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  • Need to format character precedence in Strings.

    - by Christian
    I'm currently writing a Roman Numeral Converter for the fun of it. The problem works up to the aforementioned character precedence. Since Roman Numerals are not positional, i.e. III does not symbolize 1*whatever base^2 + 1*whatever base^1 + 1*whatever base^0. That of course makes it hard when somebody types in XIV and I need to make sure that the I is not added in this case, but rather subtracted. I'm not sure how to do this. What would be the best approach to tackle this? I have both the Roman Symbols and their respective decimal numbers stored in arrays: const char cRomanArray[] = "IVXLCDM"; const int romanArray[] = { 1, 5, 10, 50, 100, 500, 1000 }; so it wouldn't be too hard for me to brute-force the damn thing by simply checking the precedence within the array, i.e. if the symbol is smaller than the next symbol, i.e. in the exampe 'XIV' if 'I' is smaller than 'V', in which case it would be because I have ordered them in the array, then I could make it subtract the value instead of add. But this seems like a very ugly solution. Are there perhaps any better ones? I was thinking something along the lines of Regular Expressions maybe( forgive me if that sounds like a horrible idea, I haven't used RegExp yet, but it sounds like it could do what I need, and that's to determine the characters in a string.)

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  • Boost Spirit and Lex parser problem

    - by bpw1621
    I've been struggling to try and (incrementally) modify example code from the documentation but with not much different I am not getting the behavior I expect. Specifically, the "if" statement fails when (my intent is that) it should be passing (there was an "else" but that part of the parser was removed during debugging). The assignment statement works fine. I had a "while" statement as well which had the same problem as the "if" statement so I am sure if I can get help to figure out why one is not working it should be easy to get the other going. It must be kind of subtle because this is almost verbatim what is in one of the examples. #include <iostream> #include <fstream> #include <string> #define BOOST_SPIRIT_DEBUG #include <boost/config/warning_disable.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/spirit/include/lex_lexertl.hpp> #include <boost/spirit/include/phoenix_operator.hpp> #include <boost/spirit/include/phoenix_statement.hpp> #include <boost/spirit/include/phoenix_container.hpp> namespace qi = boost::spirit::qi; namespace lex = boost::spirit::lex; inline std::string read_from_file( const char* infile ) { std::ifstream instream( infile ); if( !instream.is_open() ) { std::cerr << "Could not open file: \"" << infile << "\"" << std::endl; exit( -1 ); } instream.unsetf( std::ios::skipws ); return( std::string( std::istreambuf_iterator< char >( instream.rdbuf() ), std::istreambuf_iterator< char >() ) ); } template< typename Lexer > struct LangLexer : lex::lexer< Lexer > { LangLexer() { identifier = "[a-zA-Z][a-zA-Z0-9_]*"; number = "[-+]?(\\d*\\.)?\\d+([eE][-+]?\\d+)?"; if_ = "if"; else_ = "else"; this->self = lex::token_def<> ( '(' ) | ')' | '{' | '}' | '=' | ';'; this->self += identifier | number | if_ | else_; this->self( "WS" ) = lex::token_def<>( "[ \\t\\n]+" ); } lex::token_def<> if_, else_; lex::token_def< std::string > identifier; lex::token_def< double > number; }; template< typename Iterator, typename Lexer > struct LangGrammar : qi::grammar< Iterator, qi::in_state_skipper< Lexer > > { template< typename TokenDef > LangGrammar( const TokenDef& tok ) : LangGrammar::base_type( program ) { using boost::phoenix::val; using boost::phoenix::ref; using boost::phoenix::size; program = +block; block = '{' >> *statement >> '}'; statement = assignment | if_stmt; assignment = ( tok.identifier >> '=' >> expression >> ';' ); if_stmt = ( tok.if_ >> '(' >> expression >> ')' >> block ); expression = ( tok.identifier[ qi::_val = qi::_1 ] | tok.number[ qi::_val = qi::_1 ] ); BOOST_SPIRIT_DEBUG_NODE( program ); BOOST_SPIRIT_DEBUG_NODE( block ); BOOST_SPIRIT_DEBUG_NODE( statement ); BOOST_SPIRIT_DEBUG_NODE( assignment ); BOOST_SPIRIT_DEBUG_NODE( if_stmt ); BOOST_SPIRIT_DEBUG_NODE( expression ); } qi::rule< Iterator, qi::in_state_skipper< Lexer > > program, block, statement; qi::rule< Iterator, qi::in_state_skipper< Lexer > > assignment, if_stmt; typedef boost::variant< double, std::string > expression_type; qi::rule< Iterator, expression_type(), qi::in_state_skipper< Lexer > > expression; }; int main( int argc, char** argv ) { typedef std::string::iterator base_iterator_type; typedef lex::lexertl::token< base_iterator_type, boost::mpl::vector< double, std::string > > token_type; typedef lex::lexertl::lexer< token_type > lexer_type; typedef LangLexer< lexer_type > LangLexer; typedef LangLexer::iterator_type iterator_type; typedef LangGrammar< iterator_type, LangLexer::lexer_def > LangGrammar; LangLexer lexer; LangGrammar grammar( lexer ); std::string str( read_from_file( 1 == argc ? "boostLexTest.dat" : argv[1] ) ); base_iterator_type strBegin = str.begin(); iterator_type tokenItor = lexer.begin( strBegin, str.end() ); iterator_type tokenItorEnd = lexer.end(); std::cout << std::setfill( '*' ) << std::setw(20) << '*' << std::endl << str << std::endl << std::setfill( '*' ) << std::setw(20) << '*' << std::endl; bool result = qi::phrase_parse( tokenItor, tokenItorEnd, grammar, qi::in_state( "WS" )[ lexer.self ] ); if( result ) { std::cout << "Parsing successful" << std::endl; } else { std::cout << "Parsing error" << std::endl; } return( 0 ); } Here is the output of running this (the file read into the string is dumped out first in main) ******************** { a = 5; if( a ){ b = 2; } } ******************** <program> <try>{</try> <block> <try>{</try> <statement> <try></try> <assignment> <try></try> <expression> <try></try> <success>;</success> <attributes>(5)</attributes> </expression> <success></success> <attributes>()</attributes> </assignment> <success></success> <attributes>()</attributes> </statement> <statement> <try></try> <assignment> <try></try> <fail/> </assignment> <if_stmt> <try> if(</try> <fail/> </if_stmt> <fail/> </statement> <fail/> </block> <fail/> </program> Parsing error

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  • Printing Arrays from Structs

    - by Carlll
    I've been stumped for a few hours on an exercise where I must use functions to build up an array inside a struct and print it. In my current program, it compiles but crashes upon running. #define LIM 10 typedef char letters[LIM]; typedef struct { int counter; letters words[LIM]; } foo; int main(int argc, char **argv){ foo apara; structtest(apara, LIM); print_struct(apara); } int structtest(foo *p, int limit){ p->counter = 0; int i =0; for(i; i< limit ;i++){ strcpy(p->words[p->counter], "x"); //only filling arrays with 'x' as an example p->counter ++; } return; I do believe it's due to my incorrect usage/combination of pointers. I've tried adjusting them, but either an 'incompatible types' error is produced, or the array is seemingly blank } void print_struct(foo p){ printf(p.words); } I haven't made it successfully up to the print_struct stage, but I'm unsure whether p.words is the correct item to be calling. In the output, I would expect the function to return an array of x's. I apologize in advance if I've made some sort of grievous "I should already know this" C mistake. Thanks for your help.

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  • trying to make a simple grid-class, non-lvalue in assignment

    - by Tyrfing
    I'm implementing a simple C++ grid class. One Function it should support is accessed through round brackets, so that I can access the elements by writing mygrid(0,0). I overloaded the () operator and i am getting the error message: "non-lvalue in assignment". what I want to be able to do: //main cGrid<cA*> grid(5, 5); grid(0,0) = new cA(); excerpt of my implementation of the grid class: template class cGrid { private: T* data; int mWidth; int mHeight; public: cGrid(int width, int height) : mWidth(width), mHeight(height) { data = new T[width*height]; } ~cGrid() { delete data; } T operator ()(int x, int y) { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } const T &operator ()(int x, int y) const { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } The rest of the code deals with the implementation of an iterator and should not be releveant.

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  • TSQL - How to join 1..* from multiple tables in one resultset?

    - by ElHaix
    A location table record has two address id's - mailing and business addressID that refer to an address table. Thus, the address table will contain up to two records for a given addressID. Given a location ID, I need an sproc to return all tbl_Location fields, and all tbl_Address fields in one resultset: LocationID INT, ClientID INT, LocationName NVARCHAR(50), LocationDescription NVARCHAR(50), MailingAddressID INT, BillingAddressID INT, MAddress1 NVARCHAR(255), MAddress2 NVARCHAR(255), MCity NVARCHAR(50), MState NVARCHAR(50), MZip NVARCHAR(10), MCountry CHAR(3), BAddress1 NVARCHAR(255), BAddress2 NVARCHAR(255), BCity NVARCHAR(50), BState NVARCHAR(50), BZip NVARCHAR(10), BCountry CHAR(3) I've started by creating a temp table with the required fields, but am a bit stuck on how to accomplish this. I could do sub-selects for each of the required address fields, but seems a bit messy. I've already got a table-valued-function that accepts an address ID, and returns all fields for that ID, but not sure how to integrate it into my required result. Off hand, it looks like 3 selects to create this table - 1: Location, 2: Mailing address, 3: Billing address. What I'd like to do is just create a view and use that. Any assistance would be helpful. Thanks.

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  • Code Explanation (MPICH)

    - by user243680
    #include "mpi.h" #include <stdio.h> #include <math.h> double f(double a) { return (4.0 / (1.0 + a*a)); } void main(int argc, char *argv[]) { int done = 0, n, myid, numprocs,i; double PI25DT = 3.141592653589793238462643; double mypi, pi, h, sum, x; double startwtime, endwtime; int namelen; char processor_name[MPI_MAX_PROCESSOR_NAME]; MPI_Init(&argc,&argv); MPI_Comm_size(MPI_COMM_WORLD,&numprocs); MPI_Comm_rank(MPI_COMM_WORLD,&myid); MPI_Get_processor_name(processor_name,&namelen); fprintf(stderr,"Process %d on %s\n", myid, processor_name); fflush(stderr); n = 0; while (!done) { if (myid == 0) { printf("Enter the number of intervals: (0 quits) ");fflush(stdout); scanf("%d",&n); startwtime = MPI_Wtime(); } MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD); if (n == 0) done = 1; else { h = 1.0 / (double) n; sum = 0.0; for (i = myid + 1; i <= n; i += numprocs) { x = h * ((double)i - 0.5); sum += f(x); } mypi = h * sum; MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD); if (myid == 0) { printf("pi is approximately %.16f, Error is %.16f\n", pi, fabs(pi - PI25DT)); endwtime = MPI_Wtime(); printf("wall clock time = %f\n", endwtime-startwtime); } } } MPI_Finalize(); } Can anyone explain me the above code what it does??I am in lab and my miss has asked me to explain and i dont know what it is.please help

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  • Quick question on using the constructer with multiple files.

    - by sil3nt
    Hi there, I have this class header //header for class. #ifndef Container_H #define Container_H #include <iostream> using namespace std; const int DEFAULT=32; class Container{ public: Container(int maxCapacity = DEFAULT); ~Container(); void insert(int item, int index); void erase(int index); int size()const; private: int sizeC; int capacityC; int * elements; }; void info(); #endif and this source file #include "container.h" Container::Container(int maxCapacity = DEFAULT){ int y; } void Container::insert(int item, int index){ int x; } and when i compile this i get the following error message test.cpp:4: error: default argument given for parameter 1 of `Container::Container(int)' container.h:12: error: after previous specification in `Container::Container(int) what have i done wrong here?

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  • Reading Serial Data From C (OSX /dev/tty)

    - by Jud Stephenson
    I am trying to read data from a bluetooth barcode scanner (KDC300) using C. Here is the code I have so far, and the program successfully establishes a bluetooth connection to the scanner, but when a barcode is scanned, no input is displayed on the screen (Eventually more will be done with the data, but we have to get it working first, right). Here is the program: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #include <termios.h> #include <sys/ioctl.h> int main (int argc, const char * argv[]) { // define vars int STOP = 0; //char buf[255]; if(argv[1]) { int fd = open("/dev/tty.KDC1", O_RDONLY); if(fd == -1) { printf("%s", strcat("Unable to open /dev/tty.", argv[1])); } int res; while(STOP == 0) { while((res = read(fd,buf,255)) == 0); { if(res > 0) { buf[res]=0; printf("%s:%d\n", buf, res); if(buf[sizeof(buf)]=='\n') break; } } } } return 0; } If anyone has any ideas, I am at a loss on this so far. If it is any help, I can run screen /dev/tty.KDC1 and any barcodes scanned on the scanner appear in the terminal, I just can't do anything with the data. Jud

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  • Counter that will remember it's value

    - by owca
    I have a task to operate on complex number. Each number consists of double r = real part, double i = imaginary part and String name. Name must be set within constructor, so I've created int counter, then I'm sending it's value to setNextName function and get name letter back. Unfortunately incrementing this 'counter' value works only within costructor and then it is once again set to 0. How to deal with that?Some constant value? And second problem is that I also need to provide setNextNames(char c) function that will change the counter current value. The code : public class Imaginary { private double re; private double im; private String real; private String imaginary; private String name; private int counter=0; public Imaginary(double r, double u){ re = r; im = u; name = this.setNextName(counter); counter++; } public static String setNextName(int c){ String nameTab[] = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N", "O","P","Q","R","S","T","U","W","V","X","Y","Z"}; String setName = nameTab[c]; System.out.println("c: "+c); return setName; } public static String setNextName(char c){ // //don't know how to deal with this part // }

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  • Is it okay to implement reference counting through composition?

    - by Billy ONeal
    Most common re-usable reference counted objects use private inheritance to implement re-use. I'm not a huge fan of private inheritance, and I'm curious if this is an acceptable way of handling things: class ReferenceCounter { std::size_t * referenceCount; public: ReferenceCounter() : referenceCount(NULL) {}; ReferenceCounter(ReferenceCounter& other) : referenceCount(other.referenceCount) { if (!referenceCount) { referenceCount = new std::size_t(1); other.referenceCount = referenceCount; } else { ++(*referenceCount); } }; ReferenceCounter& operator=(const ReferenceCounter& other) { ReferenceCounter temp(other); swap(temp); return *this; }; void swap(ReferenceCounter& other) { std::swap(referenceCount, other.referenceCount); }; ~ReferenceCounter() { if (referenceCount) { --(*referenceCount); if (!*referenceCount) delete referenceCount; } }; operator bool() const { return referenceCount && (*referenceCount != 0); }; }; class SomeClientClass { HANDLE someHandleThingy; ReferenceCounter objectsStillActive; public: SomeClientClass() { //Construct handle thingy } ~SomeClientClass() { if (objectsStillActive) return; //Release resources }; }; or are there subtle problems with this I'm not seeing?

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  • Persist changes in C

    - by Mohit Deshpande
    I am developing a database-like application that stores a a structure containing: struct Dictionary { char *key; char *value; struct Dictionary *next; }; As you can see, I am using a linked list to store information. But the problem begins when the user exits out of the program. I want the information to be stored somewhere. So I was thinking of storing the linked list in a permanent or temporary file using fopen, then, when the user starts the program, retrieve the linked list. Here is the method that prints the linked list to the console: void PrintList() { int count = 0; struct Dictionary *current; current = head; if (current == NULL) { printf("\nThe list is empty!"); return; } printf(" Key \t Value\n"); printf(" ======== \t ========\n"); while (current != NULL) { count++; printf("%d. %s \t %s\n", count, current->key, current->value); current = current->next; } } So I am thinking of modifying this method to print the information through fprintf instead of printf and then the program would just get the infomation from the file. Could someone help me on how I can read and write to this file? What kind of file should it be, temporary or regular? How should I format the file (like I was thinking of just having the key first, then the value, then a newline character)?

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  • Convert bitmap image information into CGImage in iPhone OS 3

    - by giftederic
    I want to create a CGImage with the color information I already have Here is the code for converting the CGImage to CML, CML_color is a matrix structure - (void)CGImageReftoCML:(CGImageRef *)image destination:(CML_color &)dest{ CML_RGBA p; NSUInteger width=CGImageGetWidth(image); NSUInteger height=CGImageGetHeight(image); CGColorSpaceRef colorSpace=CGColorSpaceCreateDeviceRGB(); unsigned char *rawData=new unsigned char[height*width*4]; NSUInteger bytesPerPixel=4; NSUInteger bytesPerRow=bytesPerPixel*width; NSUInteger bitsPerComponent=8; CGContextRef context=CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); CGColorSpaceRelease(colorSpace); CGContextDrawImage(context, CGRectMake(0, 0, width, height), image); CGContextRelease(context); int index=0; for (int i=0; i<height; i++) { for (int j=0; j<width; j++) { p.red=rawData[index++]; p.green=rawData[index++]; p.blue=rawData[index++]; p.alpha=rawData[index++]; dest(i,j)=p; } } delete[] rawData; } Now I want the reverse function, which converts CML into CGImage. I know all the color and alpha information to create the image, which stored in the matrix CML, but how can I do that?

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  • Qt - no such signal error

    - by bullettime
    I'm trying to trigger a signal when a double click happens in one of the draggable widgets on the fridge magnets example. Here's the changes I made to the example source: DragLabel: class DragLabel : public QLabel { public: DragLabel(const QString &text, QWidget *parent); QString labelText() const; public slots: void testSlot(){qDebug()<<"testSlot";} //<-- implemented this slot protected: void mouseDoubleClickEvent(QMouseEvent *ev){emit testSignal();} //<-- overriden this method private: QString m_labelText; signals: void testSignal(); //<-- added this signal }; The only thing I changed in the implementation file is adding connect(this,SIGNAL(testSignal()),this,SLOT(testSlot())); to DragLabel's constructor. Trying to compile the project resulted in 'undefined reference to `DragLabel::testSignal()' and 'collect2: ld returned 1 exit status' errors. When I comment out the call to the signal, it compiles and runs, but gives off 'Object::connect: No such signal QLabel::testSignal() in draglabel.cpp' warning in the application output. Apparently testSignal() isn't being recognized as a signal. What am I missing?

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  • Delphi: Fast(er) widestring concatenation

    - by Ian Boyd
    i have a function who's job is to convert an ADO Recordset into html: class function RecordsetToHtml(const rs: _Recordset): WideString; And the guts of the function involves a lot of wide string concatenation: while not rs.EOF do begin Result := Result+CRLF+ '<TR>'; for i := 0 to rs.Fields.Count-1 do Result := Result+'<TD>'+VarAsString(rs.Fields[i].Value)+'</TD>'; Result := Result+'</TR>'; rs.MoveNext; end; With a few thousand results, the function takes, what any user would feel, is too long to run. The Delphi Sampling Profiler shows that 99.3% of the time is spent in widestring concatenation (@WStrCatN and @WstrCat). Can anyone think of a way to improve widestring concatenation? i don't think Delphi 5 has any kind of string builder. And Format doesn't support Unicode. And to make sure nobody tries to weasel out: pretend you are implementing the interface: IRecordsetToHtml = interface(IUnknown) function RecordsetToHtml(const rs: _Recordset): WideString; end; Update One I thought of using an IXMLDOMDocument, to build up the HTML as xml. But then i realized that the final HTML would be xhtml and not html - a subtle, but important, difference. Update Two Microsoft knowledge base article: How To Improve String Concatenation Performance

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  • How to determine the data type of a CvMat

    - by Chris
    When using the CvMat type, the type of data is crucial to keeping your program running. For example, depending on whether your data is type float or unsigned char, you would choose one of these two commands: cvmGet(mat, row, col); cvGetReal2D(mat, row, col); Is there a universal approach to this? If the wrong data type matrix is passed to these calls, they crash at runtime. This is becoming an issue, since a function I have defined is getting passed several different types of matrices. How do you determine the data type of a matrix so you can always access its data? I tried using the "type()" function as such. CvMat* tmp_ptr = cvCreateMat(t_height,t_width,CV_8U); std::cout << "type = " << tmp_ptr->type() << std::endl; This does not compile, saying "term does not evaluate to a function taking 0 arguments". If I remove the brackets after the word type, I get a type of 1111638032 EDIT minimal application that reproduces this... int main( int argc, char** argv ) { CvMat *tmp2 = cvCreateMat(10,10, CV_32FC1); std::cout << "tmp2 type = " << tmp2->type << " and CV_32FC1 = " << CV_32FC1 << " and " << (tmp2->type == CV_32FC1) << std::endl; } Output: tmp2 type = 1111638021 and CV_32FC1 = 5 and 0

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  • Random String Generator creates same string on multiple calls

    - by rockinthesixstring
    Hi there. I've build a random string generator but I'm having a problem whereby if I call the function multiple times say in a Page_Load method, the function returns the same string twice. here's the code ''' <summary>' ''' Generates a Random String' ''' </summary>' ''' <param name="n">number of characters the method should generate</param>' ''' <param name="UseSpecial">should the method include special characters? IE: # ,$, !, etc.</param>' ''' <param name="SpecialOnly">should the method include only the special characters and excludes alpha numeric</param>' ''' <returns>a random string n characters long</returns>' Public Function GenerateRandom(ByVal n As Integer, Optional ByVal UseSpecial As Boolean = True, Optional ByVal SpecialOnly As Boolean = False) As String Dim chars As String() ' a character array to use when generating a random string' Dim ichars As Integer = 74 'number of characters to use out of the chars string' Dim schars As Integer = 0 ' number of characters to skip out of the characters string' chars = { _ "A", "B", "C", "D", "E", "F", _ "G", "H", "I", "J", "K", "L", _ "M", "N", "O", "P", "Q", "R", _ "S", "T", "U", "V", "W", "X", _ "Y", "Z", "0", "1", "2", "3", _ "4", "5", "6", "7", "8", "9", _ "a", "b", "c", "d", "e", "f", _ "g", "h", "i", "j", "k", "l", _ "m", "n", "o", "p", "q", "r", _ "s", "t", "u", "v", "w", "x", _ "y", "z", "!", "@", "#", "$", _ "%", "^", "&", "*", "(", ")", _ "-", "+"} If Not UseSpecial Then ichars = 62 ' only use the alpha numeric characters out of "char"' If SpecialOnly Then schars = 62 : ichars = 74 ' skip the alpha numeric characters out of "char"' Dim rnd As New Random() Dim random As String = String.Empty Dim i As Integer = 0 While i < n random += chars(rnd.[Next](schars, ichars)) System.Math.Max(System.Threading.Interlocked.Increment(i), i - 1) End While rnd = Nothing Return random End Function but if I call something like this Dim str1 As String = GenerateRandom(5) Dim str2 As String = GenerateRandom(5) the response will be something like this g*3Jq g*3Jq and the second time I call it, it will be 3QM0$ 3QM0$ What am I missing? I'd like every random string to be generated as unique.

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  • Can a destructor be recursive?

    - by Cubbi
    Is this program well-defined, and if not, why exactly? #include <iostream> #include <new> struct X { int cnt; X (int i) : cnt(i) {} ~X() { std::cout << "destructor called, cnt=" << cnt << std::endl; if ( cnt-- > 0 ) this->X::~X(); // explicit recursive call to dtor } }; int main() { char* buf = new char[sizeof(X)]; X* p = new(buf) X(7); p->X::~X(); // explicit call to dtor delete[] buf; } My reasoning: although invoking a destructor twice is undefined behavior, per 12.4/14, what it says exactly is this: the behavior is undefined if the destructor is invoked for an object whose lifetime has ended Which does not seem to prohibit recursive calls. While the destructor for an object is executing, the object's lifetime has not yet ended, thus it's not UB to invoke the destructor again. On the other hand, 12.4/6 says: After executing the body [...] a destructor for class X calls the destructors for X's direct members, the destructors for X's direct base classes [...] which means that after the return from a recursive invocation of a destructor, all member and base class destructors will have been called, and calling them again when returning to the previous level of recursion would be UB. Therefore, a class with no base and only POD members can have a recursive destructor without UB. Am I right?

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  • Listing directories in Linux from C

    - by nunos
    I am trying to simulate linux command ls using linux api from c. Looking at the code it does make sense, but when I run it I get "stat error: No such file or directory". I have checked that opendir is working ok. I think the problem is in stat, which is returning -1 even though I think it should return 0. What am I missing? Thanks for your help. #include <stdio.h> #include <stdlib.h> #include <string.h> #include <dirent.h> #include <sys/stat.h> #include <errno.h> int main(int argc, char *argv[]) { DIR *dirp; struct dirent *direntp; struct stat stat_buf; char *str; if (argc != 2) { fprintf( stderr, "Usage: %s dir_name\n", argv[0]); exit(1); } if ((dirp = opendir( argv[1])) == NULL) { perror(argv[1]); exit(2); } while ((direntp = readdir( dirp)) != NULL) { if (stat(direntp->d_name, &stat_buf)==-1) { perror("stat ERROR"); exit(3); } if (S_ISREG(stat_buf.st_mode)) str = "regular"; else if (S_ISDIR(stat_buf.st_mode)) str = "directory"; else str = "other"; printf("%-25s - %s\n", direntp->d_name, str); } closedir(dirp); exit(0); }

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  • Using generics to make an algorithm work on lists of "something" instead of only String's

    - by Binary255
    Hi, I have a small algorithm which replaces the position of characters in a String: class Program { static void Main(string[] args) { String pairSwitchedStr = pairSwitch("some short sentence"); Console.WriteLine(pairSwitchedStr); Console.ReadKey(); } private static String pairSwitch(String str) { StringBuilder pairSwitchedStringBuilder = new StringBuilder(); for (int position = 0; position + 1 < str.Length; position += 2) { pairSwitchedStringBuilder.Append((char)str[position + 1]); pairSwitchedStringBuilder.Append((char)str[position]); } return pairSwitchedStringBuilder.ToString(); } } I would like to make it as generic as possible, possibly using Generics. What I'd like to have is something which works with: Anything that is built up using a list of instances. Including strings, arrays, linked lists I suspect that the solution must use generics as the algorithm is working on a list of instances of T (there T is ... something). Version of C# isn't of interest, I guess the solution will be nicer if features from C# version 2.0 is used.

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  • [Doxygen] How to documenting global dependencies for functions?

    - by Thomas Matthews
    I've got some C code from a 3rd party vendor (for an embedded platform) that uses global variables (for speed & space optimizations). I'm documenting the code, converting to Doxygen format. How do I put a note in the function documentation that the function requires on global variables and functions? Doxygen has special commands for annotating parameters and return values as describe here: Doxygen Special Commands. I did not see any commands for global variables. Example C code: extern unsigned char data_buffer[]; //!< Global variable. /*! Returns the next available data byte. * \return Next data byte. */ unsigned char Get_Byte(void) { static unsigned int index = 0; return data_buffer[index++]; //!< Uses global variable. } In the above code, I would like to add Doxygen comments that the function depends on the global variable data_buffer.

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  • Ibator didn't generate Oracle varchar2 field

    - by bugbug
    I have table APP_REQ_APPROVE_COMPARE with following fields: "ID" NUMBER NOT NULL ENABLE, "TRACK_NO" VARCHAR2(20 BYTE) NOT NULL ENABLE, "REQ_DATE" DATE NOT NULL ENABLE, "OFFCODE" CHAR(6 BYTE) NOT NULL ENABLE, "COMPARE_CASE_ID" NUMBER NOT NULL ENABLE, "VEHICLE_NAME" VARCHAR2(100 BYTE), "ENGINE_NO" VARCHAR2(100 BYTE), "BODY_NO" VARCHAR2(100 BYTE), "HOLD_SHIP" NUMBER, "OWNERSHIP" VARCHAR2(200 BYTE), "RENT_NAME" VARCHAR2(200 BYTE), "CONTRACT" VARCHAR2(100 BYTE), "CONTRACT_NO" VARCHAR2(100 BYTE), "CONTRACT_DATE" DATE, "ISLAWBREAKERRENT" CHAR(1 BYTE) NOT NULL ENABLE, "MISTAKE_DETAIL" VARCHAR2(4000 BYTE), "COMPARE_REASON" VARCHAR2(4000 BYTE), "CREATE_BY" NUMBER NOT NULL ENABLE, "CREATE_ON" DATE DEFAULT SYSDATE NOT NULL ENABLE, "UPDATE_BY" NUMBER, "UPDATE_ON" DATE, When I generate a java bean using Ibator , I didn't find trackNo, VehicalName, ... (all fields defined as varchar2). What is the problem in my case? Here is my Ibator configuration file: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE ibatorConfiguration PUBLIC "-//Apache Software Foundation//DTD Apache iBATIS Ibator Configuration 1.0//EN" "http://ibatis.apache.org/dtd/ibator-config_1_0.dtd"> <ibatorConfiguration> <classPathEntry location="/dos/connector/oracle_jdbc.jar"/> <ibatorContext id="autoPerson" defaultModelType="flat" targetRuntime="Ibatis2Java2"> <jdbcConnection connectionURL="jdbc:oracle:thin:@192.168.42.144:1521:orcl" driverClass="oracle.jdbc.driver.OracleDriver" userId="user" password="password"/> <javaModelGenerator targetPackage="com.ko.model" targetProject="FormConfig"> <property name="enableSubPackages" value="true"/> <property name="trimStrings" value="true"/> </javaModelGenerator> <sqlMapGenerator targetPackage="com.ko.map" targetProject="FormConfig"> <property name="enableSubPackages" value="true"/> </sqlMapGenerator> <daoGenerator targetPackage="com.ko.model.dao" type="SPRING" targetProject="FormConfig" implementationPackage="com.ko.model.dao.impl" > <property name="enableSubPackges" value="true"/> <property name="methodNameCalculator" value="extended"/> </daoGenerator> <table tableName="APP_REQ_APPROVE_COMPARE" domainObjectName="AppReqApproveCompare"/> <ibatorConfiguration>

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  • strange redefined symbols

    - by Chris H
    I included this header into one of my own: http://codepad.org/lgJ6KM6b When I compiled I started getting errors like this: CMakeFiles/bin.dir/SoundProjection.cc.o: In function `Gnuplot::reset_plot()': /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/new:105: multiple definition of `Gnuplot::reset_plot()' CMakeFiles/bin.dir/main.cc.o:project/gnuplot-cpp/gnuplot_i.hpp:962: first defined here CMakeFiles/bin.dir/SoundProjection.cc.o: In function `Gnuplot::set_smooth(std::basic_string, std::allocator const&)': project/gnuplot-cpp/gnuplot_i.hpp:1041: multiple definition of `Gnuplot::set_smooth(std::basic_string, std::allocator const&)' CMakeFiles/bin.dir/main.cc.o:project/gnuplot-cpp/gnuplot_i.hpp:1041: first defined here CMakeFiles/bin.dir/SoundProjection.cc.o:/usr/include/eigen2/Eigen/src/Core/arch/SSE/PacketMath.h:41: multiple definition of `Gnuplot::m_sGNUPlotFileName' I know it's hard to see in this mess, but look at where the redefinitions are taking place. They take place in files like /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/new:105. How is the new operator getting information about a gnuplot header? I can't even edit that file. How could that ever even be possible? I'm not even sure how to start debugging this. I hope I've provided enough information. I wasn't able to reproduce this in a small project. I mostly just looking for tips on how to find out why this is happening, and how to track it down. Thanks.

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  • How to set QNetworkReply properties to get correct NCBI pages?

    - by Claire Huang
    I try to get this following url using the downloadURL function: http://www.ncbi.nlm.nih.gov/nuccore/27884304 But the data is not as what we can see through the browser. Now I know it's because that I need to give the correct information such as browser, how can I know what kind of information I need to set, and how can I set it? (By setHeader function??) In VC++, we can use CInternetSession and CHttpConnection Object to get the correct information without setting any other detail information, is there any similar way in Qt or other cross-platform C++ network lib?? (Yes, I need the the cross-platform property.) QNetworkReply::NetworkError downloadURL(const QUrl &url, QByteArray &data) { QNetworkAccessManager manager; QNetworkRequest request(url); request.setHeader(QNetworkRequest::ContentTypeHeader ,"Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"); QNetworkReply *reply = manager.get(request); QEventLoop loop; QObject::connect(reply, SIGNAL(finished()), &loop, SLOT(quit())); loop.exec(); QVariant statusCodeV = reply->attribute(QNetworkRequest::RedirectionTargetAttribute); QUrl redirectTo = statusCodeV.toUrl(); if (!redirectTo.isEmpty()) { if (redirectTo.host().isEmpty()) { const QByteArray newaddr = ("http://"+url.host()+redirectTo.encodedPath()).toAscii(); redirectTo.setEncodedUrl(newaddr); redirectTo.setHost(url.host()); } return (downloadURL(redirectTo, data)); } if (reply->error() != QNetworkReply::NoError) { return reply->error(); } data = reply->readAll(); delete reply; return QNetworkReply::NoError; }

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  • LPCSTR, TCHAR, String

    - by user285327
    I am use next type of strings: LPCSTR, TCHAR, String i want to convert: 1) from TCHAR to LPCSTR 2) from String to char I convert from TCHAR to LPCSTR by that code: RunPath = TEXT("C:\\1"); LPCSTR Path = (LPCSTR)RunPath; From String to char i convert by that code: SaveFileDialog^ saveFileDialog1 = gcnew SaveFileDialog; saveFileDialog1->Title = "?????????? ?????-????????"; saveFileDialog1->Filter = "bck files (*.bck)|*.bck"; saveFileDialog1->RestoreDirectory = true; pin_ptr<const wchar_t> wch = TEXT(""); if ( saveFileDialog1->ShowDialog() == System::Windows::Forms::DialogResult::OK ) { wch = PtrToStringChars(saveFileDialog1->FileName); } else return; ofstream os(wch, ios::binary); My problem is that when i set "Configuration Properties - General Character Set in "Use Multi-Byte Character Set" the first part of code work correctly. But the second part of code return error C2440. When i set "Configuration Properties - General Character Set in "Use Unicode" the second part of code work correctly. But the first part of code return the only first character from TCHAR to LPCSTR.

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  • Error while compiling Hello world program for CUDA

    - by footy
    I am using Ubuntu 12.10 and have sucessfully installed CUDA 5.0 and its sample kits too. I have also run sudo apt-get install nvidia-cuda-toolkit Below is my hello world program for CUDA: #include <stdio.h> /* Core input/output operations */ #include <stdlib.h> /* Conversions, random numbers, memory allocation, etc. */ #include <math.h> /* Common mathematical functions */ #include <time.h> /* Converting between various date/time formats */ #include <cuda.h> /* CUDA related stuff */ __global__ void kernel(void) { } /* MAIN PROGRAM BEGINS */ int main(void) { /* Dg = 1; Db = 1; Ns = 0; S = 0 */ kernel<<<1,1>>>(); /* PRINT 'HELLO, WORLD!' TO THE SCREEN */ printf("\n Hello, World!\n\n"); /* INDICATE THE TERMINATION OF THE PROGRAM */ return 0; } /* MAIN PROGRAM ENDS */ The following error occurs when I compile it with nvcc -g hello_world_cuda.cu -o hello_world_cuda.x /tmp/tmpxft_000033f1_00000000-13_hello_world_cuda.o: In function `main': /home/adarshakb/Documents/hello_world_cuda.cu:16: undefined reference to `cudaConfigureCall' /tmp/tmpxft_000033f1_00000000-13_hello_world_cuda.o: In function `__cudaUnregisterBinaryUtil': /usr/include/crt/host_runtime.h:172: undefined reference to `__cudaUnregisterFatBinary' /tmp/tmpxft_000033f1_00000000-13_hello_world_cuda.o: In function `__sti____cudaRegisterAll_51_tmpxft_000033f1_00000000_4_hello_world_cuda_cpp1_ii_b81a68a1': /tmp/tmpxft_000033f1_00000000-1_hello_world_cuda.cudafe1.stub.c:1: undefined reference to `__cudaRegisterFatBinary' /tmp/tmpxft_000033f1_00000000-1_hello_world_cuda.cudafe1.stub.c:1: undefined reference to `__cudaRegisterFunction' /tmp/tmpxft_000033f1_00000000-13_hello_world_cuda.o: In function `cudaError cudaLaunch<char>(char*)': /usr/lib/nvidia-cuda-toolkit/include/cuda_runtime.h:958: undefined reference to `cudaLaunch' collect2: ld returned 1 exit status I am also making sure that I use gcc and g++ version 4.4 ( As 4.7 there is some problem with CUDA)

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