constructor

问题 In my one class I have many constructors like this.. public MyData(int position,String songName,String duration, boolean e) { //initialization of above variable like int, string,string and boolean } public MyData(String songName, String artistName, String duration,String downloadPath, String songSize, String albumName,String url,String trackId, boolean e) { //initialization of above variable like String,String,String,String,String,String,String,String and boolean } and some more like above.

问题 I have 2 classes, TournamentMember and Player where Player is derived from TournamentMember . Each of the classes has parametric constructor. TournamentMember has this constructor: TournamentMember(const char* name, std::string country, int height); Player class has this constructor: Player(int number, int goals, std::string position, std::string feet); I create an object from the Player class like this: Player soccer_player(40, 34, "goalkeeper", "right"); Each soccer player should have 7

问题 As far as I know, you cannot inherit constructors in C++. But there are situations, where it might be required that it looks like you can instantiate inherited classes the same way you instantiate their base: struct Base { int i; int const j; Base(int i, int j) : i(i), j(j) {} }; // option 1) struct Derived1 : Base { Derived1(int i, int j) : Base(i,j) {} }; Base* baseFactory() { return new Derived1(42,47); } // option 2) struct Derived2 : Base { }; Base* baseFactory() { Base* b = new Derived2

问题 Introduction Let's introduce this simple example: #include <cmath> class X { public: // Members /// A ^ B + A int A; /// A ^ B + B int B; public: // Specials X( const int & A, const int & B ) : A(A) , B(B) { const auto Pow = static_cast<int>(std::pow(A, B)); this->A += Pow; this->B += Pow; } }; Trivia Introduced class has two member variables: A and B . They take value of A ^ B + A and A ^ B + B , respectively. Both of them shares common complex initialization code (let's assume std::pow is

问题 I try to make a generic, but still efficient multi dimension Point class. What I have is a Dimensions enum enum Dimension : std::size_t { _2D = 2, _3D = 3 }; And a Point class template <typename T, Dimension D> class Point : public std::array<T, D> { public: T& at(size_t idx) { return std::array<T,D>::at(idx); }; const T& at(size_t idx) const { return std::array<T,D>::at(idx); }; Dimension dim() const { return D; } ... }; I would like to create nices constructors so I added (outside my class

问题 {EDIT} Actual code here: http://jsfiddle.net/r79xtbdm/ I have a constructor function as follows (pseudo-code): function Tile(<pass in arguments here>) { // set some variables here based on arguments passed (this.width, this.height) etc.. } Outside of this constructor function, I use prototype to provide a method for the function as follows: Tile.prototype.draw = function() { // do some stuff } I have another function as follows: function createTileMap() { var firstTile = new Tile(<arguments>)

问题 I read following links :- object initialized with and without parentheses types of default constructor diff b/w value,zero and default intilization I have some question which i want to clarify. 1) Given a POD class , say :- class A{ int val; }; If i create an object of type A. A obj; // will this call implicitly defined constructor provided by compiler ? Now as far as my understanding in this case constructor is not called.is it correct? new A(); // value-initialize A, which is zero

问题 I have an issue with a solution, but I don't understand the solution. It may be similar to Arduino: initialise custom object in constructor but I don't think this is the same issue. The context is the following. I am controlling a small legged robot with a Arduino board. Each leg is an object "MChLeg" that includes two servos. The servos are controlled using the library. The issue is the following: if I assign the servos in the constructor, the program compiles fine but the servos behave in a

问题 In class Node : class Node { public: int data; int numchild; Node** nodelist; Node(int data, int s); }; I want an array of pointers ( nodelist ) to other nodes, which have edges from this node. Is the following way of constructing such an array (and the above way of declaring it) a correct and the best (or easiest) way possible? If not, why and whats the best way? Node::Node(int d, int s) { data = d; numchild = s; nodelist = new Node*[s]; } 回答1: Generally you shouldn't reinvent the wheel. Raw

问题 I have a class: class Geometry{ std::vector<Subset *> subsets; int verticesCount; ... }; I want to add a copy constructor, so I can make a deep copy of that object (with own subsets , NOT only own pointers to same subsets ). I have tried this: Geometry & Geometry::operator=(const Geometry &other){ verticesCount = other.verticesCount; Subset * subset = 0; for(unsigned int i=0; i<other.subsets.size(); i++){ subset = new Subset(); subsets.push_back(subset); } ... return *this; } The problem is