Foo(int num): bar(num) This construct is called a Member Initializer List in C++. Simply said, it initializes your member bar to a value num. What is the difference between Initializing and Assignment inside a constructor? Member Initialization: Foo(int num): bar(num) {}; Member Assignment: Foo(int num) { bar = num; } There is a significant difference … Read more
In C# 5 and earlier, to give auto implemented properties an initial value, you have to do it in a constructor. Since C# 6.0, you can specify initial value in-line. The syntax is: public int X { get; set; } = x; // C# 6 or higher DefaultValueAttribute is intended to be used by the … Read more
Yes, it is possible: public class Foo { private int x; public Foo() { this(1); } public Foo(int x) { this.x = x; } } To chain to a particular superclass constructor instead of one in the same class, use super instead of this. Note that you can only chain to one constructor, and it … Read more
The compiler is allowed to make one implicit conversion to resolve the parameters to a function. What this means is that the compiler can use constructors callable with a single parameter to convert from one type to another in order to get the right type for a parameter. Here’s an example class with a constructor … Read more
Your understanding: I cannot call a non-static method from a a method of a different class. is wrong. If you have created the object of the class containing the non-static method, you can call it. You get a null pointer exception because the constructor of the ClassA does something with the CommandControl ab. And that … Read more
A constructor only builds one thing, so you can’t use a constructor to build a group of things. If you use new Class[ 20]; // 20 Classes get allocated, but each is constructed once in the constructor. class Class { Class * left; Class * right; Class( SomeObject & x ) { eatSomeData( x ); … Read more
You already have a String parameter, you can use it as it is, you do not need to create a new one, see: public Move(String r) { String move = r; } However, move will only be a local variable, you probably want something different, but that’s another step, which you will need to do … Read more
The object that you’re extending,Event, does not have a constructor that takes no arguments. So you need to call super and specify arguments like you do in your other constructor.
I think you mean this.stack = new double[default_capacity]; and also this.stack = new double[capacity];
Methods can have optional parameters, but, you can also overload – so, while you seem to want a constructor (because you’re creating objects, but, you could make it methods.. but you do need to make the object first then!): potentially you could have 2 constructors to allow for those conditions : public OpenAccount (String name, … Read more