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  • Constructors taking references in C++

    - by sasquatch
    I'm trying to create constructor taking reference to an object. After creating object using reference I need to prints field values of both objects. Then I must delete first object, and once again show values of fields of both objects. My class Person looks like this : class Person { char* name; int age; public: Person(){ int size=0; cout << "Give length of char*" << endl; cin >> size; name = new char[size]; age = 0; } ~Person(){ cout << "Destroying resources" << endl; delete[] name; delete age; } void init(char* n, int a) { name = n; age = a; } }; Here's my implementation (with the use of function show() ). My professor said that if this task is written correctly it will return an error. #include <iostream> using namespace std; class Person { char* name; int age; public: Person(){ int size=0; cout << "Give length of char*" << endl; cin >> size; name = new char[size]; age = 0; } Person(const Person& p){ name = p.name; age = p.age; } ~Person(){ cout << "Destroying resources" << endl; delete[] name; delete age; } void init(char* n, int a) { name = n; age = a; } void show(char* n, int a){ cout << "Name: " << name << "," << "age: " << age << "," << endl; } }; int main(void) { Person *p = new Person; p->init("Mary", 25); p->show(); Person &p = pRef; pRef->name = "Tom"; pRef->age = 18; Person *p2 = new Person(pRef); p->show(); p2->show(); system("PAUSE"); return 0; }

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  • C++ function will not return

    - by Mike
    I have a function that I am calling that runs all the way up to where it should return but doesn't return. If I cout something for debugging at the very end of the function, it gets displayed but the function does not return. fetchData is the function I am referring to. It gets called by outputFile. cout displays "done here" but not "data fetched" I know this code is messy but can anyone help me figure this out? Thanks //Given an inode return all data of i_block data char* fetchData(iNode tempInode){ char* data; data = new char[tempInode.i_size]; this->currentInodeSize = tempInode.i_size; //Loop through blocks to retrieve data vector<unsigned int> i_blocks; i_blocks.reserve(tempInode.i_blocks); this->currentDataPosition = 0; cout << "currentDataPosition set to 0" << std::endl; cout << "i_blocks:" << tempInode.i_blocks << std::endl; int i = 0; for(i = 0; i < 12; i++){ if(tempInode.i_block[i] == 0) break; i_blocks.push_back(tempInode.i_block[i]); } appendIndirectData(tempInode.i_block[12], &i_blocks); appendDoubleIndirectData(tempInode.i_block[13], &i_blocks); appendTripleIndirectData(tempInode.i_block[14], &i_blocks); //Loop through all the block addresses to get the actual data for(i=0; i < i_blocks.size(); i++){ appendData(i_blocks[i], data); } cout << "done here" << std::endl; return data; } void appendData(int block, char* data){ char* tempBuffer; tempBuffer = new char[this->blockSize]; ifstream file (this->filename, std::ios::binary); int entryLocation = block*this->blockSize; file.seekg (entryLocation, ios::beg); file.read(tempBuffer, this->blockSize); //Append this block to data for(int i=0; i < this->blockSize; i++){ data[this->currentDataPosition] = tempBuffer[i]; this->currentDataPosition++; } data[this->currentDataPosition] = '\0'; } void outputFile(iNode file, string filename){ char* data; cout << "File Transfer Started" << std::endl; data = this->fetchData(file); cout << "data fetched" << std::endl; char *outputFile = (char*)filename.c_str(); ofstream myfile; myfile.open (outputFile,ios::out|ios::binary); int i = 0; for(i=0; i < file.i_size; i++){ myfile << data[i]; } myfile.close(); cout << "File Transfer Completed" << std::endl; return; }

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  • Tuesday + 3 = Friday? C++ Programming Problem

    - by lampshade
    Looking at the main function, we can see that I've Hard Coded the "Monday" into my setDay public function. It is easy to grab a day of the week from the user using a c-string (as I did in setDay), but how would I ask the user to add n to the day that is set, "Monday" and come up with "Thursday"? It is hard because typdef enum { INVALID, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY} doesn't interpret 9 is 0 and/or 10 as 1. #include <iostream> using std::cout; using std::endl; class DayOfTheWeek //class is encapsulation of functions and members that manipulate the data. { public: DayOfTheWeek(); // Constructor virtual ~DayOfTheWeek(); // Destructor void setDay(const char * day); // Function to set the day void printDay() const; // Function to Print the day. const char * getDay() const; // Function to get the day. const char * plusOneDay(); // Next day function const char * minusOneDay(); // Previous day function const char * addDays(int addValue); // function that adds days based on parameter value private: char * day; // variable for the days of the week. }; DayOfTheWeek::DayOfTheWeek() : day(0) { // Usually I would allocate pointer member variables // Here in the construction of the Object } const char * DayOfTheWeek::getDay() const { return day; // we can get the day simply by returning it. } const char * DayOfTheWeek::minusOneDay() { if ( strcmp( day, "Monday" ) == 0) { cout << "The day before " << day << " is "; return "Sunday"; } else if ( strcmp( day, "Tuesday" ) == 0 ) { cout << "The day before " << day << " is "; return "Monday"; } else if ( strcmp( day, "Wednesday" ) == 0 ) { cout << "The day before " << day << " is "; return "Tuesday"; } else if ( strcmp( day, "Thursday" ) == 0 ) { cout << "The day before " << day << " is "; return "Wednesday"; } else if ( strcmp( day, "Friday" ) == 0 ) { cout << "The day before " << day << " is "; return "Thursday"; } else if ( strcmp( day, "Saturday" ) == 0 ) { cout << "The day before " << day << " is "; return "Friday"; } else if ( strcmp( day, "Sunday" ) == 0 ) { cout << "The day before " << day << " is "; return "Saturday"; } else { cout << "'" << day << "'"; return "is an invalid day of the week!"; } } const char * DayOfTheWeek::plusOneDay() { if ( strcmp( day, "Monday" ) == 0) { cout << "The day after " << day << " is "; return "Tuesday"; } else if ( strcmp( day, "Tuesday" ) == 0 ) { cout << "The day after " << day << " is "; return "Wednesday"; } else if ( strcmp( day, "Wednesday" ) == 0 ) { cout << "The day after " << day << " is "; return "Thursday"; } else if ( strcmp( day, "Thursday" ) == 0 ) { cout << "The day after " << day << " is "; return "Friday"; } else if ( strcmp( day, "Friday" ) == 0 ) { cout << "The day after " << day << " is "; return "Saturday"; } else if ( strcmp( day, "Saturday" ) == 0 ) { cout << "The day after " << day << " is "; return "Sunday"; } else if ( strcmp( day, "Sunday" ) == 0 ) { cout << "The day after " << day << " is "; return "Monday"; } else { cout << "'" << day << "'"; return " is an invalid day of the week!"; } } const char * DayOfTheWeek::addDays(int addValue) { if ( addValue < 0 ) { if ( strcmp( day, "Monday" ) == 0) { cout << day << " - " << -addValue << " = "; return "Friday"; } else if ( strcmp( day, "Tuesday" ) == 0 ) { cout << day << " - " << -addValue << " = "; return "Saturday"; } else if ( strcmp( day, "Wednesday" ) == 0 ) { cout << day << " - " << -addValue << " = "; return "Sunday"; } else if ( strcmp( day, "Thursday" ) == 0 ) { cout << day << " - " << -addValue << " = "; return "Monday"; } else if ( strcmp( day, "Friday" ) == 0 ) { cout << day << " - " << -addValue << " = "; return "Tuesday"; } else if ( strcmp( day, "Saturday" ) == 0 ) { cout << day << " - " << -addValue << " = "; return "Wednesday"; } else if ( strcmp( day, "Sunday" ) == 0 ) { cout << day << " - " << -addValue << " = "; return "Thursday"; } else { cout << "'" << day << "' "; return "is an invalid day of the week! "; } } else // if our parameter is greater than 0 (positive) { if ( strcmp( day, "Monday" ) == 0) { cout << day << " + " << addValue << " = "; return "Thursday"; } else if ( strcmp( day, "Tuesday" ) == 0 ) { cout << day << " + " << addValue << " = "; return "Friday"; } else if ( strcmp( day, "Wednesday" ) == 0 ) { cout << day << " + " << addValue << " = "; return "Saturday"; } else if ( strcmp( day, "Thursday" ) == 0 ) { cout << day << " + " << addValue << " = "; return "Sunday"; } else if ( strcmp( day, "Friday" ) == 0 ) { cout << day << " + " << addValue << " = "; return "Monday"; } else if ( strcmp( day, "Saturday" ) == 0 ) { cout << day << " + " << addValue << " = "; return "Tuesday"; } else if ( strcmp( day, "Sunday" ) == 0 ) { cout << day << " + " << addValue << " = "; return "Wednesday"; } else { cout << "'" << day << "' "; return "is an invalid day of the week! "; } } } void DayOfTheWeek::printDay() const { cout << "The Value of the " << day; } void DayOfTheWeek::setDay(const char * day) { if (day) {// Here I am allocating the object member char day pointer this->day = new char[strlen(day)+1]; size_t length = strlen(day)+1; // +1 for trailing null char strcpy_s(this->day , length , day); // copying c-strings } else day = NULL; // If their was a problem with the parameter 'day' } DayOfTheWeek::~DayOfTheWeek() { delete day; // Free the memory allocated in SetDay } int main() { DayOfTheWeek MondayObject; // declare an object MondayObject.setDay("Monday"); // Call our public function 'setDay' to set a day of the week MondayObject.printDay(); // Call our public function 'printDay' to print the day we set cout << " object is " << MondayObject.getDay() << endl; // Print the value of the object cout << MondayObject.plusOneDay() << endl; cout << MondayObject.minusOneDay() << endl; cout << MondayObject.addDays(3) << endl; MondayObject.printDay(); cout << " object is still " << MondayObject.getDay() << endl; // Print the value of the object cout << MondayObject.addDays(-3) << endl; return 0; }

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  • how to clear stack after stack overflow signal occur

    - by user353573
    In pthread, After reaching yellow zone in stack, signal handler stop the recursive function by making it return however, we can only continue to use extra area in yellow zone, how to clear the rubbish before the yellow zone in the thread stack ? (Copied from "answers"): #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <signal.h> #include <setjmp.h> #include <sys/mman.h> #include <unistd.h> #include <assert.h> #include <sys/resource.h> #define ALT_STACK_SIZE (64*1024) #define YELLOW_ZONE_PAGES (1) typedef struct { size_t stack_size; char* stack_pointer; char* red_zone_boundary; char* yellow_zone_boundary; sigjmp_buf return_point; size_t red_zone_size; } ThreadInfo; static pthread_key_t thread_info_key; static struct sigaction newAct, oldAct; bool gofromyellow = false; int call_times = 0; static void main_routine(){ // make it overflow if(gofromyellow == true) { printf("return from yellow zone, called %d times\n", call_times); return; } else { call_times = call_times + 1; main_routine(); gofromyellow = true; } } // red zone management static void stackoverflow_routine(){ fprintf(stderr, "stack overflow error.\n"); fflush(stderr); } // yellow zone management static void yellow_zone_hook(){ fprintf(stderr, "exceed yellow zone.\n"); fflush(stderr); } static int get_stack_info(void** stackaddr, size_t* stacksize){ int ret = -1; pthread_attr_t attr; pthread_attr_init(&attr); if(pthread_getattr_np(pthread_self(), &attr) == 0){ ret = pthread_attr_getstack(&attr, stackaddr, stacksize); } pthread_attr_destroy(&attr); return ret; } static int is_in_stack(const ThreadInfo* tinfo, char* pointer){ return (tinfo->stack_pointer <= pointer) && (pointer < tinfo->stack_pointer + tinfo->stack_size); } static int is_in_red_zone(const ThreadInfo* tinfo, char* pointer){ if(tinfo->red_zone_boundary){ return (tinfo->stack_pointer <= pointer) && (pointer < tinfo->red_zone_boundary); } } static int is_in_yellow_zone(const ThreadInfo* tinfo, char* pointer){ if(tinfo->yellow_zone_boundary){ return (tinfo->red_zone_boundary <= pointer) && (pointer < tinfo->yellow_zone_boundary); } } static void set_yellow_zone(ThreadInfo* tinfo){ int pagesize = sysconf(_SC_PAGE_SIZE); assert(pagesize > 0); tinfo->yellow_zone_boundary = tinfo->red_zone_boundary + pagesize * YELLOW_ZONE_PAGES; mprotect(tinfo->red_zone_boundary, pagesize * YELLOW_ZONE_PAGES, PROT_NONE); } static void reset_yellow_zone(ThreadInfo* tinfo){ size_t pagesize = tinfo->yellow_zone_boundary - tinfo->red_zone_boundary; if(mmap(tinfo->red_zone_boundary, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0) == 0){ perror("mmap failed"), exit(1); } mprotect(tinfo->red_zone_boundary, pagesize, PROT_READ | PROT_WRITE); tinfo->yellow_zone_boundary = 0; } static void signal_handler(int sig, siginfo_t* sig_info, void* sig_data){ if(sig == SIGSEGV){ ThreadInfo* tinfo = (ThreadInfo*) pthread_getspecific(thread_info_key); char* fault_address = (char*) sig_info->si_addr; if(is_in_stack(tinfo, fault_address)){ if(is_in_red_zone(tinfo, fault_address)){ siglongjmp(tinfo->return_point, 1); }else if(is_in_yellow_zone(tinfo, fault_address)){ reset_yellow_zone(tinfo); yellow_zone_hook(); gofromyellow = true; return; } else { //inside stack not related overflow SEGV happen } } } } static void register_application_info(){ pthread_key_create(&thread_info_key, NULL); sigemptyset(&newAct.sa_mask); sigaddset(&newAct.sa_mask, SIGSEGV); newAct.sa_sigaction = signal_handler; newAct.sa_flags = SA_SIGINFO | SA_RESTART | SA_ONSTACK; sigaction(SIGSEGV, &newAct, &oldAct); } static void register_thread_info(ThreadInfo* tinfo){ stack_t ss; pthread_setspecific(thread_info_key, tinfo); get_stack_info((void**)&tinfo->stack_pointer, &tinfo->stack_size); printf("stack size %d mb\n", tinfo->stack_size/1024/1024 ); tinfo->red_zone_boundary = tinfo->stack_pointer + tinfo->red_zone_size; set_yellow_zone(tinfo); ss.ss_sp = (char*)malloc(ALT_STACK_SIZE); ss.ss_size = ALT_STACK_SIZE; ss.ss_flags = 0; sigaltstack(&ss, NULL); } static void* thread_routine(void* p){ ThreadInfo* tinfo = (ThreadInfo*)p; register_thread_info(tinfo); if(sigsetjmp(tinfo->return_point, 1) == 0){ main_routine(); } else { stackoverflow_routine(); } free(tinfo); printf("after tinfo, end thread\n"); return 0; } int main(int argc, char** argv){ register_application_info(); if( argc == 2 ){ int stacksize = atoi(argv[1]); pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setstacksize(&attr, 1024 * 1024 * stacksize); { pthread_t pid0; ThreadInfo* tinfo = (ThreadInfo*)calloc(1, sizeof(ThreadInfo)); pthread_attr_getguardsize(&attr, &tinfo->red_zone_size); pthread_create(&pid0, &attr, thread_routine, tinfo); pthread_join(pid0, NULL); } } else { printf("Usage: %s stacksize(mb)\n", argv[0]); } return 0; } C language in linux, ubuntu

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  • SSRS 2005 tabs/newline characters display in table

    - by Paul Creasey
    Hi, How can i get a column in an SSRS 2005 report to render control chars like new lines and tabs? For example: SELECT VW.System_name + CHAR(13) + CHAR(9) + ' > ' + VW.PTS_NAME + CHAR(13) + CHAR(9) + CHAR(9) + ' > ' + VW.FEED_NAME as Name In SSRS (and SSMS Results to Grid Mode) table will render as: TRIPLE > HYBRIDS > HYBRID_CASHFLOWS But i would like (as rendered in SSMS Results to Text Mode): TRIPLE > HYBRIDS > HYBRID_CASHFLOWS How can this be done in SSRS 2005?

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  • Why we used double and triple pointer in objective-C or C language?

    - by Rajendra Bhole
    Hi, I confused when i want to take single pointer and when should i take double pointer? In following structure what exactly did? struct objc_class { Class isa; Class super_class; const char *name; long version; long info; long instance_size; struct objc_ivar_list *ivars; struct objc_method_list **methodLists; struct objc_cache *cache; struct objc_protocol_list *protocols; }; Why we use the "**methodLists" double pointer. Edited int sqlite3_get_table( sqlite3 *db, const char zSql, char **pazResult, int *pnRow, int *pnColumn, char *pzErrmsg ); In above scenario what will be meaning of triple pointer char **pazResult?

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  • C - array count, strtok, etc

    - by Pedro
    Hi... i have a little problem on my code... HI open a txt that have this: LEI;7671;Maria Albertina da silva;[email protected]; 9;8;12;9;12;11;6;15;7;11; LTCGM;6567;Artur Pereira Ribeiro;[email protected]; 6;13;14;12;11;16;14; LEI;7701;Ana Maria Carvalho;[email protected]; 8;13;11;7;14;12;11;16;14; LEI, LTCGM are the college; 7671, 6567, 7701 is student number; Maria, Artur e Ana are the students name; [email protected], ...@gmail are emails from students; the first number of every line is the total of classes that students have; after that is students school notes; example: College: LEI Number: 7671 Name: Maria Albertina da Silva email: [email protected] total of classes: 9 Classe Notes: 8 12 9 12 11 6 15 7 11. My code: typedef struct aluno{ char sigla[5];//college char numero[80];//number char nome[80];//student name char email[20];//email int total_notas;// total of classes char tot_not[40]; // total classes char notas[20];// classe notes int nota; //class notes char situacao[80]; //situation (aproved or disaproved) }ALUNO; void ordena(ALUNO*alunos, int tam)//bubble sort { int i=0; int j=0; char temp[100]; for( i=0;i<tam;i++) for(j=0;j<tam-1;j++) if(strcmp( alunos[i].sigla[j], alunos[i].sigla[j+1])>0){ strcpy(temp, alunos[i].sigla[j]); strcpy(alunos[i].sigla[j],alunos[i].sigla[j+1]); strcpy(alunos[i].sigla[j+1], temp); } } void xml(ALUNO*alunos, int tam){ FILE *fp; char linha[60];//line int soma, max, min, count;//biggest note and lowest note and students per course count float media; //media of notes fp=fopen("example.txt","r"); if(fp==NULL){ exit(1); } else{ while(!(feof(fp))){ soma=0; media=0; max=0; min=0; count=0; fgets(linha,60,fp); if(linha[0]=='L'){ if(ap_dados=strtok(linha,";")){ strcpy(alunos[i].sigla,ap_dados);//copy to struct // i need to call bubble sort here, but i don't know how printf("College: %s\n",alunos[i].sigla); if(ap_dados=strtok(NULL,";")){ strcpy(alunos[i].numero,ap_dados);//copy to struct printf("number: %s\n",alunos[i].numero); if(ap_dados=strtok(NULL,";")){ strcpy(alunos[i].nome, ap_dados);//copy to struct printf("name: %s\n",alunos[i].nome); if(ap_dados=strtok(NULL,";")){ strcpy(alunos[i].email, ap_dados);//copy to struct printf("email: %s\n",alunos[i].email); } } } }i++; } if(isdigit(linha[0])){ if(info_notas=strtok(linha,";")){ strcpy(alunos[i].tot_not,info_notas); alunos[i].total_notas=atoi(alunos[i].tot_not);//total classes for(z=0;z<=alunos[i].total_notas;z++){ if(info_notas=strtok(NULL,";")){ strcpy(alunos[i].notas,info_notas); alunos[i].nota=atoi(alunos[i].notas); // student class notes } soma=soma + alunos[i].nota; media=soma/alunos[i].total_notas;//doesn't work if(alunos[i].nota>max){ max=alunos[i].nota;;//doesn't work } else{ if(min<alunos[i].nota){ min=alunos[i].nota;;//doesn't work } } //now i need to count the numbers of students in the same college, but doesn't work /*If(strcmp(alunos[i].sigla, alunos[i+1].sigla)=0){ count ++; printf("%d\n", count); here for LEI should appear 2 students and for LTCGM appear 1, don't work }*/ //Now i need to see if student is aproved or disaproved // Student is disaproved if he gets 3 notes under 10, how can i do that? } printf("media %d\n",media); //media printf("Nota maxima %d\n",max);// biggest note printf("Nota minima %d\n",min); //lowest note }i++; } } } fclose(fp); } int main(int argc, char *argv[]){ ALUNO alunos; FILE *fp; int tam; fp=fopen(nomeFicheiro,"r"); alunos = (ALUNO*) calloc (tam, sizeof(ALUNO)); xml(alunos,nomeFicheiro, tam); system("PAUSE"); return 0; }

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  • Memory leak using shared_ptr

    - by nabulke
    Both code examples compile and run without problems. Using the second variant results in a memory leak. Any ideas why? Thanks in advance for any help. Variant 1: typedef boost::shared_ptr<ParameterTabelle> SpParameterTabelle; struct ParTabSpalteData { ParTabSpalteData(const SpParameterTabelle& tabelle, const string& id) :Tabelle(tabelle), Id(id) { } const SpParameterTabelle& Tabelle; string Id; }; Variant 2: struct ParTabSpalteData { ParTabSpalteData(const SpParameterTabelle& tabelle, const string& id) :Id(id) { // causes memory leak Tabelle2 = tabelle; } SpParameterTabelle Tabelle2; string Id; };

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  • Compilation problems with vector<auto_ptr<> >

    - by petersohn
    Consider the following code: #include <iostream> #include <memory> #include <vector> using namespace std; struct A { int a; A(int a_):a(a_) {} }; int main() { vector<auto_ptr<A> > as; for (int i = 0; i < 10; i++) { auto_ptr<A> a(new A(i)); as.push_back(a); } for (vector<auto_ptr<A> >::iterator it = as.begin(); it != as.end(); ++it) cout << (*it)->a << endl; } When trying to compile it, I get the following obscure compiler error from g++: g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/proba.d" -MT"src/proba.d" -o"src/proba.o" "../src/proba.cpp" /usr/include/c++/4.1.2/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_vector.h:606: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/ext/new_allocator.h:104: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/vector.tcc: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’: /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/vector.tcc:256: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/stl_construct.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = std::auto_ptr<A>, _T2 = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_uninitialized.h:86: instantiated from ‘_ForwardIterator std::__uninitialized_copy_aux(_InputIterator, _InputIterator, _ForwardIterator, __false_type) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:113: instantiated from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:254: instantiated from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _Tp = std::auto_ptr<A>]’ /usr/include/c++/4.1.2/bits/vector.tcc:279: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/stl_construct.h:81: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers make: *** [src/proba.o] Error 1 It seems to me that there is some kind of problem with consts here. Does this mean that auto_ptr can't be used in vectors?

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  • SVM in OpenCV: Visual Studio 2008 reported error wrongly (or is it right?)

    - by Risa
    I'm using MS Visual Studio 2008, OpenCV, C++ and SVM for a OCR-related project. At least I can run the code until yesterday, when I open the project to continue working, VS reported this error: error C2664: 'bool CvSVM::train(const CvMat *,const CvMat *,const CvMat *,const CvMat *,CvSVMParams)' : cannot convert parameter 1 from 'cv::Mat' to 'const CvMat *' It didn't happen before and I haven't changed any code relating to it (I only changed the parameters for the kernel). The code got error is: Mat curTrainData, curTrainLabel; CvSVM svm; . . . svm.train(curTrainData, curTrainLabel, Mat(), Mat(), params); If I hover on the code, I still got this tip: image. Which means my syntax isn't wrong. So why do VS bother to report such an error?

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  • Compilng problems with vector<auto_ptr<> >

    - by petersohn
    Consider the following code: #include <iostream> #include <memory> #include <vector> using namespace std; struct A { int a; A(int a_):a(a_) {} }; int main() { vector<auto_ptr<A> > as; for (int i = 0; i < 10; i++) { auto_ptr<A> a(new A(i)); as.push_back(a); } for (vector<auto_ptr<A> >::iterator it = as.begin(); it != as.end(); ++it) cout << (*it)->a << endl; } When trying to compile it, I get the following obscure compiler error from g++: g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/proba.d" -MT"src/proba.d" -o"src/proba.o" "../src/proba.cpp" /usr/include/c++/4.1.2/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_vector.h:606: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/ext/new_allocator.h:104: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/vector.tcc: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’: /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/vector.tcc:256: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/stl_construct.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = std::auto_ptr<A>, _T2 = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_uninitialized.h:86: instantiated from ‘_ForwardIterator std::__uninitialized_copy_aux(_InputIterator, _InputIterator, _ForwardIterator, __false_type) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:113: instantiated from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:254: instantiated from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _Tp = std::auto_ptr<A>]’ /usr/include/c++/4.1.2/bits/vector.tcc:279: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/stl_construct.h:81: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers make: *** [src/proba.o] Error 1 It seems to me that there is some kind of problem with consts here. Does this mean that auto_ptr can't be used in vectors?

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  • Scala: working around the "illegal cyclic reference"

    - by Paul Milovanov
    Hi all, I'm trying to implement a HashMap-based tree that'd support O(1) subtree lookup for a given root key. To that goal, I'm trying to do the following: scala> type Q = HashMap[Char, Q] <console>:6: error: illegal cyclic reference involving type Q type Q = HashMap[Char, Q] ^ So the question is, is there a way for me to do something of the sort without resorting to the ugly HashMap[Char, Any] with subsequent casting of values to HashMap[Char, Any]? Now, I also see that I can use something like the following to avoid the cyclic-reference error, and it might even be cleaner -- but it'd be nice to find out how to correctly do it the first way, just for the educational value. import collections.mutable.HashMap class LTree { val children = new HashMap[Char, LTree] } Thanks a bunch.

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  • array iteration strstr in c

    - by lex0273
    I was wondering if it's safe to do the following iteration to find the first occurrence of str within the array or if there is a better way. Thanks #include <stdio.h> #include <string.h> const char * list[] = {"One","Two","Three","Four","Five"}; char *c(char * str) { int i; for (i = 0; i < 5; i++) { if (strstr(str, list[i]) != NULL) return list[i]; } return "Not Found"; } int main() { char str[] = "This is a simple string of hshhs wo a char"; printf("%s", c(str)); return 0; }

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  • Threading extra state through a parser in Scala

    - by Travis Brown
    I'll give you the tl;dr up front I'm trying to use the state monad transformer in Scalaz 7 to thread extra state through a parser, and I'm having trouble doing anything useful without writing a lot of t m a -> t m b versions of m a -> m b methods. An example parsing problem Suppose I have a string containing nested parentheses with digits inside them: val input = "((617)((0)(32)))" I also have a stream of fresh variable names (characters, in this case): val names = Stream('a' to 'z': _*) I want to pull a name off the top of the stream and assign it to each parenthetical expression as I parse it, and then map that name to a string representing the contents of the parentheses, with the nested parenthetical expressions (if any) replaced by their names. To make this more concrete, here's what I'd want the output to look like for the example input above: val target = Map( 'a' -> "617", 'b' -> "0", 'c' -> "32", 'd' -> "bc", 'e' -> "ad" ) There may be either a string of digits or arbitrarily many sub-expressions at a given level, but these two kinds of content won't be mixed in a single parenthetical expression. To keep things simple, we'll assume that the stream of names will never contain either duplicates or digits, and that it will always contain enough names for our input. Using parser combinators with a bit of mutable state The example above is a slightly simplified version of the parsing problem in this Stack Overflow question. I answered that question with a solution that looked roughly like this: import scala.util.parsing.combinator._ class ParenParser(names: Iterator[Char]) extends RegexParsers { def paren: Parser[List[(Char, String)]] = "(" ~> contents <~ ")" ^^ { case (s, m) => (names.next -> s) :: m } def contents: Parser[(String, List[(Char, String)])] = "\\d+".r ^^ (_ -> Nil) | rep1(paren) ^^ ( ps => ps.map(_.head._1).mkString -> ps.flatten ) def parse(s: String) = parseAll(paren, s).map(_.toMap) } It's not too bad, but I'd prefer to avoid the mutable state. What I want Haskell's Parsec library makes adding user state to a parser trivially easy: import Control.Applicative ((*>), (<$>), (<*)) import Data.Map (fromList) import Text.Parsec paren = do (s, m) <- char '(' *> contents <* char ')' h : t <- getState putState t return $ (h, s) : m where contents = flip (,) [] <$> many1 digit <|> (\ps -> (map (fst . head) ps, concat ps)) <$> many1 paren main = print $ runParser (fromList <$> paren) ['a'..'z'] "example" "((617)((0)(32)))" This is a fairly straightforward translation of my Scala parser above, but without mutable state. What I've tried I'm trying to get as close to the Parsec solution as I can using Scalaz's state monad transformer, so instead of Parser[A] I'm working with StateT[Parser, Stream[Char], A]. I have a "solution" that allows me to write the following: import scala.util.parsing.combinator._ import scalaz._, Scalaz._ object ParenParser extends ExtraStateParsers[Stream[Char]] with RegexParsers { protected implicit def monadInstance = parserMonad(this) def paren: ESP[List[(Char, String)]] = (lift("(" ) ~> contents <~ lift(")")).flatMap { case (s, m) => get.flatMap( names => put(names.tail).map(_ => (names.head -> s) :: m) ) } def contents: ESP[(String, List[(Char, String)])] = lift("\\d+".r ^^ (_ -> Nil)) | rep1(paren).map( ps => ps.map(_.head._1).mkString -> ps.flatten ) def parse(s: String, names: Stream[Char]) = parseAll(paren.eval(names), s).map(_.toMap) } This works, and it's not that much less concise than either the mutable state version or the Parsec version. But my ExtraStateParsers is ugly as sin—I don't want to try your patience more than I already have, so I won't include it here (although here's a link, if you really want it). I've had to write new versions of every Parser and Parsers method I use above for my ExtraStateParsers and ESP types (rep1, ~>, <~, and |, in case you're counting). If I had needed to use other combinators, I'd have had to write new state transformer-level versions of them as well. Is there a cleaner way to do this? I'd love to see an example of a Scalaz 7's state monad transformer being used to thread state through a parser, but Scala 6 or Haskell examples would also be useful.

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  • Why does this XML validation via XSD fail in libxml2 (but succeed in xmllint) and how do I fix it?

    - by mtree
    If I run this XML validation via xmllint: xmllint --noout --schema schema.xsd test.xml I get this success message: .../test.xml validates However if I run the same validation via libxml2's C API: int result = xmlSchemaValidateDoc(...) I get a return value of 1845 and this failure message: Element '{http://example.com/XMLSchema/1.0}foo': No matching global declaration available for the validation root. Which I can make absolutely no sense of. :( schema.xsd: <?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE xs:schema PUBLIC "-//W3C//DTD XMLSCHEMA 200102//EN" "XMLSchema.dtd" > <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://example.com/XMLSchema/1.0" targetNamespace="http://example.com/XMLSchema/1.0" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="foo"> </xs:element> </xs:schema> test.xml: <?xml version="1.0" encoding="UTF-8"?> <foo xmlns="http://example.com/XMLSchema/1.0"> </foo> main.c: #include <stdio.h> #include <sys/stat.h> #include <sys/types.h> #include <string.h> #include <libxml/parser.h> #include <libxml/valid.h> #include <libxml/xmlschemas.h> u_int32_t get_file_size(const char *file_name) { struct stat buf; if ( stat(file_name, &buf) != 0 ) return(0); return (unsigned int)buf.st_size; } void handleValidationError(void *ctx, const char *format, ...) { char *errMsg; va_list args; va_start(args, format); vasprintf(&errMsg, format, args); va_end(args); fprintf(stderr, "Validation Error: %s", errMsg); free(errMsg); } int main (int argc, const char * argv[]) { const char *xsdPath = argv[1]; const char *xmlPath = argv[2]; printf("\n"); printf("XSD File: %s\n", xsdPath); printf("XML File: %s\n", xmlPath); int xmlLength = get_file_size(xmlPath); char *xmlSource = (char *)malloc(sizeof(char) * xmlLength); FILE *p = fopen(xmlPath, "r"); char c; unsigned int i = 0; while ((c = fgetc(p)) != EOF) { xmlSource[i++] = c; } printf("\n"); printf("XML Source:\n\n%s\n", xmlSource); fclose(p); printf("\n"); int result = 42; xmlSchemaParserCtxtPtr parserCtxt = NULL; xmlSchemaPtr schema = NULL; xmlSchemaValidCtxtPtr validCtxt = NULL; xmlDocPtr xmlDocumentPointer = xmlParseMemory(xmlSource, xmlLength); parserCtxt = xmlSchemaNewParserCtxt(xsdPath); if (parserCtxt == NULL) { fprintf(stderr, "Could not create XSD schema parsing context.\n"); goto leave; } schema = xmlSchemaParse(parserCtxt); if (schema == NULL) { fprintf(stderr, "Could not parse XSD schema.\n"); goto leave; } validCtxt = xmlSchemaNewValidCtxt(schema); if (!validCtxt) { fprintf(stderr, "Could not create XSD schema validation context.\n"); goto leave; } xmlSetStructuredErrorFunc(NULL, NULL); xmlSetGenericErrorFunc(NULL, handleValidationError); xmlThrDefSetStructuredErrorFunc(NULL, NULL); xmlThrDefSetGenericErrorFunc(NULL, handleValidationError); result = xmlSchemaValidateDoc(validCtxt, xmlDocumentPointer); leave: if (parserCtxt) { xmlSchemaFreeParserCtxt(parserCtxt); } if (schema) { xmlSchemaFree(schema); } if (validCtxt) { xmlSchemaFreeValidCtxt(validCtxt); } printf("\n"); printf("Validation successful: %s (result: %d)\n", (result == 0) ? "YES" : "NO", result); return 0; } console output: XSD File: /Users/dephiniteloop/Desktop/xml_validate/schema.xsd XML File: /Users/dephiniteloop/Desktop/xml_validate/test.gkml XML Source: <?xml version="1.0" encoding="UTF-8"?> <foo xmlns="http://example.com/XMLSchema/1.0"> </foo> Validation Error: Element '{http://example.com/XMLSchema/1.0}foo': No matching global declaration available for the validation root. Validation successful: NO (result: 1845) In case it matters: I'm on OSX 10.6.7 with its default libxml2.dylib (/Developer/SDKs/MacOSX10.6.sdk/usr/lib/libxml2.2.7.3.dylib)

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  • question about fgets

    - by user105033
    Is this safe to do? (does fgets terminate the buffer with null) or should I be setting the 20th byte to null after the call to fgets before i call clean. // strip new lines void clean(char *data) { while (*data) { if (*data == '\n' || *data == '\r') *data = '\0'; data++; } } // for this, assume that the file contains 1 line no longer than 19 bytes // buffer is freed elsewhere char *load_latest_info(char *file) { FILE *f; char *buffer = (char*) malloc(20); if (f = fopen(file, "r")) if (fgets(buffer, 20, f)) { clean(buffer); return buffer; } free(buffer); return NULL; }

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  • Arrays of pointers to arrays?

    - by a2h
    I'm using a library which for one certain feature involves variables like so: extern const u8 foo[]; extern const u8 bar[]; I am not allowed to rename these variables in any way. However, I like to be able to access these variables through an array (or other similar method) so that I do not need to continually hardcode new instances of these variables into my main code. My first attempt at creating an array is as follows: const u8* pl[] = { &foo, &bar }; This gave me the error cannot convert 'const u8 (*)[]' to 'const u8*' in initialization, and with help elsewhere along with some Googling, I changed my array to this: u8 (*pl)[] = { &foo, &bar }; Upon compiling I now get the error scalar object 'pl' requires one element in initializer. Does anyone have any ideas on what I'm doing wrong? Thanks.

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  • Trim function in C, to trim in place (without returning the string)

    - by user364100
    I can't figure out what to do to make this work. Here's my code: char* testStr = " trim this "; char** pTestStr = &testStr; trim(pTestStr); int trim(char** pStr) { char* str = *pStr; while(isspace(*str)) { (*pStr)++; str++; } if(*str == 0) { return 0; } char *end = str + strlen(str) - 1; while(end > str && isspace(*end)) end--; *(end+1) = 0; return 0; } I get an access violation on *(end+1) = 0;, but I can't declare my testStr[] as such to avoid that, because I can't pass the pointers that way. Any ideas?

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  • how to join a set of XElements to the values of a struct?

    - by jcollum
    Let's say I have a struct that contains local environments: public struct Environments { public const string Dev = "DEV"; public const string Qa1 = "SQA"; public const string Prod1 = "PROD"; public const string Prod2 = "PROD_SA"; public const string Uat = "UAT"; } And I'd like to pull a set of XElements out of an xml doc, but only those elements that have a key that matches a value in a struct. this.environments =(from e in settings.Element("Settings").Element("Environments") .Elements("Environment") .Where( x => x.HasAttribute("name") ) join f in [struct?] on e.Attribute("name") equals [struct value?]).ToDictionary(...) How would I go about doing this? Do I need reflection to get the values of the constants in the struct?

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  • std::string == operator not working

    - by Paul
    Hello, I've been using std::string's == operator for years on windows and linux. Now I am compiling one of my libraries on linux, it uses == heavily. On linux the following function fails, because the == returns false even when the strings are equal (case sensitive wise equal) const Data* DataBase::getDataByName( const std::string& name ) const { for ( unsigned int i = 0 ; i < m_dataList.getNum() ; i++ ) { if ( m_dataList.get(i)->getName() == name ) { return m_dataList.get(i); } } return NULL; } The getName() method is declared as follows virtual const std::string& getName() const; I am building with gcc 4.4.1 and libstdc++44-4.4.1. Any ideas? it looks perfectly valid to me. Paul

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  • after XOR operation find C (and XOR reversability)

    - by Jason z
    Assume: unsigned char A = 10; unsigned char B = 11; unsigned char C = 12; unsigned char Diff1 = A ^ B; unsigned char Diff2 = B ^ C; //find any of A or B or C using Diff1 and Diff2 Question is: There were 3 values initially for which we found 2 differences. Is there any way we can find any if A or B or C using 2 differences Diff1 and Diff2? I know XOR is not reversible unless you know the key, but keeping in view that unsigned __int8 is 0...255 maximum 256 different values. stay well.

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  • LNK2001: What have I forgotton to set?

    - by graham.reeds
    Following on from my previous question regarding debugging of native code, I decided to create a simple test from a console app as I wasn't getting anywhere with debugging the service directly. So I created a vc6 console app, added the dll project to the workspace and ran it. Instead of executing as expected it spat out the following linker errors: main.obj : error LNK2001: unresolved external symbol "int __stdcall hmDocumentLAdd(char *,char *,long,char *,char *,long,long,long,long *)" (?hmDocumentLAdd@@YGHPAD0J00JJJPAJ@Z) main.obj : error LNK2001: unresolved external symbol "int __stdcall hmGetDocBasePath(char *,long)" (?hmGetDocBasePath@@YGHPADJ@Z) Debug/HazManTest.exe : fatal error LNK1120: 2 unresolved externals This seems to be a simple case of forgetting something in the linker options: However everything seems to be normal, and the lib file, dll and source is available. If I change the lib file to load to nonsense it kicks up the fatal error LNK1104: cannot open file "asdf.lib", so that isn't a problem. I have previously linked to dll and they have just worked, so what I have forgotton to do?

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  • friendship and operator overloading help

    - by sil3nt
    hello there, I have the following class #ifndef Container_H #define Container_H #include <iostream> using namespace std; class Container{ friend bool operator==(const Container &rhs,const Container &lhs); public: void display(ostream & out) const; private: int sizeC; // size of Container int capacityC; // capacity of dynamic array int * elements; // pntr to dynamic array }; ostream & operator<< (ostream & out, const Container & aCont); #endif and this source file #include "container.h" /*----------------------------********************************************* note: to test whether capacityC and sizeC are equal, must i add 1 to sizeC? seeing as sizeC starts off with 0?? */ Container::Container(int maxCapacity){ capacityC = maxCapacity; elements = new int [capacityC]; sizeC = 0; } Container::~Container(){ delete [] elements; } Container::Container(const Container & origCont){ //copy constructor? int i = 0; for (i = 0; i<capacityC; i++){ //capacity to be used here? (*this).elements[i] = origCont.elements[i]; } } bool Container::empty() const{ if (sizeC == 0){ return true; }else{ return false; } } void Container::insert(int item, int index){ if ( sizeC == capacityC ){ cout << "\n*** Next: Bye!\n"; return; // ? have return here? } if ( (index >= 0) && (index <= capacityC) ){ elements[index] = item; sizeC++; } if ( (index < 0) && (index > capacityC) ){ cout<<"*** Illegal location to insert--"<< index << ". Container unchanged. ***\n"; }//error here not valid? according to original a3? have i implemented wrong? } void Container::erase(int index){ if ( (index >= 0) && (index <= capacityC) ){ //correct here? legal location? int i = 0; while (i<capacityC){ //correct? elements[index] = elements[index+1]; //check if index increases here. i++; } sizeC=sizeC-1; //correct? updated sizeC? }else{ cout<<"*** Illegal location to be removed--"<< index << ". Container unchanged. ***\n"; } } int Container::size()const{ return sizeC; //correct? } /* bool Container::operator==(const Container &rhs,const Container &lhs){ int equal = 0, i = 0; for (i = 0; i < capacityC ; i++){ if ( rhs.elements[i] == lhs.elements[i] ){ equal++; } } if (equal == sizeC){ return true; }else{ return false; } } ostream & operator<< (ostream & out, const Container & aCont){ int i = 0; for (i = 0; i<sizeC; i++){ out<< aCont.elements[i] << " " << endl; } } */ I dont have the other functions in the header file (just a quikie). Anyways, the last two functions in "/* */" I cant get to work, what am I doing wrong here? the first function is to see whether the two arrays are equal to one another

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  • C Language: Why I cannot transfer file from server to client?

    - by user275753
    I want to ask, why I cannot transfer file from server to client? When I start to send the file from server, the client side program will have problem. So, I spend some times to check the code, But I still cannot find out the problem Can anyone point out the problem for me? thanks a lot! [client side code] include include include include include include include define SA struct sockaddr define S_PORT 5678 define MAXLEN 1000 define true 1 void errexit(const char *format, ...) { va_list args; va_start(args, format); vfprintf(stderr, format, args); va_end(args); WSACleanup(); exit(1); } int main(int argc, char *argv []) { WSADATA wsadata; SOCKET sockfd; int number,message; char outbuff[MAXLEN],inbuff[MAXLEN]; char PWD_buffer[_MAX_PATH]; struct sockaddr_in servaddr; FILE *fp; int numbytes; char buf[2048]; if (WSAStartup(MAKEWORD(2,2), &wsadata) != 0) errexit("WSAStartup failed\n"); if (argc != 2) errexit("client IPaddress"); if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET ) errexit("socket error: error number %d\n", WSAGetLastError()); memset(&servaddr, 0, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(S_PORT); if ( (servaddr.sin_addr.s_addr = inet_addr(argv[1])) == INADDR_NONE) errexit("inet_addr error: error number %d\n", WSAGetLastError()); if (connect(sockfd, (SA *) &servaddr, sizeof(servaddr)) == SOCKET_ERROR) errexit("connect error: error number %d\n", WSAGetLastError()); if ( (fp = fopen("C:\\users\\pc\\desktop\\COPY.c", "wb")) == NULL){ perror("fopen"); exit(1); } printf("Still NO PROBLEM!\n"); //Receive file from server while(1){ numbytes = read(sockfd, buf, sizeof(buf)); printf("read %d bytes, ", numbytes); if(numbytes == 0){ printf("\n"); break; } numbytes = fwrite(buf, sizeof(char), numbytes, fp); printf("fwrite %d bytes\n", numbytes); } fclose(fp); close(sockfd); return 0; } server side code include include include include include include include include define SA struct sockaddr define S_PORT 5678 define MAXLEN 1000 void errexit(const char *format, ...) { va_list args; va_start(args, format); vfprintf(stderr, format, args); va_end(args); WSACleanup(); exit(1); } int main(int argc, char *argv []) { WSADATA wsadata; SOCKET listenfd, connfd; int number, message, numbytes; int h, i, j, alen; int nread; struct sockaddr_in servaddr, cliaddr; FILE *in_file, *out_file, *fp; char buf[4096]; if (WSAStartup(MAKEWORD(2,2), &wsadata) != 0) errexit("WSAStartup failed\n"); listenfd = socket(AF_INET, SOCK_STREAM, 0); if (listenfd == INVALID_SOCKET) errexit("cannot create socket: error number %d\n", WSAGetLastError()); memset(&servaddr, 0, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = htonl(INADDR_ANY); servaddr.sin_port = htons(S_PORT); if (bind(listenfd, (SA *) &servaddr, sizeof(servaddr)) == SOCKET_ERROR) errexit("can't bind to port %d: error number %d\n", S_PORT, WSAGetLastError()); if (listen(listenfd, 5) == SOCKET_ERROR) errexit("can't listen on port %d: error number %d\n", S_PORT, WSAGetLastError()); alen = sizeof(SA); connfd = accept(listenfd, (SA *) &cliaddr, &alen); if (connfd == INVALID_SOCKET) errexit("accept failed: error number %d\n", WSAGetLastError()); printf("accept one client from %s!\n", inet_ntoa(cliaddr.sin_addr)); fp = fopen ("client.c", "rb"); // open file stored in server if (fp == NULL) { printf("\nfile NOT exist"); } //Sending file while(!feof(fp)){ numbytes = fread(buf, sizeof(char), sizeof(buf), fp); printf("fread %d bytes, ", numbytes); numbytes = write(connfd, buf, numbytes); printf("Sending %d bytes\n",numbytes); } fclose (fp); closesocket(listenfd); closesocket(connfd); return 0; }

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  • Why .NET Boolean has TrueLiteral and TrueString?

    - by user309937
    Why in Boolean type there are two fields with the same value? internal const int True = 1; internal const int False = 0; internal const string TrueLiteral = "True"; internal const string FalseLiteral = "False"; and public static readonly string TrueString; public static readonly string FalseString; static Boolean() { TrueString = "True"; FalseString = "False"; } in reflector generated code, methods don't use those strings but: public string ToString(IFormatProvider provider) { if (!this) { return "False"; } return "True"; } would't it be better to use those const values?

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