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  • Pointers to class fields

    - by newbie_cpp
    My task is as follows : Using pointers to class fields, create menu allowing selection of ice, that Person can buy in Ice shop. Buyer will be charged with waffel and ice costs. Selection of ice and charging buyers account must be shown in program. Here's my Person class : #include <iostream> using namespace std; class Iceshop { const double waffel_price = 1; public: } class Person { static int NUMBER; char* name; int age; const int number; double plus, minus; public: class Account { int number; double resources; public: Account(int number, double resources) : number(number), resources(resources) {} } Person(const char* n, int age) : name(strcpy(new char[strlen(n)+1],n)), number(++NUMBER), plus(0), minus(0), age(age) {} Person::~Person(){ cout << "Destroying resources" << endl; delete [] name; } friend void show(Person &p); int* take_age(){ return &age; } char* take_name(){ return name; } void init(char* n, int a) { name = n; age = a; } Person& remittance(double d) { plus += d; return *this; } Person& paycheck(double d) { minus += d; return *this; } Account* getAccount(); }; int Person:: Person::Account* Person::getAccount() { return new Account(number, plus - minus); } void Person::Account::remittance(double d){ resources = resources + d; } void Person::Account::paycheck(double d){ resources = resources - d; } void show(Person *p){ cout << "Name: " << p->take_name() << "," << "age: " << p->take_age() << endl; } int main(void) { Person *p = new Person; p->init("Mary", 25); show(p); p->remittance(100); system("PAUSE"); return 0; } How to start this task ? Where and in what form should I store menu options ?

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  • bad file descriptor with close() socket (c++)

    - by user321246
    hi everybody! I'm running out of file descriptors when my program can't connect another host. The close() system call doesn't work, the number of open sockets increases. I can se it with cat /proc/sys/fs/file-nr Print from console: connect: No route to host close: Bad file descriptor connect: No route to host close: Bad file descriptor .. Code: #include <stdio.h> #include <stdlib.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <string.h> #include <iostream> using namespace std; #define PORT 1238 #define MESSAGE "Yow!!! Are we having fun yet?!?" #define SERVERHOST "192.168.9.101" void write_to_server (int filedes) { int nbytes; nbytes = write (filedes, MESSAGE, strlen (MESSAGE) + 1); if (nbytes < 0) { perror ("write"); } } void init_sockaddr (struct sockaddr_in *name, const char *hostname, uint16_t port) { struct hostent *hostinfo; name->sin_family = AF_INET; name->sin_port = htons (port); hostinfo = gethostbyname (hostname); if (hostinfo == NULL) { fprintf (stderr, "Unknown host %s.\n", hostname); } name->sin_addr = *(struct in_addr *) hostinfo->h_addr; } int main() { for (;;) { sleep(1); int sock; struct sockaddr_in servername; /* Create the socket. */ sock = socket (PF_INET, SOCK_STREAM, 0); if (sock < 0) { perror ("socket (client)"); } /* Connect to the server. */ init_sockaddr (&servername, SERVERHOST, PORT); if (0 > connect (sock, (struct sockaddr *) &servername, sizeof (servername))) { perror ("connect"); sock = -1; } /* Send data to the server. */ if (sock > -1) write_to_server (sock); if (close (sock) != 0) perror("close"); } return 0; }

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  • c++, object life-time of anonymous (unnamed) variables

    - by Joe Steeve
    In the following code, the object constructed in the last line of 'main()', seems to be destroyed before the end of the expression. The destructor is called before the '<<' is executed. Is this how it is supposed to be? #include <string> #include <sstream> #include <iostream> using std::string; using std::ostringstream; using std::cout; class A : public ostringstream { public: A () {} virtual ~A () { string s; s = str(); cout << "from A: " << s << std::endl; } }; int main () { string s = "Hello"; A os; os << s; cout << os.str() << std::endl; A() << "checking this"; } This is the output: Hello from A: 0x80495f7 from A: Hello This is the gdb log: (gdb) b os.cxx : 18 Breakpoint 1 at 0x80492b1: file os.cxx, line 18. (2 locations) (gdb) r Starting program: /home/joe/sandbox/test/os Hello Breakpoint 1, ~A (this=0xbffff37c, __in_chrg=<value optimized out>, __vtt_parm=<value optimized out>) at os.cxx:18 18 cout << "from A: " << s << std::endl; (gdb) p s.c_str () $1 = 0x804b45c "0x80495f7" (gdb) p *s.c_str () $2 = 48 '0' (gdb) c Continuing. from A: 0x80495f7 Breakpoint 1, ~A (this=0xbffff2bc, __in_chrg=<value optimized out>, __vtt_parm=<value optimized out>) at os.cxx:18 18 cout << "from A: " << s << std::endl; (gdb) p s.c_str () $3 = 0x804b244 "Hello" (gdb) p *s.c_str () $4 = 72 'H' (gdb) c Continuing. from A: Hello Program exited normally. (gdb)

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  • What is an overloaded operator in c++?

    - by Jeff
    I realize this is a basic question but I have searched online, been to cplusplus.com, read through my book, and I can't seem to grasp the concept of overloaded operators. A specific example from cplusplus.com is: // vectors: overloading operators example #include <iostream> using namespace std; class CVector { public: int x,y; CVector () {}; CVector (int,int); CVector operator + (CVector); }; CVector::CVector (int a, int b) { x = a; y = b; } CVector CVector::operator+ (CVector param) { CVector temp; temp.x = x + param.x; temp.y = y + param.y; return (temp); } int main () { CVector a (3,1); CVector b (1,2); CVector c; c = a + b; cout << c.x << "," << c.y; return 0; } from http://www.cplusplus.com/doc/tutorial/classes2/ but reading through it I'm still not understanding them at all. I just need a basic example of the point of the overloaded operator (which I assume is the "CVector CVector::operator+ (CVector param)"). There's also this example from wikipedia: Time operator+(const Time& lhs, const Time& rhs) { Time temp = lhs; temp.seconds += rhs.seconds; if (temp.seconds >= 60) { temp.seconds -= 60; temp.minutes++; } temp.minutes += rhs.minutes; if (temp.minutes >= 60) { temp.minutes -= 60; temp.hours++; } temp.hours += rhs.hours; return temp; } from "http://en.wikipedia.org/wiki/Operator_overloading" The current assignment I'm working on I need to overload a ++ and a -- operator. Thanks in advance for the information and sorry about the somewhat vague question, unfortunately I'm just not sure on it at all.

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  • c++ compile error

    - by Niranjan
    Hi, I am trying to develop abstract design pattern code for one of my project as below.. But, I am not able to compile the code ..giving some compile errors(like "conversion from 'ProductA1 *' to 'ProductA *' exists, but is inaccessible" ).. Can any one please help me out in this... #include "stdafx.h" #include <iostream> using namespace std; class ProductA { public: virtual void Operation1()=0; virtual void Operation2()=0; }; class ProductA1 : ProductA { public: virtual void Operation1() {cout<<"PD ProductA1 Operation1"<<endl; } virtual void Operation2() {cout<<"PD ProductA1 Operation2"<<endl; } }; class ProductA2 : ProductA { public: virtual void Operation1() {cout<<"DT ProductA2 Operation1"<<endl; } virtual void Operation2() {cout<<"DT ProductA2 Operation2"<<endl; } }; //------------------------------------------------------------- class ProductB { public: virtual void Operation3()=0; virtual void Operation4()=0; }; class ProductB1 : ProductB { public: void Operation3() { cout<<"PD ProductB1 Operation3"<<endl; } void Operation4() { cout<<"PD ProductB1 Operation4"<<endl; } }; class ProductB2 : ProductB { public: void Operation3() { cout<<"DT ProductB2 Operation3"<<endl; } void Operation4() { cout<<"DT ProductB2 Operation4"<<endl; } }; //--------------- abstrct factory --------------------------- class Factory { public: virtual ProductA* CreateA () =0; virtual ProductB* CreateB ()=0; }; class Factory1 : Factory { public: ProductA* CreateA () { return new ProductA1(); } ProductB* CreateB () { return new ProductB1(); } }; class Factory2 : Factory { public: ProductA* CreateA () { return new ProductA2(); } ProductB* CreateB () { return new ProductB2(); } }; //--------------------- client -------------------------------- int _tmain(int argc, _TCHAR* argv[]) { Factory* pf = new Factory1(); ProductA *pa = pf->CreateA(); pa->Operation1(); pa->Operation2(); ProductB *pb = pf->CreateB(); pb->Operation3(); pb->Operation4(); return 0; }

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  • Emacs, C++ code completion for vectors

    - by Caglar Toklu
    Hi, I am new to Emacs, and I have the following code as a sample. I have installed GNU Emacs 23.1.1 (i386-mingw-nt6.1.7600), installed cedet-1.0pre7.tar.gz. , installed ELPA, and company. You can find my simple Emacs configuration at the bottom. The problem is, when I type q[0] in main() and press . (dot), I see the 37 members of the vector, not Person although first_name and last_name are expected. The completion works as expected in the function greet() but it has nothing to do with vector. My question is, how can I accomplish code completion for vector elements too? #include <iostream> #include <vector> using namespace std; class Person { public: string first_name; string last_name; }; void greet(Person a_person) { // a_person.first_name is completed as expected! cout << a_person.first_name << "|"; cout << a_person.last_name << endl; }; int main() { vector<Person> q(2); Person guy1; guy1.first_name = "foo"; guy1.last_name = "bar"; Person guy2; guy2.first_name = "stack"; guy2.last_name = "overflow"; q[0] = guy1; q[1] = guy2; greet(guy1); greet(guy2); // cout q[0]. I want to see first_name or last_name here! } My Emacs configuration: ;;; This was installed by package-install.el. ;;; This provides support for the package system and ;;; interfacing with ELPA, the package archive. ;;; Move this code earlier if you want to reference ;;; packages in your .emacs. (when (load (expand-file-name "~/.emacs.d/elpa/package.el")) (package-initialize)) (load-file "~/.emacs.d/cedet/common/cedet.el") (semantic-load-enable-excessive-code-helpers) (require 'semantic-ia) (global-srecode-minor-mode 1) (semantic-add-system-include "/gcc/include/c++/4.4.2" 'c++-mode) (semantic-add-system-include "/gcc/i386-pc-mingw32/include" 'c++-mode) (semantic-add-system-include "/gcc/include" 'c++-mode) (defun my-semantic-hook () (imenu-add-to-menubar "TAGS")) (add-hook 'semantic-init-hooks 'my-semantic-hook)

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  • C++ string sort like a human being?

    - by Walter Nissen
    I would like to sort alphanumeric strings the way a human being would sort them. I.e., "A2" comes before "A10", and "a" certainly comes before "Z"! Is there any way to do with without writing a mini-parser? Ideally it would also put "A1B1" before "A1B10". I see the question "Natural (human alpha-numeric) sort in Microsoft SQL 2005" with a possible answer, but it uses various library functions, as does "Sorting Strings for Humans with IComparer". Below is a test case that currently fails: #include <set> #include <iterator> #include <iostream> #include <vector> #include <cassert> template <typename T> struct LexicographicSort { inline bool operator() (const T& lhs, const T& rhs) const{ std::ostringstream s1,s2; s1 << toLower(lhs); s2 << toLower(rhs); bool less = s1.str() < s2.str(); std::cout<<s1.str()<<" "<<s2.str()<<" "<<less<<"\n"; return less; } inline std::string toLower(const std::string& str) const { std::string newString(""); for (std::string::const_iterator charIt = str.begin(); charIt!=str.end();++charIt) { newString.push_back(std::tolower(*charIt)); } return newString; } }; int main(void) { const std::string reference[5] = {"ab","B","c1","c2","c10"}; std::vector<std::string> referenceStrings(&(reference[0]), &(reference[5])); //Insert in reverse order so we know they get sorted std::set<std::string,LexicographicSort<std::string> > strings(referenceStrings.rbegin(), referenceStrings.rend()); std::cout<<"Items:\n"; std::copy(strings.begin(), strings.end(), std::ostream_iterator<std::string>(std::cout, "\n")); std::vector<std::string> sortedStrings(strings.begin(), strings.end()); assert(sortedStrings == referenceStrings); }

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  • C++: Trouble with Pointers, loop variables, and structs

    - by Rosarch
    Consider the following example: #include <iostream> #include <sstream> #include <vector> #include <wchar.h> #include <stdlib.h> using namespace std; struct odp { int f; wchar_t* pstr; }; int main() { vector<odp> vec; ostringstream ss; wchar_t base[5]; wcscpy_s(base, L"1234"); for (int i = 0; i < 4; i++) { odp foo; foo.f = i; wchar_t loopStr[1]; foo.pstr = loopStr; // wchar_t* = wchar_t ? Why does this work? foo.pstr[0] = base[i]; vec.push_back(foo); } for (vector<odp>::iterator iter = vec.begin(); iter != vec.end(); iter++) { cout << "Vec contains: " << iter->f << ", " << *(iter->pstr) << endl; } } This produces: Vec contains: 0, 52 Vec contains: 1, 52 Vec contains: 2, 52 Vec contains: 3, 52 I would hope that each time, iter->f and iter->pstr would yield a different result. Unfortunately, iter->pstr is always the same. My suspicion is that each time through the loop, a new loopStr is created. Instead of copying it into the struct, I'm only copying a pointer. The location that the pointer writes to is getting overwritten. How can I avoid this? Is it possible to solve this problem without allocating memory on the heap?

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  • template pass by const reference

    - by 7vies
    Hi, I've looked over a few similar questions, but I'm still confused. I'm trying to figure out how to explicitly (not by compiler optimization etc) and C++03-compatible avoid copying of an object when passing it to a template function. Here is my test code: #include <iostream> using namespace std; struct C { C() { cout << "C()" << endl; } C(const C&) { cout << "C(C)" << endl; } ~C() { cout << "~C()" << endl; } }; template<class T> void f(T) { cout << "f<T>" << endl; } template<> void f(C c) { cout << "f<C>" << endl; } // (1) template<> void f(const C& c) { cout << "f<C&>" << endl; } // (2) int main() { C c; f(c); return 0; } (1) accepts the object of type C, and makes a copy. Here is the output: C() C(C) f<C> ~C() ~C() So I've tried to specialize with a const C& parameter (2) to avoid this, but this simply doesn't work (apparently the reason is explained in this question). Well, I could "pass by pointer", but that's kind of ugly. So is there some trick that would allow to do that somehow nicely? EDIT: Oh, probably I wasn't clear. I already have a templated function template<class T> void f(T) {...} But now I want to specialize this function to accept a const& to another object: template<> void f(const SpecificObject&) {...} But it only gets called if I define it as template<> void f(SpecificObject) {...}

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  • Strange behavior of std::cout &operator<<...

    - by themoondothshine
    Hey ppl, I came across something weird today, and I was wondering if any of you here could explain what's happening... Here's a sample: #include <iostream> #include <cassert> using namespace std; #define REQUIRE_STRING(s) assert(s != 0) #define REQUIRE_STRING_LEN(s, n) assert(s != 0 || n == 0) class String { public: String(const char *str, size_t len) : __data(__construct(str, len)), __len(len) {} ~String() { __destroy(__data); } const char *toString() const { return const_cast<const char *>(__data); } String &toUpper() { REQUIRE_STRING_LEN(__data, __len); char *it = __data; while(it < __data + __len) { if(*it >= 'a' && *it <= 'z') *it -= 32; ++it; } return *this; } String &toLower() { REQUIRE_STRING_LEN(__data, __len); char *it = __data; while(it < __data + __len) { if(*it >= 'A' && *it <= 'Z') *it += 32; ++it; } return *this; } private: char *__data; size_t __len; protected: static char *__construct(const char *str, size_t len) { REQUIRE_STRING_LEN(str, len); char *data = new char[len]; std::copy(str, str + len, data); return data; } static void __destroy(char *data) { REQUIRE_STRING(data); delete[] data; } }; int main() { String s("Hello world!", __builtin_strlen("Hello world!")); cout << s.toLower().toString() << endl; cout << s.toUpper().toString() << endl; cout << s.toLower().toString() << endl << s.toUpper().toString() << endl; return 0; } Now, I had expected the output to be: hello world! HELLO WORLD! hello world! HELLO WORLD! but instead I got this: hello world! HELLO WORLD! hello world! hello world! I can't really understand why the second toUpper didn't have any effect.

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  • Sprite not moving when using a function from another class SFML c++

    - by user2892932
    I have a Game.cpp, and I am calling a update function in my Player class. In my player update Function I have it to check for keyboard input, and it seems to work, but whenever I try to call the .move() function, it seems to not work. I get no errors either. I am new to sfml, and decent with c++. Help is appreciated! #include "Player.h" Player::Player(void): vel(0), maxvel(100) { Load("Assets/sss.png",true); } void Player::Update(sf::Sprite& p) { if (sf::Keyboard::isKeyPressed(sf::Keyboard::A)) { moveObject(-3,0, p); } if(sf::Keyboard::isKeyPressed(sf::Keyboard::D)) { moveObject(-3,0, p); } } Player::~Player(void) { } This is the GameObject cpp #include "GameObject.h" #include <iostream> GameObject::GameObject(void) { isLoaded = false; } void GameObject::Load(std::string flname, bool isPlayer) { if(!tex.loadFromFile(flname)) { EXIT_FAILURE; } else { if(isPlayer) { if(!tex.loadFromFile(flname, sf::IntRect(0,0,33,33))) { EXIT_FAILURE; } else { std::cout << "Loading image" << "\n"; filename = flname; spr.setTexture(tex); isLoaded = true; } } else { std::cout << "Loading image" << "\n"; filename = flname; spr.setTexture(tex); isLoaded = true; } } } void GameObject::Draw(sf::RenderWindow & window) { if(isLoaded) { window.draw(spr); window.display(); std::cout << "Sprite drew" << "\n"; } } void GameObject::setPos(float x, float y) { if(isLoaded) { spr.setPosition(x,y); } } sf::Vector2f GameObject::GetObjPos() { return spr.getPosition(); } sf::Sprite& GameObject::getSprite() { return spr; } void GameObject::moveObject(float x, float y, sf::Sprite& sp) { sp.move(x, y); } GameObject::~GameObject(void) { }

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  • C++ keeping a list of objects and calling a contructor through another function

    - by Nona Urbiz
    why isnt my object being created? When I do it like so, I am told error C2065: 'AllReferrals' : undeclared identifier as well as error C2228: left of '.push_back' must have class/struct/union. If I put the list initialization before the class I get error C2065: 'AllReferrals' : undeclared identifier. Thanks! #include <iostream> #include <fstream> #include <regex> #include <string> #include <list> #include <map> using namespace std; using namespace tr1; class Referral { public: string url; map<string, int> keywords; static bool submit(string url, string keyword, int occurrences) { //if(lots of things i'll later add){ Referral(url, keyword, occurrences); return true; //} //else // return false; } private: list<string> urls; Referral(string url, string keyword, int occurrences) { url = url; keywords[keyword] = occurrences; AllReferrals.push_back(this); } }; static list<Referral> AllReferrals; int main() { Referral::submit("url", "keyword", 1); cout << AllReferrals.size(); cout << "\n why does that ^^ say 0 (help me make it say one)?"; cout << "\n and how can i AllReferrals.push_back(this) from my constructor?"; cout << " When I do it like so, I am told error C2065: 'AllReferrals' : undeclared identifier"; cout << " as well as error C2228: left of '.push_back' must have class/struct/union."; cout << " If I put the list initialization before the class I get error C2065: 'AllReferrals' : undeclared identifier."; cout << "\n\n\t Thanks!"; getchar(); }

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  • OpenGL Coordinate system confusion

    - by user146780
    Maybe I set up GLUT wrong. Basically I want verticies to be reletive to their size in pixels. Ex:right now if I create a hexagon, it hakes up the whole screen even though the units are 6. #include <iostream> #include <stdlib.h> //Needed for "exit" function #include <cmath> //Include OpenGL header files, so that we can use OpenGL #ifdef __APPLE__ #include <OpenGL/OpenGL.h> #include <GLUT/glut.h> #else #include <GL/glut.h> #endif using namespace std; //Called when a key is pressed void handleKeypress(unsigned char key, //The key that was pressed int x, int y) { //The current mouse coordinates switch (key) { case 27: //Escape key exit(0); //Exit the program } } //Initializes 3D rendering void initRendering() { //Makes 3D drawing work when something is in front of something else glEnable(GL_DEPTH_TEST); } //Called when the window is resized void handleResize(int w, int h) { //Tell OpenGL how to convert from coordinates to pixel values glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); //Switch to setting the camera perspective //Set the camera perspective glLoadIdentity(); //Reset the camera gluPerspective(45.0, //The camera angle (double)w / (double)h, //The width-to-height ratio 1.0, //The near z clipping coordinate 200.0); //The far z clipping coordinate } //Draws the 3D scene void drawScene() { //Clear information from last draw glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); //Reset the drawing perspective glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glBegin(GL_POLYGON); //Begin quadrilateral coordinates //Trapezoid glColor3f(255,0,0); for(int i = 0; i < 6; ++i) { glVertex2d(sin(i/6.0*2* 3.1415), cos(i/6.0*2* 3.1415)); } glEnd(); //End quadrilateral coordinates glutSwapBuffers(); //Send the 3D scene to the screen } int main(int argc, char** argv) { //Initialize GLUT glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH); glutInitWindowSize(400, 400); //Set the window size //Create the window glutCreateWindow("Basic Shapes - videotutorialsrock.com"); initRendering(); //Initialize rendering //Set handler functions for drawing, keypresses, and window resizes glutDisplayFunc(drawScene); glutKeyboardFunc(handleKeypress); glutReshapeFunc(handleResize); glutMainLoop(); //Start the main loop. glutMainLoop doesn't return. return 0; //This line is never reached } How can I make it so that a polygon of 0,0 10,0 10,10 0,10 defines a polygon starting at the top left of the screen and is a width and height of 10 pixels? Thanks

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  • passing a class method as opposed to a function in std::sort

    - by memC
    hi, Within a class, I am trying to sort a vector, by passing a method of the same class. But it gives errors at the time of compilation. Can anyone tell what the problem is? Thank you! it gives the following error: argument of type bool (Sorter::)(D&, D&)' does not matchbool (Sorter::*)(D&, D&)' I have also tried using sortBynumber(D const& d1, D const& d2) #include<vector> #include<stdio.h> #include<iostream> #include<algorithm> class D { public: int getNumber(); D(int val); ~D(){}; private: int num; }; D::D(int val){ num = val; }; int D::getNumber(){ return num; }; class Sorter { public: void doSorting(); bool sortByNumber(D& d1, D& d2); std::vector<D> vec_D; Sorter(); ~Sorter(){}; private: int num; }; Sorter::Sorter(){ int i; for ( i = 0; i < 10; i++){ vec_D.push_back(D(i)); } }; bool Sorter::sortByNumber(D& d1, D& d2){ return d1.getNumber() < d2.getNumber(); }; void Sorter::doSorting(){ std::sort(vec_D.begin(), vec_D.end(), this->sortByNumber); }; int main(){ Sorter s; s.doSorting(); std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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  • error in encryption program

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

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  • error unidentfied identfier "exams" and i dont know why in c++

    - by user320950
    // basic file operations #include <iostream> #include <fstream> using namespace std; void read_file_in_array(int exam[100][3]); double calculate_total(int exam1[], int exam2[], int exam3[]); // function that calcualates grades to see how many 90,80,70,60 //void display_totals(); int main() { int go,go2,go3; go=read_file_in_array(exam); go2=calculate_total(exam1,exam2,exam3); //go3=display_totals(); cout << go,go2,go3; return 0; }/* int display_totals() { int grade_total; grade_total=calculate_total(exam1,exam2,exam3); return 0; } */ double calculate_total(int exam1[],int exam2[],int exam3[]) { int calc_tot,above90=0, above80=0, above70=0, above60=0,i,j; calc_tot=read_file_in_array(exam); for(i=0;i<100;i++) { exam1[i]=exam[100][0]; exam2[i]=exam[100][1]; exam3[i]=exam[100][2]; if(exam1[i] <=90 && exam1[i] >=100) { above90++; cout << above90; } } return exam3[i]; } void read_file_in_array(double exam[100][3]) { ifstream infile; int num, i=0,j=0; infile.open("grades.txt");// file containing numbers in 3 columns if(infile.fail()) // checks to see if file opended { cout << "error" << endl; } while(!infile.eof()) // reads file to end of line { for(i=0;i<100;i++) // array numbers less than 100 { for(j=0;j<3;j++) // while reading get 1st array or element infile >> exam[i][j]; infile >> exam[i][j]; infile >> exam[i][j]; cout << exam[i][j] << endl; } exam[i][j]=exam1[i]; exam[i][j]=exam2[i]; exam[i][j]=exam3[i]; } infile.close(); }

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  • Boost thread synchronization in release build

    - by Joseph16
    Hi, when I try to run the following code in debug and release mode in VS2005. Each time I see different output in console and It doesn't seem like the multithreading is achieved in release mode. 1. #include <boost/thread.hpp> 2. #include <iostream> 3. 4. void wait(int seconds) 5. { 6. boost::this_thread::sleep(boost::posix_time::seconds(seconds)); 7. } 8. 9. boost::mutex mutex; 10. 11. void thread() 12. { 13. for (int i = 0; i < 5; ++i) 14. { 15. //wait(1); 16. mutex.lock(); 17. std::cout << "Thread " << boost::this_thread::get_id() << ": " << i << std::endl; 18. mutex.unlock(); 19. } 20. } 21. 22. int main() 23. { 24. boost::thread t1(thread); 25. boost::thread t2(thread); 26. t1.join(); 27. t2.join(); 28. } Debug Mode Thread 00153E60: 0 Thread 00153E90: 0 Thread 00153E60: 1 Thread 00153E90: 1 Thread 00153E90: 2 Thread 00153E60: 2 Thread 00153E90: 3 Thread 00153E60: 3 Thread 00153E60: 4 Thread 00153E90: 4 Press any key to continue . . . Release Mode Thread 00153D28: 0 Thread 00153D28: 1 Thread 00153D28: 2 Thread 00153D28: 3 Thread 00153D28: 4 Thread 00153D58: 0 Thread 00153D58: 1 Thread 00153D58: 2 Thread 00153D58: 3 Thread 00153D58: 4 Press any key to continue . . .

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  • Copy constructor bug

    - by user168715
    I'm writing a simple nD-vector class, but am encountering a strange bug. I've stripped out the class to the bare minimum that still reproduces the bug: #include <iostream> using namespace std; template<unsigned int size> class nvector { public: nvector() {data_ = new double[size];} ~nvector() {delete[] data_;} template<unsigned int size2> nvector(const nvector<size2> &other) { data_ = new double[size]; int i=0; for(; i<size && i < size2; i++) data_[i] = other[i]; for(; i<size; i++) data_[i] = 0; } double &operator[](int i) {return data_[i];} const double&operator[](int i) const {return data_[i];} private: const nvector<size> &operator=(const nvector<size> &other); //Intentionally unimplemented for now double *data_; }; int main() { nvector<2> vector2d; vector2d[0] = 1; vector2d[1] = 2; nvector<3> vector3d(vector2d); for(int i=0; i<3; i++) cout << vector3d[i] << " "; cout << endl; //Prints 1 2 0 nvector<3> other3d(vector3d); for(int i=0; i<3; i++) cout << other3d[i] << " "; cout << endl; //Prints 1 2 0 } //Segfault??? On the surface this seems to work fine, and both tests print out the correct values. However, at the end of main the program crashes with a segfault, which I've traced to nvector's destructor. At first I thought the (incorrect) default assignment operator was somehow being called, which is why I added the (currently) unimplemented explicit assignment operator to rule this possibility out. So my copy constructor must be buggy, but I'm having one of those days where I'm staring at extremely simple code and just can't see it. Do you guys have any ideas?

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  • what is the wrong with this code"length indicator implementation" ?

    - by cj
    Hello, this is an implementation of length indicator field but it hang and i think stuck at a loop and don't show any thing. // readx22.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include "iostream" #include "fstream" #include "stdio.h" using namespace std; class Student { public: string id; size_t id_len; string first_name; size_t first_len; string last_name; size_t last_len; string phone; size_t phone_len; string grade; size_t grade_len; void read(fstream &ven); void print(); }; void Student::read(fstream &ven) { size_t cnt; ven >> cnt; id_len=cnt; id.reserve( cnt ); while ( -- cnt ) { id.push_back( ven.get() ); } ven >> cnt; first_len=cnt; first_name.reserve( cnt ); while ( -- cnt ) { first_name.push_back( ven.get() ); } ven >> cnt; last_len=cnt; last_name.reserve( cnt ); while ( -- cnt ) { last_name.push_back( ven.get() ); } ven >> cnt; phone_len=cnt; phone.reserve( cnt ); while ( -- cnt ) { phone.push_back( ven.get() ); } ven >> cnt; grade_len=cnt; grade.reserve( cnt ); while ( -- cnt ) { grade.push_back( ven.get() ); } } void Student::print() { // string::iterator it; for ( int i=0 ; i<id_len; i++) cout << id[i]; } int main() { fstream in; in.open ("fee.txt", fstream::in); Student x; x.read(in); x.print(); return 0; } thanks

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  • No Matching Function Error for inserting into a list in c++

    - by Josh Curren
    I am getting an error when I try to insert an item into a list (in C++). The error is that there is no matching function for call to the insert(). I also tried push_front() but got the same error. Here is the error message: main.cpp:38: error: no matching function for call to ‘std::list<Salesperson, std::allocator<Salesperson> >::insert(Salesperson&)’ /usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/bits/list.tcc:99: note: candidates are: std::_List_iterator<_Tp> std::list<_Tp, _Alloc>::insert(std::_List_iterator<_Tp>, const _Tp&) [with _Tp = Salesperson, _Alloc = std::allocator<Salesperson>] /usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/bits/stl_list.h:961: note: void std::list<_Tp, _Alloc>::insert(std::_List_iterator<_Tp>, size_t, const _Tp&) [with _Tp = Salesperson, _Alloc = std::allocator<Salesperson>] Here is the code: #include <stdlib.h> #include <iostream> #include <fstream> #include <string> #include <list> #include "Salesperson.h" #include "Salesperson.cpp" #include "OrderedList.h" #include "OrderedList.cpp" using namespace std; int main(int argc, char** argv) { cout << "\n------------ Asn 8 - Sales Report ------------" << endl; list<Salesperson> s; int id; string fName, lName; int numOfSales; string year; std::ifstream input("Sales.txt"); while( !std::getline(input, year, ',').eof() ) { input >> id; input >> lName; input >> fName; input >> numOfSales; Salesperson sp = Salesperson( id, fName, lName ); s.insert( sp ); //THIS IS LINE 38 ************************** for( int i = 0; i < numOfSales; i++ ) { double sale; input >> sale; sp.sales.insert( sale ); } } cout << endl; return (EXIT_SUCCESS); }

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  • Windows API Programing....

    - by vs4vijay
    Hello There... Its me Vijay.. I m Trying to make a CrossHair(some kind of cursor) On The Screen while running a Game (Counter Strike)... so i did this... ############################# #include<iostream.h> #include<windows.h> #include<conio.h> #include<dos.h> #include<stdlib.h> #include<process.h> #include <time.h> int main() { HANDLE hl = OpenProcess(PROCESS_ALL_ACCESS,TRUE,pid); // Here pid is the process ID of the Game... HDC hDC = GetDC(NULL); //Here i pass NULL for Entire Screen... HBRUSH hb=CreateSolidBrush(RGB(0,255,255)); SelectObject(hDC,hb); POINT p; while(!kbhit()) { int x=1360/2,y=768/2; MoveToEx(hDC,x-20,y,&p); LineTo(hDC,x+20,y); SetPixel(hDC,x,y,RGB(255,0,0)); SetPixel(hDC,x-1,y-1,RGB(255,0,0)); SetPixel(hDC,x-1,y+1,RGB(255,0,0)); SetPixel(hDC,x+1,y+1,RGB(255,0,0)); SetPixel(hDC,x+1,y-1,RGB(255,0,0)); MoveToEx(hDC,x,y-20,&p); LineTo(hDC,x,y+20); } cin.get(); return 0; } #################################### it works fine....at desktop i see crosshair...but my problem is that when i run game...the cross here got disappeared.... so i think i did not handle the process of game... so i pass the HANDLE to the GetDC(hl)... But GetDC take only HWND(Handle To Window)... so i typecast it like this... HWND hl = (HWND)OpenProcess(PROCESS_ALL_ACCESS,TRUE,pid); and passed hl to the GetDC(hl)... but it doesnt work...Whats wrong with the code... plz tell me how do i make a simple shape at the screen on a process or game... PS : (My Compiler Is DevCPP and OS WinXP SP3....)

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  • reverse a linked list?

    - by sil3nt
    Hi there, Im trying to reverse the order of the following linked list, I've done so, But the reversed list does not seem to print out. Where have I gone wrong? //reverse the linked list #include <iostream> using namespace std; struct node{ int number; node *next; }; node *A; void addNode(node *&listpointer, int num){ node *temp; temp = new node; temp->number = num; temp->next = listpointer; listpointer = temp; } void reverseNode(node *&listpointer){ node *temp,*current; current = listpointer; temp = new node; while (true){ if (current == NULL){ temp = NULL; break; } temp->number = current->number; current = current->next; temp = temp->next; } listpointer = temp; } int main(){ A = NULL; addNode(A,1); addNode(A,2); addNode(A,3); while (true){ if (A == NULL){break;} cout<< A->number << endl; A = A->next; } cout<< "****" << endl; reverseNode(A); while (true){ if (A == NULL){break;} cout<< A->number << endl; A = A->next; } cout<< "****"<< endl; return 0; }

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  • vc++ - static member is showing error

    - by prabhakaran
    I am using vc++(2010). I am trying to create a class for server side socket. Here is the header file #include<winsock.h> #include<string> #include<iostream> using namespace std; class AcceptSocket { // static SOCKET s; protected: SOCKET acceptSocket; public: AcceptSocket(){}; void setSocket(SOCKET socket); static void EstablishConnection(int portNo,string&); static void closeConnection(); static void StartAccepting(); virtual void threadDeal(); static DWORD WINAPI MyThreadFunction(LPVOID lpParam); }; SOCKET AcceptSocket::s; and the corresponding source file #include<NetWorking.h> #include<string> void AcceptSocket::setSocket(SOCKET s) { acceptSocket=s; } void AcceptSocket::EstablishConnection(int portno,string &failure) { WSAData w; int error = WSAStartup(0x0202,&w); if(error) failure=failure+"\nWSAStartupFailure"; if(w.wVersion != 0x0202) { WSACleanup(); failure=failure+"\nVersion is different"; } SOCKADDR_IN addr; addr.sin_family=AF_INET; addr.sin_port=htons(portno); addr.sin_addr.s_addr=htonl(INADDR_ANY); AcceptSocket::s=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); if(AcceptSocket::s == INVALID_SOCKET) failure=failure+"\nsocket creating error"; if(bind(AcceptSocket::s,(LPSOCKADDR) &addr,sizeof(addr)) == SOCKET_ERROR) failure=failure+"\nbinding error"; listen(AcceptSocket::s,SOMAXCONN); } void AcceptSocket::closeConnection() { if(AcceptSocket::s) closesocket(AcceptSocket::s); WSACleanup(); } void AcceptSocket::StartAccepting() { sockaddr_in addrNew; int size=sizeof(addrNew); while(1) { SOCKET temp=accept(AcceptSocket::s,(sockaddr *)&addrNew,&size); AcceptSocket * tempAcceptSocket=new AcceptSocket(); tempAcceptSocket->setSocket(temp); DWORD threadId; HANDLE thread=CreateThread(NULL,0,MyThreadFunction,(LPVOID)tempAcceptSocket,0,&threadId); } } DWORD WINAPI AcceptSocket::MyThreadFunction(LPVOID lpParam) { AcceptSocket * acceptsocket=(AcceptSocket *) lpParam; acceptsocket->threadDeal(); return 1; } void AcceptSocket::threadDeal() { "You didn't define threadDeal in the derived class"; } Now the main.cpp is #include<Networking.h> int main() { } When I am compiling The error I got is Error 1 error LNK2005: "private: static unsigned int AcceptSocket::s" (?s@AcceptSocket@@0IA) already defined in NetWorking.obj C:\Documents and Settings\prabhakaran\Desktop\check\check\main.obj check Error 2 error LNK1169: one or more multiply defined symbols found C:\Documents and Settings\prabhakaran\Desktop\check\Debug\check.exe 1 1 check Now anybody please enlighten me about this issue

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  • Is typeid of type name always evaluated at compile time in c++ ?

    - by cyril42e
    I wanted to check that typeid is evaluated at compile time when used with a type name (ie typeid(int), typeid(std::string)...). To do so, I repeated in a loop the comparison of two typeid calls, and compiled it with optimizations enabled, in order to see if the compiler simplified the loop (by looking at the execution time which is 1us when it simplifies instead of 160ms when it does not). And I get strange results, because sometimes the compiler simplifies the code, and sometimes it does not. I use g++ (I tried different 4.x versions), and here is the program: #include <iostream> #include <typeinfo> #include <time.h> class DisplayData {}; class RobotDisplay: public DisplayData {}; class SensorDisplay: public DisplayData {}; class RobotQt {}; class SensorQt {}; timespec tp1, tp2; const int n = 1000000000; int main() { int avg = 0; clock_gettime(CLOCK_REALTIME, &tp1); for(int i = 0; i < n; ++i) { // if (typeid(RobotQt) == typeid(RobotDisplay)) // (1) compile time // if (typeid(SensorQt) == typeid(SensorDisplay)) // (2) compile time if (typeid(RobotQt) == typeid(RobotDisplay) || typeid(SensorQt) == typeid(SensorDisplay)) // (3) not compile time ???!!! avg++; else avg--; } clock_gettime(CLOCK_REALTIME, &tp2); std::cout << "time (" << avg << "): " << (tp2.tv_sec-tp1.tv_sec)*1000000000+(tp2.tv_nsec-tp1.tv_nsec) << " ns" << std::endl; } The conditions in which this problem appear are not clear, but: - if there is no inheritance involved, no problem (always compile time) - if I do only one comparison, no problem - the problem only appears only with a disjunction of comparisons if all the terms are false So is there something I didn't get with how typeid works (is it always supposed to be evaluated at compilation time when used with type names?) or may this be a gcc bug in evaluation or optimization? About the context, I tracked down the problem to this very simplified example, but my goal is to use typeid with template types (as partial function template specialization is not possible). Thanks for your help!

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  • C++ include statement required if defining a map in a headerfile.

    - by Justin
    I was doing a project for computer course on programming concepts. This project was to be completed in C++ using Object Oriented designs we learned throughout the course. Anyhow, I have two files symboltable.h and symboltable.cpp. I want to use a map as the data structure so I define it in the private section of the header file. I #include <map> in the cpp file before I #include "symboltable.h". I get several errors from the compiler (MS VS 2008 Pro) when I go to debug/run the program the first of which is: Error 1 error C2146: syntax error : missing ';' before identifier 'table' c:\users\jsmith\documents\visual studio 2008\projects\project2\project2\symboltable.h 22 Project2 To fix this I had to #include <map> in the header file, which to me seems strange. Here are the relevant code files: // symboltable.h #include <map> class SymbolTable { public: SymbolTable() {} void insert(string variable, double value); double lookUp(string variable); void init(); // Added as part of the spec given in the conference area. private: map<string, double> table; // Our container for variables and their values. }; and // symboltable.cpp #include <map> #include <string> #include <iostream> using namespace std; #include "symboltable.h" void SymbolTable::insert(string variable, double value) { table[variable] = value; // Creates a new map entry, if variable name already exist it overwrites last value. } double SymbolTable::lookUp(string variable) { if(table.find(variable) == table.end()) // Search for the variable, find() returns a position, if thats the end then we didnt find it. throw exception("Error: Uninitialized variable"); else return table[variable]; } void SymbolTable::init() { table.clear(); // Clears the map, removes all elements. }

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