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  • Iterator category

    - by Knowing me knowing you
    In code: //I know that to get this effect (being able to use it with std algorithms) I can inherit like I did in line below: class Iterator //: public std::iterator<std::bidirectional_iterator_tag,T> { private: T** itData_; public: //BUT I WOULD LIKE TO BE ABLE TO DO IT BY HAND AS WELL typedef std::bidirectional_iterator_tag iterator_category; typedef T* value_type;//SHOULD IT BE T AS value_type or T*? typedef std::ptrdiff_t difference_type; typedef T** pointer;//SHOULD IT BE T* AS pointer or T**? typedef T*& reference;//SHOULD IT BE T& AS reference or T*&? }; Basically what I'm asking is if I have my variable of type T** in iterator class is it right assumption that value type for this iterator will be T* and so on as I described in comments in code, right next to relevant lines. Thank you.

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  • Error message in XSLT with C# extension function

    - by iHeartGreek
    Hi! I am received the following error while trying to implement a C# extension function in XSLT. Extension function parameters or return values which have CLR type 'Char[]' are not supported.** code: <xsl:variable name="stringList"> <xsl:value-of select="extension:GetList('AAA BBB CCC', ' ')"/> </xsl:variable> <msxsl:script language="C#" implements-prefix="extension"> <![CDATA[ public string[] GetList(string str, char[] delimiter) { ... ... return str.Split(delimiter, StringSplitOptions.None); } ]]> </msxsl:script> Can someone explain this error message and how to get past it? Thanks!

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  • Unmanaged C++ instantiation question

    - by Jim Jones
    Want to verify that my understanding of how this works. Have an unmanaged C++ Class with one public instance variable: char* character_encoding; and whose only constructor is defined as: TF_StringList(const char* encoding = "cp_1252"); when I use this class in either managed or unmanaged C++, the first thing I do is declare a pointer to an object of this class: const TF_StringList * categories; Then later I instantiate it: categories = new TF_StringList(); this gives me a pointer to an object of type TF_StringList whose variable character_encoding is set to "cp_1252"; So, is all that logic valid? Jim

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  • How to extract img src, title and alt from html using php?

    - by Sam
    I would like to create a page where all images which reside on my website are listed with title and alternative representation. I already wrote me a little program to find and load all html files, but now I am stuck at how to extract src, title and alt from the html < img src="/image/fluffybunny.jpg" title="Harvey the bunny" alt="a cute little fluffy bunny"/ I guess this should be done with some regex, but since the order of the tags may vary, and I need all of them, I don't really know how to parse this in an elegant way (I could do it the hard char by char way, but thats painful).

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  • Operator Overloading for Queue C++

    - by Josh
    I was trying to use the overload operator method to copy the entries of one queue into another, but I am going wrong with my function. I don't know how else to access the values of the queue "original" any other way than what I have below: struct Node { int item; Node* next; }; class Queue { public: [...] //Extra code here void operator = (const Queue &original); protected: Node *front, *end; } void Queue::operator=(const Queue &original) { //THIS IS WHERE IM GOING WRONG while(original.front->next != NULL) { front->item = original.front->item; front->next = new Node; front = front->next; original.front = original.front->next; } }

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  • About the String#substring() method

    - by alain.janinm
    If we take a look at the String#substring method implementation : new String(offset + beginIndex, endIndex - beginIndex, value); We see that a new String is created with the same original content (parameter char [] value). So the workaround is to use new String(toto.substring(...)) to drop the reference to the original char[] value and make it eligible for GC (if no more references exist). I would like to know if there is a special reason that explain this implementation. Why the method doesn't create herself the new shorter String and why she keeps the full original value instead? The other related question is : should we always use new String(...) when dealing with substring?

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  • Prolog .. Can i convert from a list of chars to a string or term in Prolog !!

    - by AhmadAssaf
    i use read_line_to_codes(Stream,Line) to read a line from a file .. first is there any way to read a line and assign it to a term in prolog ?? if not i managed to read a line and put it in this char list .. now this char list contains spaces .. which is bad .. so i want to convert it to a term or a string in prolog so that i can process it easier .. spaces cannot be atoms so thats a problem .. i appreciate the help !!

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  • Inheritance - initialization problem

    - by dumbquestion
    I have a c++ class derived from a base class in a framework. The derived class doesn't have any data members because I need it to be freely convertible into a base class and back - the framework is responsible for loading and saving the objects and I can't change it. My derived class just has functions for accessing the data. But there are a couple of places where I need to store some temporary local variables to speed up access to data in the base class. mydata* MyClass::getData() { if ( !m_mydata ) { // set to NULL in the constructor m_mydata = some_long_and complex_operation_to_get_the_data_in_the_base() } return m_mydata; } The problem is if I just access the object by casting the base class pointer returned from the framework to MyClass* the ctor for MyClass is never called and m_mydata is junk. Is there a way of only initializing the m_mydata pointer once?

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  • Google apps API problem with read-only feed?

    - by brandonprry
    Hi all, I am beginning to use the google data api (specifically for the finance app). I can read my portfolio's just fine, so I am authenticating correctly (or so I think). However, when i try and create a portfolio, I get a 'feed is read-only' error. The constructor for the service: public class FinanceService : Service, IService { public FinanceService(string applicationName) : base ("finance", applicationName) { this.RequestFactory = new GDataGAuthRequestFactory("finance", applicationName) { ProtocolMajor = 3 }; } } and saving it is private const string _schema = "http://schemas.google.com/finance/2007"; private const string _feed = "http://finance.google.com/finance/feeds/default/portfolios"; AtomFeed atomFeed = new AtomFeed(new Uri(_feed), this.FinanceService); return this.FinanceService.Insert(atomFeed, this as AtomEntry) as PortfolioEntry; Any idea why the atomFeed would come back ReadOnly? The credentials are legit, and I can get my current portfolios without a problem.

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  • Split text files Accross threads

    - by Kevin
    The problem: I have a few text files (10) with numbers in them on every line. I need to have them split across some threads I create using the pthread library. these threads that are created (worker threads) are to find the largest prime number that gets sent to them (and over all the largest prime from all of the text files). My current thoughts on solutions: I am thinking myself to have two arrays and all of the text files in one array and the other array will contain a binary file that I can read say 1000 lines and send the pointer to the index of that binary file in a struct that contains the id, file pointer, and file position and let it crank through that. a little bit of what I am talking about pthread_create(&threads[index],NULL,calc_sqrt,(void *)threadFields[index]);//Pass struct to each worker Struct: typedef struct threadFields{ int *id, *position; FILE *Fin; }tField; If anyone has any insight or a better solution it would be greatly appreciated Thanks

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  • C++ String tokenisation from 3D .obj files

    - by Ben
    I'm pretty new to C++ and was looking for a good way to pull the data out of this line. A sample line that I might need to tokenise is f 11/65/11 16/70/16 17/69/17 I have a tokenisation method that splits strings into a vector as delimited by a string which may be useful static void Tokenise(const string& str, vector<string>& tokens, const string& delimiters = " ") The only way I can think of doing it is to tokenise with " " as a delimiter, remove the first item from the resulting vector, then tokenise each part by itself. Is there a good way to do this all in one?

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  • a nicer way to create structs in a loop

    - by sandra
    Hi guys, I haven't coded in C++ in ages. And recently, I'm trying to work on something involving structs. Like this typedef struct{ int x; int y; } Point; Then in a loop, I'm trying to create new structs and put pointers to them them in a list. Point* p; int i, j; while (condition){ // compute values for i and j with some function... p = new Point; p* = {i, j}; //initialize my struct. list.append(p); //append this pointer to my list. } Now, my question is it possible to simplify this? I mean, the pointer variable *p outside of the loop and calling p = new Point inside the loop. Isn't there a better/nicer syntax for this?

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  • Using sscanf to parse two strings out

    - by Jessica
    I have a semi xml formatted file that contains line with the following format: <param name="Distance" value="1000Km" /> The first char in the string is usually a TAB or spaces. I've been using the following to try to parse the two strings out (from name and value): if(sscanf(lineread, "\t<param name=\"%s\" value=\"%s\" />", name, value) == 1) { //do something } name and value are char* Now, the result is always the same: name gets parse (I need to remove the quotes) and name is always empty. What am I doing wrong? Thanks, code is appreciated. Jess.

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  • PLEASE HELP JAVA/SQL question

    - by fred-ghosn
    Hello everyone, well I'm new here and I really need some help.. I want to create a table and this table's name will be inserted from a textfield. However when I run the query it's giving me an error, any help on this one? Ill paste the code here: public boolean CreateTable() { TableNumber=jTextField4.getText(); try { String password = null; String s = "CREATE TABLE '"+TableNumber+'" (Item char(50),Price char(50))"; ConnectionForOrders(); stmt = conn.createStatement(); stmt.executeUpdate(s); boolean f=false; ConnectionForOrdersclose();

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  • Storing a NTFS Security Descriptor in C

    - by Doori Bar
    My goal is to store a NTFS Security Descriptor in its identical native state. The purpose is to restore it on-demand. I managed to write the code for that purpose, I was wondering if anybody mind to validate a sample of it? (The for loop represents the way I store the native descriptor) This sample only contains the flag for "OWNER", but my intention is to apply the same method for all of the security descriptor flags. I'm just a beginner, would appreciate the heads up. Thanks, Doori Bar #define _WIN32_WINNT 0x0501 #define WINVER 0x0501 #include <stdio.h> #include <windows.h> #include "accctrl.h" #include "aclapi.h" #include "sddl.h" int main (void) { DWORD lasterror; PSECURITY_DESCRIPTOR PSecurityD1, PSecurityD2; HANDLE hFile; PSID owner; LPTSTR ownerstr; BOOL ownerdefault; int ret = 0; unsigned int i; hFile = CreateFile("c:\\boot.ini", GENERIC_READ | ACCESS_SYSTEM_SECURITY, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL); if (hFile == INVALID_HANDLE_VALUE) { fprintf(stderr,"CreateFile() failed. Error: INVALID_HANDLE_VALUE\n"); return 1; } lasterror = GetSecurityInfo(hFile, SE_FILE_OBJECT, OWNER_SECURITY_INFORMATION , &owner, NULL, NULL, NULL, &PSecurityD1); if (lasterror != ERROR_SUCCESS) { fprintf(stderr,"GetSecurityInfo() failed. Error: %lu;\n", lasterror); ret = 1; goto ret1; } ConvertSidToStringSid(owner,&ownerstr); printf("ownerstr of PSecurityD1: %s\n", ownerstr); /* The for loop represents the way I store the native descriptor */ PSecurityD2 = malloc( GetSecurityDescriptorLength(PSecurityD1) * sizeof(unsigned char) ); for (i=0; i < GetSecurityDescriptorLength(PSecurityD1); i++) ((unsigned char *) PSecurityD2)[i] = ((unsigned char *) PSecurityD1)[i]; if (IsValidSecurityDescriptor(PSecurityD2) == 0) { fprintf(stderr,"IsValidSecurityDescriptor(PSecurityD2) failed.\n"); ret = 2; goto ret2; } if (GetSecurityDescriptorOwner(PSecurityD2,&owner,&ownerdefault) == 0) { fprintf(stderr,"GetSecurityDescriptorOwner() failed."); ret = 2; goto ret2; } ConvertSidToStringSid(owner,&ownerstr); printf("ownerstr of PSecurityD2: %s\n", ownerstr); ret2: free(owner); free(ownerstr); free(PSecurityD1); free(PSecurityD2); ret1: CloseHandle(hFile); return ret; }

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  • Making uppercase of std::string

    - by Daniel K.
    Which implementation do you think is better? std::string ToUpper( const std::string& source ) { std::string result; result.reserve( source.length() ); std::transform( source.begin(), source.end(), result.begin(), std::ptr_fun<int, int>( std::toupper ) ); return result; } and... std::string ToUpper( const std::string& source ) { std::string result( source.length(), '\0' ); std::transform( source.begin(), source.end(), result.begin(), std::ptr_fun<int, int>( std::toupper ) ); return result; } Difference is that the first one uses reserve method after the default constructor, but the second one uses the constructor accepting the number of characters.

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  • In a binary search Tree

    - by user1044800
    In a binary search tree that takes a simple object.....when creating the getter and setter methods for the left, right, and parent. do I a do a null pointer? as in this=this or do I create the object in each method? Code bellow... This is my code: public void setParent(Person parent) { parent = new Person( parent.getName(), parent.getWeight()); //or is the parent supposed to be a null pointer ???? This is the code it came from: public void setParent(Node parent) { this.parent = parent; } Their code takes a node from the node class...my set parent is taking a person object from my person class.....

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  • Bad allocation exceptions in C++

    - by me1982
    Hello, In a school project of mine I was requested to create a program not using STL. In the program I use alot of Pointer* = new Something; if (Pointer == NULL) throw AllocationError(); My question is about allocation errors: 1. is there an autamtic exception thrown by new when allocation fails? 2. if so how can I catch it if I'm not using STL (#include "exception.h) 3. is using the NULL testing enugh? thank you. I'm using eclipseCDT(C++) with MinGW on windows 7.

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  • Why is comparing against "end()" iterator legal?

    - by sharptooth
    According to C++ standard (3.7.3.2/4) using (not only dereferencing, but also copying, casting, whatever else) an invalid pointer is undefined behavior (in case of doubt also see this question). Now the typical code to traverse an STL containter looks like this: std::vector<int> toTraverse; //populate the vector for( std::vector<int>::iterator it = toTraverse.begin(); it != toTraverse.end(); ++it ) { //process( *it ); } std::vector::end() is an iterator onto the hypothetic element beyond the last element of the containter. There's no element there, therefore using a pointer through that iterator is undefined behavior. Now how does the != end() work then? I mean in order to do the comparison an iterator needs to be constructed wrapping an invalid address and then that invalid address will have to be used in a comparison which again is undefined behavior. Is such comparison legal and why?

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  • template typename question

    - by stephenteh
    Hi, I have a problem with template and wondering is there a possible way to achieve what I wanted to do. Here is my question. template <typename T> class A { public: typedef T* pointer; typedef const pointer const_pointer; A() {} template <typename D> A(const D& d) { // how can I store the D type // so I can refer it later on // outside of this function } };

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  • C++ linked list based tree structure. Sanely move nodes between lists.

    - by krunk
    The requirements: Each Node in the list must contain a reference to its previous sibling Each Node in the list must contain a reference to its next sibling Each Node may have a list of child nodes Each child Node must have a reference to its parent node Basically what we have is a tree structure of arbitrary depth and length. Something like: -root(NULL) --Node1 ----ChildNode1 ------ChildOfChild --------AnotherChild ----ChildNode2 --Node2 ----ChildNode1 ------ChildOfChild ----ChildNode2 ------ChildOfChild --Node3 ----ChildNode1 ----ChildNode2 Given any individual node, you need to be able to either traverse its siblings. the children, or up the tree to the root node. A Node ends up looking something like this: class Node { Node* previoius; Node* next; Node* child; Node* parent; } I have a container class that stores these and provides STL iterators. It performs your typical linked list accessors. So insertAfter looks like: void insertAfter(Node* after, Node* newNode) { Node* next = after->next; after->next = newNode; newNode->previous = after; next->previous = newNode; newNode->next = next; newNode->parent = after->parent; } That's the setup, now for the question. How would one move a node (and its children etc) to another list without leaving the previous list dangling? For example, if Node* myNode exists in ListOne and I want to append it to listTwo. Using pointers, listOne is left with a hole in its list since the next and previous pointers are changed. One solution is pass by value of the appended Node. So our insertAfter method would become: void insertAfter(Node* after, Node newNode); This seems like an awkward syntax. Another option is doing the copying internally, so you'd have: void insertAfter(Node* after, const Node* newNode) { Node *new_node = new Node(*newNode); Node* next = after->next; after->next = new_node; new_node->previous = after; next->previous = new_node; new_node->next = next; new_node->parent = after->parent; } Finally, you might create a moveNode method for moving and prevent raw insertion or appending of a node that already has been assigned siblings and parents. // default pointer value is 0 in constructor and a operator bool(..) // is defined for the Node bool isInList(const Node* node) const { return (node->previous || node->next || node->parent); } // then in insertAfter and friends if(isInList(newNode) // throw some error and bail I thought I'd toss this out there and see what folks came up with.

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  • C++ catch constructor exception

    - by aaa
    hi. I do not seem to understand how to catch constructor exception. Here is relevant code: struct Thread { rysq::cuda::Fock fock_; template<class iterator> Thread(const rysq::cuda::Centers &centers, const iterator (&blocks)[4]) : fock_() { if (!fock_) throw; } }; Thread *ct; try { ct = new Thread(centers_, blocks); } catch(...) { return false; } // catch never happens, So catch statement do not execute and I get unhandled exception. What did I do wrong? this is straight C++ using g++.

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  • Boost::asio bug in MSVC10 - Failing BOOST_WORKAROUND in ~buffer_debug_check() in buffer.hpp

    - by shaz
    A straight compilation of example http://www.boost.org/doc/libs/1_43_0/doc/html/boost_asio/tutorial/tutdaytime3/src.html results in a runtime null pointer exception. Stack trace points to the buffer_debug_check destructor which contains this comment: // MSVC's string iterator checking may crash in a std::string::iterator // object's destructor when the iterator points to an already-destroyed // std::string object, unless the iterator is cleared first. The test #if BOOST_WORKAROUND(BOOST_MSVC, = 1400) succeeds in MSVC10 and (but) results in a null pointer exception in c:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility line 123 _Iterator_base12& operator=(const _Iterator_base12& _Right) { // assign an iterator if (_Myproxy != _Right._Myproxy) _Adopt(_Right._Myproxy->_Mycont); return (*this); } _Right._Myproxy is NULL

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  • Codesample with bufferoverflow (gets method). Why does it not behave as expected?

    - by citronas
    This an extract from an c program that should demonstrate a bufferoverflow. void foo() { char arr[8]; printf(" enter bla bla bla"); gets(arr); printf(" you entered %s\n", arr); } The question was "How many input chars can a user maximal enter without a creating a buffer overflow" My initial answer was 8, because the char-array is 8 bytes long. Although I was pretty certain my answer was correct, I tried a higher amount of chars, and found that the limit of chars that I can enter, before I get a segmentation fault is 11. (Im running this on A VirtualBox Ubuntu) So my question is: Why is it possible to enter 11 chars into that 8 byte array?

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