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• Console class in java Exception in reading password

  - by satheesh

  Hi, i am trying to use Console class in java. with this code import java.io.Console; public class ConsoleClass { public static void main(String[] args){ Console c=System.console(); char[] pw; pw=c.readPassword("%s","pw :"); for(char ch:pw){ c.format("%c",ch); } c.format("\n"); MyUtility mu =new MyUtility(); while(true){ String name=c.readLine("%s", "input?: "); c.format("output: %s \n",mu.doStuff(name)); } } } class MyUtility{ String doStuff(String arg1){ return "result is " +arg1; } } here i am getting NullPointerException when i tried to run in netbeans but i am not getting any Exception when tried to run in cmd with out netbeans IDE.Why?

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• Multiset of shared_ptrs as a dynamic priority queue: Concept and practice

  - by Sarah

  I was using a vector-based priority queue typedef std::priority_queue< Event, vector< Event >, std::greater< Event > > EventPQ; to manage my Event objects. Now my simulation has to be able to find and delete certain Event objects not at the top of the queue. I'd like to know if my planned work-around can do what I need it to, and if I have the syntax right. I'd also like to know if dramatically better solutions exist. My plan is to make EventPQ a multiset of smart pointers to Event objects: typedef std::multi_set< boost::shared_ptr< Event > > EventPQ; I'm borrowing functions of the Event class from a related post on a multimap priority queue. // Event.h #include <cstdlib> using namespace std; #include <set> #include <boost/shared_ptr.hpp> class Event; typedef std::multi_set< boost::shared_ptr< Event > > EventPQ; class Event { public: Event( double t, int eid, int hid ); ~Event(); void add( EventPQ& q ); void remove(); bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } bool operator > ( const Event & rhs ) const { return ( time > rhs.time ); } double time; int eventID; int hostID; EventPQ* mq; EventPQ::iterator mIt; }; // Event.cpp Event::Event( double t, int eid, int hid ) { time = t; eventID = eid; hostID = hid; } Event::~Event() {} void Event::add( EventPQ& q ) { mq = &q; mIt = q.insert( boost::shared_ptr<Event>(this) ); } void Event::remove() { mq.erase( mIt ); mq = 0; mIt = EventPQ::iterator(); } I was hoping that by making EventPQ a container of pointers, I could avoid wasting time copying Events into the container and avoid accidentally editing the wrong copy. Would it be dramatically easier to store the Events themselves in EventPQ instead? Does it make more sense to remove the time keys from Event objects and use them instead as keys in a multimap? Assuming the current implementation seems okay, my questions are: Do I need to specify how to sort on the pointers, rather than the objects, or does the multiset automatically know to sort on the objects pointed to? If I have a shared_ptr ptr1 to an Event that also has a pointer in the EventPQ container, how do I find and delete the corresponding pointer in EventPQ? Is it enough to .find( ptr1 ), or do I instead have to find by the key (time)? Is the Event::remove() sufficient for removing the pointer in the EventPQ container? There's a small chance multiple events could be created with the same time (obviously implied in the use of multiset). If the find() works on event times, to avoid accidentally deleting the wrong event, I was planning to throw in a further check on eventID and hostID. Does this seem reasonable? (Dumb syntax question) In Event.h, is the declaration of dummy class Event;, then the EventPQ typedef, and then the real class Event declaration appropriate? I'm obviously an inexperienced programmer with very spotty background--this isn't for homework. Would love suggestions and explanations. Please let me know if any part of this is confusing. Thanks.

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• Is calling of overload operator-> resolved at compile time?

  - by Brent

  when I tried to compile the code: (note: func and func2 is not typo) struct S { void func2() {} }; class O { public: inline S* operator->() const; private: S* ses; }; inline S* O::operator->() const { return ses; } int main() { O object; object->func(); return 0; } there is a compile error reported: D:\code>g++ operatorp.cpp -S -o operatorp.exe operatorp.cpp: In function `int main()': operatorp.cpp:27: error: 'struct S' has no member named 'func' it seems that invoke the overloaded function of "operator-" is done during compile time? I'd added "-S" option for compile only.

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• Dynamic allocated array is not freed

  - by Stefano

  I'm using the code above to dynamically allocate an array, do some work inside the function, return an element of the array and free the memory outside of the function. But when I try to deallocate the array it doesn't free the memory and I have a memory leak. The debugger pointed to the myArray variable shows me the error CXX0030. Why? struct MYSTRUCT { char *myvariable1; int myvariable2; char *myvariable2; .... }; void MyClass::MyFunction1() { MYSTRUCT *myArray= NULL; MYSTRUCT *myElement = this->MyFunction2(myArray); ... delete [] myArray; } MYSTRUCT* MyClass::MyFunction2(MYSTRUCT *array) { array = (MYSTRUCT*)operator new(bytesLength); ... return array[X]; }

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• How to return a string literal from a function

  - by skydoor

  Hi I am always confused about return a string literal or a string from a function. I was told that there might be memory leak because you don't know when the memory will be deleted? For example, in the code below, how to implement foo() so that make the output of the code is "Hello World"? void foo ( ) // you can add parameters here. { } int main () { char *c; foo ( ); printf ("%s",c); return 0; } Also if the return type of foo() is not void, but you can return char*, what should it be.

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• Sorting array of structs

  - by mrblippy

  Hi, i am having trouble making a method to sort an array of structs. i am tring to sort them in ascending order based on classcode. any help you could give would be appreciated struct unit { char classcode[4]; char *classname; }; void insertion_sort(struct unit u[], int n) { int j, p; struct unit tmp[1]; for(p = 1; p < n; p++) { tmp[0] = u[p]; for(j = p; j > 0 && (strcmp(tmp[j-1].classcode, tmp[p].classcode) > 0); j--) u[j] = u[j-1]; u[j] = tmp[0]; } }

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• error in encryption program

  - by Raja

  #include<iostream> #include<math.h> #include<string> using namespace std; int gcd(int n,int m) { if(m<=n && n%m ==0) return m; if(n<m) return gcd(m,n); else return gcd(m,n%m); } int REncryptText(char m) { int p = 11, q = 3; int e = 3; int n = p * q; int phi = (p - 1) * (q - 1); int check1 = gcd(e, p - 1); int check2 = gcd(e, q - 1); int check3 = gcd(e, phi); // // Compute d such that ed = 1 (mod phi) //i.e. compute d = e-1 mod phi = 3-1 mod 20 //i.e. find a value for d such that phi divides (ed-1) //i.e. find d such that 20 divides 3d-1. //Simple testing (d = 1, 2, ...) gives d = 7 // double d = Math.Pow(e, -1) % phi; int d = 7; // public key = (n,e) // (33,3) //private key = (n,d) //(33 ,7) double g = pow(m,e); int ciphertext = g %n; // Now say we want to encrypt the message m = 7, c = me mod n = 73 mod 33 = 343 mod 33 = 13. Hence the ciphertext c = 13. //double decrypt = Math.Pow(ciphertext, d) % n; return ciphertext; } int main() { char plaintext[80],str[80]; cout<<" enter the text you want to encrpt"; cin.get(plaintext,79); int l =strlen(plaintext); for ( int i =0 ; i<l ; i++) { char s = plaintext[i]; str[i]=REncryptText(s); } for ( int i =0 ; i<l ; i++) { cout<<"the encryption of string"<<endl; cout<<str[i]; } return 0; }

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• Should I call class destructor in this code?

  - by peterg

  I am using this sample to decode/encode some data I am retrieving/sending from/to a web server, and I want to use it like this: BOOL HandleMessage(UINT uMsg,WPARAM wParam,LPARAM lParam,LRESULT* r) { if(uMsg == WM_DESTROY) { PostQuitMessage(0); return TRUE; } else if(uMsg == WM_CREATE) { // Start timer StartTimer(); return TRUE; } else if(uMsg == WM_TIMER) { //get data from server char * test = "test data"; Base64 base64; char *temp = base64.decode(test); MessageBox(TEXT(temp), 0, 0); } } The timer is set every 5 minutes. Should I use delete base64 at the end? Does delete deallocates everything used by base64?

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• boost.asio error on read from socket.

  - by niXman

  The following code of the client: typedef boost::array<char, 10> header_packet; header_packet header; boost::system::error_code error; ... /** send header */ boost::asio::write( _socket, boost::asio::buffer(header, header.size()), boost::asio::transfer_all(), error ); /** send body */ boost::asio::write( _socket, boost::asio::buffer(buffer, buffer.length()), boost::asio::transfer_all(), error ); of the server: struct header { boost::uint32_t header_length; boost::uint32_t id; boost::uint32_t body_length; }; static header unpack_header(const header_packet& data) { header hdr; sscanf(data.data(), "%02d%04d%04d", &hdr.header_length, &hdr.id, &hdr.body_length); return hdr; } void connection::start() { boost::asio::async_read( _socket, boost::asio::buffer(_header, _header.size()), boost::bind( &connection::read_header_handler, shared_from_this(), boost::asio::placeholders::error ) ); } /***************************************************************************/ void connection::read_header_handler(const boost::system::error_code& e) { if ( !e ) { std::cout << "readed header: " << _header.c_array() << std::endl; std::cout << constants::unpack_header(_header); boost::asio::async_read( _socket, boost::asio::buffer(_body, constants::unpack_header(_header).body_length), boost::bind( &connection::read_body_handler, shared_from_this(), boost::asio::placeholders::error ) ); } else { /** report error */ std::cout << "read header finished with error: " << e.message() << std::endl; } } /***************************************************************************/ void connection::read_body_handler(const boost::system::error_code& e) { if ( !e ) { std::cout << "readed body: " << _body.c_array() << std::endl; start(); } else { /** report error */ std::cout << "read body finished with error: " << e.message() << std::endl; } } On the server side the method read_header_handler() is called, but the method read_body_handler() is never called. Though the client has written down the data in a socket. The header is readed and decoded successfully. What's the error?

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• How to approach copying objects with smart pointers as class attributes?

  - by tomislav-maric

  From the boost library documentation I read this: Conceptually, smart pointers are seen as owning the object pointed to, and thus responsible for deletion of the object when it is no longer needed. I have a very simple problem: I want to use RAII for pointer attributes of a class that is Copyable and Assignable. The copy and assignment operations should be deep: every object should have its own copy of the actual data. Also, RTTI needs to be available for the attributes (their type may also be determined at runtime). Should I be searching for an implementation of a Copyable smart pointer (the data are small, so I don't need Copy on Write pointers), or do I delegate the copy operation to the copy constructors of my objects as shown in this answer? Which smart pointer do I choose for simple RAII of a class that is copyable and assignable? (I'm thinking that the unique_ptr with delegated copy/assignment operations to the class copy constructor and assignment operator would make a proper choice, but I am not sure) Here's a pseudocode for the problem using raw pointers, it's just a problem description, not a running C++ code: // Operation interface class ModelOperation { public: virtual void operate = (); }; // Implementation of an operation called Special class SpecialModelOperation : public ModelOperation { private: // Private attributes are present here in a real implementation. public: // Implement operation void operate () {}; }; // All operations conform to ModelOperation interface // These are possible operation names: // class MoreSpecialOperation; // class DifferentOperation; // Concrete model with different operations class MyModel { private: ModelOperation* firstOperation_; ModelOperation* secondOperation_; public: MyModel() : firstOperation_(0), secondOperation_(0) { // Forgetting about run-time type definition from input files here. firstOperation_ = new MoreSpecialOperation(); secondOperation_ = new DifferentOperation(); } void operate() { firstOperation_->operate(); secondOperation_->operate(); } ~MyModel() { delete firstOperation_; firstOperation_ = 0; delete secondOperation_; secondOperation_ = 0; } }; int main() { MyModel modelOne; // Some internal scope { // I want modelTwo to have its own set of copied, not referenced // operations, and at the same time I need RAII to work for it, // as soon as it goes out of scope. MyModel modelTwo (modelOne); } return 0; }

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• C++ - Opening a file inside a function using fopen

  - by Josh

  I am using Visual Studio 2005 (C++). I am passing a string into a function as a char array. I want to open the file passed in as a parameter and use it. I know my code works to an extent, because if I hardcode the filename as the first parameter it works perfectly. I do notice if I look at the value as a watch, the value includes the address aside the string literal. I have tried passing in the filename as a pointer, but it then complains about type conversion with __w64. As I said before it works fine with "filename.txt" in place of fileName. I am stumped. void read(char fileName[50],int destArray[MAX_R][MAX_C],int demSize[2]) { int rows=0; int cols=0; int row=0; int col=0; FILE * f = fopen(fileName,"r"); ...

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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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• [c++] upload image to imageshack

  - by cinek1lol

  Hi! I would like to send pictures via a program written in C + +. - OK WinExec("C:\\curl\\curl.exe -H Expect: -F \"fileupload=@C:\\curl\\ok.jpg\" -F \"xml=yes\" -# \"http://www.imageshack.us/index.php\" -o data.txt -A \"Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1\" -e \"http://www.imageshack.us\"", NULL); It works, but I would like to send the pictures from pre-loaded carrier to a variable char (you know what I mean? First off, I load the pictures into a variable and then send the variable), cause now I have to specify the path of the picture on a disk. I wanted to write this program in c++ by using the curl library, not through exe. extension. I have also found such a program (which has been modified by me a bit) #include <stdio.h> #include <string.h> #include <iostream> #include <curl/curl.h> #include <curl/types.h> #include <curl/easy.h> int main(int argc, char *argv[]) { CURL *curl; CURLcode res; struct curl_httppost *formpost=NULL; struct curl_httppost *lastptr=NULL; struct curl_slist *headerlist=NULL; static const char buf[] = "Expect:"; curl_global_init(CURL_GLOBAL_ALL); /* Fill in the file upload field */ curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "send", CURLFORM_FILE, "nowy.jpg", CURLFORM_END); curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "nowy.jpg", CURLFORM_COPYCONTENTS, "nowy.jpg", CURLFORM_END); curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "submit", CURLFORM_COPYCONTENTS, "send", CURLFORM_END); curl = curl_easy_init(); headerlist = curl_slist_append(headerlist, buf); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "http://www.imageshack.us/index.php"); if ( (argc == 2) && (!strcmp(argv[1], "xml=yes")) ) curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist); curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost); res = curl_easy_perform(curl); curl_easy_cleanup(curl); curl_formfree(formpost); curl_slist_free_all (headerlist); } system("pause"); return 0; }

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• emacs: how do I use edebug on code that is defined in a macro?

  - by Cheeso

  I don't even know the proper terminology for this lisp syntax, so I don't know if the words I'm using to ask the question, make sense. But the question makes sense, I'm sure. So let me just show you. cc-mode (cc-fonts.el) has things called "matchers" which are bits of code that run to decide how to fontify a region of code. That sounds simple enough, but the matcher code is in a form I don't completely understand, with babckticks and comma-atsign and just comma and so on, and furthermore it is embedded in a c-lang-defcost, which itself is a macro. And I want to run edebug on that code. Look: (c-lang-defconst c-basic-matchers-after "Font lock matchers for various things that should be fontified after generic casts and declarations are fontified. Used on level 2 and higher." t `(;; Fontify the identifiers inside enum lists. (The enum type ;; name is handled by `c-simple-decl-matchers' or ;; `c-complex-decl-matchers' below. ,@(when (c-lang-const c-brace-id-list-kwds) `((,(c-make-font-lock-search-function (concat "\\<\\(" (c-make-keywords-re nil (c-lang-const c-brace-id-list-kwds)) "\\)\\>" ;; Disallow various common punctuation chars that can't come ;; before the '{' of the enum list, to avoid searching too far. "[^\]\[{}();,/#=]*" "{") '((c-font-lock-declarators limit t nil) (save-match-data (goto-char (match-end 0)) (c-put-char-property (1- (point)) 'c-type 'c-decl-id-start) (c-forward-syntactic-ws)) (goto-char (match-end 0))))))) I am reading up on lisp syntax to figure out what those things are and what to call them, but aside from that, how can I run edebug on the code that follows the comment that reads ;; Fontify the identifiers inside enum lists. ? I know how to run edebug on a defun - just invoke edebug-defun within the function's definition, and off I go. Is there a corresponding thing I need to do to edebug the cc-mode matcher code forms?

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• Assigning large UInt32 constants in VB.Net

  - by Kumba

  I inquired on VB's erratic behavior of treating all numerics as signed types back in this question, and from the accepted answer there, was able to get by. Per that answer: Visual Basic Literals Also keep in mind you can add literals to your code in VB.net and explicitly state constants as unsigned. So I tried this: Friend Const POW_1_32 As UInt32 = 4294967296UI And VB.NET throws an Overflow error in the IDE. Pulling out the integer overflow checks doesn't seem to help -- this appears to be a flaw in the IDE itself. This, however, doesn't generate an error: Friend Const POW_1_32 As UInt64 = 4294967296UL So this suggests to me that the IDE isn't properly parsing the code and understanding the difference between Int32 and UInt32. Any suggested workarounds and/or possible clues on when MS will make unsigned data types intrinsic to the framework instead of the hacks they currently are?

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• help me with xor encryption in c#

  - by x86shadow

  I wrote this code in c# to encrypt a text with a key : using System; using System.Linq; using System.Collections.Generic; using System.Text; namespace ENCRYPT { class XORENC { private static int Bin2Dec(string num) { int _num = 0; for (int i = 0; i < num.Length; i++) { _num += (int)Math.Pow(2, num.Length - i - 1) * int.Parse(num[i].ToString()); } return _num; } private static string Dec2Bin(int num) { if (num < 2) return num.ToString(); return Dec2Bin(num / 2) + (num % 2).ToString(); } public static string StrXor(string str, string key) { string _str = ""; string _key = ""; string _dec = ""; string _temp = ""; for (int i = 0; i < str.Length; i++) { _temp = Dec2Bin(str[i]); for (int j = 0; j < 8 - _temp.Length + 1; j++) { _temp = '0' + _temp; } _str += _temp; } for (int i = 0; i < key.Length; i++) { _temp = Dec2Bin(key[i]); for (int j = 0; j < 8 - _temp.Length + 1; j++) { _temp = '0' + _temp; } _key += _temp; } while (_key.Length < _str.Length) { _key += _key; } if (_key.Length > _str.Length) _key = _key.Substring(0, _str.Length); for (int i = 0; i < _str.Length; i++) { if (_str[i] == _key[i]) { _dec += '0'; } else { _dec += '1'; } } _str = ""; for (int i = 0; i < _dec.Length; i = i + 8) { char _chr = (char)0; _chr = (char)Bin2Dec(_dec.Substring(i, 8)); _str += _chr; } return _str; } } } the problem is that I always get error when I want to decrypt an encryted text with this code. see the example below for more info : string enc_text = ENCRYPT.XORENC("abc","a"); //enc_text = " ??" string dec_text = ENCRYPT.XORENC(enc_text,"a"); //ERROR any one can help ?

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• How to use the vtable to determine class type

  - by Alex Silverman

  I was recently on an interview for a position where C/C++ is the primary language and during one question I was told that it's possible to use the vtable to determine which class in a hierarchy a base pointer actually stores. So if, for example you have class A { public: A() {} virtual ~A() {} virtual void method1() {} }; class B : public A { public: B() {} virtual ~B() {} virtual void method1() {} }; and you instantiate A * pFoo = new B(), is it indeed possible to use the vtable to determine whether pFoo contains a pointer to an instance of A or B?

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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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• setsockopt (sys/socket.h)

  - by lojin

  The prototype for setsockopt is: int setsockopt(int socket, int level, int option_name, const void *option_value, socklen_t option_len); Are the following all correct ? Which are not ? a.) int buffsize = 50000; setsockopt(s, SOL_SOCKET, SO_RCVBUF, (char *)&buffsize, sizeof(buffsize)); b.) int buffsize = 50000; setsockopt(s, SOL_SOCKET, SO_RCVBUF, (void *)&buffsize, sizeof(buffsize)); c.) char *buffsize = "50000"; setsockopt(s, SOL_SOCKET, SO_RCVBUF, buffsize, strlen(buffsize)); d.) setsockopt(s, SOL_SOCKET, SO_RCVBUF, "50000", 5);

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• [C++] Wrong EOF when unzipping binary file

  - by djzmo

  Hello there, I tried to unzip a binary file to a membuf from a zip archive using Lucian Wischik's Zip Utils: http://www.wischik.com/lu/programmer/zip_utils.html http://www.codeproject.com/KB/files/zip_utils.aspx FindZipItem(hz, filename.c_str(), true, &j, &ze); char *content = new char[ze.unc_size]; UnzipItem(hz, j, content, ze.unc_size); delete[] content; But it didn't unzip the file correctly. It stopped at the first 0x00 of the file. For example when I unzip an MP3 file, it will only unzip the first 4 bytes: 0x49443303 (ID3\0) because the 5th to 8th byte is 0x00000000. I also tried to capture the ZR_RESULT, and it always return ZR_OK (which means completed without errors). I think this guy also had the same problem, but no one replied to his question: http://www.codeproject.com/KB/files/zip_utils.aspx?msg=2876222#xx2876222xx Any kind of help would be appreciated :)

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• Is there a way to use template specialization to separate new from new[]?

  - by Marlon

  I have an auto pointer class and in the constructor I am passing in a pointer. I want to be able to separate new from new[] in the constructor so that I can properly call delete or delete[] in the destructor. Can this be done through template specialization? I don't want to have to pass in a boolean in the constructor. template <typename T> class MyAutoPtr { public: MyAutoPtr(T* aPtr); }; // in use: MyAutoPtr<int> ptr(new int); MyAutoPtr<int> ptr2(new int[10]);

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• MinMax Heap implementation without an array

  - by user576531

  Hi. I found lots of MinMax Heap implementations, that were storing data in an array. It is realy easy to implement, that is way I am looking for something different. I want to create a MinMax Heap using only elements of the Heap with pointers to left child and right child (and afcourse a key to compare). So the Heap have only pointer to the root object (min level), and a root object have a pointer to his children (max level) and so on. I know how to insert a new object (finding a proper path by using binary represenation of int depending on Heap size), but I don't know how to implement the rest (push up (down) the element, find parent or grandparent). Thx for help

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• recv receiving not whole data sometime

  - by milo

  hi all, i have following issue: here is the chunk of code: void get_all_buf(int sock, std::string & inStr) { int n = 1; char c; char temp[1024*1024]; bzero(temp, sizeof(temp)); n = recv(sock, temp, sizeof(temp), 0); inStr = temp; }; but sometimes recv returning not whole data (data length always less then sizeof(temp)), only it's part. write side always sends me whole data (i got it with sniffer). what matter? thx. P.S. i know, good manner suggests me to check n (if (n < 0) perror ("error while receiving data), but it doesn't matter now - it's not reason of my problem. P.S.2 i've forgot - it's blocking socket.

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• C# StringBuilder question

  - by andrew

  in a C# file i have a class Archiver { [DllImport("Archiver.dll")] public static extern void archive(string data, StringBuilder response); } string data is an input, and StringBuilder response is where the function writes something the archive function prototype (written in C) looks like this: void archive(char * dataChr, char * outChr); and it receives a string in dataChr, and then does a strcpy(outChr,"some big text"); from C# i call it something like this: string message = "some text here"; StringBuilder response = new StringBuilder(10000); Archiver.archive(message,response); this works, but the problem, as you might see is that i give a value to the StringBuilder size, but the archive function might give back a (way) larger text than the size i've given to my StringBuilder. any way to fix this?

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• Redirecting one file to another using dub2 and strtok

  - by Sergiy Zakharov

  OK, here goes. I have to write a program, in which I need to use strtok and dup2 to redirect one file to another, but I need to also have the user to actually put the command cat < file1 file2, but not from the shell, but instead by using my program. That's why I need strtok. And the reason my program doesn't work is probably because of that, because I don't really understand how strtok works. I found a similar program on the internet, but they just take the ls command and redirect it to the file. That's it. My program is much more complicated. I mean, it would've been easier just to say in shell cat < file1 file2, but for some reason they want us to do it this way. So, anyways, here is what I have so far (here I just combined what I have found on the internet with what I already had from before. We had to do something similar but then the user would just go ls or ls -l. Very simple stuff. This is much harder, for me, at least.) #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <errno.h> #include <sys/wait.h> #include <string.h> int main() { pid_t pid; char line[256]; char *args[129]; int i; int fd; int status; char *temp; while (1) { printf(">"); if (fgets(line, 256, stdin) == 0) { exit(0); } else { pid = fork(); if (pid == 0) { i = 0; temp = strtok("<",line); while (temp != NULL) { args[i++] = temp; temp = strtok(">",line); args[i] = '\0'; } fd = open("hello", O_RDONLY); dup2(fd, STDIN_FILENO); fd = open("world", O_WRONLY|O_CREAT|O_TRUNC, S_IRWXU); dup2(fd, STDOUT_FILENO ); close(fd); execvp(args[0], args); } else { close(fd); wait(&status); } } } } Any help would be greatly appreciated.

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