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  • Pass the current state of a function into another function in C/C++

    - by sand
    Is there a way to pass the current state of a function into another function in C/C++? I mean all the parameters and local variables by current state. For example: void funcA (int a, int b) { char c; int d, e; // Do something with the variables. // ... funcB(); // Do something more. } void funcB() { // funcB() should be able to access variables a,b,c,d & e // and any change in these variables reflect into funcA(). } The code is in bad shape if there is a need for funcB() kind of functions. But can it be achieved? This can help if someone is starting to re-factor a long method with multiple parameters.

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  • Polymorphic behavior not being implemented

    - by Garrett A. Hughes
    The last two lines of this code illustrate the problem: the compiler works when I use the reference to the object, but not when I assign the reference to an array element. The rest of the code is in the same package in separate files. BioStudent and ChemStudent are separate classes, as well as Student. package pkgPoly; public class Poly { public static void main(String[] arg) { Student[] stud = new Student[3]; // create a biology student BioStudent s1 = new BioStudent("Tom"); // create a chemistry student ChemStudent s2 = new ChemStudent("Dick"); // fill the student body with studs stud[0] = s0; stud[1] = s1; // compiler complains that it can't find symbol getMajor on next line System.out.println("major: " + stud[0].getMajor() ); // doesn't compile; System.out.println("major: " + s0.getMajor() ); // works: compiles and runs correctly } }

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  • How to link .lib library in linux

    - by giga
    I'm pretty new to c programming and want to port a windows c application to linux. My code uses a .lib file va_g729.lib - is it possible to use the same library in Linux and compile it with gcc? All my .c and .h files along with the one .lib files are in the same directory. What I'm doing now is executing this command in the directory: gcc *.c -lm and I get following errors: lbcodec2.c:(.text+0xa6b): undefined reference to `va_g729a_init_encoder' lbcodec2.c:(.text+0xa83): undefined reference to `va_g729a_encoder' collect2: error: ld returned 1 exit status Is it possible to link the .lib file and compile with gcc? Thanks.

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  • Unusual conversion error (string to integer) asp.net

    - by Phil
    I have my repeater item template: <ItemTemplate> <tr><td><%#Container.DataItem("Category")%></td></tr> </ItemTemplate> Hooked up to: s = "SQL that works ok on server" x = New SqlCommand(s, c) x.Parameters.Add("@contentid", SqlDbType.Int) x.Parameters("@contentid").Value = contentid c.Open() r = x.ExecuteReader If r.HasRows Then Linksrepeater.DataSource = r Linksrepeater.DataBind() End If c.Close() r.Close() When I run the code I get: Invalid Cast Exception was not handled by user code (Conversion from string "category" to type 'Integer' is not valid.) I'm not sure how / why it is trying to convert "Category" to integer as in the db it is a string. Can you please tell me how to avoid this error? thanks.

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  • Check constraint on table lookup

    - by bzamfir
    Hi, I have a table, department , with several bit fields to indicate department types One is Warehouse (when true, indicate the department is warehouse) And I have another table, ManagersForWarehouses with following structure: ID autoinc WarehouseID int (foreign key reference DepartmentID from departments) ManagerID int (foreign key reference EmployeeID from employees) StartDate EndDate To set new manager for warehouse, I insert in this table with EndDate null, and I have a trigger that sets EndDate for previous record for that warehouse = StartDate for new manager, so a single manager appears for a warehouse at a certain time. I want to add two check constraints as follows, but not sure how to do this do not allow to insert into ManagersForWarehouses if WarehouseID is not marked as warehouse Do not allow to uncheck Warehouse if there are records in ManagersForWarehouses Thanks

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  • Global Import/using Aliasing in .NET

    - by Josh Stodola
    Using import aliasing in a single class, we can reference class library namespaces by assigning our own custom alias like this: ' VB Imports Db = Company.Lib.Data.Objects // C# using Db = Company.Lib.Data.Objects; And then we are able to reference the classes inside of Company.Lib.Data.Objects by using the Db alias that we assigned. Is it possible to do this at the global level so that the alias is applied to the entire solution instead of the given file? Currently, we are working with web applications, so I was hoping we could add something to web.config, but I am also interested in whether or not this is possible with windows forms, console apps, and/or class libraries.

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  • Preserving NULL values in a Double Variable

    - by Sam
    Hi, I'm working on a vb.net application which imports from an Excel spreadsheet. If rdr.HasRows Then Do While rdr.Read() If rdr.GetValue(0).Equals(System.DBNull.Value) Then Return Nothing Else Return rdr.GetValue(0) End If Loop Else I was using string value to store the double values and when preparing the database statement I'd use this code: If (LastDayAverage = Nothing) Then command.Parameters.AddWithValue("@WF_LAST_DAY_TAG", System.DBNull.Value) Else command.Parameters.AddWithValue("@WF_LAST_DAY_TAG", Convert.ToDecimal(LastDayAverage)) End If I now have some data with quite a few decimal places and the data was put into the string variable in scientific notation, so this seems to be the wrong approach. It didn't seem right using the string variable to begin with. If I use a double or decimal type variable, the blank excel values come across as 0.0. How can I preserve the blank values? Thanks

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  • An attempt to attach an auto-named database for file failed in Vb.Net

    - by user2454135
    I am Trying to connect database for first time , and I am getting this error : An attempt to attach an auto-named database for file VBTestDB.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share. and getting error on myconnect.Open() Heres my code : Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim myconnect As New SqlClient.SqlConnection myconnect.ConnectionString = "Data Source=.\SQLEXPRESS;AttachDbFilename=VBTestDB.mdf;Integrated Security=True;User Instance=True;" Dim mycommand As SqlClient.SqlCommand = New SqlClient.SqlCommand() mycommand.Connection = myconnect mycommand.CommandText = "INSERT INTO Card (CardNo,Name) VALUES (@cardno,@name)" myconnect.Open() Try mycommand.Parameters.Add("@cardno", SqlDbType.Int).Value = TextBox1.Text mycommand.Parameters.Add("@name", SqlDbType.NVarChar).Value = TextBox2.Text mycommand.ExecuteNonQuery() MsgBox("Success") Catch ex As System.Data.SqlClient.SqlException MsgBox(ex.Message) End Try myconnect.Close() End Sub

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  • WorkFlow and WCF dynamically launching WorkFlows

    - by Raj73
    I have a WF which will be hosted on WCF . The service Contract will contain a single operation containing two parameters. Parameter1 will be a string and will contain the name of the workflow to invoke and parameter two will contain the input for the invoked Work Flow. All operations will take the same parameter. All the operations will return the same return value. I have created the service implementation and I would like to depending on the value of parameter1 start executing the appropriate workflow and return the value (There can be number of workflow classes say Operation1, Operation2...which will be the passed in as the value in Parameter1). How can I instantiate different workflow classes and pass parameters and get the return values from them which I should then pass back to the calling Client. (Also Should I be using ReceiveActivities in all of my Launchable WorkFlow Classes ? ) Any code samples or pointers would help

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  • linq2sql left join with "multiselect"

    - by just_azho
    Hi, folks I'm trying to achieve following by linq2sql, but not successful. I've Member and Reference tables. DB is design in such a manner that Member can have multiple (=0) References. What I want as a result of query is, list (rows) of members, where all references of the member are "collected" in one column. What I had achieved is following query, but for this one there exist a row for each Reference. var refs = (from m in db.Members join r in db.References on m.PID equals r.PID into g from o in g.DefaultIfEmpty() select new { member = m, name = (o == null ? "" : o.NameSurname) }); I feel I need to insert SelectMany somewher :) Could you please give hints on achieving the goal?

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  • Initializing a value through a Session variable

    - by William Calleja
    I need to Initialize a value in a Javascript by using a c# literal that makes reference to a Session Variable. I am using the following code <script type="text/javascript" language="javascript" > var myIndex = <%= !((Session["myIndex"]).Equals(null)||(Session["myIndex"]).Equals("")) ? Session["backgroundIndex"] : "1" %>; However the code above is giving me a classic Object reference not set to an instance of an object. error. Why? Shouldn't (Session["myIndex"]).Equals(null) capture this particular error?

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  • How much RAM used by Python dict or list?

    - by Who8MyLunch
    My problem: I am writing a simple Python tool to help me visualize my data as a function of many parameters. Each change in parameters involves a non-trivial amount of time, so I would like to cache each step's resulting imagery and supporting data in a dictionary. But then I worry that this dictionary could grow too large over time. Most of my data is in the form of Numpy arrays. My question: How would one go about computing the total number of bytes used by a Python dictionary. The dictionary itself may contain lists and other dictionaries, each of which contain data stored in Numpy arrays. Ideas?

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  • Singelton restricted to instance of dll

    - by codeySmurf
    If I create a singleton class in the context of a dll, the singleton class is instantiated once and used by all instances of the dll. I am using a dll as a plug-in for an application. Now the following thing came to my mind: If I use a singleton Class, it will be shared across multiple instances of the plug-in. However, this makes it difficult to manage the lifetime of the singleton class efficiently. The only way I could think of would be to use a reference count and to make the singleton delete its self when the reference count is 0. Does anyone have any better ideas on that? Is there any good way to restrict the singleton object to one instance of the dll? Language is c++

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  • Do fields need to be explicitly final to have a "proper" immutable object?

    - by Yishai
    You often read about immutable objects requiring final fields to be immutable in Java. Is this in fact the case, or is it simply enough to have no public mutability and not actually mutate the state? For example, if you have an immutable object built by the builder pattern, you could do it by having the builder assign the individual fields as it builds, or having the builder hold the fields itself and ultimately return the immutable object by passing the values to its (private) constructor. Having the fields final has the obvious advantage of preventing implementation errors (such as allowing code to retain a reference to the builder and "building" the object multiple times while in fact mutating an existing object), but having the Builder store its data inside the object as it is built would seem to be DRYer. So the question is: Assuming the Builder does not leak the Object early and stops itself from modifying the object once built (say by setting its reference to the object as null) is there actually anything gained (such as improved thread safety) in the "immutability" of the object if the object's fields were made final instead?

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  • Updating the collections of entities with NHibernate the correct way

    - by karel_evzen
    A simple question regarding how NHibernate works: I have a parent entity that has a collection of other child entities. Those child entities have a reference to the parent entity they belong to. Now I want to implement an Add method to the parent entity that would add a child to it. Should that Add method only add the child to its new parents collection, or should it also update the parent reference of the child or should it also remove the added entity from its previous parents collection? Do I have to do all these things in that method or will NHibernate do something for me? Thanks.

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  • Singleton wrapper for Context

    - by kpdvx
    I'm considering creating a singleton wrapper for a Context so my model objects, if necessary, can open and read from a database connection. My model objects do not have access to a Context, and I'd like to avoid needing to pass a reference to a Context from object to object. I was planning to place into this singleton a reference to the Context returned by Application.getApplicationContext(). This singleton object would be initialized in my custom Application instance before anything else would need to or have a chance to use it. Can anyone think of a reason to not do this?

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  • Is it thread safe to read a form controls value (but not change it) without using Invoke/BeginInvoke from another thread

    - by goku_da_master
    I know you can read a gui control from a worker thread without using Invoke/BeginInvoke because my app is doing it now. The cross thread exception error is not being thrown and my System.Timers.Timer thread is able to read gui control values just fine (unlike this guy: can a worker thread read a control in the GUI?) Question 1: Given the cardinal rule of threads, should I be using Invoke/BeginInvoke to read form control values? And does this make it more thread-safe? The background to this question stems from a problem my app is having. It seems to randomly corrupt form controls another thread is referencing. (see question 2) Question 2: I have a second thread that needs to update form control values so I Invoke/BeginInvoke to update those values. Well this same thread needs a reference to those controls so it can update them. It holds a list of these controls (say DataGridViewRow objects). Sometimes (not always), the DataGridViewRow reference gets "corrupt". What I mean by corrupt, is the reference is still valid, but some of the DataGridViewRow properties are null (ex: row.Cells). Is this caused by question 1 or can you give me any tips on why this might be happening? Here's some code (the last line has the problem): public partial class MyForm : Form { void Timer_Elapsed(object sender) { // we're on a new thread (this function gets called every few seconds) UpdateUiHelper updateUiHelper = new UpdateUiHelper(this); foreach (DataGridViewRow row in dataGridView1.Rows) { object[] values = GetValuesFromDb(); updateUiHelper.UpdateRowValues(row, values[0]); } // .. do other work here updateUiHelper.UpdateUi(); } } public class UpdateUiHelper { private readonly Form _form; private Dictionary<DataGridViewRow, object> _rows; private delegate void RowDelegate(DataGridViewRow row); private readonly object _lockObject = new object(); public UpdateUiHelper(Form form) { _form = form; _rows = new Dictionary<DataGridViewRow, object>(); } public void UpdateRowValues(DataGridViewRow row, object value) { if (_rows.ContainsKey(row)) _rows[row] = value; else { lock (_lockObject) { _rows.Add(row, value); } } } public void UpdateUi() { foreach (DataGridViewRow row in _rows.Keys) { SetRowValueThreadSafe(row); } } private void SetRowValueThreadSafe(DataGridViewRow row) { if (_form.InvokeRequired) { _form.Invoke(new RowDelegate(SetRowValueThreadSafe), new object[] { row }); return; } // now we're on the UI thread object newValue = _rows[row]; row.Cells[0].Value = newValue; // randomly errors here with NullReferenceException, but row is never null! }

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  • Flex: Problem with CollectionEvent on ArrayCollection

    - by dasnervtdoch
    Hi there, got a reference to an arrayCollection and add event listener like this: collection.addEventListener(CollectionEvent.COLLECTION_CHANGE, onCollectionChange); that´s fine. Now some other component does have the same reference and is adding items to and removing items from that collection. Each time the handler is called: private function onProjectPersonsChange(event:Event):void { if (event.kind == CollectionEventKind.ADD) { //do something } else if (event.kind == CollectionEventKind.REMOVE) { //do something //here is the problem: event.items.length = 0 } else { trace('CollectionEvent: kind not handled!'); } } Does somebody know why the removed item is not in 'items'? Thanks in advance!

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  • XPath to find an element with a similar sibling

    - by user364902
    Suppose I have this XML: <x> <e a='1' b='A'/> <e a='1' b='B'/> <e a='1' b='A'/> </x> I'd like to write an xpath to find any elements e which: Have attribute @b = 'A' Have the same value for attribute @a The xpath can't reference the literal value of attribute @a, however. It can reference the literal value of attribute @b. Or more generally, I want to find if there are any instances where there are two or more elements e[@b=A'] with the same value for attribute @a. Is this possible?

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