Suppose we want two constructors for a class representing complex numbers: Complex (double re, double img) // construct from cartesian coordinates Complex (double A, double w) // construct from polar coordinates but the parameters (number and type) are the same: what is the more elegant way to identify what is intended? Adding a thir...
I know it is a strange question did someone have had a case where a C# object return null after newing it up? ...
Consider the following code: using System; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { var square = new Square(4); Console.WriteLine(square.Calculate()); } } class MathOp { protected MathOp(Func<int> calc) { _calc ...
What is the difference between: long myLong; float myFloat = (float) myLong; and: float myFloat = float(myLong); ...
Well, maybe it is a stupid question, but I cannot resolve this problem. In my ServiceBrowser class I have this line: ServiceResolver serviceResolver = new ServiceResolver(ifIndex, serviceName, regType, domain); And compiler complains about it. It says: cannot find symbol symbol : constructor ServiceResolver(int,java.lang.String,java...
Sorry if this is a bit random, but is it good practice to give all fields of a class a value when the class is instanciated? I'm just wondering if its better practice to have a constuctor that takes no parameters and gives all the fields default values, or whether fields that have values should be assigned and others left alone until req...
I have a varargs contructor like this : public class Sentence { public String[] str; public Sentence(Object... text){ StringBuilder sb = new StringBuilder(); for (Object o : text) { sb.append(o.toString()) .append(" "); } System.out.println(sb.toString()); } } Con...
Here is an extract from item 56 of the book "C++ Gotchas": It's not uncommon to see a simple initialization of a Y object written any of three different ways, as if they were equivalent. Y a( 1066 ); Y b = Y(1066); Y c = 1066; In point of fact, all three of these initializations will probably result in the same obje...
I have a class with an object as a member which doesn't have a default constructor. I'd like to initialize this member in the constructor, but it seems that in C++ I can't do that. Here is the class: #include <boost/asio.hpp> #include <boost/array.hpp> using boost::asio::ip::udp; template<class T> class udp_sock { public: ...
While trying to answer this question I found that the code int* p = new int[10](); compiles fine with VC9 compiler and initializes the integers to 0. So my questions are: First of all is this valid C++ or is it a microsoft extension? Is it guaranteed to initialize all the elements of the array? Also, is there any difference if I do new...
I have always been a good boy when writing my classes, prefixing all member variables with m_: class Test { int m_int1; int m_int2; public: Test(int int1, int int2) : m_int1(int1), m_int2(int2) {} }; int main() { Test t(10, 20); // Just an example } However, recently I forgot to do that and ended up writing: class Te...
I'm not sure how to describe this but I'm trying to create a base class that contains a shared (factory) function called FromXml. I want this function to instantiate an object of the proper type and then fill it via an XmlDocument. For example, let's say I have something like this: Public Class XmlObject Public Shared Function Fro...
I have the following code. Which is "correct" and which I do not understand: private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText("You have " + i + " seconds."); } } ); } I create ...
I need to create class Dog and PurebredDog extending Dog. Problem is that Dog can be at once single object and array of objects (Dogs and PurebreedDogs : Dog pack[]={new Dog(76589,"As","black",18, "Ann","Kowalsky"), new PurebreedDog(45321,"Labrador","Elf","black",25, "Angus","Ma...
Consider the following code: struct Calc { Calc(const Arg1 & arg1, const Arg2 & arg2, /* */ const ArgN & argn) : arg1(arg1), arg2(arg2), /* */ argn(argn), coef1(get_coef1()), coef2(get_coef2()) { } int Calc1(); int Calc2(); int Calc3(); private: const Arg1 & arg1; const Arg2 & arg2; // ... const...
Hello Can I call constructor explicitly, without using new, if I already have a memory for object? class Object1{ char *str; public: Object1(char*str1){ str=strdup(str1); puts("ctor"); puts(str); } ~Object1(){ puts("dtor"); puts(str); free(str); } }; Object1 ooo[2] = ...
I'm reading a book about java. It just got to explaining how you create a class called "deck" which contains an array of cards as its instance variable(s). Here is the code snippit: class Deck { Card[] cards; public Deck (int n) { cards = new Card[n]; } } why isn't the this. command used? for example why i...
Is there difference in behavior between a constructor call and a procedure call in Delphi records? I have a D2010 code sample I want to convert to D2009 (which I am using). The sample uses a parameterless constructor, which is not permitted in Delphi 2009. If I substitute a simple parameterless procedure call, is there any functional dif...
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 o...
So here is my code: public MyClass (int y) { super(y,x,x); //some code } My problem is that in this case i want to generate a 'x' and sent to the super constructor. However the call to the superconstructor must be the first line in this constructor. Of course I could do something like this: int x; { x = generateX(); } B...