Search Results

Search found 1621 results on 65 pages for 'cout'.

Page 57/65 | < Previous Page | 53 54 55 56 57 58 59 60 61 62 63 64  | Next Page >

  • Calling Base Class Functions with Inherited Type

    - by Kein Mitleid
    I can't describe exactly what I want to say but I want to use base class functions with an inherited type. Like I want to declare "Coord3D operator + (Coord3D);" in one class, but if I use it with Vector3D operands, I want it to return Vector3D type instead of Coord3D. With this line of code below, I add two Vector3D's and get a Coord3D in return, as told to me by the typeid().name() function. How do I reorganize my classes so that I get a Vector3D on return? #include <iostream> #include <typeinfo> using namespace std; class Coord3D { public: float x, y, z; Coord3D (float = 0.0f, float = 0.0f, float = 0.0f); Coord3D operator + (Coord3D &); }; Coord3D::Coord3D (float a, float b, float c) { x = a; y = b; z = c; } Coord3D Coord3D::operator+ (Coord3D &param) { Coord3D temp; temp.x = x + param.x; temp.y = y + param.y; temp.z = z + param.z; return temp; } class Vector3D: public Coord3D { public: Vector3D (float a = 0.0f, float b = 0.0f, float c = 0.0f) : Coord3D (a, b, c) {}; }; int main () { Vector3D a (3, 4, 5); Vector3D b (6, 7, 8); cout << typeid(a + b).name(); return 0; }

    Read the article

  • how to remove subsets form given text file

    - by user324887
    i have a problem like this 10 20 30 40 70 20 30 70 30 40 10 20 29 70 80 90 20 30 40 40 45 65 10 20 80 45 65 20 I want to remove all subset transaction from this file. output file should be like follows 10 20 30 40 70 29 70 80 90 20 30 40 40 45 65 10 20 80 Where records like 20 30 70 30 40 10 20 45 65 20 are removed because of they are subset of other records. i AM using set for this but i am not able to create one set for one line can anybody know how to do this please help me here i am sending you my code include include include using namespace std; using namespace std; set s1; int main() { FILE fp = fopen ( "abc.txt", "r" ); if ( fp != NULL ) { char line [ 128 ]; / or other suitable maximum line size */ while ( fgets ( line, sizeof line, fp ) != NULL ) /* read a line */ { istringstream iss(line); do { string sub; iss >> sub; s1.insert(sub); } while (iss); for (set<string>::const_iterator p = s1.begin( );p != s1.end( ); ++p) cout << *p << endl; } } }

    Read the article

  • What happens to class members when malloc is used instead of new?

    - by Felix
    I'm studying for a final exam and I stumbled upon a curious question that was part of the exam our teacher gave last year to some poor souls. The question goes something like this: Is the following program correct, or not? If it is, write down what the program outputs. If it's not, write down why. The program: #include<iostream.h> class cls { int x; public: cls() { x=23; } int get_x(){ return x; } }; int main() { cls *p1, *p2; p1=new cls; p2=(cls*)malloc(sizeof(cls)); int x=p1->get_x()+p2->get_x(); cout<<x; return 0; } My first instinct was to answer with "the program is not correct, as new should be used instead of malloc". However, after compiling the program and seeing it output 23 I realize that that answer might not be correct. The problem is that I was expecting p2->get_x() to return some arbitrary number (whatever happened to be in that spot of the memory when malloc was called). However, it returned 0. I'm not sure whether this is a coincidence or if class members are initialized with 0 when it is malloc-ed. Is this behavior (p2->x being 0 after malloc) the default? Should I have expected this? What would your answer to my teacher's question be? (besides forgetting to #include <stdlib.h> for malloc :P)

    Read the article

  • C when to allocate and free memory - before function call, after function call...etc

    - by Keith P
    I am working with my first straight C project, and it has been a while since I worked on C++ for that matter. So the whole memory management is a bit fuzzy. I have a function that I created that will validate some input. In the simple sample below, it just ignores spaces: int validate_input(const char *input_line, char* out_value){ int ret_val = 0; /*false*/ int length = strlen(input_line); cout << "length = " << length << "\n"; out_value =(char*) malloc(sizeof(char) * length + 1); if (0 != length){ int number_found = 0; for (int x = 0; x < length; x++){ if (input_line[x] != ' '){ /*ignore space*/ /*get the character*/ out_value[number_found] = input_line[x]; number_found++; /*increment counter*/ } } out_value[number_found + 1] = '\0'; ret_val = 1; } return ret_val; } Instead of allocating memory inside the function for out_value, should I do it before I call the function and always expect the caller to allocate memory before passing into the function? As a rule of thumb, should any memory allocated inside of a function be always freed before the function returns?

    Read the article

  • Replacing symbol from object file at compile time. For example swapping out main

    - by Anthony Sottile
    Here's the use case: I have a .cpp file which has functions implemented in it. For sake of example say it has the following: [main.cpp] #include <iostream> int foo(int); int foo(int a) { return a * a; } int main() { for (int i = 0; i < 5; i += 1) { std::cout << foo(i) << std::endl; } return 0; } I want to perform some amount of automated testing on the function foo in this file but would need to replace out the main() function to do my testing. Preferably I'd like to have a separate file like this that I could link in over top of that one: [mymain.cpp] #include <iostream> #include <cassert> extern int foo(int); int main() { assert(foo(1) == 1); assert(foo(2) == 4); assert(foo(0) == 0); assert(foo(-2) == 4); return 0; } I'd like (if at all possible) to avoid changing the original .cpp file in order to do this -- though this would be my approach if this is not possible: do a replace for "(\s)main\s*\(" == "\1__oldmain\(" compile as usual. The environment I am targeting is a linux environment with g++.

    Read the article

  • Enumeration trouble: redeclared as different kind of symbol

    - by Matt
    Hello all. I am writing a program that is supposed to help me learn about enumeration data types in C++. The current trouble is that the compiler doesn't like my enum usage when trying to use the new data type as I would other data types. I am getting the error "redeclared as different kind of symbol" when compiling my trangleShape function. Take a look at the relevant code. Any insight is appreciated! Thanks! (All functions are their own .cpp files.) header file #ifndef HEADER_H_INCLUDED #define HEADER_H_INCLUDED #include <iostream> #include <iomanip> using namespace std; enum triangleType {noTriangle, scalene, isoceles, equilateral}; //prototypes void extern input(float&, float&, float&); triangleType extern triangleShape(float, float, float); /*void extern output (float, float, float);*/ void extern myLabel(const char *, const char *); #endif // HEADER_H_INCLUDED main function //8.1 main // this progam... #include "header.h" int main() { float sideLength1, sideLength2, sideLength3; char response; do //main loop { input (sideLength1, sideLength2, sideLength3); triangleShape (sideLength1, sideLength2, sideLength3); //output (sideLength1, sideLength2, sideLength3); cout << "\nAny more triangles to analyze? (y,n) "; cin >> response; } while (response == 'Y' || response == 'y'); myLabel ("8.1", "2/11/2011"); return 0; } triangleShape shape # include "header.h" triangleType triangleShape(sideLenght1, sideLength2, sideLength3) { triangleType triangle; return triangle; }

    Read the article

  • Inheritance and choose constructor from base class

    - by myle
    My question is rather simple, but I am stuck. How can I choose the desired constructor from base class? // node.h #ifndef NODE_H #define NODE_H #include <vector> // definition of an exception-class class WrongBoundsException { }; class Node { public: ... Node(double, double, std::vector<double>&) throw (WrongBoundsException); ... }; #endif // InternalNode.h #ifndef INTERNALNODE_H #define INTERNALNODE_H #include <vector> #include "Node.h" class InternalNode : public Node { public: // the position of the leftmost child (child left) int left_child; // the position of the parent int parent; InternalNode(double, double, std::vector<double>&, int parent, int left_child) throw (WrongBoundsException); private: int abcd; }; #endif // InternalNode.cpp #include "InternalNode.h" #define UNDEFINED_CHILD -1 #define ROOT -1 // Here is the problem InternalNode::InternalNode(double a, double b, std::vector<double> &v, int par, int lc) throw (WrongBoundsException) : Node(a, b, v), parent(par), left_child(lc) { std::cout << par << std::endl; } I get: $ g++ InternalNode.cpp InternalNode.cpp:16: error: declaration of ‘InternalNode::InternalNode(double, double, std::vector &, int, int) throw (WrongBoundsException)’ throws different exceptions InternalNode.h:17: error: from previous declaration ‘InternalNode::InternalNode(double, double, std::vector &, int, int)’ UPDATE 0: Fixed missing : UPDATE 1: Fixed throw exception

    Read the article

  • how to use iterator in c++?

    - by tsubasa
    I'm trying to calculate distance between 2 points. The 2 points I stored in a vector in c++: (0,0) and (1,1). I'm supposed to get results as 0 1.4 1.4 0 but the actual result that I got is 0 1 -1 0 I think there's something wrong with the way I use iterator in vector. Could somebody help? I posted the code below. typedef struct point { float x; float y; } point; float distance(point *p1, point *p2) { return sqrt((p1->x - p2->x)*(p1->x - p2->x) + (p1->y - p2->y)*(p1->y - p2->y)); } int main() { vector <point> po; point p1; p1.x=0; p1.y=0; point p2; p2.x=1; p2.y=1; po.push_back(p1); po.push_back(p2); vector <point>::iterator ii; vector <point>::iterator jj; for (ii=po.begin(); ii!=po.end(); ii++) { for (jj=po.begin(); jj!=po.end(); jj++) { cout<<distance(ii,jj)<<" "; } } return 0; }

    Read the article

  • Scope of the c++ using directive

    - by ThomasMcLeod
    From section 7.3.4.2 of the c++11 standard: A using-directive specifies that the names in the nominated namespace can be used in the scope in which the using-directive appears after the using-directive. During unqualified name lookup (3.4.1), the names appear as if they were declared in the nearest enclosing namespace which contains both the using-directive and the nominated namespace. [ Note: In this context, “contains” means “contains directly or indirectly”. —end note ] What do the second and third sentences mean exactly? Please give example. Here is the code I am attempting to understand: namespace A { int i = 7; } namespace B { using namespace A; int i = i + 11; } int main(int argc, char * argv[]) { std::cout << A::i << " " << B::i << std::endl; return 0; } It print "7 7" and not "7 18" as I would expect. Sorry for the typo, the program actually prints "7 11".

    Read the article

  • Can C++ do something like an ML case expression?

    - by Nathan Andrew Mullenax
    So, I've run into this sort of thing a few times in C++ where I'd really like to write something like case (a,b,c,d) of (true, true, _, _ ) => expr | (false, true, _, false) => expr | ... But in C++, I invariably end up with something like this: bool c11 = color1.count(e.first)>0; bool c21 = color2.count(e.first)>0; bool c12 = color1.count(e.second)>0; bool c22 = color2.count(e.second)>0; // no vertex in this edge is colored // requeue if( !(c11||c21||c12||c22) ) { edges.push(e); } // endpoints already same color // failure condition else if( (c11&&c12)||(c21&&c22) ) { results.push_back("NOT BICOLORABLE."); return true; } // nothing to do: nodes are already // colored and different from one another else if( (c11&&c22)||(c21&&c12) ) { } // first is c1, second is not set else if( c11 && !(c12||c22) ) { color2.insert( e.second ); } // first is c2, second is not set else if( c21 && !(c12||c22) ) { color1.insert( e.second ); } // first is not set, second is c1 else if( !(c11||c21) && c12 ) { color2.insert( e.first ); } // first is not set, second is c2 else if( !(c11||c21) && c22 ) { color1.insert( e.first ); } else { std::cout << "Something went wrong.\n"; } I'm wondering if there's any way to clean all of those if's and else's up, as it seems especially error prone. It would be even better if it were possible to get the compiler complain like SML does when a case expression (or statement in C++) isn't exhaustive. I realize this question is a bit vague. Maybe, in sum, how would one represent an exhaustive truth table with an arbitrary number of variables in C++ succinctly? Thanks in advance.

    Read the article

  • Managing libraries and imports in a programming language

    - by sub
    I've created an interpreter for a stupid programming language in C++ and the whole core structure is finished (Tokenizer, Parser, Interpreter including Symbol tables, core functions, etc.). Now I have a problem with creating and managing the function libraries for this interpreter (I'll explain what I mean with that later) So currently my core function handler is horrible: // Simplified version myLangResult SystemFunction( name, argc, argv ) { if ( name == "print" ) { if( argc < 1 ) { Error('blah'); } cout << argv[ 0 ]; } else if ( name == "input" ) { if( argc < 1 ) { Error('blah'); } string res; getline( cin, res ); SetVariable( argv[ 0 ], res ); } else if ( name == "exit ) { exit( 0 ); } And now think of each else if being 10 times more complicated and there being 25 more system functions. Unmaintainable, feels horrible, is horrible. So I thought: How to create some sort of libraries that contain all the functions and if they are imported initialize themselves and add their functions to the symbol table of the running interpreter. However this is the point where I don't really know how to go on. What I wanted to achieve is that there is e.g.: an (extern?) string library for my language, e.g.: string, and it is imported from within a program in that language, example: import string myString = "abcde" print string.at( myString, 2 ) # output: c My problems: How to separate the function libs from the core interpreter and load them? How to get all their functions into a list and add it to the symbol table when needed? What I was thinking to do: At the start of the interpreter, as all libraries are compiled with it, every single function calls something like RegisterFunction( string namespace, myLangResult (*functionPtr) ); which adds itself to a list. When import X is then called from within the language, the list built with RegisterFunction is then added to the symbol table. Disadvantages that spring to mind: All libraries are directly in the interpreter core, size grows and it will definitely slow it down.

    Read the article

  • Usage of VIsual Memory Leak Detector

    - by Yan Cheng CHEOK
    I found a very interesting memory leak detector by using Visual C++. http://www.codeproject.com/KB/applications/visualleakdetector.aspx I try it out, but cannot make it works to detect a memory leak code. I am using MS Visual Studio 2008. Any step I had missed out? #include "stdafx.h" #include "vld.h" #include <iostream> void fun() { new int[1000]; } int _tmain(int argc, _TCHAR* argv[]) { fun(); std::cout << "lead?" << std::endl; getchar(); return 0; } The output when I run in debug mode is : ... ... 'Test.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.4053_x-ww_e6967989\msvcr80.dll', Symbols loaded. 'Test.exe': Loaded 'C:\WINDOWS\system32\msvcrt.dll', Symbols loaded (source information stripped). 'Test.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.30729.1_x-ww_f863c71f\msvcp90d.dll', Symbols loaded. 'Test.exe': Loaded 'C:\Program Files\Visual Leak Detector\bin\dbghelp.dll', Symbols loaded (source information stripped). Visual Leak Detector Version 1.9d installed. No memory leaks detected. Visual Leak Detector is now exiting. The program '[5468] Test.exe: Native' has exited with code 0 (0x0).

    Read the article

  • Specifying character

    - by danutenshu
    So below I have a code in C++ that is supposed to invert the arguments in a vector, but not the sequence. I have listed my problems as sidenotes in the code below. The invert function is supposed to invert each argument, and then the main function just outputs the inverted words in same order For instance, program("one two three four")=ruof eerth owt eno #include <iostream> #include <string> using namespace std; int invert(string normal) { string inverted; for (int num=normal.size()-1; num>=0; num--) { inverted.append(normal[num]); //I don't know how to get each character //I need another command for append } return **inverted**; <---- } int main(int argc, char* argv[]) { string text; for (int a=1; a<argc; a++) { text.append(invert(argv[a])); //Can't run the invert function text.append(" "); } cout << text << endl; return 0; }

    Read the article

  • [C++][Boost] Acceptor and Problems with Async_Accept

    - by bobber205
    See code. :P I am able to receive new connections before async_accept() has been called. My delegate function is also never called so I can't manage any connections I receive, rendering the new connections useless. ;) So here's my question. Is there a way to prevent the Boost ASIO acceptor from getting new connections on its own and only getting connections from async_accept()? Thanks! bool AlexSocket::StartListening(int port) { bool didStart = false; if (!this->listening) { //try to listen acceptor = new tcp::acceptor(this->myService); boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), port); acceptor->open(endpoint.protocol()); acceptor->set_option(boost::asio::ip::tcp::acceptor::reuse_address(true)); acceptor->bind(endpoint); //CAN GET NEW CONNECTIONS HERE (before async_accept is called) acceptor->listen(); didStart = true; //probably change? tcp::socket* tempNewSocket = new tcp::socket(this->myService); acceptor->async_accept(*tempNewSocket, boost::bind(&AlexSocket::NewConnection, this, tempNewSocket, boost::asio::placeholders::error) ); } else //already started! return false; this->listening = didStart; return didStart; } //this function is never called :( void AlexSocket::NewConnection(tcp::socket* s, const boost::system::error_code& error) { cout << "New Connection Made" << endl; //Start new accept async tcp::socket* tempNewSocket = new tcp::socket(this->myService); acceptor->async_accept(*tempNewSocket, boost::bind(&AlexSocket::NewConnection, this, tempNewSocket, boost::asio::placeholders::error) ); }

    Read the article

  • How to change the meaning of pointer access operator

    - by kumar_m_kiran
    Hi All, This may be very obvious question, pardon me if so. I have below code snippet out of my project, #include <stdio.h> class X { public: int i; X() : i(0) {}; }; int main(int argc,char *arv[]) { X *ptr = new X[10]; unsigned index = 5; cout<<ptr[index].i<<endl; return 0; } Question Can I change the meaning of the ptr[index] ? Because I need to return the value of ptr[a[index]] where a is an array for subindexing. I do not want to modify existing source code. Any new function added which can change the behavior is needed. Since the access to index operator is in too many places (536 to be precise) in my code, and has complex formulas inside the index subscript operator, I am not inclined to change the code in many locations. PS : 1. I tried operator overload and came to conclusion that it is not possible. 2. Also p[i] will be transformed into *(p+i). I cannot redefine the basic operator '+'. So just want to reconfirm my understanding and if there are any possible short-cuts to achieve. Else I need fix it by royal method of changing every line of code :) .

    Read the article

  • I want tell the VC++ Compiler to compile all code. Can it be done?

    - by KGB
    I am using VS2005 VC++ for unmanaged C++. I have VSTS and am trying to use the code coverage tool to accomplish two things with regards to unit tests: See how much of my referenced code under test is getting executed See how many methods of my code under test (if any) are not unit tested at all Setting up the VSTS code coverage tool (see the link text) and accomplishing task #1 was straightforward. However #2 has been a surprising challenge for me. Here is my test code. class CodeCoverageTarget { public: std::string ThisMethodRuns() { return "Running"; } std::string ThisMethodDoesNotRun() { return "Not Running"; } }; #include <iostream> #include "CodeCoverageTarget.h" using namespace std; int main() { CodeCoverageTarget cct; cout<<cct.ThisMethodRuns()<<endl; } When both methods are defined within the class as above the compiler automatically eliminates the ThisMethodDoesNotRun() from the obj file. If I move it's definition outside the class then it is included in the obj file and the code coverage tool shows it has not been exercised at all. Under most circumstances I want the compiler to do this elimination for me but for the code coverage tool it defeats a significant portion of the value (e.g. finding untested methods). I have tried a number of things to tell the compiler to stop being smart for me and compile everything but I am stumped. It would be nice if the code coverage tool compensated for this (I suppose by scanning the source and matching it up with the linker output) but I didn't find anything to suggest it has a special mode to be turned on. Am I totally missing something simple here or is this not possible with the VC++ compiler + VSTS code coverage tool? Thanks in advance, KGB

    Read the article

  • invalid scalar hex value 0x8000000 and over

    - by kioto
    Hi. I found a problem getting hex value from yaml file. It couldn't get hex value 0x80000000 and over. Following is a sample C++ program. // ymlparser.cpp #include <iostream> #include <fstream> #include "yaml-cpp/yaml.h" int main(void) { try { std::ifstream fin("hex.yaml"); YAML::Parser parser(fin); YAML::Node doc; parser.GetNextDocument(doc); int num1; doc["hex1"] >> num1; printf("num1 = 0x%x\n", num1); int num2; doc["hex2"] >> num2; printf("num2 = 0x%x\n", num2); return 0; } catch(YAML::ParserException& e) { std::cout << e.what() << "\n"; } } hex.yaml hex1: 0x7FFFFFFF hex2: 0x80000000 Error message is here. $ ./ymlparser num1 = 0x7fffffff terminate called after throwing an instance of 'YAML::InvalidScalar' what(): yaml-cpp: error at line 2, column 7: invalid scalar Aborted Environment yaml-cpp : getting from svn, March.22.2010 or v0.2.5 OS : Ubuntu 9.10 i386 I need to get hex the value on yaml-cpp now, but I have no idea. Please tell me how to get it another way. Thanks,

    Read the article

  • push(ing)_back objects pointers within a loop

    - by Jose Manuel Albornoz
    Consider the following: I have a class CDevices containing, amongst others, a string member class CDevice { public: CDevice(void); ~CDevice(void); // device name std::string Device_Name; etc... } and somewhere else in my code I define another class that contains a vector of pointers to CDevices class CDevice; class CServers { public: CServers(void); ~CServers(void); // Devices vector vector<CDevice*> Devices; etc... } The problem appears in the following lines in my main.c pDevice = new CDevice; pDevice->Device_Name = "de"; Devices.push_back(pDevice); pDevice->Device_Name = " revolotiunibus"; Devices.push_back(pDevice); pDevice->Device_Name = " orbium"; Devices.push_back(pDevice); pDevice->Device_Name = " coelestium"; Devices.push_back(pDevice); for(int i = 0; i < (int)Devices.size(); ++i) cout << "\nLoad name = " << Devices.at(i)->Device_Name << endl; The output I get is " coelestium" repeated four times: each time I push_back a new element into the vector all of the already existing elements take the value of the one which has just been added. I have also tried using iterators to recover each element in the vector with the same results. Could someone please tell me what's wrong here? Thankx

    Read the article

  • Copy constructor demo (crashing...)

    - by AKN
    Here is the program... class CopyCon { public: char *name; CopyCon() { name = new char; } CopyCon(const CopyCon &objCopyCon) { name = new char; _tcscpy(name,objCopyCon.name); } ~CopyCon() { if( name != NULL ) { delete name; name = NULL; } } }; int main() { CopyCon objCopyCon1; objCopyCon1.name = "Hai"; CopyCon objCopyCon2(objCopyCon1); objCopyCon1.name = "Hello"; cout<<objCopyCon2.name<<endl; return 0; } Once the code execution completes, when the destructor called, it crashes on 'delete' saying... Debug Error! Program: ... HEAP CORRUPTION DETECTED: after Normal block (#124) at 0x00366990. CRT detected that the application wrote to memory after end of heap buffer. (Press Retry to debug the application) Don't we have to clear the heap memory in destructor. What's wrong with this program? Pls someone help! Copy constructor works perfectly as intended. But still... !?

    Read the article

  • Opencv video frame not showing Sobel output

    - by user1016950
    This is a continuation question from Opencv video frame giving me an error I think I closed it off, Im new to Stackoverflow. I have code below that Im trying to see its Sobel edge image. However the program runs but the output is just a grey screen where if I mouseover the cursor disappears. Does anyone see the error? or is it a misunderstanding about the data structures Im using IplImage *frame, *frame_copy = 0; // capture frames from video CvCapture *capture = cvCaptureFromFile( "lightinbox1.avi"); //Allows Access to video propertys cvQueryFrame(capture); //Get the number of frames int nframe=(int) cvGetCaptureProperty(capture,CV_CAP_PROP_FRAME_COUNT); //Name window cvNamedWindow( "video:", 1 ); //start loop for(int i=0;i<nframe;i++){ //prepare capture frame extraction cvGrabFrame(capture); cout<<"We are on frame "<<i<<"\n"; //Get this frame frame = cvRetrieveFrame( capture ); con2txt(frame); frame_copy = cvCreateImage(cvSize(frame->width,frame->height),IPL_DEPTH_8U,frame->nChannels ); //show and destroy frame cvCvtColor( frame,frame,CV_RGB2GRAY); //Create Sobel output frame_copy1 = cvCreateImage(cvSize(frame->width,frame->height),IPL_DEPTH_16S,1 ); cvSobel(frame_copy,frame_copy1,2,2,3); cvShowImage("video:",frame_copy1); cvWaitKey(33);} cvReleaseCapture(&capture);

    Read the article

  • HashMap Memory Leak because of Dynamic Array

    - by Jake M
    I am attempting to create my own HashMap to understand how they work. I am using an array of Linked Lists to store the values(strings) in my hashmap. I am creating the array like this: Node** list; Instead of this: Node* list[nSize]; This is so the array can be any size at runtime. But I think I am getting a memory leak because of how I am doing this. I dont know where the error is but when I run the following simple code the .exe crashes. Why is my application crashing and how can I fix it? Note: I am aware that using a vector would be much better than an array but this is just for learning and I want to challenge myself to create the hashmap using a 'Dynamic' Array. PS: is that the correct term(Dynamic Array) for the kind of array I am using? struct Node { // to implement }; class HashMap { public: HashMap(int dynSize) { *list = new Node[dynSize]; size = dynSize; for (int i=0; i<size; i++) list[i] = NULL; cout << "END\n"; } ~HashMap() { for (int i=0; i<size; i++) delete list[i]; } private: Node** list; // I could use a vector here but I am experimenting with a pointer to an array(pointer), also its more elegant int size; }; int main() { // When I run this application it crashes. Where is my memory leak? HashMap h(5); system("PAUSE"); return 0; }

    Read the article

  • How to compare two structure strings in C++

    - by Arvandor
    Ok, so this week in class we're working with arrays. I've got an assignment that wanted me to create a structure for an employee containing an employee ID, first name, last name, and wages. Then it has me ask users for input for 5 different employees all stored in an array of this structure, then ask them for a search field type, then a search value. Lastly, display all the information for all positive search results. I'm still new, so I'm sure it isn't a terribly elegant program, but what I'm trying to do now is figure out how to compare a user entered string with the string stored in the structure... I'll try to give all the pertinent code below. struct employee { int empid, string firstname, string lastname, float wage }; employee emparray[] = {}; employee value[] = {}; //Code for populating emparray and structure, then determine search field etc. cout << "Enter a search value: "; cin >> value.lastname; for(i = 0; i < 5; i++) { if(strcmp(value.lastname.c_str, emparray[i].lastname.c_str) == 0) { output(); } } Which... I thought would work, but it's giving me the following error.. Error 1 error C3867: 'std::basic_string<_Elem,_Traits,_Alloc>::c_str': function call missing argument list; use '&std::basic_string<_Elem,_Traits,_Alloc>::c_str' to create a pointer to member d:\myfile Any thoughts on what's going on? Is there a way to compare two .name notated strings without totally revamping the program? IF you want to drill me on best practices, please feel free, but also please try to solve my particular problem.

    Read the article

  • waveInProc / Windows audio question...

    - by BTR
    I'm using the Windows API to get audio input. I've followed all the steps on MSDN and managed to record audio to a WAV file. No problem. I'm using multiple buffers and all that. I'd like to do more with the buffers than simply write to a file, so now I've got a callback set up. It works great and I'm getting the data, but I'm not sure what to do with it once I have it. Here's my callback... everything here works: // Media API callback void CALLBACK AudioRecorder::waveInProc(HWAVEIN hWaveIn, UINT uMsg, DWORD dwInstance, DWORD dwParam1, DWORD dwParam2) { // Data received if (uMsg == WIM_DATA) { // Get wav header LPWAVEHDR mBuffer = (WAVEHDR *)dwParam1; // Now what? for (unsigned i = 0; i != mBuffer->dwBytesRecorded; ++i) { // I can see the char, how do get them into my file and audio buffers? cout << mBuffer->lpData[i] << "\n"; } // Re-use buffer mResultHnd = waveInAddBuffer(hWaveIn, mBuffer, sizeof(mInputBuffer[0])); // mInputBuffer is a const WAVEHDR * } } // waveInOpen cannot use an instance method as its callback, // so we create a static method which calls the instance version void CALLBACK AudioRecorder::staticWaveInProc(HWAVEIN hWaveIn, UINT uMsg, DWORD_PTR dwInstance, DWORD_PTR dwParam1, DWORD_PTR dwParam2) { // Call instance version of method reinterpret_cast<AudioRecorder *>(dwParam1)->waveInProc(hWaveIn, uMsg, dwInstance, dwParam1, dwParam2); } Like I said, it works great, but I'm trying to do the following: Convert the data to short and copy into an array Convert the data to float and copy into an array Copy the data to a larger char array which I'll write into a WAV Relay the data to an arbitrary output device I've worked with FMOD a lot and I'm familiar with interleaving and all that. But FMOD dishes everything out as floats. In this case, I'm going the other way. I guess I'm basically just looking for resources on how to go from LPSTR to short, float, and unsigned char. Thanks much in advance!

    Read the article

  • Boost threading/mutexs, why does this work?

    - by Flamewires
    Code: #include <iostream> #include "stdafx.h" #include <boost/thread.hpp> #include <boost/thread/mutex.hpp> using namespace std; boost::mutex mut; double results[10]; void doubler(int x) { //boost::mutex::scoped_lock lck(mut); results[x] = x*2; } int _tmain(int argc, _TCHAR* argv[]) { boost::thread_group thds; for (int x = 10; x>0; x--) { boost::thread *Thread = new boost::thread(&doubler, x); thds.add_thread(Thread); } thds.join_all(); for (int x = 0; x<10; x++) { cout << results[x] << endl; } return 0; } Output: 0 2 4 6 8 10 12 14 16 18 Press any key to continue . . . So...my question is why does this work(as far as i can tell, i ran it about 20 times), producing the above output, even with the locking commented out? I thought the general idea was: in each thread: calculate 2*x copy results to CPU register(s) store calculation in correct part of array copy results back to main(shared) memory I would think that under all but perfect conditions this would result in some part of the results array having 0 values. Is it only copying the required double of the array to a cpu register? Or is it just too short of a calculation to get preempted before it writes the result back to ram? Thanks.

    Read the article

  • Splitting a C++ class into files now won't compile.

    - by vgm64
    Hi. I am teaching myself to write classes in C++ but can't seem to get the compilation to go through. If you can help me figure out not just how, but why, it would be greatly appreciated. Thank you in advance! Here are my three files: make_pmt.C #include <iostream> #include "pmt.h" using namespace std; int main() { CPMT *pmt = new CPMT; pmt->SetVoltage(900); pmt->SetGain(2e6); double voltage = pmt->GetVoltage(); double gain= pmt->GetGain(); cout << "The voltage is " << voltage << " and the gain is " << gain << "." <<endl; return 0; } pmt.C #include "pmt.h" using namespace std; class CPMT { double gain, voltage; public: double GetGain() {return gain;} double GetVoltage() {return voltage;} void SetGain(double g) {gain=g;} void SetVoltage(double v) {voltage=v;} }; pmt.h #ifndef PMT_H #define PMT_H 1 using namespace std; class CPMT { double gain, voltage; public: double GetGain(); double GetVoltage(); void SetGain(double g); void SetVoltage(double v); }; #endif And for reference, I get a linker error (right?): Undefined symbols: "CPMT::GetVoltage()", referenced from: _main in ccoYuMbH.o "CPMT::GetGain()", referenced from: _main in ccoYuMbH.o "CPMT::SetVoltage(double)", referenced from: _main in ccoYuMbH.o "CPMT::SetGain(double)", referenced from: _main in ccoYuMbH.o ld: symbol(s) not found collect2: ld returned 1 exit status

    Read the article

< Previous Page | 53 54 55 56 57 58 59 60 61 62 63 64  | Next Page >