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  • ASP.NET MVC4: How to convert an IEnumerable to a string for ViewBag

    - by sehummel
    This is what I'm trying to do, but it doesn't work: HardwareType hwt = new HardwareType { HType = "PC" }; IEnumerable<Hardware> Pcs = db.Hardware.Where(h => h.HardwareType.Contains(hwt)); ViewBag.Pcs = Pcs.ToString(); So how do I convert my IEnumerable to a string (or other primitive data type) so the compiler won't give me an error when I try to use it in my Razor? @foreach (var item in ViewBag.Pcs) { <li><a href="#" class="btn"><i class="icon-hdd"></i> @item.HType</a></li> }

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  • Reference to an instance method of a particular object

    - by Andrey
    In the following code, if i try to pass method reference using the class name, works. But passing the reference variable compiler gives an error, i do not understand why? public class User { private String name; public User(String name) { this.name = name; } public void printName() { System.out.println(name); } } public class Main { public static void main(String[] args) { User u1 = new User("AAA"); User u2 = new User("BBB"); User u3 = new User("ZZZ"); List<User> userList = Arrays.asList(u1, u2, u3); userList.forEach(User::printName); // works userList.forEach(u1::printName); // compile error } } Thanks,

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  • Array::ConvertAll in managed C++

    - by danny.lesnik
    This is a continuation from this post. I'm trying to parse this string in managed C++: String ^ rgba = "[0.09019608,0.5176471,0.9058824,1]"; cli::array<System::Double> ^ RGB = System::Array::ConvertAll<String,cli::array<System::Double> >((rgba->Substring(1,rgba->Length-2)->Split(',')),double::Parse); Compiler throws me the following error: Error 15 error C2770: invalid explicit generic argument(s) for 'cli::array<Type,dimension> ^System::Array::ConvertAll(cli::array<TInput,1> ^,System::Converter<TInput,TOutput> ^)' What am I doing wrong?

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  • Contents changed(cleared?) when access the pointer returned by std::string::c_str()

    - by justamask
    string conf()     {         vector v;         //..         v = func(); //this function returns a vector         return v[1];     }     void test()     {         const char* p = conf().c_str();         // the string object will be alive as a auto var         // so the pointer should be valid till the end of this function,right?           // ... lots of steps, but none of them would access the pointer p         // when access p here, SOMETIMES the contents would change ... Why?         // the platform is solaris 64 bit         // compiler is sun workshop 12         // my code is compiled as  ELF 32-bit MSB relocatable SPARC32PLUS Version 1, V8+ Required         // but need to link with some shared lib which are ELF 32-bit MSB dynamic lib SPARC Version 1, dynamically linked, stripped     }

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  • ToList()-- Does it Create a New List?

    - by Ngu Soon Hui
    Let's say I have a class public class MyObject { public int SimpleInt{get;set;} } And I have a List<MyObject>, and I ToList() it and then change one of the SimpleInt, will my change be propagated back to the original list. In other words, what would be the output of the following method? public void RunChangeList() { var objs = new List<MyObject>(){new MyObject(){SimpleInt=0}}; var whatInt = ChangeToList(objs ); } public int ChangeToList(List<MyObject> objects) { var objectList = objects.ToList(); objectList[0].SimpleInt=5; return objects[0].SimpleInt; } Why? P/S: I'm sorry if it seems obvious to find out. But I don't have compiler with me now...

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  • STL: how to overload operator= for <vector> ?

    - by MBes
    There's simple example: #include <vector> int main() { vector<int> veci; vector<double> vecd; for(int i = 0;i<10;++i){ veci.push_back(i); vecd.push_back(i); } vecd = veci; // <- THE PROBLEM } The thing I need to know is how to overload operator = so that I could make assignment like this: vector<double> = vector<int>; I've just tried a lot of ways, but always compiler has been returning errors... Is there any option to make this code work without changing it? I can write some additional lines, but can't edit or delete the existing ones. Ty.

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  • How to explain to a developer that adding extra if - else if conditions is not a good way to "improv

    - by Lilit
    Recently I've bumped into the following C++ code: if (a) { f(); } else if (b) { f(); } else if (c) { f(); } Where a, b and c are all different conditions, and they are not very short. I tried to change the code to: if (a || b || c) { f(); } But the author opposed saying that my change will decrease readability of the code. I had two arguments: 1) You should not increase readability by replacing one branching statement with three (though I really doubt that it's possible to make code more readable by using else if instead of ||). 2) It's not the fastest code, and no compiler will optimize this. But my arguments did not convince him. What would you tell a programmer writing such a code? Do you think complex condition is an excuse for using else if instead of OR?

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  • Syncronizing indices of function pointer table to table contents

    - by Thomas Matthews
    In the embedded system I'm working on, we are using a table of function pointers to support proprietary Dynamic Libraries. We have a header file that uses named constants (#define) for the function pointer indices. These values are used in calculating the location in the table of the function's address. Example: *(export_table.c)* // Assume each function in the table has an associated declaration typedef void (*Function_Ptr)(void); Function_Ptr Export_Function_Table[] = { 0, Print, Read, Write, Process, }; Here is the header file: *export_table.h* #define ID_PRINT_FUNCTION 1 #define ID_READ_FUNCTION 2 #define ID_WRITE_FUNCTION 3 #define ID_PROCESS_FUNCTION 4 I'm looking for a scheme to define the named constants in terms of their location in the array so that when the order of the functions changes, the constants will also change. (Also, I would like the compiler or preprocessor to calculate the indices to avoid human mistakes like typeo's.)

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  • strenge exception phenomenon in win7

    - by Level 2
    Hello all, I spot some interesting artcles about exception handle in codeproject http://www.codeproject.com/KB/cpp/seexception.aspx after reading, I decided to do some experiment. The first time I try to excute the following code char *p; p[0] = 0; The program died without question. But After serveral time I execute the same problem binary code. It magically did fine. even the following code is doing well. any clue or explain? char *p p[1000] = 'd'; cout<<p[1000]<<endl; my os is windows 7 64bit and compiler is vs2008 rc1.

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  • Haskell: Problems with overloading: Interpreter can´t tell which + to use

    - by Ben
    Hi, I want to make functions Double - Double an instance of the Num typeclass. I want to define the sum of two functions as sum of their images. So I wrote instance Num Function where f + g = (\ x - (f x) + (g x)) Here the compiler complains he can´t tell whether I´m using Prelude.+ or Module.+ in the lambda expression. So I imported Prelude qualified as P and wrote instance Num Function where f + g = (\ x - (f x) P.+ (g x)) This compiles just fine, but when I try to add two functions in GHCi the interpreter complains again he can´t tell whether I´m using Prelude.+ or Module.+. Is there any way I can solve this problem?

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  • how to databind a datalist's page index to a button's commandname?

    - by korben
    i got this inside a button inside a datalist CommandName="<%# Container.ItemIndex %>" when i click the button, i'm expecting commandname to = 0, then 1, then 2, etc, as the datalist progresses, and i'm using that value in the button click's c# but i'm getting this error, i'm pretty sure i'm using this exact setup on another page and i have no problems, any idea what's going on? Server Error in '/' Application. Compilation Error Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. Compiler Error Message: CS0117: 'System.Web.UI.Control' does not contain a definition for 'ItemIndex'

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  • Order of operations in C. ++ vs |=, which occurs first?

    - by chris
    I have the following code that I'm reading through: if( (i%2) == 0 ){ *d = ((b & 0x0F) << 4); } else{ *d++ |= (b & 0x0F); }; I'm looking specifically at the else statement and wondering in what order this occurs? I don't have a regular C compiler, so I can't test this. When we are performing *d++ |= (b & 0x0F);, what order does this occur in?

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  • Iterate Through JSON Data for Specific Element - Similar to XPath

    - by Highroller
    I am working on an embedded system and my theory of the overall process follows this methodology: 1. Send a command to the back end asking for account information in JSON format. 2. The back end writes a JSON file with all accounts and associated information (there could be 0 to 16 accounts). 3. Here's where I get stuck - use JavaScript (we are using the JQuery library) to iterate through the returned information for a specific element (similar to XPath) and build an array based on the number of elements found to populate a drop-down box to select the account you want to view and then do stuff with the account info. So my code looks like this: loadAccounts = function() { $.getJSON('/info?q=voip.accounts[]', function(result) { var sipAcnts = $("#sipacnts"); $(sipAcnts).empty(); // empty the dropdown (if necessarry) // Get the 'label' element and stick it in an array // build the array and append it to the sipAcnts dropdown // use array index to ref the accounts info and do stuff with it } So what I need is the JSON version of XPath to build the array of voip.accounts.label. The first account info looks something like this: { "result_set": { "voip.accounts[0]": { "label": "Dispatch1", "enabled": true, "user": "1234", "name": "Jane Doe", "type": "sip", "sip": { "lots and lots of stuff": }, } } } Am I over complicating the issue? Any wisdom anyone could thrown down would be greatly appreciated.

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  • c: memory allocation (what's going on)

    - by facha
    Hi, everyone Please take a look at this piece of code. I'm allocating one byte for the first variable and another byte for the second one. However, it seems like the compiler allocates more (or I'm missing something). The program outputs both strings, even though their length is more the one byte. void main() { char* some1 = malloc(1); sprintf(some1,"cool"); char* some2 = malloc(1); sprintf(some2,"face"); printf("%s ",some1); printf("%s\n",some2); } Please, could anyone spot some light on what's going on when memory is being allocated.

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  • How do I prevent race condition WITHOUT using locks in C++?

    - by Hristo
    How do I prevent a race condition WITHOUT locking or using mutexes/semaphors in C++? I'm dealing with a nested for loop in which I will be setting a value in an array: for (int i = 0; i < m; ++i) for (int j = 0; j < n; ++j) for (int k = 0; k < o; ++k) array[k] += foo(...); More or less, I want to deal with this so that I can ensure different threads running at the same time don't write to array[k] at the same time. Any suggestions on how to approach this? Edit: I am running on a Linux machine and I also have to use the Intel compiler. I will be using "icc" instead of "gcc" to compile the code.

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  • Collision Detection (Ground & Slopes) in 2D Platform Game using Pygame Rects

    - by RedCap
    Hi, First off, I am not after any instructions on logic for collision detection; I get it. What I am trying to work out is the least complicated way to do this with Pygame using Sprites & Rects. I want to be able to check collisions for the Player against ground, walls & slopes. In theory it is quite straight forward, but I'm having difficulty because it seems like you cannot do this with one Rect. One Rect is simple enough to get you collisions in the X plane against walls. The same Rect could be used also be used in the Y plane against solids, but not with slopes - since with the collision routines in Pygame it checks the whole Rect (or mask), rather than perhaps just the bottom middle of the Rect. It seems in addition you need to have a number of "sprites" to check collisions with, that are 1x1 pixel in various places around the Player. What's the easiest way to do this, without having a bunch of 3, 4, or more separate "collision pixels" to check against slopes? Geoff

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  • Output Unicode to Console Using C++

    - by Jesse Foley
    I'm still learning C++, so bear with me and my sloppy code. The compiler I use is Dev C++. I want to be able to output Unicode characters to the Console using cout. Whenver i try things like: # #include directive here (include iostream) using namespace std; int main() { cout << "Hello World!\n"; cout << "Blah blah blah some gibberish unicode: ÐAßGg\n"; system("PAUSE"); return 0; } It outputs strange characters to the console, like µA¦Gg. Why does it do that, and how can i get to to display ÐAßGg? Or is this not possible with Windows?

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  • Why is there "data" and "newtype" in Haskell?

    - by martingw
    To me it seems that a newtype definition is just a data definition that obeys some restrictions (only one constructor and such), and that due to these restrictions the runtime system can handle newtypes more efficiently. Ok, and the handling of pattern matching for undefined values is slightly different. But suppose Haskell would only knew data definitions, no newtypes: Couldn't the compiler find out for himself whether a given data definition obeys these restrictions, and automatically treat it more efficiently? I'm sure I'm missing out on something, these Haskell designers are so clever, there must be some deeper reason for this...

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  • C++ Translation Phase Confusion

    - by blakecl
    Can someone explain why the following doesn't work? int main() // Tried on several recent C++ '03 compilers. { #define FOO L const wchar_t* const foo = FOO"bar"; // Will error out with something like: "identifier 'L' is undefined." #undef FOO } I thought that preprocessing was done in an earlier translation phase than string literal operations and general token translation. Wouldn't the compiler be more or less seeing this: int main() { const wchar_t* const foo = L"bar"; } It would be great if someone could cite an explanation from the standard.

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  • Whats the difference between a C++ and a Cocoa Project in Xcode?

    - by david
    I need to work with TagLib for my project. I've created a framework (and I tried using it as a lib) but the compiler cannot find #include < strings on compiling (No such file or Directory). I've created a test C++ project and it #includes < strings just fine. I've looked at the project settings and I cannot find a difference between them. But the standard cocoa projects obviously so not have the search path set to include C++ libraries (Or am I completely getting it wrong?). I've searched for a solution but no one else seems to have run into this problem.

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  • problem in getting value of the object attribute in flex

    - by madanmohan
    i have an xml which contains 'interface' sub tag, iam converting xml to object using SampleXmlDecoder. compiler did not allow me to access the value of the 'inteface' attrible of the resultobject. var xml:XML = event.result as XML; var xmlDoc : XMLDocument = new XMLDocument(xml.toString()); var decoder : SimpleXMLDecoder = new SimpleXMLDecoder(true) var resultObj : Object = decoder.decodeXML(xmlDoc); var o:Object = new Object(); o.someprop = resultObj.maintag.item.interface; its treating interface as keyword. can anyone tell me the solution for this. Thanks in advance

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  • How can I get a list of modified records from a SQL Server database?

    - by Pixelfish
    I am currently in the process of revamping my company's management system to run a little more lean in terms of network traffic. Right now I'm trying to figure out an effective way to query only the records that have been modified (by any user) since the last time I asked. When the application starts it loads the job information and caches it locally like the following: SELECT * FROM jobs. I am writing out the date/time a record was modified ala UPDATE jobs SET Widgets=@Widgets, LastModified=GetDate() WHERE JobID=@JobID. When any user requests the list of jobs I query all records that have been modified since the last time I requested the list like the following: SELECT * FROM jobs WHERE LastModified>=@LastRequested and store the date/time of the request to pass in as @LastRequest when the user asks again. In theory this will return only the records that have been modified since the last request. The issue I'm running into is when the user's date/time is not quite in sync with the server's date/time and also of server load when querying an un-indexed date/time column. Is there a more effective system then querying date/time information?

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  • How to understand the programming of an operating system

    - by piemesons
    Hello, I want to learn the operating system. How it works. I don't want to make my own operating system. I just want to learn how it works. As I can find out source code of any open source OS. But how to start. Like starting from the first elementary kernel (whatever it is). Somebody suggested I try to implement Linux from scratch etc. Please guide me in a proper way. I want to know about the proper path to follow. I am ready to invest three to four years just to understand the basics. I have good fundamentals of C, C++, PHP, OOP and compiler design.

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  • When to use try/catch

    - by coffeeaddict
    I'm always finding myself wanting to put a try/catch around the lets say Business Layer methods. But I feel though that I don't need a try/catch if I'm simply rethrowing it up to the Presentation Layer. Is that right? I should not be rethrowing an exception from code that's wrapped in a try/catch in a BL method and should be letting the caller which would be from the Presentation Layer code be using a try/catch to handle it there? The BL method will throw an error without the try/catch anyway..the compiler will. So it wouldn't make sense to use a try/catch in a BL method that's to be consumed by a layer higher up correct?

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  • How do XAML files associate with cs files?

    - by LLS
    It seems that XAML files should have corresponding .cs files in a C# project. I know Visual Studio does all the things for us. I'm just curious how they are linked together? I mean, are they specified in the project file, or just because they have the same names? And also, App.xaml file specifies the startup file, but how does the compiler know? Is it possible to appoint another file other than App.xaml to do the same things as App.xaml does?

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