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  • Does C99 guarantee that arrays are contiguous ?

    - by kriss
    Following an hot comment thread in another question, I came to debate of what is and what is not defined in C99 standard about C arrays. Basically when I define a 2D array like int a[5][5], does the standard C99 garantee or not that it will be a contiguous block of ints, can I cast it to (int *)a and be sure I will have a valid 1D array of 25 ints. As I understand the standard the above property is implicit in the sizeof definition and in pointer arithmetic, but others seems to disagree and says casting to (int*) the above structure give an undefined behavior (even if they agree that all existing implementations actually allocate contiguous values). More specifically, if we think an implementation that would instrument arrays to check array boundaries for all dimensions and return some kind of error when accessing 1D array, or does not give correct access to elements above 1st row. Could such implementation be standard compilant ? And in this case what parts of the C99 standard are relevant.

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  • [PHP] Invalid argument supplied for foreach()

    - by Roberto Aloi
    It often happens to me to handle data that can be either an array or a null variable and to feed some foreach with these data. $values = get_values(); foreach ($values as $value){ ... } When you feed a foreach with data that are not an array, you get a warning: Warning: Invalid argument supplied for foreach() in [...] Assuming it's not possible to refactor the get_values() function to always return an array (backward compatibility, not available source code, whatever other reason), I'm wondering which is the cleanest and most efficient way to avoid these warnings: Casting $values to array Initializing $values to array Wrapping the foreach with an if Other (please suggest)

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  • Why doesn't an octal literal as a string cast to a number?

    - by Andy E
    In JavaScript, why does an octal number string cast as a decimal number? I can cast a hex literal string using Number() or +, why not an octal? For instance: 1000 === +"1000" // -> true 0xFF === +"0xFF" // -> true 0100 === +"0100" // -> false - +"0100" gives 100, not 64 I know I can parse with parseInt("0100" [, 8]), but I'd like to know why casting doesn't work like it does with hex and dec numbers. Also, does anyone know why octal literals are dropped from ECMAScript 5th Edition in strict mode?

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  • How is conversion of float/double to int handled in printf?

    - by Sandip
    Consider this program int main() { float f = 11.22; double d = 44.55; int i,j; i = f; //cast float to int j = d; //cast double to int printf("i = %d, j = %d, f = %d, d = %d", i,j,f,d); //This prints the following: // i = 11, j = 44, f = -536870912, d = 1076261027 return 0; } Can someone explain why the casting from double/float to int works correctly in the first case, and does not work when done in printf? This program was compiled on gcc-4.1.2 on 32-bit linux machine.

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  • F# return type coercion

    - by Alex
    Hi, In F# I have a function that returns System.Linq.Expression instances: and System.Object with member this.ToExpression() = match this with | :? System.Int32 -> Expression.Constant(this) :> Expression | :? System.Boolean -> Expression.Constant(this) :> Expression | :? Tml.Runtime.Seq as s -> s.ToExpression() | _ -> failwith "bad expression" If I omit the type coercions on the return values F# will infer the return type of the function to ConstantExpression. My first thought was to explicitly mark the return type as being : #Expression, but that didn't work. Is there a more elegant way of doing this that doesn't involve manually casting return types to the most generic type? Thanks.

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  • (MyClassName)object vs. object as MyClassName

    - by Matthew Doyle
    Hello all, I was wondering what is the better method for Casting objects for C#: MyClassName test = (MyClassName)object; MyClassName test = object as MyClassName; I know already that if you do the first way, you get an exception, and the second way it sets test as null. However, I was wondering why do one over the other? I see the first way a lot, but I like how the second way because then I can check for null... If there isn't a 'better way' of doing it, what are the guidelines for using one way or the other?

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  • How to get parent item in Treeview

    - by Anu
    Hi,To get the child items as string i used the following code private void treeview1_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e) { if (treeview1.SelectedItem != null) { Animal bar = (Animal)treeview1.SelectedItem; string str = bar.Name; int boxty = bar.BoxType; int boxno = bar.BoxNo; } } It works fine .But when i click on parent(instead of + sign),it goes to this code and shows error.Ofcourse im casting SelectedItem to my List-Animal. But i dont want this.I have to check,whether the clciked item is parent,if it is so then i will skip this coding.Only when i click the child items it will go to this coding. How can i do that?How can i identify the selected item is parent.

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  • How to handle subclasses in JasperReports?

    - by gotch4
    I've two classes (A and B) that extend a base class BASE. I need to make a report that takes an array of such classes and the prints the fields of A or B. I tought of using conditional expressions, then casting to one or another (depending on a field value). But I can't cast, because I don't know how to refere to the current bean. To do this I am using a JRBeanCollectionDataSource filled with a List<BASE>. How do I cast every bean to A or B in a report (or subreport)? I tried: ((A)this) but it says basically that this contains the report instance, not the current bean and gives error.

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  • How can avoid at this line an OverflowException?

    - by SoMoS
    LastInput.time is an Integer and m_idleTime is an Integer too. This line sometimes generates an Overflow exception, I think that this happens when both values are big negative values. (Environment.TickCount - lastInput.time) > m_idleTime How can I avoid that? With casting? (CType(Environment.TickCount,Long) - CType(lastInput.time,Long)) > m_idleTime Or maybe with this cast? CType((Environment.TickCount - lastInput.time),Long) > m_idleTime Thanks in advance.

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  • Good way to format decimal in SQL Server

    - by Brad
    We store a decimal(9,8) in our database. It can have any number of places after the decimal point (well, no more than 8). I am frustrated because I want to display it as human-readable text as part of a larger string created on the server. I want as many decimals to the right of the decimal point as are non-zero, for example: 0.05 0.12345 3.14159265 Are all good If I do CAST(d AS varchar(50)) I get formatting like: 0.05000000 0.12345000 3.14159265 I get similar output if I cast/convert to a float or other type before casting to a varchar. I know how to do a fixed number of decimal places, such as: 0.050 0.123 3.142 But that is not what I want. Yes, I know I can do this through complicated string manipulation (REPLACE, etc), there should be a good way to do it.

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  • Read tab delimited text file into MySQL table with PHP

    - by Simon S
    I am trying to read in a series of tab delimited text files into existing MySQL tables. The code I have is quite simple: $lines = file("import/file_to_import.txt"); foreach ($lines as $line_num => $line) { if($line_num > 1) { $arr = explode("\t", $line); $sql = sprintf("INSERT INTO my_table VALUES('%s', '%s', '%s', %s, %s);", trim((string)$arr[0]), trim((string)$arr[1]), trim((string)$arr[2]), trim((string)$arr[3]), trim((string)$arr[4])); mysql_query($sql, $database) or die(mysql_error()); } } But no matter what I do (hence the casting before each variable in the sprintf statement) I get the "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1" error. I echo out the code, paste it into a MySQL editor and it runs fine, it just won't execute from the PHP script. What am I doing wrong?? Si

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  • setting value to the instance of primitive types

    - by Samreen
    I have a function which performs some operation i.e. fetches some data from database. The generic it takes is primitive type always i.e. int, char, bool, string etc. I can easily create its instance. But I can't set the value that I have fetched from database to this instance. public T PerformOperation<T>() { object instance = (T)Activator.CreateInstance(typeof(T)); object result=FetchData(); instance = (T)result; //It gives error on this statement } The function is called as: int result = PerformOperation<int>(); Is there some way of casting the object Type to any generic type which is always primitive?

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  • Create manual versions

    - by rayman
    Hi, Iam planning to create an app, and not to publish it at the google market. i want the users to update thire app once in a while when an updates will be rlsd via server(let's not get into the idea how i gonna do this)... so for this i need to give to each app some ID, so i know that that user gotta update his app, and not new installation (i wanna avoid the case the user will have two versions of the app).. and ofcourse install the app to new users. how could i sign those apps with version when i rls an update manually? mybe some other idea? thanks, ray.

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  • eclipse: how to debug a Java program as a .jar file?

    - by Jason S
    I use ant for creating .jar files in Eclipse. Works great. I have a .jar file I am working on that expects the code to be in a .jar file (it looks for .properties files in the same directory as the .jar file) -- the standard Eclipse "Run" and "Debug" menus execute the main() method of a specified Java class... but they do it from the directory containing the compiled class files, not a jar file. Is there a way to change this behavior so Eclipse runs code from the appropriate .jar file instead? (My workaround right now is to run the .jar file externally, with it suspended waiting for a debugger, per Dave Ray's answer to one of my other questions.)

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  • How to better design it ???

    - by Deepak
    public interface IBasePresenter { } public interface IJobViewPresenter : IBasePresenter { } public interface IActivityViewPresenter : IBasePresenter { } public class BaseView { public IBasePresenter Presenter { get; set; } } public class JobView : BaseView { public IJobViewPresenter JobViewPresenter { get { this.Presenter as IJobViewPresenter;} } } public class ActivityView : BaseView { public IActivityViewPresenter ActivityViewPresenter { get { this.Presenter as IActivityViewPresenter;} } } Lets assume that I need a IBasePresenter property on BaseView. Now this property is inherited by JobView and ActivityView but if I need reference to IJobViewPresenter object in these derived classes then I need to type cast IBasePresenter property to IJobViewPresenter or IActivityPresenter (which I want to avoid) or create JobViewPresenter and ActivityViewPresenter on derived classes (as shown above). I want to avoid type casting in derived classes and still have reference to IJobViewPresenter or IActivityViewPresenter and still have IBasePresenter in BaseView. Is there a way I can achieve it ?

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  • Deserialize Stream to List<T> or any other type

    - by Sam
    Attempting to deserialize a stream to List<T> (or any other type) and am failing with the error: The type arguments for method 'Foo.Deserialize<T>(System.IO.Stream)' cannot be inferred from the usage. Try specifying the type arguments explicitly. This fails: public static T Deserialize<T>(this Stream stream) { BinaryFormatter bin = new BinaryFormatter(); return (T)bin.Deserialize(stream); } But this works: public static List<MyClass.MyStruct> Deserialize(this Stream stream) { BinaryFormatter bin = new BinaryFormatter(); return (List<MyClass.MyStruct>)bin.Deserialize(stream); } or: public static object Deserialize(this Stream stream) { BinaryFormatter bin = new BinaryFormatter(); return bin.Deserialize(stream); } Is it possible to do this without casting, e.g. (List<MyStruct>)stream.Deserialize()?

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  • Play 2.0 RESTful request post-processing

    - by virtualeyes
    In regard to this question I am curious how one can do post-request REST processing a la (crude): def postProcessor[T](content: T) = { request match { case Accepts.Json() => asJson(content) case Accepts.Xml() => asXml(content) case _ => content } } overriding onRouteRequest in Global config does not appear to provide access to body of the response, so it would seem that Action composition is the way to go to intercept the response and do post-processing task(s). Question: is this a good idea, or is it better to do content-type casting directly within a controller (or other class) method where the type to cast is known? Currently I'm doing this kind of thing everywhere: toJson( i18n("account not found") ) toJson( Map('orderNum-> orderNum) ) while I'd like the toJson/toXml conversion to happen based on accepts header post-request.

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  • Can anyone tell me what's wrong in this part of code

    - by Mobin
    string name = ((DateTimePicker)sender).Name.ToString(); name = name.Substring(0, name.Length - 1); name = name + "4"; TimeSpan duration = new TimeSpan(); duration = ((DateTimePicker)sender).Value - ((DateTimePicker)panel2.Controls[name]).Value; name = name.Substring(0, name.Length - 1); name = name + "6"; ((MaskedTextBox)panel2.Controls[name]).Text = duration.ToString(); On execution it gives me Object reference not set to instance of an object similar functionality is used on other places but I can't find out what I have to reinitialize here :$ The casting for datetimepicker is fine I have to get a name for the datetiempicker to identify the row it's on in my form and the picker before that to calculate their differences and then print that difference in a maskedtext box from the control whose name I make using names of two datetimepickers but when I access controls in the error line I get this message.

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  • Triangular bounding volumes

    - by Cheery
    I've come up with an alternative for beziers that might be easier to ray-trace, perhaps even though a plain vertex shader. Though there's missing a piece. I need to find the parametric surface equation from the surface normals I have for edge vertices. I also have to know it's peak and valley so I can constraint the depth of my bounding triangle. Image explains the overall idea: I build a bounding-volume from a control triangle. Then apply a function to each parametric coordinate of the triangle (s+t+u=1 where s,t,u = 0) to get the height coordinate for that certain point. Simply put, it produces a procedurally generated height-map for the triangle's surface. I just need to find a function that generates the height-map so I can make it work.

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  • C typedef struct uncertainty.

    - by Emanuel Ey
    Consider the following typedef struct in C: 21:typedef struct source{ 22: double ds; //ray step 23: double rx,zx; //source coords 24: double rbox1, rbox2; //the box that limits the range of the rays 25: double freqx; //source frequency 26: int64_t nThetas; //number of launching angles 27: double theta1, thetaN; //first and last launching angle 28:}source_t; I get the error: globals.h:21: error: redefinition of 'struct source' globals.h:28: error: conflicting types for 'source_t' globals.h:28: note: previous declaration of 'source_t' was here I've tried using other formats for this definition: struct source{ ... }; typedef struct source source_t; and typedef struct{ ... }source_t; Which both return the same error. Why does this happen? it looks perfectly right to me.

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  • ASP.NET MVC 2: Deserialize SPROC Response

    - by dcolumbus
    I need to ask a general question. I don't have the code in front of me because I'm writing this on my iPhone. I have a Class that represents a certain XML schema. I have a SPROC that returns this XML. What I need to do is deserialize the XML to this Class. XML: <xml> <person> <firstName>Bob</firstName> <lastName>Robby</lastName> </person> </xml> I need to deserialize this XML into the custom Person Class so I can loop through this Model and spit it out in the View. I'm sure there's some kind of casting involved, I just don't know how to do it.

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  • C++ cast syntax styles

    - by palm3D
    A question related to Regular cast vs. static_cast vs. dynamic_cast: What cast syntax style do you prefer in C++? C-style cast syntax: (int)foo C++-style cast syntax: static_cast<int>(foo) constructor syntax: int(foo) They may not translate to exactly the same instructions (do they?) but their effect should be the same (right?). If you're just casting between the built-in numeric types, I find C++-style cast syntax too verbose. As a former Java coder I tend to use C-style cast syntax instead, but my local C++ guru insists on using constructor syntax. What do you think?

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  • What wording in the C++ standard allows static_cast<non-void-type*>(malloc(N)); to work?

    - by ben
    As far as I understand the wording in 5.2.9 Static cast, the only time the result of a void*-to-object-pointer conversion is allowed is when the void* was a result of the inverse conversion in the first place. Throughout the standard there is a bunch of references to the representation of a pointer, and the representation of a void pointer being the same as that of a char pointer, and so on, but it never seems to explicitly say that casting an arbitrary void pointer yields a pointer to the same location in memory, with a different type, much like type-punning is undefined where not punning back to an object's actual type. So while malloc clearly returns the address of suitable memory and so on, there does not seem to be any way to actually make use of it, portably, as far as I have seen.

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  • php / mysql - select id from one table excepting ids which are in second table

    - by John
    hello. for example i have 2 tables: 1 . users: id Name 1 Mike 2 Adam 3 Tom 4 John 5 Andy 6 Ray 2 . visits: userID date 1 ... 3 ... 6 ... i want to make a page which can be visited once in 12 hours, when user visits that page his id is included in database ( visits ), how i can select all users ( from database users) excepting users who visited page in <= 12 hours ( users from database visits )?

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  • Reading int from a hidden field in .aspx

    - by vikp
    Hi, I'm struggling to read an int from the hidden field on aspx page. <input type = "hidden" id = "myIntegerId" name = "integerId" value= "<%: Model.MyObjectId %>" runat = "server" /> The value is definately on the form, I can see it in the debugger and print it with <%: % When I read the form values in the controller, instead of an int I recieve a following string: <%: Model.MyObjectId % I have tried casting data in the hidden field to string and calling ToString() method on that field, neither has worked. The data is submitted using the post event. I have a feeling that I'm missing something very basic... Any help is greately appreciated. Thanks

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