Search Results

Search found 2727 results on 110 pages for 'operator overloading'.

Page 87/110 | < Previous Page | 83 84 85 86 87 88 89 90 91 92 93 94  | Next Page >

  • How to create and Expression tree to do the same as "StartsWith"

    - by Jonathan
    Hi to all. Currently, I have this method to compare two numbers Private Function ETForGreaterThan(ByVal query As IQueryable(Of T), ByVal propertyValue As Object, ByVal propertyInfo As PropertyInfo) As IQueryable(Of T) Dim e As ParameterExpression = Expression.Parameter(GetType(T), "e") Dim m As MemberExpression = Expression.MakeMemberAccess(e, propertyInfo) Dim c As ConstantExpression = Expression.Constant(propertyValue, propertyValue.GetType()) Dim b As BinaryExpression = Expression.GreaterThan(m, c) Dim lambda As Expression(Of Func(Of T, Boolean)) = Expression.Lambda(Of Func(Of T, Boolean))(b, e) Return query.Where(lambda) End Function It works fine and is consumed in this way query = ETForGreaterThan(query, Value, propertyInfo) As you can see, I give it an IQueryable collection and it add a where clause to it, base on a property and a value. Y can construct Lessthan, LessOrEqualThan etc equivalents as Expression has this operators predefined. ¿How can I transform this code to do the same with strings? Expression don't give me a predefined operator like "contains" or "startwith" and I'm really noob with Expression trees. Thanks, and please Post your answer in C#/VB. Choose the one that make you feel more confortable.

    Read the article

  • Best way to validate currency input?

    - by Abe Miessler
    I have created the TextBox and CompareValidator below which I thought would allow input in the following forms: 5 5.00 $5.00 Unfortunately it's not allowing the version with the dollar sign in it. What is the point of doing a type check against currency if you don't allow the dollar sign? Is there a way to allow this symbol? <asp:TextBox ID="tb_CostShare" runat="server" Text='<%# Eval("CostShare", "{0:$0.00}")%>' CausesValidation="true" /> <asp:CompareValidator ID="vld_CostShare" runat="server" ControlToValidate="tb_CostShare" Operator="DataTypeCheck" Type="Currency" ValidationGroup="vld" ErrorMessage="You must enter a dollar amount for 'Cost Share'." />

    Read the article

  • Is call to function object inlined?

    - by dehmann
    In the following code, Foo::add calls a function via a function object: struct Plus { inline int operator()(int x, int y) const { return x + y; } }; template<class Fct> struct Foo { Fct fct; Foo(Fct f) : fct(f) {} inline int add(int x, int y) { return fct(x,y); // same efficiency adding directly? } }; Is this the same efficiency as calling x+y directly in Foo::add? In other words, does the compiler typically directly replace fct(x,y) with the actual call, inlining the code, when compiling with optimizations enabled?

    Read the article

  • C++ and preprocessor macro gotcha

    - by aaa
    hello. Appologies for yet another gotcha question. Can you figure out what is wrong with the statement below? gcc error states: "type name declared as function returning array". #define MACRO(a) (a)[1] class index { typedef int index_type[2]; index_type& operator[](int i); }; int k = 0; int i = MACRO(index()[k]); ps: is such questions are deemed too annoying, I am going to stop.

    Read the article

  • What is the best solution to replace a new memory allocator in an existing code?

    - by O. Askari
    During the last few days I've gained some information about memory allocators other than the standard malloc(). There are some implementations that seem to be much better than malloc() for applications with many threads. For example it seems that tcmalloc and ptmalloc have better performance. I have a C++ application that uses both malloc and new operators in many places. I thought replacing them with something like ptmalloc may improve its performance. But I wonder how does the new operator act when used in C++ application that runs on Linux? Does it use the standard behavior of malloc or something else? What is the best way to replace the new memory allocator with the old one in the code? Is there any way to override the behavior or new and malloc or do I need to replace all the calls to them one by one?

    Read the article

  • Fulltext search not returning expected results

    - by Puneet
    I am experimenting with SQL Server full text search. I have a simple Categories table with Id as the primary key: CREATE TABLE [dbo].[Category]( [Id] [int] IDENTITY(1,1) NOT NULL, [CategoryName] [varchar](100) NOT NULL, ) My Query is: SELECT * FROM FREETEXTTABLE (Category, CategoryName, 'music') AS F INNER JOIN Category C ON F.[Key] = C.Id ORDER BY F.Rank DESC This returns me several records with the word music in them, but it does NOT return any record with word ‘musical’. Although, it can be said that the string being searched is not very big and using the LIKE operator will resolve it. I would like to use fulltext search because this simple example is going to be extended to include other tables and fileds.

    Read the article

  • 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>?

    Read the article

  • C++ / Java: Toggle boolean statement?

    - by Martijn Courteaux
    Hi, Is there a short way to toggle a boolean? With integers we can do operations like this: int i = 4; i *= 4; // equals 16 /* Which is equivalent to */ i = i * 4; So is there also something for booleans (like the *= operator for ints)? In C++: bool booleanWithAVeryLongName = true; booleanWithAVeryLongName = !booleanWithAVeryLongName; // Can it shorter? booleanWithAVeryLongName !=; // Or something? In Java: boolean booleanWithAVeryLongName = true; booleanWithAVeryLongName = !booleanWithAVeryLongName; // Can it shorter? booleanWithAVeryLongName !=; // Or something?

    Read the article

  • What is wrong with my SQL syntax for an UPDATE with a JOIN?

    - by Phil H
    I have two tables, related by a common key. So TableA has key AID and value Name and TableB has keys AID, BID and values Name, Value: AID Name 74 Alpha AID BID Name Value 74 4 Beta Brilliance I would like to update the TableB Value here from Brilliance to Barmy, using just the Name fields. I thought I could do it via an UPDATE containing a JOIN, but Access (I know...) is complaining with 'Syntax error (missing operator) in query expression ' and then everything from 'Barmy' here: UPDATE tB SET tB.BValue='Barmy' FROM TableB tB INNER JOIN TableA tA ON tB.AID=tA.AID WHERE tB.Name='Beta' AND tA.Name='Alpha'; What is my heinous crime? Or is it just Access not conforming?

    Read the article

  • C# logic order and compiler behavior

    - by Terrapin
    In C#, (and feel free to answer for other languages), what order does the runtime evaluate a logic statement? Example: DataTable myDt = new DataTable(); if (myDt != null && myDt.Rows.Count > 0) { //do some stuff with myDt } Which statement does the runtime evaluate first - myDt != null or: myDt.Rows.Count > 0 ? Is there a time when the compiler would ever evaluate the statement backwards? Perhaps when an "OR" operator is involved?

    Read the article

  • 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?

    Read the article

  • C++: Vector3 type "wall" ?

    - by anon
    Say I have: class Vector3 { float x, y, z; ... bunch of cuntions .. static operator+(const Vector3&, const Vector3); }; Now, suppose I want to have classes: Position, Velocity, that are exactly like Vector3 (basically, I want typedef Vector3 Position; typedef Vector3 Velocity; Except, given: Position position; Vector3 vector3; Velocity velocity; I want to make sure the following can't happen: position + vector3; vector3 + velocity; velocity + position; What is the best way to achieve this?

    Read the article

  • JavaScript eval() with `this`

    - by mojuba
    If I define a JavaScript code snippet in my HTML, like so: <div id=myElem onMyUpdate="alert('Update called for ' + this.id)">... then what is the most elegant way of evaluating it from within JavaScript with this properly assigned? What I came up with so far is something like this: if (elem.hasAttribute('onMyUpdate')) (function () { eval(elem.getAttribute('onMyUpdate')) }).call(elem); which looks terrible (to me), but works. Any better/more elegant alternatives? MDN says there used to be the second argument to eval() for doing just that but it's deprecated now; MDN then suggests to use operator with() instead, which, if you follow the link provided, turns out to be made deprecated by the latest standard. Dead end, in other words. (As a side note, StackOverflow ignores the word this in search terms and thus it may miss relevant answers - is there a way of telling it not to?) Edit: I forgot to mention: no jQuery please, just vanilla JavaScript

    Read the article

  • Assigning two strings together getting Access Read Violation

    - by Jay Bell
    I am trying to pass a string to a class mutator and set the private member to that string here is the code that is sending the string void parseTradePairs(Exchange::Currency *curr, std::string *response, int begin, int exit) { int start; int end; string temp; string dataResponse; CURL *tempCurl; initializeCurl(tempCurl); int location = response->find("marketid", begin); if(location <= exit) { start = location + 11; begin = response->find("label", start); end = begin - start - 3; findStrings(start, end, temp, response); getMarketInfo(tempCurl, temp, dataResponse); curr->_coin->setExch(temp); // here is the line of code that is sending the string dataResponse >> *(curr->_coin); curr->_next = new Exchange::Currency(curr, curr->_position + 1); parseTradePairs(curr->_next, response, begin, exit); } } and here is the mutator within the coin class that is receiving the string and assigning it to _exch void Coin::setExch(string exch) { _exch = exch; } I have stepped through it and made sure that exch has the string in it. "105" but soon as it hits _exch = exch; I get the reading violation. I tried passing as pointer as well. I do not believe it should go out of scope. and the string variable in the class is initialized to zero in the default constructor but again that should matter unless I am trying to read from it instead of writing to it. /* defualt constructor */ Coin::Coin() { _id = ""; _label = ""; _code= ""; _name = ""; _marketCoin = ""; _volume = 0; _last = 0; _exch = ""; } Exchange::Exchange(std::string str) { _exch = str; _currencies = new Currency; std::string pair; std::string response; CURL *curl; initializeCurl(curl); getTradePairs(curl, response); int exit = response.find_last_of("marketid"); parseTradePairs(_currencies, &response, 0, exit); } int main(void) { CURL *curl; string str; string id; Coin coin1; initializeCurl(curl); Exchange ex("cryptsy"); curl_easy_cleanup(curl); system("pause"); return 0; } class Exchange { public: typedef struct Currency { Currency(Coin *coin, Currency *next, Currency *prev, int position) : _coin(coin), _next(next), _prev(prev), _position(position) {} Currency(Currency *prev, int position) : _prev(prev), _position(position), _next(NULL), _coin(&Coin()){} Currency() : _next(NULL), _prev(NULL), _position(0) {} Coin *_coin; Currency *_next; Currency *_prev; int _position; }; /* constructor and destructor */ Exchange(); Exchange(std::string str); ~Exchange(); /* Assignment operator */ Exchange& operator =(const Exchange& copyExchange); /* Parse Cryptsy Pairs */ friend void parseTradePairs(Currency *curr, std::string *response, int begin, int exit); private: std::string _exch; Currency *_currencies; }; here is what i changed it to to fix it. typedef struct Currency { Currency(Coin *coin, Currency *next, Currency *prev, int position) : _coin(coin), _next(next), _prev(prev), _position(position) {} Currency(Currency *prev, int position) : _prev(prev), _position(position), _next(NULL), _coin(&Coin()){} Currency() { _next = NULL; _prev = NULL; _position = 0; _coin = new Coin(); } Coin *_coin; Currency *_next; Currency *_prev; int _position; };

    Read the article

  • I serialized a C++ object, how to allocate memory for it without knowing what type it is?

    - by Neo_b
    Hello, I have serialized a C++ object and I wish to allocate space for it, although I can't use the "new" operator, because I do not know the object's class. I tried using malloc(sizeof(object)), although trying to typecast the pointer to the type the serialized object is of, the program shut down. Where is the information about the object class stored? class object { public: virtual void somefunc(); int someint; }; class objectchild:public object { } object *o=(object*)malloc(sizeof(objectchild)); cout << int(dynamic_cast<objectchild*>(o)) << endl; This causes a program shutdown. Thank you in advance.

    Read the article

  • How do I iterate over a tuple

    - by Caligo
    How can I iterate over a tuple starting from, say, index 1 to 2? The following doesn't work. using boost::fusion::cons; typedef cons<A, cons<B, cons<C, cons<D> > > > MyTuple; MyTuple tuple_; template <class T> struct DoSomething{ DoSomething(T& t) : t_(&t){ } template <class U> void operator()(U u){ boost::fusion::at<mpl::int_<u> >(*t_); } T* t_; }; boost::mpl::for_each< boost::mpl::range_c<int, 1, 3> >( DoSomething<MyTuple>(tuple_) );

    Read the article

  • Access SQL query to SELECT from one table and INSERT into another

    - by typoknig
    Below is my query. Access does not like it, giving me the error Syntax error (missing operator) in query expression 'answer WHERE question = 1'. Hopefully you can see what I am trying to do. Please pay particular attention to 3rd, 4th, and 5th lines under the SELECT statement. INSERT INTO Table2 (respondent,1,2,3-1,3-2,3-3,4,5) SELECT respondent, answer WHERE question = 1, answer WHERE question = 2, answer WHERE answer = 'text 1' AND question = 3, answer WHERE answer = 'text 2' AND question = 3, answer WHERE answer = 'text 3' AND question = 3, answer WHERE question = 4, longanswer WHERE question 5 FROM Table1 GROUP BY respondent;

    Read the article

  • How to declare a pointer to a variable as a parameter of a function in C++?

    - by Keand64
    I have a function that takes a pointer to a D3DXVECTOR3, but I have no reason to declare this beforehand. The most logical solution to me was using new: Function( //other parameters, new D3DXVECTOR3(x, y, 0)); but I don't know how I would go about deleting it, beign intitialized in a function. My next thought was to use the & operator, like so: Function( //other parameters, &D3DVECTOR3(x, y, 0)); but I don't know if this is a valid way to go about doing this. (It doesn't get an error, but neither does int *x; x = 50;). So should I use new, &, or some other technique I'm overlooking?

    Read the article

  • How to insert into std::map.

    - by Knowing me knowing you
    In code below: map<string,vector<int>> create(ifstream& in, const vector<string>& vec) { /*holds string and line numbers into which each string appears*/ typedef map<string,vector<int>> myMap; typedef vector<string>::const_iterator const_iter; myMap result; string tmp; unsigned int lineCounter = 0; while(std::getline(in,tmp)) { const_iter beg = vec.begin(); const_iter end = vec.end(); while (beg < end) { if ( tmp.find(*beg) != string::npos) { result[*beg].push_back(lineCounter);//THIS IS THE LINE I'M ASKING FOR } ++beg; } ++lineCounter; } return result; } How should I do it (check line commented in code) if I want to use insert method of map instead of using operator[]? Thank you.

    Read the article

  • How do I do division on HH:MM:SS format time strings in C#?

    - by Jake
    I have a series of times that are coming to me as strings from a web service. The times are formated as HH:MM:SS:000 (3 milisecond digits). I need to compare two times to determine if one is more than twice as long as the other: if ( timeA / timeB > 2 ) What's the simplest way to work with the time strings? If I was writing in Python this would be the answer to my question: Difference between two time intervals in Python Edit: What I'm really looking for is a way to get the ratio of timeA to timeB, which requires division, not subtraction. Unfortunately, the DateTime structure doesn't appear to have a division operator. Updated the question title to reflect this.

    Read the article

  • C pointer question, dereferencing crash

    - by skynorth
    Why do this work? int *var; while(scanf("%d", &var) && *var != 0) printf("%d \n", var); While this does not? int *var; while(scanf("%d", &var) && var != 0) printf("%d \n", var); Doesn't * (dereference operator) give you the value pointed by the pointer? So why does *var != 0 crash the program, while var != 0 does not?

    Read the article

  • deleting dynamically allocated object that contains vector in C++ STL

    - by kobac
    I have a class class ChartLine{ protected: vector<Point> line; // points connecting the line CString name; //line name for legend CPen pen; //color, size and style properties of the line }; where Point is a structure struct Point{ CString x; double y; }; In main() I dynamically allocate objects of type ChartLine with new operator. If I use delete afterwards, will default destructor ~ChartLine() properly dealocate (or clear) member ChartLine::line(which is vector btw) or I would have to clear that vector in ~ChartLine() manually? Thanks in advance. Cheers.

    Read the article

  • RegularExpressionValidator always fails, but ValidationExpression works in testing

    - by Jerph
    I found the answer to this, but it's a bit of a gotcha so I wanted to share it here. I have a regular expression that validates passwords. They should be 7 to 60 characters with at least one numeric and one alpha character. Pretty standard. I used positive lookaheads (the (?= operator) to implement it: (?=^.{7,60}$)(?=.*[0-9].*)(?=.*[a-zA-Z].*) I checked this expression in my unit tests using Regex.IsMatch(), and it worked fine. However, when I use it in a RegularExpressionValidator, it always fails. Why?

    Read the article

  • How to retrieve all keys (or values) from a std::map?

    - by Owen
    This is one of the possible ways I come out: struct RetrieveKey { template <typename T> typename T::first_type operator()(T keyValuePair) const { return keyValuePair.first; } }; map<int, int> m; vector<int> keys; // Retrieve all keys transform(m.begin(), m.end(), back_inserter(keys), RetrieveKey()); // Dump all keys copy(keys.begin(), keys.end(), ostream_iterator<int>(cout, "\n")); Of course, we can also retrieve all values from the map by defining another functor RetrieveValues. Is there any other way to achieve this easily? (I'm always wondering why std::map does not include a member function for us to do so.)

    Read the article

  • Any way to make a generic List where I can add a type AND a subtype?

    - by user383178
    I understand why I cannot do the following: private class Parent { }; private class Child extends Parent { }; private class GrandChild extends Child { }; public void wontCompile(List<? extends Parent> genericList, Child itemToAdd) { genericList.add(itemToAdd); } My question is there ANY practical way to have a typesafe List where you can call add(E) where E is known to be only a Parent or a Child? I vaguely remember some use of the "|" operator as used for wildcard bounds, but I cannot find it in the spec... Thanks!

    Read the article

< Previous Page | 83 84 85 86 87 88 89 90 91 92 93 94  | Next Page >