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• Why are some C#4 features allowed even when targeting 3.5?

  - by Greg

  We upgraded to VS 2010, but we haven't yet upgraded to .NET 4.0. All of our projects are still explicitly targeting 3.5. Today, a developer checked in code that looked like this: delegate T Generator<out T>(); As far as I know, "in T" and "out T" are C# 4.0 features. According to our build server, which doesn't have .NET 4.0 installed on it, I'm right. The check-in broke the build. But, why the heck does it build on his machine? Why is VS just ignoring the target framework for the project? Other C# 4.0 features, like the dynamic keyword, do not build on the developer's machine.

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• How do I create a set with std::pair thats sorted based on the ::second pair member using bind

  - by Stone Free

  I know I could use the following: template <typename Pair> struct ComparePairThroughSecond : public std::unary_function<Pair, bool> { bool operator ()(const Pair& p1, const Pair& p2) const { return p1.second < p2.second; } }; std::set<std::pair<int, long>, ComparePairThroughSecond> somevar; but wondered if it could be done with boost::bind

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• Why does a Linq Cast<T> operation fail when I have an implicit cast defined?

  - by Ryan Versaw

  I've created two classes, with one of them having an implicit cast between them: public class Class1 { public int Test1; } public class Class2 { public int Test2; public static implicit operator Class1(Class2 item) { return new Class1{Test1 = item.Test2}; } } When I create a new list of one type and try to Cast<T> to the other, it fails with an InvalidCastException: List<Class2> items = new List<Class2>{new Class2{Test2 = 9}}; foreach (Class1 item in items.Cast<Class1>()) { Console.WriteLine(item.Test1); } This, however, works fine: foreach (Class1 item in items) { Console.WriteLine(item.Test1); } Why is the implicit cast not called when using Cast<T>?

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• Does std::multiset guarantee insertion order?

  - by Naveen

  I have a std::multiset which stores elements of class A. I have provided my own implementation of operator< for this class. My question is if I insert two equivalent objects into this multiset is their order guaranteed? For example, first I insert a object a1 into the set and then I insert an equivalent object a2 into this set. Can I expect the a1 to come before a2 when I iterate through the set? If no, is there any way to achieve this using multiset?

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• C++: conjunction of binds?

  - by Helltone

  Suppose the following two functions: #include <iostream> #include <cstdlib> // atoi #include <cstring> // strcmp #include <boost/bind.hpp> bool match1(const char* a, const char* b) { return (strcmp(a, b) == 0); } bool match2(int a, const char* b) { return (atoi(b) == a); } Each of these functions takes two arguments, but can be transformed into a callable object that takes only one argument by using (std/boost)bind. Something along the lines of: boost::bind(match1, "a test"); boost::bind(match2, 42); I want to be able to obtain, from two functions like these that take one argument and return bool, a callable object that takes two arguments and returns the && of the bools. The type of the arguments is arbitrary. Something like an operator&& for functions that return bool.

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• Is there a shorthand way to denullify a string in C#?

  - by Moose Factory

  Is there a shorthand way to denullify a string in C#? It would be the equivalent of (if 'x' is a string): string y = x == null ? "" : x; I guess I'm hoping there's some operator that would work something like: string y = #x; Wishful thinking, huh? The closest I've got so far is an extension method on the string class: public static string ToNotNull(this string value) { return value == null ? "" : value; } which allows me to do: string y = x.ToNotNull(); Any improvements on that, anyone?

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• Function return type style

  - by JB

  I'm learning c++0x, at least the parts supported by the Visual C++ Express 2010 Beta. This is a question about style rather than how it works. Perhaps it's too early for style and good practice to have evolved yet for a standard that isn't even released yet... In c++0x you can define the return type of a method using - type at the end of the function instead of putting the type at the start. I believe this change in syntax is required due to lambdas and some use cases of the new decltype keyword, but you can use it anywhere as far as I know. // Old style int add1(int a, int b) { return a + b; } // New style return type auto add2(int a, int b) -> int { return a + b; } My question really then, is given that some functions will need to be defined in the new way is it considered good style to define all functions in this way for consistency? Or should I stick to only using it when necessary?

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• Why isn't Perl's File::GlobMapper exporting globmap?

  - by justintime

  The following is pretty well copied from the documentation. use File::GlobMapper qw( globmap ); for my $pair (globmap '<*.tar.gz>' => '<#1.tgz>' ) { } And it gives String found where operator expected at globmapper_test1.pl line 4, near "globmap '<*.tar.gz>'" (Do you need to predeclare globmap?) (Using ActivePerl 5.10.0 on Windows) Side questions - if GlobMapper only exports one function, why is it set so you have to export it explicitly?

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• T-SQL Operations on a Calculated Date Field

  - by firedrawndagger

  Can I do WHERE operations on a calculated date field? I have a lookup field, which has been written badly in SQL and unfortunately I can't change it. But basically it stores dates as characters such as "July-2010" or "June-2009" (along with other non date data). I want to extract the dates first (which I did using a LIKE opertor) and then extract data based on a date range. SELECT BusinessUnit, Lookup, ReleaseDate FROM ( SELECT TOP 10 LookupColumn As Lookup, BU as BusinessUnit, CONVERT(DATETIME, REPLACE(LookupColumn,'-',' ')) as ReleaseDate FROM [dbo].[LookupTable] WHERE LookupColumn LIKE N'%-2010' ) MyTable ORDER BY ReleaseDate WHERE ReleaseDate = '2010-02-01' I'm having issues with WHERE operator. I would assume creating a subquery to encapsulate the calculated field would allow me to do operations with it such as WHERE but maybe I'm wrong. Bottom line is it possible to do operations on calculated fields?

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• Can you pass parameters for OnAction in MS Project VBA?

  - by Anne Schuessler

  The way I can define a method to be executed with OnAction in VBA with Microsoft Project is as follows (and works correctly): .OnAction = "Macro ""DoSomething""" ... where DoSomething is the method to execute. I would like to pass a parameter to that method but can't find a way to pass it with this syntax. Does anybody have an idea how to do this? I'm getting the feeling that this is an impossible task, but maybe there's some VBA secret I'm not aware of. Please note that VBA in MS Project seems to have its quirks and is slightly different than VBA for Excel or Access. This seems to be the case for the OnAction property which needs the extra Macro keyword to work correctly. If I'm wrong here please enlighten me.

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• Using pipes inside a class in C++

  - by Paul

  I'm trying to use this tutorial to make plots with Gnuplot in C++. However I will be using the pipe to Gnuplot from within a class, but then I run into some problems: I've got a header file where I declare all variables etc. I need to declare the pipe-variable here too, but how do I do that? I've tried doing it straight away, but it doesn't work: Logger.h: class Logger { FILE pipe; } Logger.cpp: Logger::Logger() { //Constructor *pipe = popen("gnuplot -persist","w"); } Gives the error Logger.cpp:28: error: no match for ‘operator=’ in ‘*((Logger*)this)->Logger::pipe = popen(((const char*)"gnuplot -persist"), ((const char*)"w"))’ Suggestions?

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• Storing expression template functors

  - by UncaughtException

  Hello guys, at the moment I'm really interested in expression templates and want to code a library for writing and differentiating mathematical functions with a lambda-style syntax. At the moment, I'm able to write (_x * _x)(2); and get the correct result 4. But I would really like to do something like MathFunction f = _x * _x; f(2);, but I don't have any ideas on how to cope with the recursive expression templates on the right side. Is it possible to achieve this without using the 'auto'-Keyword instead of MathFunction or having to make the operator() virtual? Thanks for your help!

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• Returnimng collection of interfaces

  - by apoorv020

  I have created the following interface public interface ISolutionSpace { public boolean isFeasible(); public boolean isSolution(); public Set<ISolutionSpace> generateChildren(); } However, in the implementation of ISolutionSpace in a class called EightQueenSolutionSpace, I am going to return a set of EightQueenSolutionSpace instances, like the following stub: @Override public Set<ISolutionSpace> generateChildren() { return new HashSet<EightQueenSolutionSpace>(); } However this stub wont compile. What changes do I need to make? EDIT: I tried 'HashSet' as well and had tried using the extends keyword. However since 'ISolutionSpace' is an interface and EightQueenSolutionSpace is an implementation(and not a subclass) of 'ISolutionSpace', it is still not working.

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• MySQL Join Comma Separated Field

  - by neeraj

  I have two tables. First Table is a batch table that contain comma separated student id in field "batch" batch -------------- id batch -------------- 1 1,2 2 3,4 Second Table is marks marks ---------------------- id studentid subject marks 1 1 English 50 2 2 English 40 3 3 English 70 4 1 Math 65 5 4 English 66 6 5 English 75 7 2 Math 55 How we can find those students of first batch id =1 who have scored more than 45 marks in English without using sub query. Problem i found to get this done using a single query is that we can not use IN as an association operator in JOIN statement What changes are required in below query to make it work? SELECT * FROM batch INNER JOIN marks ON marks.studentid IN(batch.batch) where batch.id = 1

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• How can I check the type of an object against a list of types?

  - by RookieRick

  Given a collection IEnumerable<Type> supportedTypes What's the best way to check whether a given object is one of those types (or a derived type)? My first instinct was to do something like: // object target is a parameter passed to the method in which I'm doing this. if (supportedTypes.Count( supportedType => target is supportedType ) > 0) { // Yay my object is of a supported type!!! } ..but that doesn't seem to be working. Can I not use the "is" keyword in a lambda expression like this?

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• SQL server 2005 query not running

  - by Aayushi

  Hi, Before posting this question, I have tried so many things but that was not helpful for me. I want to rename the column of table at sql server 2005, following query I have run at sql server2005: 1) ALTER TABLE Details RENAME COLUMN AccountID TO UID; but it gives me the error: Incorrect syntax near the keyword 'COLUMN'. 2)I have added one new column in the table by query: ALTER TABLE Details ADD BID uniqueidentifier; and then I want to set the coulmn property to not null . How can i do that? Thanks in advance AS

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• Why exactly is calling the destructor for the second time undefined behavior in C++?

  - by sharptooth

  As mentioned in this answer simply calling the destructor for the second time is already undefined behavior 12.4/14(3.8). For example: class Class { public: ~Class() {} }; // somewhere in code: { Class* object = new Class(); object->~Class(); delete object; // UB because at this point the destructor call is attempted again } In this example the class is designed in such a way that the destructor could be called multiple times - no things like double-deletion can happen. The memory is still allocated at the point where delete is called - the first destructor call doesn't call the ::operator delete() to release memory. For example, in Visual C++ 9 the above code looks working. Even C++ definition of UB doesn't directly prohibit things qualified as UB from working. So for the code above to break some implementation and/or platform specifics are required. Why exactly would the above code break and under what conditions?

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• Free PHP framework/library for single-sign on / cross domain login

  - by Dennis Cheung

  I am looking for free (non GPL is better) SSO framework/library implementation or code samples. There are many kind of SSO implementation. Sharing cookie, sharing session, one time token, associative accounts, etc, etc. (BTW, any good article compare them?) Is there any keyword I should google and reuse before before I start to implement our own wheel. I know OpenID, but which is too much and it is not our need. We rather keep it KISS. We just want share the credentials of user that could save users from another login form.

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• Trying to create fields based on a case statement

  - by dido

  I'm having some trouble with the query below. I am trying to determine if the "category" field is A, B or C and then creating a field based on the category. That field would sum up payments field. But I'm running into error saying "incorrect syntax near keyword As". I am creating this in a SQL View. Using SQL Server 2008 SELECT r.id, r.category CASE WHEN r.category = 'A' then SUM(r.payment) As A_payments WHEN r.category = 'B' then SUM(r.payment) As B_payments WHEN r.category = 'C' then SUM(r.payment) As C_payments END FROM r_invoiceTable As r GROUP BY r.id, r.category I have data where all of the above cases should be executed because the data that I have has A,B and C Sample Data- r_invoiceTable Id --- Category ---- Payment 222 A ---- 50 444 A ---- 30 111 B ---- 90 777 C ---- 20 555 C ---- 40 Desired Output A_payments = 80, B_payments = 90, C_payments = 60

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• C++ Word-Number to int

  - by Andrew

  I'm developing a program that makes basic calculations using words instead of numbers. E.g. five + two would output seven. The program becomes more complex, taking input such as two_hundred_one + five_thousand_six (201 + 5006) Through operator overloading methods, I split each number and assign it to it's own array index. two would be [0], hundred is [1], and one is [2]. Then the array recycles for 5006. My problem is, to perform the actual calculation, I need to convert the words stored in the array to actual integers. I have const string arrays such as this as a library of the words: const string units[] = { "", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; const string teens[] = { "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" }; const string tens[] = { "", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety" }; If my 'token' array has stored in it two hundred one in index 0, 1, and 2, I'm not sure what the best way to convert these to ints would involve.

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• GQL Query with __key__ in List of KEYs

  - by bossylobster

  In the GQL reference [1], it is encouraged to use the IN keyword with a list of values, and to construct a Key from hand the GQL query SELECT * FROM MyModel WHERE __key__ = KEY('MyModel', 'my_model_key') will succeed. However, using the code you would expect to work: SELECT * FROM MyModel WHERE __key__ IN (KEY('MyModel', 'my_model_key1'), KEY('MyModel', 'my_model_key2')) in the Datastore Viewer, there is a complaint of "Invalid GQL query string." What is the correct way to format such a query? [1] http://code.google.com/appengine/docs/python/datastore/gqlreference.html PS I know there are more efficient ways to do this in Python (without constructing a GQL query) and using the remote_api, but each call to the remote_api counts against quota. In an environment where quota is not (necessarily) free, quick and dirty queries are very helpful.

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• Replacing keywords in text with php & mysql

  - by intacto

  Hello, I have a news site containing an archive with more than 1 million news. I created a word definitions database with about 3000 entries, consisting of word-definition pairs. What I want to do is adding a definition next to every occurence of these words in the news. I cant make a static change as I can add a new keyword everyday, so i can make it realtime or cached. The question is, a str_replace or a preg_replace would be very slow for searching 3 thousand keywords in a text and replacing them. Are there any fast alternatives?

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• Listing C/C++ functions (Code analysis in Unix)

  - by Jond

  Whether we're maintaining unfamiliar code or checking out the implementation details of an Apache module it can help if we can quickly traverse the code and build up an overview of what we're looking at. Grep serves most of my daily needs but there are some cases where it just wont do. Here's a common example of how it can help. To find the definition of a PHP function I'm interested in I can type this at the command line: grep -r "function myfunc" . This could be adapted very quickly to C or C++ if we know the return type, but things become more complicated if, say, I want to list every method that my class provides: grep "function " ./src/mine.class.php Since there's no single keyword that denotes a function or method in C++ and because it's generally more complex syntax, I think I'd need some kind of static code analysis tool, smart use of the C Preprocessor or blind faith the coder followed strict code guidelines (# of whitespace, position of curlies etc) to get these sorts of results. What would you recommend? p.s. be nice, this is my first post ;-) :p

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• Undefined / Uninitialized default values in a class

  - by Jir

  Let's suppose you have this class: class A { public: A () {} A (double val) : m_val(val) {} ~A () {} private: double m_val; }; Once I create an instance of A, how can I check if m_val has been initialized/defined? Put it in other words, is there a way to know if m_val has been initialized/defined or not? Something along the lines of the defined operator in Python, I suppose. (But correct me if I'm wrong.) I thought of modifying the class and the c-tors the following way: class A { public: A () : defined(false) {} A (double val) : m_val(val), defined(true) {} ~A () {} private: double m_val; bool defined; }; How do you rate this solution? Any suggestion? TIA, Chris

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• MYSQL - REMOVE HTML TAGS from Record

  - by Dam

  Need help to form the MYSQL query from table one column having the bellow content Row1 : this is first <a href='mytext.txt'>row</a> from the table Row 2 : THis is the second row <img src ='mytext.jpg'> my image is there Row 3 : <p>This is the Third row my mytext is there </p> Row 4 : <p class='te_mytext'>This is the Third row my text is there </p> this is the table rows i try to search the keyword as 'mytext' my query is SELECT * from table WHERE colmn_name ` like '%mytext%' " i will get all the 4 rows as result but the result is wrong ..... need to get the correct output as only Row 3 the reason this row only having the mytext inside the content all other are not in content but mytext having in all rows how can i write the Query MYSQL please help me (NOT in PHP only MYSQL )

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