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• Flushing of cout prior to reading input using cin .. why?

  - by yapkm01

  Why does cout has to be flushed before cin starts reading? Aren't they of different buffer? I can have reading of input into a buffer while same time putting it on output buffer (before flushing) .. 2 different buffers. I am confused here.

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• program crashes at CIN input | C++

  - by TimothyTech

  hello okay, so i made a DOS program however my game always crashes on my second time running to the cin function. #include <iostream> #include <string> #include <ctime> #include <cstdlib> using namespace std; //call functions int create_enemyHP (int a); int create_enemyAtk (int a); int find_Enemy(int a); int create_enemyDef (int a); // user information int userHP = 100; int userAtk = 10; int userDef = 5; string userName; //enemy Information int enemyHP; int enemyAtk; int enemyDef; string enemies[] = {"Raider", "Bandit", "Mugger"}; int sizeOfEnemies = sizeof(enemies) / sizeof(int); string currentEnemy; int chooseEnemy; // ACTIONS int journey; int test; int main() { // main menu cout << "welcome brave knight, what is your name? " ; cin >> userName; cout << "welcome " << userName << " to Darland" << endl; //TRAVELING MENU: cout << "where would you like to travel? " << endl; cout << endl << " 1.> Theives Pass " << endl; cout << " 2.> Humble Town " << endl; cout << " 3.> Mission HQ " << endl; cin >> journey; if (journey == 1) { // action variable; string c_action; cout << "beware your journey grows dangerous " << endl; //begins battle // Creating the enemy, HP ATK DEF AND TYPE. ; srand(time(0)); enemyHP = create_enemyHP(userHP); enemyAtk = create_enemyAtk(userAtk); enemyDef = create_enemyDef(userDef); chooseEnemy = find_Enemy(sizeOfEnemies); currentEnemy = enemies[chooseEnemy]; cout << " Here comes a " << currentEnemy << endl; cout << "stats: " << endl; cout << "HP :" << enemyHP << endl; cout << "Attack : " << enemyAtk << endl; cout << "Defense : " << enemyDef << endl; ACTIONS: cout << "Attack <A> | Defend <D> | Items <I>"; cin >> c_action; //if ATTACK/DEFEND/ITEMS choice if (c_action == "A" || c_action == "a"){ enemyHP = enemyHP - userAtk; cout << " you attack the enemy reducing his health to " << enemyHP << endl; userHP = userHP - enemyAtk; cout << "however he lashes back causing you to have " << userHP << "health left " << endl; //end of ATTACK ACTION } the last line "cin c_action crashes. i use two other pages. they just create the functions. is it a complier issue. also why does my complier always shutdown after it runs he app. is there a way to stop it?

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• file doesn't open, running outside of debugger results in seg fault (c++)

  - by misterich

  Hello (and thanks in advance) I'm in a bit of a quandry, I cant seem to figure out why I'm seg faulting. A couple of notes: It's for a course -- and sadly I am required to use use C-strings instead of std::string. Please dont fix my code (I wont learn that way and I will keep bugging you). please just point out the flaws in my logic and suggest a different function/way. platform: gcc version 4.4.1 on Suse Linux 11.2 (2.6.31 kernel) Here's the code main.cpp: // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <cstdlib> /// EXIT_SUCCESS, EXIT_FAILURE #include <iostream> /// cin, cout, ifstream #include <cassert> /// assert // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header for the dictionary class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR CONSTANTS #define ENTER '\n' /// Used to accept new lines, quit program. #define SPACE ' ' /// One way to end the program // /////////////////////////////////////////////////////////////////////////////////// // CUSTOM DATA TYPES /// File Namespace -- keep it local namespace { /// Possible program prompts to display for the user. enum FNS_Prompts { fileName_, /// prints out the name of the file noFile_, /// no file was passed to the program tooMany_, /// more than one file was passed to the program noMemory_, /// Not enough memory to use the program usage_, /// how to use the program word_, /// ask the user to define a word. notFound_, /// the word is not in the dictionary done_, /// the program is closing normally }; } // /////////////////////////////////////////////////////////////////////////////////// // Namespace using namespace std; /// Nothing special in the way of namespaces // /////////////////////////////////////////////////////////////////////////////////// // FUNCTIONS /** prompt() prompts the user to do something, uses enum Prompts for parameter. */ void prompt(FNS_Prompts msg /** determines the prompt to use*/) { switch(msg) { case fileName_ : { cout << ENTER << ENTER << "The file name is: "; break; } case noFile_ : { cout << ENTER << ENTER << "...Sorry, a dictionary file is needed. Try again." << endl; break; } case tooMany_ : { cout << ENTER << ENTER << "...Sorry, you can only specify one dictionary file. Try again." << endl; break; } case noMemory_ : { cout << ENTER << ENTER << "...Sorry, there isn't enough memory available to run this program." << endl; break; } case usage_ : { cout << "USAGE:" << endl << " lookup.exe [dictionary file name]" << endl << endl; break; } case done_ : { cout << ENTER << ENTER << "like Master P says, \"Word.\"" << ENTER << endl; break; } case word_ : { cout << ENTER << ENTER << "Enter a word in the dictionary to get it's definition." << ENTER << "Enter \"?\" to get a sorted list of all words in the dictionary." << ENTER << "... Press the Enter key to quit the program: "; break; } case notFound_ : { cout << ENTER << ENTER << "...Sorry, that word is not in the dictionary." << endl; break; } default : { cout << ENTER << ENTER << "something passed an invalid enum to prompt(). " << endl; assert(false); /// something passed in an invalid enum } } } /** useDictionary() uses the dictionary created by createDictionary * - prompts user to lookup a word * - ends when the user enters an empty word */ void useDictionary(Dictionary &d) { char *userEntry = new char; /// user's input on the command line if( !userEntry ) // check the pointer to the heap { cout << ENTER << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } do { prompt(word_); // test code cout << endl << "----------------------------------------" << endl << "Enter something: "; cin.getline(userEntry, INPUT_LINE_MAX_LEN, ENTER); cout << ENTER << userEntry << endl; }while ( userEntry[0] != NIL && userEntry[0] != SPACE ); // GARBAGE COLLECTION delete[] userEntry; } /** Program Entry * Reads in the required, single file from the command prompt. * - If there is no file, state such and error out. * - If there is more than one file, state such and error out. * - If there is a single file: * - Create the database object * - Populate the database object * - Prompt the user for entry * main() will return EXIT_SUCCESS upon termination. */ int main(int argc, /// the number of files being passed into the program char *argv[] /// pointer to the filename being passed into tthe program ) { // EXECUTE /* Testing code * / char tempFile[INPUT_LINE_MAX_LEN] = {NIL}; cout << "enter filename: "; cin.getline(tempFile, INPUT_LINE_MAX_LEN, '\n'); */ // uncomment after successful debugging if(argc <= 1) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// no file was passed to the program } else if(argc > 2) { prompt(tooMany_); prompt(usage_); return EXIT_FAILURE; /// more than one file was passed to the program } else { prompt(fileName_); cout << argv[1]; // print out name of dictionary file if( !argv[1] ) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// file does not exist } /* file.open( argv[1] ); // open file numEntries >> in.getline(file); // determine number of dictionary objects to create file.close(); // close file Dictionary[ numEntries ](argv[1]); // create the dictionary object */ // TEMPORARY FILE FOR TESTING!!!! //Dictionary scrabble(tempFile); Dictionary scrabble(argv[1]); // creaate the dicitonary object //*/ useDictionary(scrabble); // prompt the user, use the dictionary } // exit return EXIT_SUCCESS; /// terminate program. } Dict.h/.cpp #ifndef DICT_H #define DICT_H // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (Custom header files) #include "entry.h" /// class for dictionary entries // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define INPUT_LINE_MAX_LEN 256 /// Maximum length of each line in the dictionary file class Dictionary { public : // // Do NOT modify the public section of this class // typedef void (*WordDefFunc)(const char *word, const char *definition); Dictionary( const char *filename ); ~Dictionary(); const char *lookupDefinition( const char *word ); void forEach( WordDefFunc func ); private : // // You get to provide the private members // // VARIABLES int m_numEntries; /// stores the number of entries in the dictionary Entry *m_DictEntry_ptr; /// points to an array of class Entry // Private Functions }; #endif ----------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <iostream> /// cout, getline #include <fstream> // ifstream #include <cstring> /// strchr // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header file required by assignment //#include "entry.h" /// Dicitonary Entry Class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define COMMA ',' /// Delimiter for file #define ENTER '\n' /// Carriage return character #define FILE_ERR_MSG "The data file could not be opened. Program will now terminate." #pragma warning(disable : 4996) /// turn off MS compiler warning about strcpy() // /////////////////////////////////////////////////////////////////////////////////// // Namespace reference using namespace std; // /////////////////////////////////////////////////////////////////////////////////// // PRIVATE MEMBER FUNCTIONS /** * Sorts the dictionary entries. */ /* static void sortDictionary(?) { // sort through the words using qsort } */ /** NO LONGER NEEDED?? * parses out the length of the first cell in a delimited cell * / int getWordLength(char *str /// string of data to parse ) { return strcspn(str, COMMA); } */ // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC MEMBER FUNCTIONS /** constructor for the class * - opens/reads in file * - creates initializes the array of member vars * - creates pointers to entry objects * - stores pointers to entry objects in member var * - ? sort now or later? */ Dictionary::Dictionary( const char *filename ) { // Create a filestream, open the file to be read in ifstream dataFile(filename, ios::in ); /* if( dataFile.fail() ) { cout << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } */ if( dataFile.is_open() ) { // read first line of data // TEST CODE in.getline(dataFile, INPUT_LINE_MAX_LEN) >> m_numEntries; // TEST CODE char temp[INPUT_LINE_MAX_LEN] = {NIL}; // TEST CODE dataFile.getline(temp,INPUT_LINE_MAX_LEN,'\n'); dataFile >> m_numEntries; /** Number of terms in the dictionary file * \todo find out how many lines in the file, subtract one, ingore first line */ //create the array of entries m_DictEntry_ptr = new Entry[m_numEntries]; // check for valid memory allocation if( !m_DictEntry_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // loop thru each line of the file, parsing words/def's and populating entry objects for(int EntryIdx = 0; EntryIdx < m_numEntries; ++EntryIdx) { // VARIABLES char *tempW_ptr; /// points to a temporary word char *tempD_ptr; /// points to a temporary def char *w_ptr; /// points to the word in the Entry object char *d_ptr; /// points to the definition in the Entry int tempWLen; /// length of the temp word string int tempDLen; /// length of the temp def string char tempLine[INPUT_LINE_MAX_LEN] = {NIL}; /// stores a single line from the file // EXECUTE // getline(dataFile, tempLine) // get a "word,def" line from the file dataFile.getline(tempLine, INPUT_LINE_MAX_LEN); // get a "word,def" line from the file // Parse the string tempW_ptr = tempLine; // point the temp word pointer at the first char in the line tempD_ptr = strchr(tempLine, COMMA); // point the def pointer at the comma *tempD_ptr = NIL; // replace the comma with a NIL ++tempD_ptr; // increment the temp def pointer // find the string lengths... +1 to account for terminator tempWLen = strlen(tempW_ptr) + 1; tempDLen = strlen(tempD_ptr) + 1; // Allocate heap memory for the term and defnition w_ptr = new char[ tempWLen ]; d_ptr = new char[ tempDLen ]; // check memory allocation if( !w_ptr && !d_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // copy the temp word, def into the newly allocated memory and terminate the strings strcpy(w_ptr,tempW_ptr); w_ptr[tempWLen] = NIL; strcpy(d_ptr,tempD_ptr); d_ptr[tempDLen] = NIL; // set the pointers for the entry objects m_DictEntry_ptr[ EntryIdx ].setWordPtr(w_ptr); m_DictEntry_ptr[ EntryIdx ].setDefPtr(d_ptr); } // close the file dataFile.close(); } else { cout << ENTER << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } } /** * cleans up dynamic memory */ Dictionary::~Dictionary() { delete[] m_DictEntry_ptr; /// thou shalt not have memory leaks. } /** * Looks up definition */ /* const char *lookupDefinition( const char *word ) { // print out the word ---- definition } */ /** * prints out the entire dictionary in sorted order */ /* void forEach( WordDefFunc func ) { // to sort before or now.... that is the question } */ Entry.h/cpp #ifndef ENTRY_H #define ENTRY_H // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C++ Std lib) #include <cstdlib> /// EXIT_SUCCESS, NULL // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define NIL '\0' /// C-String terminator #define MEM_ERR_MSG "Memory allocation has failed. Program will now terminate." // /////////////////////////////////////////////////////////////////////////////////// // CLASS DEFINITION class Entry { public: Entry(void) : m_word_ptr(NULL), m_def_ptr(NULL) { /* default constructor */ }; void setWordPtr(char *w_ptr); /// sets the pointer to the word - only if the pointer is empty void setDefPtr(char *d_ptr); /// sets the ponter to the definition - only if the pointer is empty /// returns what is pointed to by the word pointer char getWord(void) const { return *m_word_ptr; } /// returns what is pointed to by the definition pointer char getDef(void) const { return *m_def_ptr; } private: char *m_word_ptr; /** points to a dictionary word */ char *m_def_ptr; /** points to a dictionary definition */ }; #endif -------------------------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "entry.h" /// class header file // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC FUNCTIONS /* * only change the word member var if it is in its initial state */ void Entry::setWordPtr(char *w_ptr) { if(m_word_ptr == NULL) { m_word_ptr = w_ptr; } } /* * only change the def member var if it is in its initial state */ void Entry::setDefPtr(char *d_ptr) { if(m_def_ptr == NULL) { m_word_ptr = d_ptr; } }

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• A Linker Resolution Problem in a C++ Program

  - by Vlad

  We have two source files, a.cpp and b.cpp and a header file named constructions.h. We define a simple C++ class with the same name (class M, for instance) in each source file, respectively. The file a.cpp looks like this: #include "iostream" #include "constructions.h" class M { int i; public: M(): i( -1 ) { cout << "M() from a.cpp" << endl; } M( int a ) : i( a ) { cout << "M(int) from a.cpp, i: " << i << endl; } M( const M& b ) { i = b.i; cout << "M(M&) from a.cpp, i: " << i << endl; } M& operator = ( M& b ) { i = b.i; cout << "M::operator =(), i: " << i << endl; return *this; } virtual ~M(){ cout << "M::~M() from a.cpp" << endl; } operator int() { cout << "M::operator int() from a.cpp" << endl; return i; } }; void test1() { cout << endl << "Example 1" << endl; M b1; cout << "b1: " << b1 << endl; cout << endl << "Example 2" << endl; M b2 = 5; cout << "b2: " << b2 << endl; cout << endl << "Example 3" << endl; M b3(6); cout << "b3: " << b3 << endl; cout << endl << "Example 4" << endl; M b4 = b1; cout << "b4: " << b4 << endl; cout << endl << "Example 5" << endl; M b5; b5 = b2; cout << "b5: " << b5 << endl; } int main(int argc, char* argv[]) { test1(); test2(); cin.get(); return 0; } The file b.cpp looks like this: #include "iostream" #include "constructions.h" class M { public: M() { cout << "M() from b.cpp" << endl; } ~M() { cout << "M::~M() from b.cpp" << endl; } }; void test2() { M m; } Finally, the file constructions.h contains only the declaration of the function "test2()" (which is defined in "b.cpp"), so that it can be used in "a.cpp": using namespace std; void test2(); We compiled and linked these three files using either VS2005 or the GNU 4.1.0 compiler and the 2.16.91 ld linker under Suse. The results are surprising and different between the two build environments. But in both cases it looks like the linker gets confused about which definition of the class M it should use. If we comment out the definition of test2() from b.cpp and its invocation from a.cpp, then all the C++ objects created in test1() are of the type M defined in a.cpp and the program executes normally under Windows and Suse. Here is the run output under Windows: Example 1 M() from a.cpp M::operator int() from a.cpp b1: -1 Example 2 M(int) from a.cpp, i: 5 M::operator int() from a.cpp b2: 5 Example 3 M(int) from a.cpp, i: 6 M::operator int() from a.cpp b3: 6 Example 4 M(M&) from a.cpp, i: -1 M::operator int() from a.cpp b4: -1 Example 5 M() from a.cpp M::operator =(), i: 5 M::operator int() from a.cpp b5: 5 M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp If we enable the definition of test2() in "b.cpp" but comment out its invocation from main(), then the results are different. Under Suse, the C++ objects created in test1() are still of the type M defined in a.cpp and the program still seems to execute normally. The VS2005 versions behave differently in Debug or Release mode: in Debug mode, the program still seems to execute normally, but in Release mode, b1 and b5 are of the type M defined in b.cpp (as the constructor invocation proves), although the other member functions called (including the destructor), belong to M defined in a.cpp. Here is the run output for the executable built in Release mode: Example 1 M() from b.cpp M::operator int() from a.cpp b1: 4206872 Example 2 M(int) from a.cpp, i: 5 M::operator int() from a.cpp b2: 5 Example 3 M(int) from a.cpp, i: 6 M::operator int() from a.cpp b3: 6 Example 4 M(M&) from a.cpp, i: 4206872 M::operator int() from a.cpp b4: 4206872 Example 5 M() from b.cpp M::operator =(), i: 5 M::operator int() from a.cpp b5: 5 M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp Finally, if we allow the call to test2() from main, the program misbehaves in all circumstances (that is under Suse and under Windows in both Debug and Release modes). The Windows-Debug version finds a memory corruption around the variable m, defined in test2(). Here is the Windows output in Release mode (test2() seems to have created an instance of M defined in b.cpp): Example 1 M() from b.cpp M::operator int() from a.cpp b1: 4206872 Example 2 M(int) from a.cpp, i: 5 M::operator int() from a.cpp b2: 5 Example 3 M(int) from a.cpp, i: 6 M::operator int() from a.cpp b3: 6 Example 4 M(M&) from a.cpp, i: 4206872 M::operator int() from a.cpp b4: 4206872 Example 5 M() from b.cpp M::operator =(), i: 5 M::operator int() from a.cpp b5: 5 M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M() from b.cpp M::~M() from b.cpp And here is the Suse output. The objects created in test1() are of the type M defined in a.cpp but the object created in test2() is also of the type M defined in a.cpp, unlike the object created under Windows which is of the type M defined in b.cpp. The program crashed in the end: Example 1 M() from a.cpp M::operator int() from a.cpp b1: -1 Example 2 M(int) from a.cpp, i: 5 M::operator int() from a.cpp b2: 5 Example 3 M(int) from a.cpp, i: 6 M::operator int() from a.cpp b3: 6 Example 4 M(M&) from a.cpp, i: -1 M::operator int() from a.cpp b4: -1 Example 5 M() from a.cpp M::operator =(), i: 5 M::operator int() from a.cpp b5: 5 M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M::~M() from a.cpp M() from a.cpp M::~M() from a.cpp Segmentation fault (core dumped) I couldn't make the angle brackets appear using Markdown, so I used quotes around the header file name iostream. Otherwise, the code could be copied verbatim and tried. It is purely scholastic. The statement cin.get() at the end of main() was included just to facilitate running the program directly from VS2005 (cause it to display the output window until we could analyze the output). We are looking for a software engineer in Sunnyvale, CA and may offer that position to the programmer capable of providing an intelligent and comprehensive explanation of these anomalies. I can be contacted at [email protected].

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• fatal error C1075: end of file found before the left brace and read and write files not working

  - by user320950

  could someone also tell me if the actions i am attempting to do which are stated in the comments are correct or not. i am new at c++ and i think its correct but i have doubts #include<iostream> #include<fstream> #include<cstdlib> #include<iomanip> using namespace std; int main() { ifstream in_stream; // reads itemlist.txt ofstream out_stream1; // writes in items.txt ifstream in_stream2; // reads pricelist.txt ofstream out_stream3;// writes in plist.txt ifstream in_stream4;// read recipt.txt ofstream out_stream5;// write display.txt float price=' ',curr_total=0.0; int wrong=0; int itemnum=' '; char next; in_stream.open("ITEMLIST.txt", ios::in); // list of avaliable items if( in_stream.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; out_stream1.open("listWititems.txt", ios::out); // list of avaliable items if(out_stream1.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here1, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit(1); } else{ cout << " System ran correctly " << endl; } in_stream2.open("PRICELIST.txt", ios::in); if( in_stream2.fail() ) { wrong++; cout << " the error occured here2, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit (1); } else{ cout << " System ran correctly " << endl; } out_stream3.open("listWitdollars.txt", ios::out); if(out_stream3.fail() ) { wrong++; cout << " the error occured here3, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit (1); } else{ cout << " System ran correctly " << endl; } in_stream4.open("display.txt", ios::in); if( in_stream4.fail() ) { wrong++; cout << " the error occured here4, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit (1); } else{ cout << " System ran correctly " << endl; } out_stream5.open("showitems.txt", ios::out); if( out_stream5.fail() ) { wrong++; cout << " the error occured here5, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit (1); } else{ cout << " System ran correctly " << endl; } in_stream.close(); // closing files. out_stream1.close(); in_stream2.close(); out_stream3.close(); in_stream4.close(); out_stream5.close(); system("pause"); in_stream.setf(ios::fixed); while(in_stream.eof()) { in_stream >> itemnum; cin.clear(); cin >> next; } out_stream1.setf(ios::fixed); while (out_stream1.eof()) { out_stream1 << itemnum; cin.clear(); cin >> next; } in_stream2.setf(ios::fixed); in_stream2.setf(ios::showpoint); in_stream2.precision(2); while((price== (price*1.00)) && (itemnum == (itemnum*1))) { while (in_stream2 >> itemnum >> price) // gets itemnum and price { while (in_stream2.eof()) // reads file to end of file { in_stream2 >> itemnum; in_stream2 >> price; price++; curr_total= price++; in_stream2 >> curr_total; cin.clear(); // allows more reading cin >> next; } } } out_stream3.setf(ios::fixed); out_stream3.setf(ios::showpoint); out_stream3.precision(2); while((price== (price*1.00)) && (itemnum == (itemnum*1))) { while (out_stream3 << itemnum << price) { while (out_stream3.eof()) // reads file to end of file { out_stream3 << itemnum; out_stream3 << price; price++; curr_total= price++; out_stream3 << curr_total; cin.clear(); // allows more reading cin >> next; } return itemnum, price; } } in_stream4.setf(ios::fixed); in_stream4.setf(ios::showpoint); in_stream4.precision(2); while ( in_stream4.eof()) { in_stream4 >> itemnum >> price >> curr_total; cin.clear(); cin >> next; } out_stream5.setf(ios::fixed); out_stream5.setf(ios::showpoint); out_stream5.precision(2); out_stream5 <<setw(5)<< " itemnum " <<setw(5)<<" price "<<setw(5)<<" curr_total " <<endl; // sends items and prices to receipt.txt out_stream5 << setw(5) << itemnum << setw(5) <<price << setw(5)<< curr_total; // sends items and prices to receipt.txt out_stream5 << " You have a total of " << wrong++ << " errors " << endl; }

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• Invalid conversion from int to int

  - by FOXMULDERIZE

  #include <iostream> #include<fstream> using namespace std; void showvalues(int,int,int []); void showvalues2(int,int); void sumtotal(int,int); int main() { const int SIZE_A= 9; int arreglo[SIZE_A]; ifstream archivo_de_entrada; archivo_de_entrada.open("numeros.txt"); int count,suma,total,a,b,c,d,e,f; int total1=0; int total2=0; //lee/// for(count =0 ;count < SIZE_A;count++) archivo_de_entrada>>arreglo[count] ; archivo_de_entrada.close(); showvalues(0,3,9); HERE IS THE PROBLEM showvalues2(5,8); sumtotal(total1,total2); system("pause"); return 0; } void showvalues(int a,int b,int v) { //muestra//////////////////////// cout<< "los num son "; for(count = a ;count <= b;count++) total1 = total1 + arreglo[count]; cout <<total1<<" "; cout <<endl; } void showvalues2(int c,int d) { ////////////////////////////// cout<< "los num 2 son "; for(count =5 ;count <=8;count++) total2 = total2 + arreglo[count]; cout <<total2<<" "; cout <<endl; } void sumtotal(int e,int f) { ///////////////////////////////// cout<<"la suma de t1 y t2 es "; total= total1 + total2; cout<<total; cout <<endl; }

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• i see the file but when i open it nothing is in it in c++ i/o stream and dont know why

  - by user320950

  #include<iostream> #include<fstream> #include<cstdlib> #include<iomanip> using namespace std; int main() { ifstream in_stream; // reads ITEMSLIST.txt ofstream out_stream1; // writes in listWititems.txt ifstream in_stream2; // reads PRICELIST.txt ofstream out_stream3;// writes in listWitprices.txt ifstream in_stream4;// read display.txt ofstream out_stream5;// write showitems.txt double p1=0.0,p2=0.0; int wrong=0; int count =0; char next; in_stream.open("ITEMLIST.txt", ios::in); // list of avaliable items /*if( in_stream.fail() )// check to see if itemlist.txt is open { wrong++; // counts number of errors cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ out_stream1.open("listWititems.txt", ios::out); // list of avaliable items /* if( out_stream1.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ in_stream2.open("PRICELIST.txt", ios::in); /*if( in_stream2.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ out_stream3.open("listWitdollars.txt", ios::out); /*if( out_stream3.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ in_stream4.open("display.txt", ios::in); /*if( in_stream4.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ out_stream5.open("showitems.txt", ios::out); /*if( out_stream5.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; }*/ in_stream.setf(ios::fixed); while(!in_stream.eof()) // reads to end of file and gets p1 which is itemnum, clears and gets next character { in_stream >> p1; cin.clear(); cin >> next; } out_stream1.setf(ios::fixed); while (!out_stream1.eof()) { out_stream1 << p1; cin.clear(); cin >> next; } in_stream2.setf(ios::fixed); in_stream2.setf(ios::showpoint); in_stream2.precision(2); while(!in_stream2.eof()) // reads file to end of file { in_stream2 >> p1 >> p2 >> count; // gets p1,p2, and count which is current total in_stream2 >> p2; p1 += p2; p2++; cin.clear(); // allows more reading cin >> next; return p1, p2; } out_stream3.setf(ios::fixed); out_stream3.setf(ios::showpoint); out_stream3.precision(2); while(!out_stream3.eof()) // reads file to end of file { out_stream3 << p1 << p2 << count; out_stream3 << p2; p1 += p2; p2++; cin.clear(); // allows more reading cin >> next; return p1, p2; } in_stream4.setf(ios::fixed); in_stream4.setf(ios::showpoint); in_stream4.precision(2); while (!in_stream4.eof()) { in_stream4 >> p1 >> p2 >> count; cin.clear(); cin >> next; } out_stream5.setf(ios::fixed); out_stream5.setf(ios::showpoint); out_stream5.precision(2); out_stream5 <<setw(5)<< " itemnum " <<setw(5)<<" price "<<setw(5)<<" curr_total " <<endl; // sends items and prices to receipt.txt out_stream5 << setw(5) << p1 << setw(5) <<p2 << setw(5)<< count; // sends items and prices to receipt.txt out_stream5 << " You have a total of " << wrong++ << " errors " << endl; in_stream.close(); // closing files. out_stream1.close(); in_stream2.close(); out_stream3.close(); in_stream4.close(); out_stream5.close(); system("pause"); }

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• Simple C++ program on multidimensional arrays - Getting C2143 error among others. Not sure why?

  - by noobzilla

  Here is my simple multidimensional array program. The first error occurs where I declare the function addmatrices and then a second one where it is implemented. I am also getting an undefined variable error for bsize. What am I doing incorrectly? #include <iostream> #include <fstream> #include <string> #include <iomanip> using namespace std; //Function declarations void constmultiply (double matrixA[][4], int asize, double matrixC[][4], int bsize, double multiplier); //Pre: The address of the output file, the matrix to be multiplied by the constant, the matrix in which // the resultant values will be stored and the multiplier are passed in. //Post: The matrix is multiplied by the multiplier and the results are displayed on screen and written to the // output file. int addmatrices (double matrixA[][4], int asize, double matrixB[]4], int bsize, double matrixC[][4], int csize); //Pre: The addresses of three matrices are passed in //Post: The values in each of the two matrices are added together and put into a third matrix //Error Codes int INPUT_FILE_FAIL = 1; int UNEQUAL_MATRIX_SIZE = 2; //Constants const double multiplier = 2.5; const int rsize = 4; const int csize = 4; //Main Driver int main() { //Declare the two matrices double matrix1 [rsize][csize]; double matrix2 [rsize][csize]; double matrix3 [rsize][csize]; //Variables double temp; string filename; //Declare filestream object ifstream infile; //Ask the user for the name of the input file cout << "Please enter the name of the input file: "; cin >> filename; //Open the filestream object infile.open(filename.c_str()); //Verify that the input file opened correctly if (infile.fail()) { cout << "Input file failed to open" <<endl; exit(INPUT_FILE_FAIL); } //Begin reading in data from the first matrix for (int i = 0; i <= 3; i++)//i = row { for (int j = 0; j <= 3; j++)// j = column { infile >> temp; matrix1[i][j] = temp; } } //Begin reading in data from the second matrix for (int k = 0; k <= 3; k++)// k = row { for (int l = 0; l <= 3; l++)// l = column { infile >> temp; matrix2[k][l] = temp; } } //Notify user cout << "Input file open, reading matrices...Done!" << endl << "Read in 2 matrices..."<< endl; //Output the values read in for Matrix 1 for (int i = 0; i <= 3; i++) { for (int j = 0; j <= 3; j ++) { cout << setprecision(1) << matrix1[i][j] << setw(8); } cout << "\n"; } cout << setw(40)<< setfill('-') << "-" << endl ; //Output the values read in for Matrix 2 for (int i = 0; i <= 3; i++) { for (int j = 0; j <= 3; j ++) { cout << setfill(' ') << setprecision(2) << matrix2[i][j] << setw(8); } cout << "\n"; } cout << setw(40)<< setfill('-') << "-" << endl ; //Multiply matrix 1 by the multiplier value constmultiply (matrix1, rsize, matrix3, rsize, multiplier); //Output matrix 3 values to screen for (int i = 0; i <= 3; i++) { for (int j = 0; j <= 3; j ++) { cout << setfill(' ') << setprecision(2) << matrix3[i][j] << setw(8); } cout << "\n"; } cout << setw(40)<< setfill('-') << "-" << endl ; // //Add matrix1 and matrix2 // addmatrices (matrix1, 4, matrix2, 4, matrix3, 4); // //Finished adding. Now output matrix 3 values to screen // for (int i = 0; i <= 3; i++) // { //for (int j = 0; j <= 3; j ++) //{ // cout << setfill(' ') << setprecision(2) << matrix3[i][j] << setw(8); //} //cout << "\n"; // } // cout << setw(40)<< setfill('-') << "-" << endl ; //Close the input file infile.close(); return 0; } //Function implementation void constmultiply (double matrixA[][4], int asize, double matrixC[][4], int bsize, double multiplier) { //Loop through each row and multiply the value at that location with the multiplier for (int i = 0; i < asize; i++) { for (int j = 0; j < 4; j++) { matrixC[i][j] = matrixA[i][j] * multiplier; } } } int addmatrices (double matrixA[][4], int asize, double matrixB[]4], int bsize, double matrixC[][4], int csize) { //Remember that you can only add two matrices that have the same shape - i.e. They need to have an equal //number of rows and columns. Let's add some error checking for that: if(asize != bsize) { cout << "You are attempting to add two matrices that are not equal in shape. Program terminating!" << endl; return exit(UNEQUAL_MATRIX_SIZE); } //Confirmed that the matrices are of equal size, so begin adding elements for (int i = 0; i < asize; i++) { for (int j = 0; j < bsize; j++) { matrixC[i][j] = matrixA[i][j] + matrixB[i][j]; } } }

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• C++ pointers on example

  - by terence6

  I have a sample code : #include <iostream> #include <conio.h> using namespace std; int main () { int firstvalue = 5, secondvalue = 15; int * p1, * p2; p1 = &firstvalue; p2 = &secondvalue; cout << "1.p1: " << p1 << ", p2: " << p2 << endl; cout << "1.*p1: " << *p1 << ", *p2: " << *p2 << endl; *p1 = 10; cout << "2.p1: " << p1 << ", p2: " << p2 << endl; cout << "2.*p1: " << *p1 << ", *p2: " << *p2 << endl; *p2 = *p1; cout << "3.p1: " << p1 << ", p2: " << p2 << endl; cout << "3.*p1: " << *p1 << ", *p2: " << *p2 << endl; p1 = p2; cout << "4.p1: " << p1 << ", p2: " << p2 << endl; cout << "4.*p1: " << *p1 << ", *p2: " << *p2 << endl; *p1 = 20; cout << "5.p1: " << p1 << ", p2: " << p2 << endl; cout << "5.*p1: " << *p1 << ", *p2: " << *p2 << endl; cout << "firstvalue is " << firstvalue << endl; cout << "secondvalue is " << secondvalue << endl; cout << "firstvalue is " << &firstvalue << endl; cout << "secondvalue is " << &secondvalue << endl; getch(); return 0; } And here's the output : 1.p1: 0041FB40, p2: 0041FB34 1.*p1: 5, *p2: 15 2.p1: 0041FB40, p2: 0041FB34 2.*p1: 10, *p2: 15 3.p1: 0041FB40, p2: 0041FB34 3.*p1: 10, *p2: 10 4.p1: 0041FB34, p2: 0041FB34 4.*p1: 10, *p2: 10 5.p1: 0041FB34, p2: 0041FB34 5.*p1: 20, *p2: 20 firstvalue is 10 secondvalue is 20 firstvalue is 0041FB40 secondvalue is 0041FB34 What is copied in the line "p1 = p2" ? Does p1 become reference to p2 or does it work in different way ?

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• Implicit constructor available for all types derived from Base excepted the current type?

  - by Vincent

  The following code sum up my problem : template<class Parameter> class Base {}; template<class Parameter1, class Parameter2, class Parameter> class Derived1 : public Base<Parameter> { }; template<class Parameter1, class Parameter2, class Parameter> class Derived2 : public Base<Parameter> { public : // Copy constructor Derived2(const Derived2& x); // An EXPLICIT constructor that does a special conversion for a Derived2 // with other template parameters template<class OtherParameter1, class OtherParameter2, class OtherParameter> explicit Derived2( const Derived2<OtherParameter1, OtherParameter2, OtherParameter>& x ); // Now the problem : I want an IMPLICIT constructor that will work for every // type derived from Base EXCEPT // Derived2<OtherParameter1, OtherParameter2, OtherParameter> template<class Type, class = typename std::enable_if</* SOMETHING */>::type> Derived2(const Type& x); }; How to restrict an implicit constructor to all classes derived from the parent class excepted the current class whatever its template parameters, considering that I already have an explicit constructor as in the example code ? EDIT : For the implicit constructor from Base, I can obviously write : template<class OtherParameter> Derived2(const Base<OtherParameter>& x); But in that case, do I have the guaranty that the compiler will not use this constructor as an implicit constructor for Derived2<OtherParameter1, OtherParameter2, OtherParameter> ? EDIT2: Here I have a test : (LWS here : http://liveworkspace.org/code/cd423fb44fb4c97bc3b843732d837abc) #include <iostream> template<typename Type> class Base {}; template<typename Type> class Other : public Base<Type> {}; template<typename Type> class Derived : public Base<Type> { public: Derived() {std::cout<<"empty"<<std::endl;} Derived(const Derived<Type>& x) {std::cout<<"copy"<<std::endl;} template<typename OtherType> explicit Derived(const Derived<OtherType>& x) {std::cout<<"explicit"<<std::endl;} template<typename OtherType> Derived(const Base<OtherType>& x) {std::cout<<"implicit"<<std::endl;} }; int main() { Other<int> other0; Other<double> other1; std::cout<<"1 = "; Derived<int> dint1; // <- empty std::cout<<"2 = "; Derived<int> dint2; // <- empty std::cout<<"3 = "; Derived<double> ddouble; // <- empty std::cout<<"4 = "; Derived<double> ddouble1(ddouble); // <- copy std::cout<<"5 = "; Derived<double> ddouble2(dint1); // <- explicit std::cout<<"6 = "; ddouble = other0; // <- implicit std::cout<<"7 = "; ddouble = other1; // <- implicit std::cout<<"8 = "; ddouble = ddouble2; // <- nothing (normal : default assignment) std::cout<<"\n9 = "; ddouble = Derived<double>(dint1); // <- explicit std::cout<<"10 = "; ddouble = dint2; // <- implicit : WHY ?!?! return 0; } The last line worry me. Is it ok with the C++ standard ? Is it a bug of g++ ?

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• GLSL compiler messages from different vendors [on hold]

  - by revers

  I'm writing a GLSL shader editor and I want to parse GLSL compiler messages to make hyperlinks to invalid lines in a shader code. I know that these messages are vendor specific but currently I have access only to AMD's video cards. I want to handle at least NVidia's and Intel's hardware, apart from AMD's. If you have video card from different vendor than AMD, could you please give me the output of following C++ program: #include <GL/glew.h> #include <GL/freeglut.h> #include <iostream> using namespace std; #define STRINGIFY(X) #X static const char* fs = STRINGIFY( out vec4 out_Color; mat4 m; void main() { vec3 v3 = vec3(1.0); vec2 v2 = v3; out_Color = vec4(5.0 * v2.x, 1.0); vec3 k = 3.0; float = 5; } ); static const char* vs = STRINGIFY( in vec3 in_Position; void main() { vec3 v(5); gl_Position = vec4(in_Position, 1.0); } ); void printShaderInfoLog(GLint shader) { int infoLogLen = 0; int charsWritten = 0; GLchar *infoLog; glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLogLen); if (infoLogLen > 0) { infoLog = new GLchar[infoLogLen]; glGetShaderInfoLog(shader, infoLogLen, &charsWritten, infoLog); cout << "Log:\n" << infoLog << endl; delete [] infoLog; } } void printProgramInfoLog(GLint program) { int infoLogLen = 0; int charsWritten = 0; GLchar *infoLog; glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLogLen); if (infoLogLen > 0) { infoLog = new GLchar[infoLogLen]; glGetProgramInfoLog(program, infoLogLen, &charsWritten, infoLog); cout << "Program log:\n" << infoLog << endl; delete [] infoLog; } } void initShaders() { GLuint v = glCreateShader(GL_VERTEX_SHADER); GLuint f = glCreateShader(GL_FRAGMENT_SHADER); GLint vlen = strlen(vs); GLint flen = strlen(fs); glShaderSource(v, 1, &vs, &vlen); glShaderSource(f, 1, &fs, &flen); GLint compiled; glCompileShader(v); bool succ = true; glGetShaderiv(v, GL_COMPILE_STATUS, &compiled); if (!compiled) { cout << "Vertex shader not compiled." << endl; succ = false; } printShaderInfoLog(v); glCompileShader(f); glGetShaderiv(f, GL_COMPILE_STATUS, &compiled); if (!compiled) { cout << "Fragment shader not compiled." << endl; succ = false; } printShaderInfoLog(f); GLuint p = glCreateProgram(); glAttachShader(p, v); glAttachShader(p, f); glLinkProgram(p); glUseProgram(p); printProgramInfoLog(p); if (!succ) { exit(-1); } delete [] vs; delete [] fs; } int main(int argc, char* argv[]) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA); glutInitWindowSize(600, 600); glutCreateWindow("Triangle Test"); glewInit(); GLenum err = glewInit(); if (GLEW_OK != err) { cout << "glewInit failed, aborting." << endl; exit(1); } cout << "Using GLEW " << glewGetString(GLEW_VERSION) << endl; const GLubyte* renderer = glGetString(GL_RENDERER); const GLubyte* vendor = glGetString(GL_VENDOR); const GLubyte* version = glGetString(GL_VERSION); const GLubyte* glslVersion = glGetString(GL_SHADING_LANGUAGE_VERSION); GLint major, minor; glGetIntegerv(GL_MAJOR_VERSION, &major); glGetIntegerv(GL_MINOR_VERSION, &minor); cout << "GL Vendor : " << vendor << endl; cout << "GL Renderer : " << renderer << endl; cout << "GL Version : " << version << endl; cout << "GL Version : " << major << "." << minor << endl; cout << "GLSL Version : " << glslVersion << endl; initShaders(); return 0; } On my video card it gives: Status: Using GLEW 1.7.0 GL Vendor : ATI Technologies Inc. GL Renderer : ATI Radeon HD 4250 GL Version : 3.3.11631 Compatibility Profile Context GL Version : 3.3 GLSL Version : 3.30 Vertex shader not compiled. Log: Vertex shader failed to compile with the following errors: ERROR: 0:1: error(#132) Syntax error: '5' parse error ERROR: error(#273) 1 compilation errors. No code generated Fragment shader not compiled. Log: Fragment shader failed to compile with the following errors: WARNING: 0:1: warning(#402) Implicit truncation of vector from size 3 to size 2. ERROR: 0:1: error(#174) Not enough data provided for construction constructor WARNING: 0:1: warning(#402) Implicit truncation of vector from size 1 to size 3. ERROR: 0:1: error(#132) Syntax error: '=' parse error ERROR: error(#273) 2 compilation errors. No code generated Program log: Vertex and Fragment shader(s) were not successfully compiled before glLinkProgram() was called. Link failed. Or if you like, you could give me other compiler messages than proposed by me. To summarize, the question is: What are GLSL compiler messages formats (INFOs, WARNINGs, ERRORs) for different vendors? Please give me examples or pattern explanation. EDIT: Ok, it seems that this question is too broad, then shortly: How does NVidia's and Intel's GLSL compilers present ERROR and WARNING messages? AMD/ATI uses patterns like this: ERROR: <position>:<line_number>: <message> WARNING: <position>:<line_number>: <message> (examples are above).

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• How does gluLookAt work?

  - by Chan

  From my understanding, gluLookAt( eye_x, eye_y, eye_z, center_x, center_y, center_z, up_x, up_y, up_z ); is equivalent to: glRotatef(B, 0.0, 0.0, 1.0); glRotatef(A, wx, wy, wz); glTranslatef(-eye_x, -eye_y, -eye_z); But when I print out the ModelView matrix, the call to glTranslatef() doesn't seem to work properly. Here is the code snippet: #include <stdlib.h> #include <stdio.h> #include <GL/glut.h> #include <iomanip> #include <iostream> #include <string> using namespace std; static const int Rx = 0; static const int Ry = 1; static const int Rz = 2; static const int Ux = 4; static const int Uy = 5; static const int Uz = 6; static const int Ax = 8; static const int Ay = 9; static const int Az = 10; static const int Tx = 12; static const int Ty = 13; static const int Tz = 14; void init() { glClearColor(0.0, 0.0, 0.0, 0.0); glEnable(GL_DEPTH_TEST); glShadeModel(GL_SMOOTH); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); GLfloat lmodel_ambient[] = { 0.8, 0.0, 0.0, 0.0 }; glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient); } void displayModelviewMatrix(float MV[16]) { int SPACING = 12; cout << left; cout << "\tMODELVIEW MATRIX\n"; cout << "--------------------------------------------------" << endl; cout << setw(SPACING) << "R" << setw(SPACING) << "U" << setw(SPACING) << "A" << setw(SPACING) << "T" << endl; cout << "--------------------------------------------------" << endl; cout << setw(SPACING) << MV[Rx] << setw(SPACING) << MV[Ux] << setw(SPACING) << MV[Ax] << setw(SPACING) << MV[Tx] << endl; cout << setw(SPACING) << MV[Ry] << setw(SPACING) << MV[Uy] << setw(SPACING) << MV[Ay] << setw(SPACING) << MV[Ty] << endl; cout << setw(SPACING) << MV[Rz] << setw(SPACING) << MV[Uz] << setw(SPACING) << MV[Az] << setw(SPACING) << MV[Tz] << endl; cout << setw(SPACING) << MV[3] << setw(SPACING) << MV[7] << setw(SPACING) << MV[11] << setw(SPACING) << MV[15] << endl; cout << "--------------------------------------------------" << endl; cout << endl; } void reshape(int w, int h) { float ratio = static_cast<float>(w)/h; glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0, ratio, 1.0, 425.0); } void draw() { float m[16]; glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glGetFloatv(GL_MODELVIEW_MATRIX, m); gluLookAt( 300.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f ); glColor3f(1.0, 0.0, 0.0); glutSolidCube(100.0); glGetFloatv(GL_MODELVIEW_MATRIX, m); displayModelviewMatrix(m); glutSwapBuffers(); } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(400, 400); glutInitWindowPosition(100, 100); glutCreateWindow("Demo"); glutReshapeFunc(reshape); glutDisplayFunc(draw); init(); glutMainLoop(); return 0; } No matter what value I use for the eye vector: 300, 0, 0 or 0, 300, 0 or 0, 0, 300 the translation vector is the same, which doesn't make any sense because the order of code is in backward order so glTranslatef should run first, then the 2 rotations. Plus, the rotation matrix, is completely independent of the translation column (in the ModelView matrix), then what would cause this weird behavior? Here is the output with the eye vector is (0.0f, 300.0f, 0.0f) MODELVIEW MATRIX -------------------------------------------------- R U A T -------------------------------------------------- 0 0 0 0 0 0 0 0 0 1 0 -300 0 0 0 1 -------------------------------------------------- I would expect the T column to be (0, -300, 0)! So could anyone help me explain this? The implementation of gluLookAt from http://www.mesa3d.org void GLAPIENTRY gluLookAt(GLdouble eyex, GLdouble eyey, GLdouble eyez, GLdouble centerx, GLdouble centery, GLdouble centerz, GLdouble upx, GLdouble upy, GLdouble upz) { float forward[3], side[3], up[3]; GLfloat m[4][4]; forward[0] = centerx - eyex; forward[1] = centery - eyey; forward[2] = centerz - eyez; up[0] = upx; up[1] = upy; up[2] = upz; normalize(forward); /* Side = forward x up */ cross(forward, up, side); normalize(side); /* Recompute up as: up = side x forward */ cross(side, forward, up); __gluMakeIdentityf(&m[0][0]); m[0][0] = side[0]; m[1][0] = side[1]; m[2][0] = side[2]; m[0][1] = up[0]; m[1][1] = up[1]; m[2][1] = up[2]; m[0][2] = -forward[0]; m[1][2] = -forward[1]; m[2][2] = -forward[2]; glMultMatrixf(&m[0][0]); glTranslated(-eyex, -eyey, -eyez); }

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• Templated << friend not working when in interrelationship with other templated union types

  - by Dwight

  While working on my basic vector library, I've been trying to use a nice syntax for swizzle-based printing. The problem occurs when attempting to print a swizzle of a different dimension than the vector in question. In GCC 4.0, I originally had the friend << overloaded functions (with a body, even though it duplicated code) for every dimension in each vector, which caused the code to work, even if the non-native dimension code never actually was called. This failed in GCC 4.2. I recently realized (silly me) that only the function declaration was needed, not the body of the code, so I did that. Now I get the same warning on both GCC 4.0 and 4.2: LINE 50 warning: friend declaration 'std::ostream& operator<<(std::ostream&, const VECTOR3<TYPE>&)' declares a non-template function Plus the five identical warnings more for the other function declarations. The below example code shows off exactly what's going on and has all code necessary to reproduce the problem. #include <iostream> // cout, endl #include <sstream> // ostream, ostringstream, string using std::cout; using std::endl; using std::string; using std::ostream; // Predefines template <typename TYPE> union VECTOR2; template <typename TYPE> union VECTOR3; template <typename TYPE> union VECTOR4; typedef VECTOR2<float> vec2; typedef VECTOR3<float> vec3; typedef VECTOR4<float> vec4; template <typename TYPE> union VECTOR2 { private: struct { TYPE x, y; } v; struct s1 { protected: TYPE x, y; }; struct s2 { protected: TYPE x, y; }; struct s3 { protected: TYPE x, y; }; struct s4 { protected: TYPE x, y; }; struct X : s1 { operator TYPE() const { return s1::x; } }; struct XX : s2 { operator VECTOR2<TYPE>() const { return VECTOR2<TYPE>(s2::x, s2::x); } }; struct XXX : s3 { operator VECTOR3<TYPE>() const { return VECTOR3<TYPE>(s3::x, s3::x, s3::x); } }; struct XXXX : s4 { operator VECTOR4<TYPE>() const { return VECTOR4<TYPE>(s4::x, s4::x, s4::x, s4::x); } }; public: VECTOR2() {} VECTOR2(const TYPE& x, const TYPE& y) { v.x = x; v.y = y; } X x; XX xx; XXX xxx; XXXX xxxx; // Overload for cout friend ostream& operator<<(ostream& os, const VECTOR2<TYPE>& toString) { os << "(" << toString.v.x << ", " << toString.v.y << ")"; return os; } friend ostream& operator<<(ostream& os, const VECTOR3<TYPE>& toString); friend ostream& operator<<(ostream& os, const VECTOR4<TYPE>& toString); }; template <typename TYPE> union VECTOR3 { private: struct { TYPE x, y, z; } v; struct s1 { protected: TYPE x, y, z; }; struct s2 { protected: TYPE x, y, z; }; struct s3 { protected: TYPE x, y, z; }; struct s4 { protected: TYPE x, y, z; }; struct X : s1 { operator TYPE() const { return s1::x; } }; struct XX : s2 { operator VECTOR2<TYPE>() const { return VECTOR2<TYPE>(s2::x, s2::x); } }; struct XXX : s3 { operator VECTOR3<TYPE>() const { return VECTOR3<TYPE>(s3::x, s3::x, s3::x); } }; struct XXXX : s4 { operator VECTOR4<TYPE>() const { return VECTOR4<TYPE>(s4::x, s4::x, s4::x, s4::x); } }; public: VECTOR3() {} VECTOR3(const TYPE& x, const TYPE& y, const TYPE& z) { v.x = x; v.y = y; v.z = z; } X x; XX xx; XXX xxx; XXXX xxxx; // Overload for cout friend ostream& operator<<(ostream& os, const VECTOR3<TYPE>& toString) { os << "(" << toString.v.x << ", " << toString.v.y << ", " << toString.v.z << ")"; return os; } friend ostream& operator<<(ostream& os, const VECTOR2<TYPE>& toString); friend ostream& operator<<(ostream& os, const VECTOR4<TYPE>& toString); }; template <typename TYPE> union VECTOR4 { private: struct { TYPE x, y, z, w; } v; struct s1 { protected: TYPE x, y, z, w; }; struct s2 { protected: TYPE x, y, z, w; }; struct s3 { protected: TYPE x, y, z, w; }; struct s4 { protected: TYPE x, y, z, w; }; struct X : s1 { operator TYPE() const { return s1::x; } }; struct XX : s2 { operator VECTOR2<TYPE>() const { return VECTOR2<TYPE>(s2::x, s2::x); } }; struct XXX : s3 { operator VECTOR3<TYPE>() const { return VECTOR3<TYPE>(s3::x, s3::x, s3::x); } }; struct XXXX : s4 { operator VECTOR4<TYPE>() const { return VECTOR4<TYPE>(s4::x, s4::x, s4::x, s4::x); } }; public: VECTOR4() {} VECTOR4(const TYPE& x, const TYPE& y, const TYPE& z, const TYPE& w) { v.x = x; v.y = y; v.z = z; v.w = w; } X x; XX xx; XXX xxx; XXXX xxxx; // Overload for cout friend ostream& operator<<(ostream& os, const VECTOR4& toString) { os << "(" << toString.v.x << ", " << toString.v.y << ", " << toString.v.z << ", " << toString.v.w << ")"; return os; } friend ostream& operator<<(ostream& os, const VECTOR2<TYPE>& toString); friend ostream& operator<<(ostream& os, const VECTOR3<TYPE>& toString); }; // Test code int main (int argc, char * const argv[]) { vec2 my2dVector(1, 2); cout << my2dVector.x << endl; cout << my2dVector.xx << endl; cout << my2dVector.xxx << endl; cout << my2dVector.xxxx << endl; vec3 my3dVector(3, 4, 5); cout << my3dVector.x << endl; cout << my3dVector.xx << endl; cout << my3dVector.xxx << endl; cout << my3dVector.xxxx << endl; vec4 my4dVector(6, 7, 8, 9); cout << my4dVector.x << endl; cout << my4dVector.xx << endl; cout << my4dVector.xxx << endl; cout << my4dVector.xxxx << endl; return 0; } The code WORKS and produces the correct output, but I prefer warning free code whenever possible. I followed the advice the compiler gave me (summarized here and described by forums and StackOverflow as the answer to this warning) and added the two things that supposedly tells the compiler what's going on. That is, I added the function definitions as non-friends after the predefinitions of the templated unions: template <typename TYPE> ostream& operator<<(ostream& os, const VECTOR2<TYPE>& toString); template <typename TYPE> ostream& operator<<(ostream& os, const VECTOR3<TYPE>& toString); template <typename TYPE> ostream& operator<<(ostream& os, const VECTOR4<TYPE>& toString); And, to each friend function that causes the issue, I added the <> after the function name, such as for VECTOR2's case: friend ostream& operator<< <> (ostream& os, const VECTOR3<TYPE>& toString); friend ostream& operator<< <> (ostream& os, const VECTOR4<TYPE>& toString); However, doing so leads to errors, such as: LINE 139: error: no match for 'operator<<' in 'std::cout << my2dVector.VECTOR2<float>::xxx' What's going on? Is it something related to how these templated union class-like structures are interrelated, or is it due to the unions themselves? Update After rethinking the issues involved and listening to the various suggestions of Potatoswatter, I found the final solution. Unlike just about every single cout overload example on the internet, I don't need access to the private member information, but can use the public interface to do what I wish. So, I make a non-friend overload functions that are inline for the swizzle parts that call the real friend overload functions. This bypasses the issues the compiler has with templated friend functions. I've added to the latest version of my project. It now works on both versions of GCC I tried with no warnings. The code in question looks like this: template <typename SWIZZLE> inline typename EnableIf< Is2D< typename SWIZZLE::PARENT >, ostream >::type& operator<<(ostream& os, const SWIZZLE& printVector) { os << (typename SWIZZLE::PARENT(printVector)); return os; } template <typename SWIZZLE> inline typename EnableIf< Is3D< typename SWIZZLE::PARENT >, ostream >::type& operator<<(ostream& os, const SWIZZLE& printVector) { os << (typename SWIZZLE::PARENT(printVector)); return os; } template <typename SWIZZLE> inline typename EnableIf< Is4D< typename SWIZZLE::PARENT >, ostream >::type& operator<<(ostream& os, const SWIZZLE& printVector) { os << (typename SWIZZLE::PARENT(printVector)); return os; }

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• operator overloading of stream extraction operator in C++ help

  - by Crystal

  I'm having some trouble overloading my stream extraction operator in C++ for a hw assignment. I'm not really sure why I am getting these compile errors since I thought I was doing it right... Here is my code: Complex.h #ifndef COMPLEX_H #define COMPLEX_H class Complex { //friend ostream &operator<<(ostream &output, const Complex &complexObj) const; public: Complex(double = 0.0, double = 0.0); // constructor Complex operator+(const Complex &) const; // addition Complex operator-(const Complex &) const; // subtraction void print() const; // output private: double real; // real part double imaginary; // imaginary part }; #endif Complex.cpp #include <iostream> #include "Complex.h" using namespace std; // Constructor Complex::Complex(double realPart, double imaginaryPart) : real(realPart), imaginary(imaginaryPart) { } // addition operator Complex Complex::operator+(const Complex &operand2) const { return Complex(real + operand2.real, imaginary + operand2.imaginary); } // subtraction operator Complex Complex::operator-(const Complex &operand2) const { return Complex(real - operand2.real, imaginary - operand2.imaginary); } // Overload << operator ostream &Complex::operator<<(ostream &output, const Complex &complexObj) const { cout << '(' << complexObj.real << ", " << complexObj.imaginary << ')'; return output; // returning output allows chaining } // display a Complex object in the form: (a, b) void Complex::print() const { cout << '(' << real << ", " << imaginary << ')'; } main.cpp #include <iostream> #include "Complex.h" using namespace std; int main() { Complex x; Complex y(4.3, 8.2); Complex z(3.3, 1.1); cout << "x: "; x.print(); cout << "\ny: "; y.print(); cout << "\nz: "; z.print(); x = y + z; cout << "\n\nx = y + z: " << endl; x.print(); cout << " = "; y.print(); cout << " + "; z.print(); x = y - z; cout << "\n\nx = y - z: " << endl; x.print(); cout << " = "; y.print(); cout << " - "; z.print(); cout << endl; } Compile erros: complex.cpp(23) : error C2039: '<<' : is not a member of 'Complex' complex.h(5) : see declaration of 'Complex' complex.cpp(24) : error C2270: '<<' : modifiers not allowed on nonmember functions complex.cpp(25) : error C2248: 'Complex::real' : cannot access private member declared in class 'Complex' complex.h(13) : see declaration of 'Complex::real' complex.h(5) : see declaration of 'Complex' complex.cpp(25) : error C2248: 'Complex::imaginary' : cannot access private member declared in class 'Complex' complex.h(14) : see declaration of 'Complex::imaginary' complex.h(5) : see declaration of 'Complex' Thanks!

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• how can udp data can passed through RS232 in ansi c?

  - by moon

  i want to transmit and receive data on RS232 using udp and i want to know about techniques which allow me to transmit and receive data on a faster rate and also no lose of data is there? thanx in advance. i have tried but need improvements if possible #include <stdio.h> #include <dos.h> #include<string.h> #include<conio.h> #include<iostream.h> #include<stdlib.h> #define PORT1 0x3f8 void main() { int c,ch,choice,i,a=0; char filename[30],filename2[30],buf; FILE *in,*out; clrscr(); while(1){ outportb(PORT1+0,0x03); outportb(PORT1+1,0); outportb(PORT1+3,0x03); outportb(PORT1+2,0xc7); outportb(PORT1+4,0x0b); cout<<"\n==============================================================="; cout<<"\n\t*****Serial Communication By BADR-U-ZAMAN******\nCommunication between two computers By serial port"; cout<<"\nPlease select\n[1]\tFor sending file \n[2]\tFor receiving file \n[3]\tTo exit\n"; cout<<"=================================================================\n"; cin>>choice; if(choice==1) { strcpy(filename,"C:\\TC\\BIN\\badr.cpp"); cout<<filename; for(i=0;i<=strlen(filename);i++) outportb(PORT1,filename[i]); in=fopen(filename,"r"); if (in==NULL) { cout<<"cannot open a file"; a=1; } if(a!=1) cout<<"\n\nFile sending.....\n\n"; while(!feof(in)) { buf=fgetc(in); cout<<buf; outportb(PORT1,buf); delay(5); } } else { if(choice==3) exit(0); i=0; buf='a'; while(buf!=NULL) { c=inportb(PORT1+5); if(c&1) { buf=inportb(PORT1); filename2[i]=buf; i++; } } out=fopen(filename2,"t"); cout<<"\n Filename received:"<<filename[2]; cout<<"\nReading from the port..."; cout<<"writing to file"<<filename2; do { c=inportb(PORT1+5); if(c&1) { buf=inportb(PORT1); cout<<buf; fputc(buf,out); delay(5); } if(kbhit()) { ch=getch(); } }while(ch!=27); } getch(); } }

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• Can i use a switch to hold a function?

  - by TIMOTHY

  I have a 3 file program, basically teaching myself c++. I have an issue. I made a switch to use the math function. I need and put it in a variable, but for some reason I get a zero as a result. Also another issue, when I select 4 (divide) it crashes... Is there a reason? Main file: #include <iostream> #include "math.h" #include <string> using namespace std; int opersel; int c; int a; int b; string test; int main(){ cout << "Welcome to Math-matrix v.34"<< endl; cout << "Shall we begin?" <<endl; //ASK USER IF THEY ARE READY TO BEGIN string answer; cin >> answer; if(answer == "yes" || answer == "YES" || answer == "Yes") { cout << "excellent lets begin..." << endl; cout << "please select a operator..." << endl << endl; cout << "(1) + " << endl; cout << "(2) - " << endl; cout << "(3) * " << endl; cout << "(4) / " << endl; cin >> opersel; switch(opersel){ case 1: c = add(a,b); break; case 2: c = sub(a,b); break; case 3: c = multi(a,b); break; case 4: c = divide(a,b); break; default: cout << "error... retry" << endl; }// end retry cout << "alright, how please select first digit?" << endl; cin >> a; cout << "excellent... and your second?" << endl; cin >> b; cout << c; cin >> test; }else if (answer == "no" || answer == "NO" || answer == "No"){ }//GAME ENDS }// end of int main Here is my math.h file #ifndef MATH_H #define MATH_H int add(int a, int b); int sub(int a, int b); int multi(int a, int b); int divide(int a, int b); #endif Here is my math.cpp: int add(int a, int b) { return a + b; } int sub(int a, int b) { return a - b; } int multi(int a, int b) { return a * b; } int divide(int a, int b) { return a / b; } }// end of int main

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• Reversing a number in c++

  - by Marcel Bujnowski

  I created a program to show the sum and show the reversed number a person has typed. The sum function works but the revers function is not. Can anyone give me any tips on how to fix it. I created a program to show the sum and show the reversed number a person has typed. The sum function works but the revers function is not. Can anyone give me any tips on how to fix it. #include<iostream> #include<iomanip> using namespace std; void printSum(int n, bool reverse); int sm(int n); int reverseInt(int n); void printAddTable(int n); int main() { int reverse; int sum=0; int n; cout<<"Enter N value:"<<endl; cin>>n; if(n>0) { reverse = true; printSum( n, reverse); // calls the printSum Method } else { //cout<<"enter positive Number only:"<<endl; } sum = sm(n); //err // calls the sum Method reverse = reverseInt(n); // calls the reverseInt Method cout<<"The reverse value is:"<<reverse; printAddTable(n); // calls the printAddTable Method //getch() } //end of main() void printSum(int n, bool reverse) { int sum=0; // print sum of reverse numbers for(int i=n; i>=1; i--) { sum=sum+i; cout<<i<< " "<<"+"<<" "; } cout<<sum; } int sm(int n) {int sum =0; for(int i=1; i<=n; i++) { sum = sum + i ; cout << endl; cout<<i<<" "<<"+"<<" "<<endl; // print n positive integers cout << endl; } cout<< "Are " <<n<< " positive integers"<<endl; cout<< "Sum is "<<sum <<endl; return sum; } int reverseInt(int n) { int reminder=0; int sum =0; while(n<=0) { reminder = n/10; sum = (sum * 10) + reminder; // it returns the reverse number n = n % 10; } return sum; } void printAddTable(int n) { for(int i=1; i<=n; i++) { cout<<i<<endl; for(int j=1; j<=n; j++) // print n X n add table { cout<<i+j<<endl; } } } {

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• Program instantly closing [migrated]

  - by Ben Clayton

  I made this program and when I compiled it there were no errors but the program just instantly closed, any answers would be appreciated. #include <iostream> //Main commands #include <string> // String commands #include <windows.h> // Sleep using namespace std; int main () { //Declaring variables float a; bool end; std::string input; end = false; // Making sure program doesn't end instantly cout << "Enter start then the number you want to count down from." << ".\n"; while (end = false){ cin >> input; cout << ".\n"; if (input.find("end") != std::string::npos) // Ends the program if user types end end = true; else if (input.find("start" || /* || is or operator*/ "restart") != std::string::npos) // Sets up the countdown timer if the user types start { cin >> a; cout << ".\n"; while (a>0){ Sleep(100); a = a - 0.1; cout << a << ".\n"; } cout << "Finished! Enter restart and then another number, or enter end to close the program" << ".\n"; } else // Tells user to start program cout << "Enter start"; } return 0; // Ends program when (end = true) }

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• assistance required, hangman game.

  - by Phillip Gibson

  I am making a hangman game and am having trouble with part of it. I have selected a random word from a file, but I want to display the word as a series of undersocres __ and then match the letter chosen to a position in the undersocres. Can anyone help me? cout <<"1. Select to play the game\n"; cout <<"2. Ask for help\n"; cout <<"3. Select to quit the game\n"; cout << "Enter a selection: "; int number; cin >> number; while(number < 1 || number > 3 || cin.fail()) { if(cin.fail()) { cin.sync(); cin.clear(); cout << "You have not entered a number, please enter a menu selection between 1 and 3\n"; cin >> number; } else { cout << "Your selection must be between 1 and 3!\n"; cin >> number; } } switch (number) { case 1: { string word; string name; cout << " Whats your name? "; cin >> name; Player player(); ifstream FileReader; FileReader.open("words.txt"); if(!FileReader.is_open()) cout << "Error"; //this is for the random selection of words srand(time(0)); int randnum = rand()%10+1; for(int counter = 0; counter < randnum; counter++) { getline(FileReader, word, '\n'); } cout << "my word: " << word << "\n"; // get length of word int length; //create for loop for(int i = 0; i < length; i++) cout << "_"; //_ _ _ _ _ SetCursorPos(2,10); FileReader.close(); break;

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• [C++] A minimalistic smart array (container) class template

  - by legends2k

  I've written a (array) container class template (lets call it smart array) for using it in the BREW platform (which doesn't allow many C++ constructs like STD library, exceptions, etc. It has a very minimal C++ runtime support); while writing this my friend said that something like this already exists in Boost called MultiArray, I tried it but the ARM compiler (RVCT) cries with 100s of errors. I've not seen Boost.MultiArray's source, I've just started learning template only lately; template meta programming interests me a lot, although am not sure if this is strictly one, which can be categorised thus. So I want all my fellow C++ aficionados to review it ~ point out flaws, potential bugs, suggestions, optimisations, etc.; somthing like "you've not written your own Big Three which might lead to...". Possibly any criticism that'll help me improve this class and thereby my C++ skills. smart_array.h #include <vector> using std::vector; template <typename T, size_t N> class smart_array { vector < smart_array<T, N - 1> > vec; public: explicit smart_array(vector <size_t> &dimensions) { assert(N == dimensions.size()); vector <size_t>::iterator it = ++dimensions.begin(); vector <size_t> dimensions_remaining(it, dimensions.end()); smart_array <T, N - 1> temp_smart_array(dimensions_remaining); vec.assign(dimensions[0], temp_smart_array); } explicit smart_array(size_t dimension_1 = 1, ...) { static_assert(N > 0, "Error: smart_array expects 1 or more dimension(s)"); assert(dimension_1 > 1); va_list dim_list; vector <size_t> dimensions_remaining(N - 1); va_start(dim_list, dimension_1); for(size_t i = 0; i < N - 1; ++i) { size_t dimension_n = va_arg(dim_list, size_t); assert(dimension_n > 0); dimensions_remaining[i] = dimension_n; } va_end(dim_list); smart_array <T, N - 1> temp_smart_array(dimensions_remaining); vec.assign(dimension_1, temp_smart_array); } smart_array<T, N - 1>& operator[](size_t index) { assert(index < vec.size() && index >= 0); return vec[index]; } size_t length() const { return vec.size(); } }; template<typename T> class smart_array<T, 1> { vector <T> vec; public: explicit smart_array(vector <size_t> &dimension) : vec(dimension[0]) { assert(dimension[0] > 0); } explicit smart_array(size_t dimension_1 = 1) : vec(dimension_1) { assert(dimension_1 > 0); } T& operator[](size_t index) { assert(index < vec.size() && index >= 0); return vec[index]; } size_t length() { return vec.size(); } }; Sample Usage: #include <iostream> using std::cout; using std::endl; int main() { // testing 1 dimension smart_array <int, 1> x(3); x[0] = 0, x[1] = 1, x[2] = 2; cout << "x.length(): " << x.length() << endl; // testing 2 dimensions smart_array <float, 2> y(2, 3); y[0][0] = y[0][1] = y[0][2] = 0; y[1][0] = y[1][1] = y[1][2] = 1; cout << "y.length(): " << y.length() << endl; cout << "y[0].length(): " << y[0].length() << endl; // testing 3 dimensions smart_array <char, 3> z(2, 4, 5); cout << "z.length(): " << z.length() << endl; cout << "z[0].length(): " << z[0].length() << endl; cout << "z[0][0].length(): " << z[0][0].length() << endl; z[0][0][4] = 'c'; cout << z[0][0][4] << endl; // testing 4 dimensions smart_array <bool, 4> r(2, 3, 4, 5); cout << "z.length(): " << r.length() << endl; cout << "z[0].length(): " << r[0].length() << endl; cout << "z[0][0].length(): " << r[0][0].length() << endl; cout << "z[0][0][0].length(): " << r[0][0][0].length() << endl; // testing copy constructor smart_array <float, 2> copy_y(y); cout << "copy_y.length(): " << copy_y.length() << endl; cout << "copy_x[0].length(): " << copy_y[0].length() << endl; cout << copy_y[0][0] << "\t" << copy_y[1][0] << "\t" << copy_y[0][1] << "\t" << copy_y[1][1] << "\t" << copy_y[0][2] << "\t" << copy_y[1][2] << endl; return 0; }

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• A minimalistic smart array (container) class template

  - by legends2k

  I've written a (array) container class template (lets call it smart array) for using it in the BREW platform (which doesn't allow many C++ constructs like STD library, exceptions, etc. It has a very minimal C++ runtime support); while writing this my friend said that something like this already exists in Boost called MultiArray, I tried it but the ARM compiler (RVCT) cries with 100s of errors. I've not seen Boost.MultiArray's source, I've started learning templates only lately; template meta programming interests me a lot, although am not sure if this is strictly one that can be categorized thus. So I want all my fellow C++ aficionados to review it ~ point out flaws, potential bugs, suggestions, optimizations, etc.; something like "you've not written your own Big Three which might lead to...". Possibly any criticism that will help me improve this class and thereby my C++ skills. Edit: I've used std::vector since it's easily understood, later it will be replaced by a custom written vector class template made to work in the BREW platform. Also C++0x related syntax like static_assert will also be removed in the final code. smart_array.h #include <vector> #include <cassert> #include <cstdarg> using std::vector; template <typename T, size_t N> class smart_array { vector < smart_array<T, N - 1> > vec; public: explicit smart_array(vector <size_t> &dimensions) { assert(N == dimensions.size()); vector <size_t>::iterator it = ++dimensions.begin(); vector <size_t> dimensions_remaining(it, dimensions.end()); smart_array <T, N - 1> temp_smart_array(dimensions_remaining); vec.assign(dimensions[0], temp_smart_array); } explicit smart_array(size_t dimension_1 = 1, ...) { static_assert(N > 0, "Error: smart_array expects 1 or more dimension(s)"); assert(dimension_1 > 1); va_list dim_list; vector <size_t> dimensions_remaining(N - 1); va_start(dim_list, dimension_1); for(size_t i = 0; i < N - 1; ++i) { size_t dimension_n = va_arg(dim_list, size_t); assert(dimension_n > 0); dimensions_remaining[i] = dimension_n; } va_end(dim_list); smart_array <T, N - 1> temp_smart_array(dimensions_remaining); vec.assign(dimension_1, temp_smart_array); } smart_array<T, N - 1>& operator[](size_t index) { assert(index < vec.size() && index >= 0); return vec[index]; } size_t length() const { return vec.size(); } }; template<typename T> class smart_array<T, 1> { vector <T> vec; public: explicit smart_array(vector <size_t> &dimension) : vec(dimension[0]) { assert(dimension[0] > 0); } explicit smart_array(size_t dimension_1 = 1) : vec(dimension_1) { assert(dimension_1 > 0); } T& operator[](size_t index) { assert(index < vec.size() && index >= 0); return vec[index]; } size_t length() { return vec.size(); } }; Sample Usage: #include "smart_array.h" #include <iostream> using std::cout; using std::endl; int main() { // testing 1 dimension smart_array <int, 1> x(3); x[0] = 0, x[1] = 1, x[2] = 2; cout << "x.length(): " << x.length() << endl; // testing 2 dimensions smart_array <float, 2> y(2, 3); y[0][0] = y[0][1] = y[0][2] = 0; y[1][0] = y[1][1] = y[1][2] = 1; cout << "y.length(): " << y.length() << endl; cout << "y[0].length(): " << y[0].length() << endl; // testing 3 dimensions smart_array <char, 3> z(2, 4, 5); cout << "z.length(): " << z.length() << endl; cout << "z[0].length(): " << z[0].length() << endl; cout << "z[0][0].length(): " << z[0][0].length() << endl; z[0][0][4] = 'c'; cout << z[0][0][4] << endl; // testing 4 dimensions smart_array <bool, 4> r(2, 3, 4, 5); cout << "z.length(): " << r.length() << endl; cout << "z[0].length(): " << r[0].length() << endl; cout << "z[0][0].length(): " << r[0][0].length() << endl; cout << "z[0][0][0].length(): " << r[0][0][0].length() << endl; // testing copy constructor smart_array <float, 2> copy_y(y); cout << "copy_y.length(): " << copy_y.length() << endl; cout << "copy_x[0].length(): " << copy_y[0].length() << endl; cout << copy_y[0][0] << "\t" << copy_y[1][0] << "\t" << copy_y[0][1] << "\t" << copy_y[1][1] << "\t" << copy_y[0][2] << "\t" << copy_y[1][2] << endl; return 0; }

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• Structures not working correctly?

  - by booby

  Fraction AddFractions(const Fraction& frac1, const Fraction& frac2) { Fraction frac3; if (frac1.denom == frac2.denom) { frac3.num = frac1.num + frac2.num; frac3.denom = frac1.denom; } else { frac3.denom = (frac1.denom * frac2.denom); frac3.num = (frac1.num * frac2.denom) + (frac2.num * frac1.denom); } return frac3; } This is my prototype and there is a structure defined as Fraction with int num and int denom when I call the function it just gives me back garbage? I don't know what's wrong with it. Please help. =( cout << "Please enter two Fractions" << endl; cout << endl; GetFraction(frac1); cout << "Your fisrt fraction is: "; PrintFraction(frac1); cout << endl; cout << endl; GetFraction(frac2); cout << "Your second fraction is: "; PrintFraction(frac2); cout << endl; do { choice1 = MathMenu(); if (choice1 == ErrorOpt) { cout << "There was an error with what you have entered" << endl; } else if(choice1 != QuitOpt) { // do the math options switch (choice1) { case AddOpt: AddFractions(frac1, frac2); break; case SubtractOpt: SubtractFractions(frac1, frac2); break; case MultiplyOpt: MultiplyFractions(frac1, frac2); break; case DivideOpt: DivideFractions(frac1, frac2); break; } //print the results PrintFraction(frac1); PrintMathOption(choice1); PrintFraction(frac2); cout << " = "; Standardize(frac3); Reduce(frac3); PrintFraction(frac3); cout << endl; Pause();

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• How to get this wavefront .obj data onto the frustum?

  - by NoobScratcher

  I've finally figured out how to get the data from a .obj file and store the vertex positions x,y,z into a structure called Points with members x y z which are of type float. I want to know how to get this data onto the screen. Here is my attempt at doing so: //make a fileobject and store list and the index of that list in a c string ifstream file (list[index].c_str() ); std::vector<int>faces; std::vector<Point>points; points.push_back(Point()); Point p; int face[4]; while ( !file.eof() ) { char modelbuffer[10000]; //Get lines and store it in line string file.getline(modelbuffer, 10000); switch(modelbuffer[0]) { case 'v' : sscanf(modelbuffer, "v %f %f %f", &p.x, &p.y, &p.z); points.push_back(p); cout << "Getting Vertex Positions" << endl; cout << "v" << p.x << endl; cout << "v" << p.y << endl; cout << "v" << p.z << endl; break; case 'f': sscanf(modelbuffer, "f %d %d %d %d", face, face+1, face+2, face+3 ); cout << face[0] << endl; cout << face[1] << endl; cout << face[2] << endl; cout << face[3] << endl; faces.push_back(face[0]); faces.push_back(face[1]); faces.push_back(face[2]); faces.push_back(face[3]); } GLuint vertexbuffer; glGenBuffers(1, &vertexbuffer); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); glBufferData(GL_ARRAY_BUFFER, points.size(), points.data(), GL_STATIC_DRAW); //glBufferData(GL_ARRAY_BUFFER,sizeof(points), &(points[0]), GL_STATIC_DRAW); glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0); glVertexPointer(3, GL_FLOAT, sizeof(points),points.data()); glIndexPointer(GL_DOUBLE, 0, faces.data()); glDrawArrays(GL_QUADS, 0, points.size()); glDrawElements(GL_QUADS, faces.size(), GL_UNSIGNED_INT, faces.data()); } As you can see I've clearly failed the end part but I really don't know why its not rendering the data onto the frustum? Does anyone have a solution for this?

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• Diamond problem in C++

  - by Jack

  I know the diamond problem. I am using gcc compiler. I have some scenarios I need explanation about. 1) class A{ public: virtual void eat(){cout<<"A eat\n";} }; class B:public A{ public: void eat(){ cout<<"B eat\n";}}; class C:public A{ public: void eat(){ cout<<"C eat\n";}}; class D:public B,C{ public: void eat(){ cout<<"D eat\n";}}; int main() { A * a = new D(); a->eat(); getch(); return 0; } Why doesn't this work? 2) class A{ public: void eat(){cout<<"A eat\n";} }; class B:virtual public A{ public: void eat(){ cout<<"B eat\n";}}; class C:virtual public A{ public: void eat(){ cout<<"C eat\n";}}; class D: public B,C{ public: void eat(){ cout<<"D eat\n";}}; int main() { A * a = new D(); a->eat(); getch(); return 0; } When I do this what happens in the background. How does the ambiguity get removed. Is the concept of vtables involved here?

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• base destructor called twice after derived object?

  - by sil3nt

  hey there, why is the base destructor called twice at the end of this program? #include <iostream> using namespace std; class B{ public: B(){ cout << "BC" << endl; x = 0; } virtual ~B(){ cout << "BD" << endl; } void f(){ cout << "BF" << endl; } virtual void g(){ cout << "BG" << endl; } private: int x; }; class D: public B{ public: D(){ cout << "dc" << endl; y = 0; } virtual ~D(){ cout << "dd" << endl; } void f(){ cout << "df" << endl; } virtual void g(){ cout << "dg" << endl; } private: int y; }; int main(){ B b, * bp = &b; D d, * dp = &d; bp->f(); bp->g(); bp = dp; bp->f(); bp->g(); }

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