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  • Why won't this static_cast in C++ work?

    - by samoz
    When I try to use a static_cast to cast a double* to an int*, I get the following error: invalid static_cast from type ‘double*’ to type ‘int*’ Here is the code: #include <iostream> int main() { double* p = new double(2); int* r; r=static_cast<int*>(p); std::cout << *r << std::endl; } I understand that there would be problems converting between a double and an int, but why is there a problem converting between a double* and an int*?

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  • floats in NSArray

    - by JordanC
    I have an NSArray of floats which I did by encapsulating the floats using [NSNumber numberWithFloat:myFloat] ; Then I passed that array somewhere else and I need to pull those floats out of the array and perform basic arithmatic. When I try [myArray objectAtIndex:i] ; The compiler complains that I'm trying to perform arithmatic on a type id. It also won't let me cast to float or double. Any ideas? This seems like it should be an easy problem. Maybe it will come to me after another cup of coffee, but some help would be appreciated. Thanks.

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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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  • How to solve this Java type safety warning? (Struts2)

    - by Nicolas Raoul
    Map session = ActionContext.getContext().getSession(); session.put("user", user); This code generates a warning: Type safety: The method put(Object, Object) belongs to the raw type Map. References to generic type Map should be parameterized. Map<String, Serializable> session = (Map<String, Serializable>)ActionContext.getContext().getSession(); session.put("user", user); This code generates a warning: Type safety: Unchecked cast from Map to Map. The getSession method belongs to Struts2 so I can't modify it. I would like to avoid using @SuppressWarnings because other warnings can be useful. I guess all Struts2 users in the world faced the same problem... is there an elegant solution?

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  • check existense between two IEnumerable

    - by sunglim
    IEnumerable<String> existedThings = from mdinfo in mdInfoTotal select mdinfo.ItemNo; IEnumerable<String> thingsToSave = from item in lbXReadSuccess.Items.Cast<ListItem>() select item.Value; Here are two IEnumerable. I want to check whether a value in existedThings exist in thingsToSave. O.K. I can do that with 3 line code. bool hasItemNo; foreach(string itemNo in existedThings) hasItemNo= thingsToSave.Contains(itemNo); But, It looks dirty. I just want to know if there better solution.

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  • View changes nvarchars to varchars in SQL Server 2008

    - by Traples
    I have a view in a SQL Server 2008 db that simply exposes about 20 fields of one table to be consumed via ODBC to a client. When I tried to replicate this view in another database, the client could not consume the data source. Then I noticed some weirdness. The columns in the view are shown, in SQL Server Management Studio, to be varchar(100), while the columns in the table are defined as nvarchar(100). There are no CAST or CONVERT statements in the view, it is a simple SELECT statement. Example: Table - Columns: Desc1 (nvarchar(100), null) View - SELECT TOP 100 PERCENT Desc1 FROM... Columns: Desc1 (varchar(100), null) Any ideas why the columns are defined as varchar in the view instead of nvarchar?

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  • SQL Server 2012 memory usage steadily growing

    - by pgmo
    I am very worried about the SQL Server 2012 Express instance on which my database is running: the SQL Server process memory usage is growing steadily (1.5GB after only 2 days working). The database is made of seven tables, each having a bigint primary key (Identity) and at least one non-unique index with some included columns to serve the majority of incoming queries. An external application is calling via Microsoft OLE DB some stored procedures, each of which do some calculations using intermediate temporary tables and/or table variables and finally do an upsert (UPDATE....IF @@ROWCOUNT=0 INSERT.....) - I never DROP those temporary tables explicitly: the frequency of those calls is about 100 calls every 5 seconds (I saw that the DLL used by the external application open a connection to SQL Server, do the call and then close the connection for each and every call). The database files are organized in only one filgegroup, recovery type is set to simple. Some questions to diagnose the problem: is that steadily growing memory normal? did I do any mistake in database design which probably lead to this behaviour? (no explicit temp-table drop, filegroup organization, etc) can SQL Server manage such a stored procedure call rate (100 calls every 5 seconds, i.e. 100 upsert every 5 seconds, beyond intermediate calculations)? do the continuous "open connection/do sp call/close connection" pattern disturb SQL Server? is it possible to diagnose what is causing such a memory usage? Perhaps queues of wating requests? (I ran sp_who2, but I didn't see a big amount of orphan connections from the external application) if I restrict the amount of memory which SQL Server is allowed to use, may I sooner or later get into trouble?

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  • Dynamic Object Not Creating for Privately Inherited Class.

    - by mahesh
    Hi, What is the reason for the following code that does not let me to create object. class base { public: void foo() { cout << "base::foo()"; } }; class derived : private base { public: void foo() { cout << "deived::foo()"; } }; void main() { base *d = new derived(); d->foo(); } It Gives me error : " 'type cast' : conversion from 'derived *' to 'base *' exists, but is inaccessible" Thanks in advance :)

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  • 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.

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  • 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?

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  • ParentViewController returns nil

    - by Andreas Johannessen
    Hi I know there are many questions on this, but I don't get it to work. I present a UITabBarController with the presentModalViewController. However when I try to get title from the navigationItem title attribute in the UINavigationController class that presents the tabcontroller, it returns nil no matter what I do. I have the NSLog in the viewDidLoad method in tabcontroller class. I also cast the UIViewController which is returned by the self.parentViewController property. Then I try to access the title through: NSLog(@"%@", castedViewController.navigationItem.title); Any suggestions?

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  • 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;

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  • Glib::ustring and Japanese characters

    - by user294787
    Glib::ustring is supposed to work well with UTF8 but I have a problem when working with Japanese strings. If you compare those two strings, "???" and "???", using == operator or compare method, it will answer that those two strings are equals. I don't understand why. How Glib::ustring works ? The only way I found to get false to the comparison is to compare strings of different sizes. For example "?????" and "????". Very strange...

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  • 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?

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  • Mixing LINQ to SQL with properties of objects in a generic list

    - by BPotocki
    I am trying to accomplish something like this query: var query = from a in DatabaseTable where listOfObjects.Any(x => x.Id == a.Id) select a; Basically, I want to filter the results where a.Id equals a property of one of the objects in the generic list "listOfObjects". I'm getting the error "Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator." Any ideas on how to filter this in an easily readable way using "contains" or another method? Thanks in advance.

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  • 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.

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  • casting issue with realpath function (c programming)

    - by Ralph
    When I compile the following code: #define _POSIX_C_SOURCE 200112L #define _ISOC99_SOURCE #define __EXTENSIONS__ #include <stdio.h> #include <limits.h> #include <stdlib.h> int main(int argc, char *argv[]) { char *symlinkpath = argv[1]; char actualpath [PATH_MAX]; char *ptr; ptr = realpath(symlinkpath, actualpath); printf("%s\n", ptr); } I get a warning on the line that contains the call to the realpath function, saying: warning: assignment makes pointer from integer without a cast Anybody know what's up? I'm running Ubuntu Linux 9.04

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  • Converting c++ string to int

    - by skazhy
    Hi! I have the following data in a c++ string John Doe 01.01.1970 I need to extract the date and time from it into int variables. I tried it like this: int last_space = text_string.find_last_of(' '); int day = int(text_string.substr(last_space + 1, 2)); But I got invalid cast from type ‘std::basic_string’ to type ‘int’. When I extract the "John Doe" part in another string variable, all works fine. What's wrong? I am trying to compile it with g++ -Wall -Werror.

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  • Print unique ascii characters in eclipse console

    - by Shaded
    Hey guys, Kind of a strange question but... here it goes. Recently my application threw an IOException that the text only had a clubs symbol in it (like the suit in cards) I know this is probably because there was a number in there that was cast to a char and printed to the screen, and I've found where that might have happened. The only problem is, I can't recreate it in eclipse because the eclipse console doesn't want to print those characters for me. All I get are boxes. I figure this is an encoding issue or something but I need eclipse to print out those characters just like the windows console would. Is there a setting I can change to do this?

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  • Solving C++ 'target of assignment not really an lvalue' errors

    - by Jason
    Given this code: void FrMemCopy(void *to, const void *from, size_t sz) { size_t sz8 = sz >> 3; size_t sz1 = sz - (sz8 << 3); while (sz8-- != 0) { *((double *)to)++ = *((double *)from)++; } while (sz1-- != 0) { *((char *)to)++ = *((char *)from)++; } } I am receiving target of assignment not really an lvalue warnings on the 2 lines inside the while loops. Can anyone break down those lines? a cast then an increment? What is a simplier way to write that? What does the error mean?

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  • How do I use a custom select statement in Hibernate using the HibernateDaoSupport class

    - by Bill Leeper
    I am trying to write a custom select statement in Hibernate using the getHibernateTemplate() method. I am having problems with the resulting mapping. Example Code: List<User> users = getHibernateTemplate().find("Select user, sysdate as latestPost from User as user"); for (User user : users) { assertNotNull(users.name); } The goal of the above line is to eventually have a join where I get the max(date) of posts made by the user. The problem I am having is that the resulting users list is not a list of User objects and I get a class cast exception. Hopefully that is enough code. It is a greatly simplified version of my problem and a combination of snippets from various parts of my application.

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  • Hex to bin after logical operations

    - by user355926
    I want: 111 || 100 ---> 111, not 1 100 && 100 ---> 100, not 1 101 && 010 ---> 000, not 0 Broken code #include <stdio.h> main(void){ string hexa = 0xff; strig hexa2 = 0xf1; // CONVERT TO INT??? cast int hexa3 = hexa || hexa2; int hexa4 = hexa && hexa2; puts(hexa3); puts(hexa4); }

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  • So I dynamically load a jar at runtime how do I use it?

    - by justinhj
    So question 194698 shows how to load a jar file at runtime and you can load individual named classes and get a Class object. Now my problem is I want to be able to cast those Classes to the types they really are, but I can't because I can't use an import since the whole point is to load it at runtime rather than compile time. It seems like the way to go is to use reflection to discover the functions and field names, but that seems brittle since the API in the jar files could change and the code won't break until it is run. Is there a better way?

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  • 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?

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  • 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'." />

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