %>"); ctrl.val(ctrl.val().replace('$','')) }); asp.net validation: <asp:CompareValidator ID="CompareValidator4" runat="server" Type="Double" ControlToValidate="tb" Operator="DataTypeCheck" ValidationGroup="vld_Page" ErrorMessage="Some error" /> My problem is that when someone enters a dollar sign in the TextBox "tb" and changes focus the validation happens first and THEN the jQuery removes the dollar sign. Is it possible to have the jQuery run first or to force the validation to run again after the jQuery executes?

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• DependencyProperty Orientation problem

  - by byte

  I am learning WPF and am trying to create my first UserControl. My UserControl consists of StackPanel StackPanel contains a Label and TextBox I am trying to create two Dependency Properties Text for the Label Orientation for the StackPanel - The orientation will affect the position of the Label and TextBox effectively I have successfully created a Text dependency property and bind it to my UserControls . But when I created the Orientation property, I seem to get following error in get property The as operator must be used with a reference type or nullable type ('System.Windows.Controls.Orientation' is a non-nullable value type) public static DependencyProperty OrientationProperty = DependencyProperty.Register("Orientation", typeof(System.Windows.Controls.Orientation), typeof(MyControl), new PropertyMetadata((System.Windows.Controls.Orientation)(Orientation.Horizontal))); public Orientation Orientation { get { return GetValue(OrientationProperty) as System.Windows.Controls.Orientation; } set { SetValue(OrientationProperty, value); } } Appreciate your help.

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• sql boolean truth test: zero OR null

  - by AK

  Is there way to test for both 0 and NULL with one equality operator? I realize I could do this: WHERE field = 0 OR field IS NULL But my life would be a hundred times easier if this would work: WHERE field IN (0, NULL) (btw, why doesn't that work?) I've also read about converting NULL to 0 in the SELECT statement (with COALESCE). The framework I'm using would also make this unpleasant. Realize this is oddly specific, but is there any way to test for 0 and NULL with one WHERE predicate?

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• .NET 4.0 Generic Invariant, Covariant, Contravariant

  - by Sameer Shariff

  Here's the scenario i am faced with: public abstract class Record { } public abstract class TableRecord : Record { } public abstract class LookupTableRecord : TableRecord { } public sealed class UserRecord : LookupTableRecord { } public interface IDataAccessLayer<TRecord> where TRecord : Record { } public interface ITableDataAccessLayer<TTableRecord> : IDataAccessLayer<TTableRecord> where TTableRecord : TableRecord { } public interface ILookupTableDataAccessLayer<TLookupTableRecord> : ITableDataAccessLayer<TLookupTableRecord> where TLookupTableRecord : LookupTableRecord { } public abstract class DataAccessLayer<TRecord> : IDataAccessLayer<TRecord> where TRecord : Record, new() { } public abstract class TableDataAccessLayer<TTableRecord> : DataAccessLayer<TTableRecord>, ITableDataAccessLayer<TTableRecord> where TTableRecord : TableRecord, new() { } public abstract class LookupTableDataAccessLayer<TLookupTableRecord> : TableDataAccessLayer<TLookupTableRecord>, ILookupTableDataAccessLayer<TLookupTableRecord> where TLookupTableRecord : LookupTableRecord, new() { } public sealed class UserDataAccessLayer : LookupTableDataAccessLayer<UserRecord> { } Now when i try to cast UserDataAccessLayer to it's generic base type ITableDataAccessLayer<TableRecord>, the compiler complains that it cannot implicitly convert the type.

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• How often do you implement the big three?

  - by Neil Butterworth

  I was just musing about the number of questions here that either are about the "big three" (copy constructor, assignment operator and destructor) or about problems caused by them not being implemented correctly, when it occurred to me that I could not remember the last time I had implemented them myself. A swift grep on my two most active projects indicate that I implement all three in only one class out of about 150. That's not to say I don't implement/declare one or more of them - obviously base classes need a virtual destructor, and a large number of my classes forbid copying using the private copy ctor & assignment op idiom. But fully implemented, there is this single lonely class, which does some reference counting. So I was wondering am I unusual in this? How often do you implement all three of these functions? Is there any pattern to the classes where you do implement them?

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• Reading in data from a file into an array

  - by Sam

  If I have an options file along the lines of this: size = 4 data = 1100010100110010 And I have a 2d size * size array that I want to populate the values in data into, what's the best way of doing it? To clarify, for the example I have I'd want an array like this: int[4][4] array = {{1,1,0,0}, {0,1,0,1}, {0,0,1,1}, {0,0,1,0}}. (Not real code but you get the idea). Size can be really be any number though. I'm thinking I'd have to read in the size, maloc an array and then maybe read in a string full of data then loop through each char in the data, cast it to an int and stick it in the appropriate index? But I really have no idea how to go about it, have been searching for a while with no luck. Any help would be cool! :)

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• Wrong command in shell

  - by jask

  I have this command in a shell archive: sh -c $POSTGRESbin'psql -U '$POSTGRESuser' -h localhost -d '$POSTGRESdb' -c "select preview from '$fildCatalog' where preview <>'nodata' and id_registro in (select distinct(id_record) from e3_article_items where id_catalog=2101 and id_article in (select id_article from document_articles where id_document in(select distinct(id_document) from p3_logical_pages where id_logical_page in (select id_logical_page from p3_flatplan_pages where id_edition=1536 and id_logical_page is not null order by cast(pagenumber as numeric)))));"' > $queryFolder$highFile"_"$previewFile; But in <'nodata' appear an error and I don't know how can I resolve it. The error is: ERROR: column "nodata" does not exist LINE 1: select preview from XT_FIJOS where preview <>nodata and id_r... Can anybody help me ? Thanks !! ^

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• Boost::asio bug in MSVC10 - Failing BOOST_WORKAROUND in ~buffer_debug_check() in buffer.hpp

  - by shaz

  A straight compilation of example http://www.boost.org/doc/libs/1_43_0/doc/html/boost_asio/tutorial/tutdaytime3/src.html results in a runtime null pointer exception. Stack trace points to the buffer_debug_check destructor which contains this comment: // MSVC's string iterator checking may crash in a std::string::iterator // object's destructor when the iterator points to an already-destroyed // std::string object, unless the iterator is cleared first. The test #if BOOST_WORKAROUND(BOOST_MSVC, = 1400) succeeds in MSVC10 and (but) results in a null pointer exception in c:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility line 123 _Iterator_base12& operator=(const _Iterator_base12& _Right) { // assign an iterator if (_Myproxy != _Right._Myproxy) _Adopt(_Right._Myproxy->_Mycont); return (*this); } _Right._Myproxy is NULL

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• Class interaction

  - by user1264391

  Ok so I'm doing a simulation about a "Mall" I have many classes in the same "level" which corresponds to each person's personality. For example I have the class: clown, thief, assassin, materialist, etc. in the same level And a father class called Clients. In the Client class I have some methods for eating,walking, etc. and each specific class has a specific method, the thief steals, assassin kills, etc. I was wondering how could I put every "client" in a list and still cast every specific method?

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• I want to retrieve some information based on Caller ID

  - by Hassan Al-Jeshi

  Hello, my friend has a Real Estate company that receives a lot of phone calls everyday. He wants to have a solution such that when somebody call to his company, the operator sees all the information about the person who is calling based on the database he have right now and the caller ID. Is there a ready made software or solution that can do the job?? Since I'm a software engineer myself, I would never mind developing something from scratch or built on a ready made system (with a team of course), but I need some direction on how to start?? Notes: 1- cost is not an issue 2- the customers database is there but we never mind replacing it in a format to suit the new solution Best Regards,

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• Why wasn't C# designed with 'const' for variables and methods?

  - by spoulson

  I suspect const was simplified for the C# spec for general language simplicity. Was there a specific reason we can't declare variable references or methods as const like we can with C++? e.g.: const MyObject o = new MyObject(); // Want const cast referenece of MyObject o.SomeMethod(); // Theoretically legal because SomeMethod is const o.ChangeStuff(); // Theoretically illegal because ChangeStuff is not const class MyObject { public int val = 0; public void SomeMethod() const { // Do stuff, but can't mutate due to const declaration. } public void ChangeStuff() { // Code mutates this instance. Can't call with const reference. val++; } }

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