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• Connect to Facebook with Javascript Client Library using Adobe AIR

  - by Chuck Hriczko

  I'm having an issue connecting to Facebook through the Javascript Client Library in Adobe AIR. It works fine in the browser but in Adobe AIR it seems to not be able to find the Facebook functions. Here is some code I copied from the Facebook website: (Oh and I have the xd_receiver.htm file in the correct path too) <textarea style="width: 1000px; height: 300px;" id="_traceTextBox"> </textarea> <script src="http://static.ak.connect.facebook.com/js/api_lib/v0.4/FeatureLoader.js.php" type="text/javascript"></script> // var api = FB.Facebook.apiClient; // require user to login api.requireLogin(function(exception){ FB.FBDebug.logLevel=1; FB.FBDebug.dump("Current user id is " + api.get_session().uid); // Get friends list //5-14-09: this code below is broken, correct code follows //api.friends_get(null, function(result){ // Debug.dump(result, 'friendsResult from non-batch execution '); // }); api.friends_get(new Array(), function(result, exception){ FB.FBDebug.dump(result, 'friendsResult from non-batch execution '); }); }); }); //]]> </script>

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• Returning reference to object is not changing the address in c++

  - by ashish-sangwan

  I am trying to understand functions returning a reference. For that I have written a simple program: #include<iostream> using namespace std; class test { int i; friend test& func(); public: test(int j){i=j;} void show(){cout<<i<<endl;} }; test& func() { test temp(10); return temp; //// Address of temp=0xbfcb2874 } int main() { test obj1(50); // Address of obj1=0xbfcb28a0 func()=obj1; <= Problem:The address of obj1 is not changing obj1.show(); // // Address of obj1=0xbfcb28a0 return 0; } I ran the program using gdb and observed that the address of obj1 still remains same, but I expect it to get changed to 0xbfcb2874. I am not clear with the concept. Please help.

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• System Calls in windows & Native API?

  - by claws

  Recently I've been using lot of Assembly language in *NIX operating systems. I was wondering about the windows domain. Calling convention in linux: mov $SYS_Call_NUM, %eax mov $param1 , %ebx mov $param2 , %ecx int $0x80 Thats it. That is how we should make a system call in linux. Reference of all system calls in linux: Regarding which $SYS_Call_NUM & which parameters we can use this reference : http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.html OFFICIAL Reference : http://kernel.org/doc/man-pages/online/dir_section_2.html Calling convention in Windows: ??? Reference of all system calls in Windows: ??? Unofficial : http://www.metasploit.com/users/opcode/syscalls.html , but how do I use these in assembly unless I know the calling convention. OFFICIAL : ??? If you say, they didn't documented it. Then how is one going to write libc for windows without knowing system calls? How is one gonna do Windows Assembly programming? Atleast in the driver programming one needs to know these. right? Now, whats up with the so called Native API? Is Native API & System calls for windows both are different terms referring to same thing? In order to confirm I compared these from two UNOFFICIAL Sources System Calls: http://www.metasploit.com/users/opcode/syscalls.html Native API: http://undocumented.ntinternals.net/aindex.html My observations: All system calls are beginning with letters Nt where as Native API is consisting of lot of functions which are not beginning with letters Nt. System Call of windows are subset of Native API. System calls are just part of Native API. Can any one confirm this and explain.

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• Improving File Read Performance (single file, C++, Windows)

  - by david

  I have large (hundreds of MB or more) files that I need to read blocks from using C++ on Windows. Currently the relevant functions are: errorType LargeFile::read( void* data_out, __int64 start_position, __int64 size_bytes ) const { if( !m_open ) { // return error } else { seekPosition( start_position ); DWORD bytes_read; BOOL result = ReadFile( m_file, data_out, DWORD( size_bytes ), &bytes_read, NULL ); if( size_bytes != bytes_read || result != TRUE ) { // return error } } // return no error } void LargeFile::seekPosition( __int64 position ) const { LARGE_INTEGER target; target.QuadPart = LONGLONG( position ); SetFilePointerEx( m_file, target, NULL, FILE_BEGIN ); } The performance of the above does not seem to be very good. Reads are on 4K blocks of the file. Some reads are coherent, most are not. A couple questions: Is there a good way to profile the reads? What things might improve the performance? For example, would sector-aligning the data be useful? I'm relatively new to file i/o optimization, so suggestions or pointers to articles/tutorials would be helpful.

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• ERROR 2019 Linker Error Visual Studio

  - by Corrie Duck

  Hey I hope someone can tell me know to fix this issue I am having i keep getting an error 2019 from Visual studio for the following file. Now most of the functions have been removed so excuse the empty varriables etc. Error error LNK2019: unresolved external symbol "void * __cdecl OpenOneDevice(void *,struct _SP_DEVICE_INTERFACE_DATA *,char *)" (?OpenOneDevice@@YAPAXPAXPAU_SP_DEVICE_INTERFACE_DATA@@PAD@Z) referenced in function _wmain c:\Users\K\documents\visual studio 2010\Projects\test2\test2\test2.obj test2 #include "stdafx.h" #include <windows.h> #include <setupapi.h> SP_DEVICE_INTERFACE_DATA deviceInfoData; HDEVINFO hwDeviceInfo; HANDLE hOut; char *devName; // HANDLE OpenOneDevice(IN HDEVINFO hwDeviceInfo,IN PSP_DEVICE_INTERFACE_DATA DeviceInfoData,IN char *devName); // HANDLE OpenOneDevice(IN HDEVINFO HardwareDeviceInfo,IN PSP_DEVICE_INTERFACE_DATA DeviceInfoData,IN char *devName) { PSP_DEVICE_INTERFACE_DETAIL_DATA functionClassDeviceData = NULL; ULONG predictedLength = 0, requiredLength = 0; HANDLE hOut = INVALID_HANDLE_VALUE; SetupDiGetDeviceInterfaceDetail(HardwareDeviceInfo, DeviceInfoData, NULL, 0, &requiredLength, NULL); predictedLength = requiredLength; functionClassDeviceData = (PSP_DEVICE_INTERFACE_DETAIL_DATA)malloc(predictedLength); if(NULL == functionClassDeviceData) { return hOut; } functionClassDeviceData->cbSize = sizeof (SP_DEVICE_INTERFACE_DETAIL_DATA); if (!SetupDiGetDeviceInterfaceDetail(HardwareDeviceInfo, DeviceInfoData, functionClassDeviceData, predictedLength, &requiredLength, NULL)) { free( functionClassDeviceData ); return hOut; } //strcpy(devName,functionClassDeviceData->DevicePath) ; hOut = CreateFile(functionClassDeviceData->DevicePath, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL); free(functionClassDeviceData); return hOut; } // int _tmain(int argc, _TCHAR* argv[]) { hOut = OpenOneDevice (hwDeviceInfo, &deviceInfoData, devName); if(hOut != INVALID_HANDLE_VALUE) { // error report } return 0; } Been driving me mad for hours. Any help appreciated. SOLVED THANKS TO CHRIS :-) Add #pragma comment (lib, "Setupapi.lib") Thanks

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• Using parameterized function calls in SELECT statements. SQL Server

  - by geekzlla

  I have taken over some code from a previous developer and have come across this SQL statement that calls several SQL functions. As you can see, the function calls in the select statement pass a parameter to the function. How does the SQL statement know what value to replace the variable with? For the below sample, how does the query engine know what to replace nDeptID with when it calls, fn_SelDeptName_DeptID(nDeptID) nDeptID IS a column in table Note. SELECT STATEMENT: SELECT nCustomerID AS [Customer ID], nJobID AS [Job ID], dbo.fn_SelDeptName_DeptID(nDeptID) AS Department, nJobTaskID AS JobTaskID, dbo.fn_SelDeptTaskDesc_OpenTask(nJobID, nJobTaskID) AS Task, nStandardNoteID AS StandardNoteID, dbo.fn_SelNoteTypeDesc(nNoteID) AS [Note Type], dbo.fn_SelGPAStandardNote(nStandardNoteID) AS [Standard Note], nEntryDate AS [Entry Date], nUserName as [Added By], nType AS Type, nNote AS Note FROM Note WHERE nJobID = 844261 ORDER BY nJobID, Task, [Entry Date] ====================== Function fn_SelDeptName_DeptID: ALTER FUNCTION [dbo].[fn_SelDeptName_DeptID] (@iDeptID int) RETURNS varchar(25) -- Used by DataCollection for Job Tracking -- if the Deptartment isnt found return an empty string BEGIN -- Return the Department name for the given DeptID. DECLARE @strDeptName varchar(25) IF @iDeptID = 0 SET @strDeptName = '' ELSE BEGIN SET @strDeptName = (SELECT dName FROM Department WHERE dDeptID = @iDeptID) IF (@strDeptName IS NULL) SET @strDeptName = '' END RETURN @strDeptName END ========================== Thanks in advance.

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• Problem with incomplete input when using Attoparsec

  - by Dan Dyer

  I am converting some functioning Haskell code that uses Parsec to instead use Attoparsec in the hope of getting better performance. I have made the changes and everything compiles but my parser does not work correctly. I am parsing a file that consists of various record types, one per line. Each of my individual functions for parsing a record or comment works correctly but when I try to write a function to compile a sequence of records the parser always returns a partial result because it is expecting more input. These are the two main variations that I've tried. Both have the same problem. items :: Parser [Item] items = sepBy (comment <|> recordType1 <|> recordType2) endOfLine For this second one I changed the record/comment parsers to consume the end-of-line characters. items :: Parser [Item] items = manyTill (comment <|> recordType1 <|> recordType2) endOfInput Is there anything wrong with my approach? Is there some other way to achieve what I am attempting?

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• How should I manage/declare dependencies between open source C# projects?

  - by munificent

  I've got a game (a roguelike to be specific) in C# that I'm in the process of cleaning up to open source. One step I'd like to take is splitting it into three distinct pieces: A simple package of utility classes, things like 2D arrays, vectors, etc. A terminal UI package that gives you a curses-like display. It depends on 1. The actual game, which uses 1 and 2. Right now, these are all separate projects in the same solution, but I'd kind of like to make them completely separate projects (in the "open source project" sense, not the "visual studio project" use of the term) with their own names and repos. I think, at the very least, #1 is generally useful even if you aren't building game, and I don't want someone to have to build an entire game just to get some handy functions. What I'm not sure about is how to handle the dependencies if I split up the solution. If someone decides they want to sync the game, how should I ensure they also get 1 and 2? Include the built dependent .dlls in the games repo? Just document, "you need these other projects and they must be in a path relative to the game like this". Just leave it all one giant solution and a single repo. Something I'm not thinking of?

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• Enumeration trouble: redeclared as different kind of symbol

  - by Matt

  Hello all. I am writing a program that is supposed to help me learn about enumeration data types in C++. The current trouble is that the compiler doesn't like my enum usage when trying to use the new data type as I would other data types. I am getting the error "redeclared as different kind of symbol" when compiling my trangleShape function. Take a look at the relevant code. Any insight is appreciated! Thanks! (All functions are their own .cpp files.) header file #ifndef HEADER_H_INCLUDED #define HEADER_H_INCLUDED #include <iostream> #include <iomanip> using namespace std; enum triangleType {noTriangle, scalene, isoceles, equilateral}; //prototypes void extern input(float&, float&, float&); triangleType extern triangleShape(float, float, float); /*void extern output (float, float, float);*/ void extern myLabel(const char *, const char *); #endif // HEADER_H_INCLUDED main function //8.1 main // this progam... #include "header.h" int main() { float sideLength1, sideLength2, sideLength3; char response; do //main loop { input (sideLength1, sideLength2, sideLength3); triangleShape (sideLength1, sideLength2, sideLength3); //output (sideLength1, sideLength2, sideLength3); cout << "\nAny more triangles to analyze? (y,n) "; cin >> response; } while (response == 'Y' || response == 'y'); myLabel ("8.1", "2/11/2011"); return 0; } triangleShape shape # include "header.h" triangleType triangleShape(sideLenght1, sideLength2, sideLength3) { triangleType triangle; return triangle; }

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• Linq-to-XML explicit casting in a generic method

  - by vlad

  I've looked for a similar question, but the only one that was close didn't help me in the end. I have an XML file that looks like this: <Fields> <Field name="abc" value="2011-01-01" /> <Field name="xyz" value="" /> <Field name="tuv" value="123.456" /> </Fields> I'm trying to use Linq-to-XML to get the values from these fields. The values can be of type Decimal, DateTime, String and Int32. I was able to get the fields one by one using a relatively simple query. For example, I'm getting the 'value' from the field with the name 'abc' using the following: private DateTime GetValueFromAttribute(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == "abc" select (DateTime)field.Attribute("value")).FirstOrDefault() } this is placed in a separate function that simply returns this value, and everything works fine (since I know that there is only one element with the name attribute set to 'abc'). however, since I have to do this for decimals and integers and dates, I was wondering if I can make a generic function that works in all cases. this is where I got stuck. here's what I have so far: private T GetValueFromAttribute<T>(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == attName select (T)field.Attribute("value").Value).FirstOrDefault(); } this doesn't compile because it doesn't know how to convert from String to T. I tried boxing and unboxing (i.e. select (T) (Object) field.Attribute("value").Value but that throws a runtime Specified cast is not valid exception as it's trying to convert the String to a DateTime, for instance. Is this possible in a generic function? can I put a constraint on the generic function to make it work? or do I have to have separate functions to take advantage of Linq-to-XML's explicit cast operators?

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• Are there Windows API binaries for Subversion or do I have to build SVN to call the API from Windows

  - by JeffH

  I want to call a Subversion API from a Visual Studio 2003 C++ project. I know there are threads here, here, here, and here that tell how to get started with C#.NET on Windows (the consensus seems to be SharpSvn, which I've used easily and successfully on another project) but that's not what I want. I've read the chapter on using APIs in the red-bean book which says: Subversion is primarily a set of C libraries, with header (.h) files that live in the subversion/include directory of the source tree. These headers are copied into your system locations (e.g., /usr/local/include) when you build and install Subversion itself from source. These headers represent the entirety of the functions and types meant to be accessible by users of the Subversion libraries. I'd like to use CollabNet Subversion but there doesn't seem to be API binary downloads, and I'd just as soon not build the whole thing if I can avoid it. Considering another approach, I found RapidSVN's C++ API, but it doesn't appear to offer Windows API binaries either and seems to require building SVN (which I would be willing to do as a last choice if RapidSVN's API is higher-level than the stock SVN offering.) Does calling the API from C++ in Windows have to be this much more work compared to using SharpSvn under .NET, or is there something I haven't found that would help me achieve my goal?

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• Should I use a binary or a text file for storing protobuf messages?

  - by nbolton

  Using Google protobuf, I am saving my serialized messaged data to a file - in each file there are several messages. We have both C++ and Python versions of the code, so I need to use protobuf functions that are available in both languages. I have experimented with using SerializeToArray and SerializeAsString and there seems to be the following unfortunate conditions: SerializeToArray: As suggested in one answer, the best way to use this is to prefix each message with it's data size. This would work great for C++, but in Python it doesn't look like this is possible - am I wrong? SerializeAsString: This generates a serialized string equivalent to it's binary counterpart - which I can save to a file, but what happens if one of the characters in the serialization result is \n - how do we find line endings, or the ending of messages for that matter? Update: Please allow me to rephrase slightly. As I understand it, I cannot write binary data in C++ because then our Python application cannot read the data, since it can only parse string serialized messages. Should I then instead use SerializeAsString in both C++ and Python? If yes, then is it best practice to store such data in a text file rather than a binary file? My gut feeling is binary, but as you can see this doesn't look like an option.

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• Cleaning up when exiting an OpenGL app

  - by Daniel

  This might be a dumb question but I've spent some time asking Google and haven't been able to find anything. I have an an OSX OpenGL app I'm trying to modify. When I create the app a whole bunch of initialisation functions are called -- including methods where I can specify my own mouse and keyboard handlers etc. For example: glutInit(&argc, argv); glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA); glutInitWindowPosition(100, 100); glutInitWindowSize(700, 700); glutCreateWindow("Map Abstraction"); glutReshapeFunc(resizeWindow); glutDisplayFunc(renderScene); glutIdleFunc(renderScene); glutMouseFunc(mousePressedButton); glutMotionFunc(mouseMovedButton); glutKeyboardFunc(keyPressed); At some point I pass control to glutMainLoop and my application runs. In the process of running I create a whole bunch of objects. I'd like to clean these up. Is there any way I can tell GLUT to call a cleanup method before it quits?

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• Const_cast on a this pointer - would I get told off by other C++ coders for doing this?

  - by BeeBand

  I have a class Game e.g. class Game { public: InitObjects(); ... }; And I have another class Grid, that needs to be initialised with a non-const reference to that Game object. ( A Grid object needs to call functions that can update a Game object ). class Grid { public: Grid(Game & g): game(g){} ... private: Game & game; ... }; The Game object is responsible for initialising the Grid. I did this: void Game::InitObjects() { grid = new Grid(*(const_cast<Game*>(this)) ); } grid is not a member of a Game - it's a global ( argh - i know... I don't mind making it a member, but I have the same problem right? ). Can some seasoned C++ folk tell me if this odd looking const_cast is acceptable?

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• Is there a way to log every gui event in Delphi?

  - by awmross

  The Delphi debugger is great for debugging linear code, where one function calls other functions in a predictable, linear manner, and we can step through the program line by line. I find the debugger less useful when dealing with event driven gui code, where a single line of code can cause new events to be trigerred, which may in turn trigger other events. In this situation, the 'step through the code' approach doesn't let me see everything that is going on. The way I usually solve this is to 1) guess which events might be part of the problem, then 2) add breakpoints or logging to each of those events. The problem is that this approach is haphazard and time consuming. Is there a switch I can flick in the debugger to say 'log all gui events'? Or is there some code I can add to trap events, something like procedure GuiEventCalled(ev:Event) begin log(ev); ev.call(); end The end result I'm looking for is something like this (for example): FieldA.KeyDown FieldA.KeyPress FieldA.OnChange FieldA.OnExit FieldB.OnEnter This would take all the guesswork out of Delphi gui debugging. I am using Delphi 2010

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• What are the default return values for operator< and operator[] in C++ (Visual Studio 6)?

  - by DustOff

  I've inherited a large Visual Studio 6 C++ project that needs to be translated for VS2005. Some of the classes defined operator< and operator[], but don't specify return types in the declarations. VS6 allows this, but not VS2005. I am aware that the C standard specifies that the default return type for normal functions is int, and I assumed VS6 might have been following that, but would this apply to C++ operators as well? Or could VS6 figure out the return type on its own? For example, the code defines a custom string class like this: class String { char arr[16]; public: operator<(const String& other) { return something1 < something2; } operator[](int index) { return arr[index]; } }; Would VS6 have simply put the return types for both as int, or would it have been smart enough to figure out that operator[] should return a char and operator< should return a bool (and not convert both results to int all the time)? Of course I have to add return types to make this code VS2005 C++ compliant, but I want to make sure to specify the same type as before, as to not immediately change program behavior (we're going for compatibility at the moment; we'll standardize things later).

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• setting the openCV configuration in an openGL project produce several errors

  - by GolSa

  I have a win32 solution which is set for openGL; it works well; but I want to write a function which use functions of openCV; I set the configuration for openCV for both X86 and X64;;I commented the openCV function and just to test the correctness of configuration, I run it; but when I want to run it on X64 I faced with the error below: Error 1 error C2065: 'GWL_HINSTANCE' : undeclared identifier D:\matrix\matrixProjection\src\ControllerMain.cpp 35 1 matrixProjection Error 2 error C2664: 'CreateDialogParamW' : cannot convert parameter 4 from 'BOOL (__cdecl *)(HWND,UINT,WPARAM,LPARAM)' to 'DLGPROC' D:\matrix\matrixProjection\src\DialogWindow.cpp 47 1 matrixProjection Error 2 points to this line of code: HWND DialogWindow::create() { /*-->this line*/ handle = ::CreateDialogParam(instance, MAKEINTRESOURCE(id), parentHandle, Win::dialogProcedure, (LPARAM)controller); return handle; } but on Debug Win32 configure, it runs; I used openGL32 in my project; is there any probability to be the cause? is there any X64 version for openGL? I know that there is something needed in X64 mode which my solution can not handle it; I googled a lot about it but I did not find any solution; How can I solve that?

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• Do I need to Salt and Hash a randomly generated token?

  - by wag2639

  I'm using Adam Griffiths's Authentication Library for CodeIgniter and I'm tweaking the usermodel. I came across a generate function that he uses to generate tokens. His preferred approach is to reference a value from random.org but I considered that superfluous. I'm using his fall back approach of randomly generating a 20 character long string: $length = 20; $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; $token = ''; for ($i = 0; $i < $length; $i++) { $token .= $characters[mt_rand(0, strlen($characters)-1)]; } He then hashes this token using a salt (I'm combing code from different functions) sha1($this->CI->config->item('encryption_key').$str); I was wondering if theres any reason to to run the token through the salted hash? I've read that simply randomly generating strings was a naive way of making random passwords but is the sh1 hash and salt necessary? Note: I got my encryption_key from https://www.grc.com/passwords.htm (63 random alpha-numeric)

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• Easiest way to remove Keys from a 2D Array?

  - by dbemerlin

  Hi, I have an Array that looks like this: array( 0 => array( 'key1' => 'a', 'key2' => 'b', 'key3' => 'c' ), 1 => array( 'key1' => 'c', 'key2' => 'b', 'key3' => 'a' ), ... ) I need a function to get an array containing just a (variable) number of keys, i.e. reduce_array(array('key1', 'key3')); should return: array( 0 => array( 'key1' => 'a', 'key3' => 'c' ), 1 => array( 'key1' => 'c', 'key3' => 'a' ), ... ) What is the easiest way to do this? If possible without any additional helper function like array_filter or array_map as my coworkers already complain about me using too many functions. The source array will always have the given keys so it's not required to check for existance. Bonus points if the values are unique (the keys will always be related to each other, meaning that if key1 has value a then the other key(s) will always have value b). My current solution which works but is quite clumsy (even the name is horrible but can't find a better one): function get_unique_values_from_array_by_keys(array $array, array $keys) { $result = array(); $found = array(); if (count($keys) > 0) { foreach ($array as $item) { if (in_array($item[$keys[0]], $found)) continue; array_push($found, $item[$keys[0]]); $result_item = array(); foreach ($keys as $key) { $result_item[$key] = $item[$key]; } array_push($result, $result_item); } } return $result; } Addition: PHP Version is 5.1.6.

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• Best way reading from dirty excel sheets

  - by Ten Ton Gorilla

  I have to manipulate some Excel documents with C#. It's a batch process with no user interaction. It's going to parse data into a database, then output nice reports. The data is very dirty and cannot be ready using ADO. The data is nowhere near a nice table format. Best is defined as the most stable(updates less likely to break)/ clear(succinct) code. Fast doesn't matter. If it runs in less than 8 hours I'm fine. I have the logic to find the data worked out. All I need to make it run is basic cell navigation and getvalue type functions. Give me X cell value as string, if it matches Y value with levenshtein distance < 3, then give me Z cell value. My question is, what is the best way to dig into the excel? VSTO? Excel Objects Library? Third Option I'm not aware of?

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• java number exceeds long.max_value - how to detect?

  - by jurchiks

  I'm having problems detecting if a sum/multiplication of two numbers exceeds the maximum value of a long integer. Example code: long a = 2 * Long.MAX_VALUE; System.out.println("long.max * smth > long.max... or is it? a=" + a); This gives me -2, while I would expect it to throw a NumberFormatException... Is there a simple way of making this work? Because I have some code that does multiplications in nested IF blocks or additions in a loop and I would hate to add more IFs to each IF or inside the loop. Edit: oh well, it seems that this answer from another question is the most appropriate for what I need: http://stackoverflow.com/a/9057367/540394 I don't want to do boxing/unboxing as it adds unnecassary overhead, and this way is very short, which is a huge plus to me. I'll just write two short functions to do these checks and return the min or max long. Edit2: here's the function for limiting a long to its min/max value according to the answer I linked to above: /** * @param a : one of the two numbers added/multiplied * @param b : the other of the two numbers * @param c : the result of the addition/multiplication * @return the minimum or maximum value of a long integer if addition/multiplication of a and b is less than Long.MIN_VALUE or more than Long.MAX_VALUE */ public static long limitLong(long a, long b, long c) { return (((a > 0) && (b > 0) && (c <= 0)) ? Long.MAX_VALUE : (((a < 0) && (b < 0) && (c >= 0)) ? Long.MIN_VALUE : c)); } Tell me if you think this is wrong.

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• Tips for submitting a library to Boost?

  - by AraK

  Hi everyone, Summer is coming, and a group of friends and I are getting ready for it :) We decided to build a compile-time Arbitrary precision Unsigned Integers. We would like to provide a set of integers algorithms(functions) with the library. We have seen a number of requests for such a library(SoC2010, C++0x Standard Library wishlist). Also, a regular run-time bigint is requested usually with that, but we don't want to go into the hassle of memory management. The idea came to me from a library called TTMath, unfortunately this library works only on specific platforms because Assembly was used extensively in the library. We would like to write a standard library, depending on the C++ standard library and Boost. Also, we would like to use the available C++0x facilities in current compilers like user-defined literals and others. This would technically make the library non-standard for a while, but we think that it is a matter of time the new standards will be official. Your hints on the whole process including design, implementation, documentation, maintainable of the library are more than welcom. We are a group of students and fresh graduates who are looking for something interesting in the summer, but we see that Boost is full of gurus and we don't want to forget something too obvious. We are communicating on-line, so there is no shared white-boards :( Thanks,

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• Prolog Backtracking

  - by AhmadAssaf

  I am trying to do a word calculator .. read words from a file .. translate them into numbers and then calculate the result .. i managed to do all of that but i think i have two bugs in my program .. I mainly have two functions ... extract(Words), calculate( Words,0). extract will read from the file .. and then return a list of Words .. ex: [one,plus,three] .. now calculate will translate the value for these words into numbers and calculate .. i managed to do that also .. now the bugs are : i must stop reading and terminate if i encounter stop in the file .. so if Words was [stop] End. i tried the following ... execute :- extract(Words), Words = [stop],nl,print('Terminating ...'),!. execute :- extract(Words), calculate( Words,0). it successfully terminates .. but it skips lines as i extract more than once .. i have tried to do .. execute :- extract(Words), Words \= [stop],execute(Words). execute(Words) :- calculate( Words,0). if the Words is not stop .. then go and calculate .. but its not working !! i appreciate the help .. Thank You

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• Why can't I extract a C++ type from a Python type using boost::python::extractor?

  - by Robin

  I've wrapped a C++ class using Py++ and everything is working great in Python. I can instantiate the c++ class, call methods, etc. I'm now trying to embed some Python into a C++ application. This is also working fine for the most-part. I can call functions on a Python module, get return values, etc. The python code I'm calling returns one of the classes that I wrapped: import _myextension as myext def run_script(arg): my_cpp_class = myext.MyClass() return my_cpp_class I'm calling this function from C++ like this: // ... excluding error checking, ref counting, etc. for brevity ... PyObject *pModule, *pFunc, *pArgs, *pReturnValue; Py_Initialize(); pModule = PyImport_Import(PyString_FromString("cpp_interface")); pFunc = PyObject_GetAttrString(pModule, "run_script"); pArgs = PyTuple_New(1); PyTuple_SetItem(pArgs, 0, PyString_FromString("an arg")); pReturnValue = PyObject_CallObject(pFunc, pArgs); bp::extract< MyClass& > extractor(pReturnValue); // PROBLEM IS HERE if (extractor.check()) { // This check is always false MyClass& cls = extractor(); } The problem is the extractor never actually extracts/converts the PyObject* to MyClass (i.e. extractor.check() is always false). According to the docs this is the correct way to extract a wrapped C++ class. I've tried returning basic data types (ints/floats/dicts) from the Python function and all of them are extracted properly. Is there something I'm missing? Is there another way to get the data and cast to MyClass?

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• Advice on Linq to SQL mapping object design

  - by fearofawhackplanet

  I hope the title and following text are clear, I'm not very familiar with the correct terms so please correct me if I get anything wrong. I'm using Linq ORM for the first time and am wondering how to address the following. Say I have two DB tables: User ---- Id Name Phone ----- Id UserId Model The Linq code generator produces a bunch of entity classes. I then write my own classes and interfaces which wrap these Linq classes: class DatabaseUser : IUser { public DatabaseUser(User user) { _user = user; } public Guid Id { get { return _user.Id; } } ... etc } so far so good. Now it's easy enough to find a users phones from Phones.Where(p => p.User = user) but surely comsumers of the API shouldn't need to be writing their own Linq queries to get at data, so I should wrap this query in a function or property somewhere. So the question is, in this example, would you add a Phones property to IUser or not? In other words, should my interface specifically be modelling my database objects (in which case Phones doesn't belong in IUser), or are they actually simply providing a set of functions and properties which are conceptually associated with a User (in which case it does)? There seems drawbacks to both views, but I'm wondering if there is a standard approach to the problem. Or just any general words of wisdom you could share. My first thought was to use extension methods but in fact that doesn't work in this case.

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