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  • Is void *p = 0L valid?

    - by Artefacto
    In this answer, sassman initializes a pointer with: zend_class_entry* ce = 0L; My question is – is this valid? I would say it isn't, to initialize the variable with a null pointer either an unadorned (and possibly casted to void *) 0 constant, or some macro that evaluates to that such as NULL should be used. However, I can't find definitive language in the standard that supports this interpretation. All it says is: An integer constant expression with the value 0, or such an expression cast to type void *, is called a null pointer constant.

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  • .NET CF 2.0: Stream implements IDisposable ... kind of?

    - by mvanbem
    I've run into something odd in a .NET CF 2.0 project for Pocket PC 2003 (Visual Studio 2005). I was dealing with a System.IO.Stream object and found that the IDE wouldn't auto-complete the Dispose() method. I typed it in manually and received: 'System.IO.Stream.Dispose(bool)' is inaccessible due to its protection level The error is referring to the protected Dispose(bool) method. Dispose() is either private or not present. Question 1: How is this possible? Stream implements IDisposable: public abstract class Stream : MarshalByRefObject, IDisposable ... and IDisposable requires a Dispose() method: public interface IDisposable { void Dispose(); } I know the compiler won't let me get away with that in my code. Question 2: Will I cause problems by working around and disposing my streams directly? IDisposable idisp = someStream; idisp.Dispose(); The implicit cast is accepted by the compiler.

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  • A Solution For (IEnumerable<Base>)Derive; Yet?

    - by acidzombie24
    I have D1 and D2 which derive from B. When i write var ls = (IEnumerable<B>)(cond?lsD1:lsD2); I get a runtime cast error. IIRC this is a well known problem. My question is 1) Is this allowed yet? perhaps in .NET 4? I have 2010 but my project is a few months old, large and targets 3.5. 2) Is there a simple workaround? I only need to read the list not add anything or remove. Actually, ToArray() would probably work but is there another solution?

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  • define macro in C wont work

    - by Spidfire
    Im trying to make a macro in C that can tell if a char is a hex number ( 0-9 a-z A-Z) #define _hex(x) (((x) >= "0" && (x) <= "9" )||( (x) >= "a" && (x) <= "z") || ((x) >= "A" && (x) <= "Z") ? "true" : "false") this what ive come up with but it wont work with a loop like this char a; for(a = "a" ; a < "z";a++){ printf("%s => %s",a, _hex(a)); } but it gives a error test.c:8: warning: assignment makes integer from pointer without a cast test.c:8: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer test.c:9: warning: comparison between pointer and integer

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  • BIND: How do I allow DNS query from specific external host?

    - by krbvroc1
    I'm running Centos 5.8 (bind 9.3.6). Here is my issue... I run my own DNS server to serve the local machine. I would like to use my DNS server from home. Since my home is a dynamic IP address, I am not sure how this would be accomplished. In my named.conf, there is an allow-query{} and allow-recursion{}. It seems both of those take an IP address, but i need to specify a hostname (at least a cname). This is not a public DNS server (so any is not an option). My hostname/cname is already updated automatically using nsupdate. The only solution I can think of, which I do not like, is to change my nsupdate script to somehow modify the named.conf to search/replace the allow-query/recursion IP address. That would require restarting named whenever the hostname changes as well as Is there some other way to handle this?

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  • How can I pass a type as a parameter in scala?

    - by rsan
    I'm having a really hard time trying to figure out how can I store or pass a type in scala. What I want to achive is something like this: abstract class Foo( val theType : type ) object Foo{ case object Foo1 extends Foo(String) case object Foo2 extends Foo(Long) } So at some point I can do this: theFoo match{ case String => "Is a string" case Long => "Is a long" } and when obtaining the object being able to cast it: theFoo.asInstanceOf[Foo1.theType] Is this possible? If is possible, is a good aproach? What I'm trying to achieve ultimately is writing a pseudo schema for byte stream treatment. E.g if I have an schema Array(Foo1,Foo1,Foo2,Foo3,Foo1) I could parse Arrays of bytes that complain with that schema, if at some point I have a different stream of bytes I could just write a new schema Array(Foo3, Foo4, Foo5) without having to reimplement parsing logic. Regards,

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  • Determine an object's class returned by a factory method (Error: function does not take 1 arguments

    - by tzippy
    I have a factorymethod that either returns an object of baseclass or one that is of derivedclass (a derived class of baseclass). The derived class has a method virtual void foo(int x) that takes one argument. baseclass however has virtual void foo() without an argument. In my code, a factory method returns a pointer of type bar that definetly points to an object of class derivedclass. However since this is only known at runtime I get a compiler error saying that foo() does not take an argument. Can I cast this pointer to a pointer of type derivedclass? std::auto_ptr<baseclass> bar = classfactory::CreateBar(); //returns object of class derivedclass bar->foo(5); class baseclass { public: virtual void foo(); } class derivedclass : public baseclass { public: virtual void foo(int x); }

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  • Java generic function for performing calculations on integer, on double?

    - by Daniel
    Is this possible? Surely if you passed in a double, any sort of function implementation code which casts an object to an Integer would not be able to work unless the cast 'Integer' was specifically used? I have a function like: public static void increment(Object o){ Integer one = (Integer)o; system.out.println(one++); } I cant see how this could be made generic for a double? I tried public static <E> void increment(E obj){ E one = (E)o; system.out.println(one++); } but it didn't like it?

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  • What do C# Table Adapters actually return?

    - by Raven Dreamer
    I'm working on an application that manipulates SQL tables in a windows form application. Up until now, I've only been using the pre-generated Fill queries, and self-made update and delete queries (which return nothing). I am interested in storing the value of a single value from a single column (an 'nchar(15)' name), and though I have easily written the SQL code to return that value to the application, I have no idea what it will be returned as. SELECT [Contact First Name] FROM ContactSkillSet WHERE [Contact ID] = @CurrentID Can the result be stored directly as a string? Do I need to cast it? Invoke a toString method?

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  • Casting in mixed type calculations in C?

    - by yCalleecharan
    Hi, If I define these variables: double x0, xn, h; int n; and I have this mathematical expression: h = (xn - x0)/n; Is it necessary that I cast n into double prior doing the division for maximum accuracy like in h = (xn - x0)/ (double) n; I wrote a program to check the above but both expressions give the same answers. I understand that C will promote the integer to double type as variables xn and x0 are of type double but strangely enough in a book, the second expression with casting was emphasized. Thanks a lot...

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  • Wherewith replace Dictionary.Where(p => p.Key is T)

    - by abatishchev
    I have a System.Collections.Generic.Dictionary<System.Web.UI.Control, object> where all keys can be either type of System.Web.UI.WebControls.HyperLink or type of System.Web.UI.WebControls.Label. I want to change Text property of each control. Because HyperLink doesn't implement (why??) ITextControl, I need to cast Label or HyperLink explicitly: Dictionary<Control,object> dic = .. dic .Where(p => p.Key is HyperLink) .ForEach(c => ((HyperLink)c).Text = "something") dic .Where(p => p.Key is Label) .ForEach(c => ((Label)c).Text = "something") Are there ways to workaround such approach?

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  • Implicit type conversion in DB/2 inserts?

    - by IronGoofy
    We're using SQL Inserts to insert some data via a script into DB/2 tables, e.g. CREATE TABLE TICKETS (TICKETID VARCHAR(10) NOT NULL); On my home installation, this statement works fine (note that I'm using an integer which is autoatically cast into a VarChar): INSERT INTO TICKETS (TICKETID) VALUES (1); while at my customer's site I get a type error. My question(s): Is this behavior version dependent? (I use a DB2 Express V9.7, while the customer has an Enterprise V9.5) Is there a config option to change the behavior? (I would like my home install to behave as close as possible as the production environment is going to be.)

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  • error message fix

    - by user1722654
    for (int i = 0; i < dataGridView1.Rows.Count; i++) { //bool sleected = false; if (dataGridView1.Rows[i].Cells[3].Value != null) { selected.Add(i); } } //string donew = ""; // line off error textBox1.Text = ((String)dataGridView1.Rows[1].Cells[2].Value); /* for (int i = 0; i < selected.Count; i++) { textAdded.Add((String)dataGridView1.Rows[0].Cells[2].Value); // donew += (String)dataGridView1.Rows[selected[i]].Cells[2].Value; }*/ I keep getting the error Unable to cast object of type 'System.Double' to type 'System.String' What can I do to overcome this?

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  • C++ Inheritance Question

    - by shaz
    I have a base class MessageHandler and 2 derived classes, MessageHandler_CB and MessageHandler_DQ. The derived classes redefine the handleMessage(...) method. MH_DQ processes a message and puts the result in a deque while MH_CB processes the message and then executes a callback function. The base class has a static callback function that I pass along with a this pointer to a library which calls the static callback when a new message is available for processing. My problem comes when I am in the static callback with a void * pointing to either a MH_DQ or a MH_CB. If I cast it to the base class the empty MessageHandler::handleMessage(...) method is called, rather than the version in the appropriate derived class. What is the best way to address this situation from a design perspective and/or what language features might help me to implement a solution to my problem? Thanks in advance!

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  • MSSQL 2012 Error 26 and remote connection

    - by Rayfloyd
    I'm trying to set up MSSQL 2012 for a school project and I need to be able to connect to it remotely as my teammates will also be working on it. I did a clean install of SQL Server 2012 Express. Knowing I can't connect remotely straight off, I tweaked the settings that needed tweaking according to the internet. What I did 1.Made sure remote connections were allowed 2.Enabled TCP/IP 3.Removed 0s from Dynamic ports and set 1433 in TCP Port 4.Enabled Named Pipes 5.Created Outbound and Inbound traffic rules in the firewall for TCP port 1433 and UDP port 1434 6.Port forwarded 1433 to my "server" and 1434 too 7.made sure I was pingable 8.SQL Server authentication is enabled 9.I have restarted my computer so that changes to the config are saved So whenever I try to connect using management studio on another computer than the server using myusername.dyndns.org\SQLEXPRESS I get error 26 I have been searching for different solutions for 3 hours with no luck.

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  • Getting the fractional part of a float without using modf()

    - by knight666
    Hi, I'm developing for a platform without a math library, so I need to build my own tools. My current way of getting the fraction is to convert the float to fixed point (multiply with (float)0xFFFF, cast to int), get only the lower part (mask with 0xFFFF) and convert it back to a float again. However, the imprecision is killing me. I'm using my Frac() and InvFrac() functions to draw an anti-aliased line. Using modf I get a perfectly smooth line. With my own method pixels start jumping around due to precision loss. This is my code: const float fp_amount = (float)(0xFFFF); const float fp_amount_inv = 1.f / fp_amount; inline float Frac(float a_X) { return ((int)(a_X * fp_amount) & 0xFFFF) * fp_amount_inv; } inline float Frac(float a_X) { return (0xFFFF - (int)(a_X * fp_amount) & 0xFFFF) * fp_amount_inv; } Thanks in advance!

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  • Setting up a reverse proxy [on hold]

    - by mrwooster
    I am looking for the best solution for setting up a very low maintenance reverse proxy for a production website (example.com). The setup is as follows: A blog with will be hosted on heroku, and will reside at example.com/blog A static info page which will be hosted on S3 and will reside at example.com/signup A dynamic content management system, provided and hosted by an external vendor which will respond to requests for any other pages. The two solutions which come to mind are: Use HAProxy Ask the external vendor to reverse proxy requests for /blog and /signup The obvious solution would be to use HAProxy, but, if at all possible, I would like to avoid having to setup and maintain another server (especially such a critical one). I came across a company called Snapt which offers hosted HAProxy solutions, but its more geared towards load-balancing than reverse proxying. Option 2 is a possibility, but gives us very little control over changes and configuration. I see a lot of sites hosting blogs on /blog so this must be fairly common practice, am I missing an obvious solution?

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  • Is it possible in Scala to force the caller to specify a type parameter for a polymorphic method ?

    - by Alex Kravets
    //API class Node class Person extends Node object Finder { def find[T <: Node](name: String): T = doFind(name).asInstanceOf[T] } //Call site (correct) val person = find[Person]("joe") //Call site (dies with a ClassCast inside b/c inferred type is Nothing) val person = find("joe") In the code above the client site "forgot" to specify the type parameter, as the API writer I want that to mean "just return Node". Is there any way to define a generic method (not a class) to achieve this (or equivalent). Note: using a manifest inside the implementation to do the cast if (manifest != scala.reflect.Manifest.Nothing) won't compile ... I have a nagging feeling that some Scala Wizard knows how to use Predef.<:< for this :-) Ideas ?

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  • C++, is it possible to obtain the dimension of an array?

    - by aaa
    hi. Suppose I have some pointer, which I want to reinterpret as static dimension array reference: double *p; double (&r)[4] = ?(p); // some construct? // clarify template< size_t N> void function(double (&a)[N]); ... double *p; function(p); // this will not work. // I would like to cast p as to make it appear as double[N] Is it possible to do so? how do I do it?

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  • Upcasting in C#: Making a Fruit a Pear

    - by Adam Kane
    Why can't I upcast (?) a Fruit to a Pear? public static class PearGenerator { public static Pear CreatePear () { // Make a new generic fruit. Fruit genericFruit = new Fruit(); // Upcast it to a pear. (Throws exception: Can't cast a Fruit to a Pear.) Pear pear = (Pear)genericFruit; // Return freshly grown pear. return ( pear ); } } public class Fruit { // some code } public class Pear : Fruit { public void PutInPie () { // some code } } Thanks!

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  • How to do hex8 encoding in c?

    - by Tech163
    I am trying to encode a string in hex8 using c. The script I have right now is: int hex8 (char str) { str = printf("%x", str); if(strlen(str) == 1) { return printf("%s", "0", str); } else { return str; } } In this function, I will need to add a 0 ahead of the string if the length is less than 1. I don't know why I'm getting: passing argument 1 of 'strlen' makes pointer from integer without a cast Does anyone know why?

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  • Server IP must be a LAN IP (Port Forwarding Netgear Router)? [closed]

    - by rphello101
    I'm trying to set up a server (Apache) on my computer (fairly new to it). As I understand it, for it to be accessible to other computers, I need to forward port 80. When I try to forward the port though, I get the error: Server IP must be a LAN IP. I noticed in ipconfig that my default gateway is different than my wireless router. My computer is not hardwired, not on WiFi. Furthermore, I do not, at this point, have a static IP. I read that it should still work with a dynamic IP until it changes. Any ideas on what I can do? I'm using Windows 7 in case it matters.

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  • Network license control for a Java application

    - by user1461615
    I have been tasked with providing some form of network license control for a Java application. The app would be stored on a network drive and run from a client machine. The basic idea is that it will be able to work out how many times it is being run concurrently and prevent the N+1th user from running the software where N is the number of concurrent licenses the customer has purchased. Is this possible somehow with a Java application? I implemented a "solution" which relied on multi-cast UDP communication between the running instances of the application but this didn't work because on most networks this kind of communication is blocked by security measures. Is there a better way? I don't even mind if it requires JNI/JNA. N.B. The solution does not have to be that sophisticated or highly secure.

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  • C++: Checking for non-numeric input and assigning to a double

    - by Brundle
    Here is the code I have at the moment: char ch; int sum = 0; double values[10]; int i = 0; cin >> ch; while (!isalpha(ch)) { values[i] = ch; sum += values[i]; i++; cin >> ch; } What is happening is that if I enter the value 1, that gets assigned to ch as a char. Now ch is assigning it's value to a double and doing an implicit cast. So it is assigning the ASCII value of '1' to values[i]. I want it to just assign 1 to values[i]. Is there a better way to do this? Or is there something that I'm missing?

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  • C# Why does calling an interface member from a class generate an error?

    - by Jack
    So I have an interface: interface IFoo { int Bar(); int this[int i] {get; set;} } And a class that derives from it class Foo : IFoo { public int IFoo.Bar() { //Implementation { public int IFoo.this[int i] { //Implementation } } Now, I try to do this: var fooey = new Foo(); int i = Fooey.Bar(); or this: int i = Fooey[4]; I would expect these to work properly. However, the compiler generates an error as if such members don't exist. Why is that? I am aware I can cast Foo as IFoo, but I am also aware that casting is costly to performance, which is often the reason to use interfaces in the first place. EDIT 1: These are the errors generated 'Foo' does not contain a definition for 'Bar' and no extension method 'Bar' accepting a first argument of type 'Foo' could be found (are you missing a using directive or an assembly reference?) "Cannot apply indexing to an expression of type 'Foo'"

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