Access to an array from another class

Question

Hello, I just started to learn C #, I encountered such a problem.

It is necessary to initialize the array and its size from the keyboard, and then open access to it and its elements for another class.

Non-working code:

namespace ConsoleApplication1 { class MainClass { static void Main() { Massive instance = new Massive(); Console.WriteLine("Размер массива: "); instance.Size = Convert.ToInt32(Console.ReadLine()); Console.WriteLine(instance.Size); instance.Input(); instance.Output(); Console.ReadKey(); } } class Massive { int i; int size = 0; int []mass = new int[size]; //инициализатор поля не может обращаться к нестатическому полю public int Size { set { size = value; } get { return size; } } public void Input() { for (i = 0; i < size; i++) { Console.WriteLine("Введите элемент массива: "); mass[i] = Convert.ToInt32(Console.ReadLine()); } } public void Output() { for (i = 0; i < size; i++) { Console.Write(" "+mass[i]); } } } class Massive2 : Massive { //доступ к массиву и его элементам с класса Massive } }

Updated code

  using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace ConsoleApplication1 { class MainClass { static void Main() { Massive instance = new Massive(); Console.WriteLine("Размер массива: "); instance.Size = Convert.ToInt32(Console.ReadLine()); Console.WriteLine(instance.Size); instance.Input(); instance.Output(); Massive2 instance2 = new Massive2(); Console.WriteLine(); instance2.Method(); Console.ReadKey(); } } class Massive { int[] mass = null; int i; public int Size { set { if (value > 0) mass = new int[value]; else mass = null; } get { return (mass != null) ? mass.Length : 0; } } public int this[int index] { get { return mass[index]; } //ошибка здесь set { mass[index] = value; } } public void Input() { for (int i = 0; i < Size; i++) { Console.WriteLine("Введите элемент массива: "); mass[i] = Convert.ToInt32(Console.ReadLine()); } } public void Output() { for (i = 0; i < Size; i++) { Console.Write(" " + mass[i]); } } } class Massive2 : Massive { public void Method() { //доступ к массиву и его элементам с класса Massive int test = this[4]; Console.WriteLine(test); } }

}

so, instance2 is a completely different object, where Size is zero and mass is null.

Answer 1 · 2017-02-11T18:49:25

 class Massive { int i; int size = 0; int []mass = null; public int Size { set { size = value; // check for size > 0 mass = new int[size]; } get { return size; } } public int this[int index] { get { return mass[index]; } set { mass[index] = value } } ...

You can do without the size field, and use the array itself to get its length:

 class Massive { int []mass = null; public int Size { set { if (value > 0) mass = new int[value]; else mass = null; } get { return (mass != null)? mass.Length : 0; } } public int this[int index] { get { return mass[index]; } set { mass[index] = value } } public void Input() { for (int i = 0; i < Size; i++) { Console.WriteLine("Введите элемент массива: "); mass[i] = Convert.ToInt32(Console.ReadLine()); } } ...

Update

 static void Main() { Massive2 instance2 = new Massive2(); Console.WriteLine("Размер массива: "); instance2.Size = Convert.ToInt32(Console.ReadLine()); Console.WriteLine(instance2.Size); instance2.Input(); instance2.Output(); instance2.Method(); Console.ReadKey(); }

And how do you get access to some element of mass in the class Massive2: Massive?
but I get the error "Object link does not indicate an object instance."
, well, make sure that before that you have appointed a Size at least five
I can not understand why it is impossible, Size is not less than five.
@mwchqq so, instance2 is a completely different object, for which Size is zero and mass is null.

Access to an array from another class

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