我的代码有什么问题（它处理数组大小）？

Question

I am initializing array size to 1 but I am updating it in the subsequent lines. It is not even storing the first element in the array as the array size is 1 initially but I expected it would. Could someone provide me with an explanation? Here is the code:

  class Program
  {
    static void Main(string[] args)
    {
      int num = int.Parse(Console.ReadLine());
      Console.Write("The binary number for " + num + " is  ");
      int size = 1;
      int[] binary = new int[size];
      size = 0;
      while(num>=1)
      {
        if (num % 2 == 0)
          binary[size++] = 0;
        else
          binary[size++] = 1;
          //size += 1;
          num = num / 2;
      }

      for (int i = size - 1; i >= 0; i--)
      {
        Console.Write(binary[i]);
      }
      Console.WriteLine();
      Console.Write("The Compliment of this number is  ");
      for (int i = size - 1; i >= 0; i--)
      {
        if (binary[i] == 0)
          binary[i] = 1;
        else
          binary[i] = 0;
      }
      for (int i = size - 1; i >= 0; i--)
      {
          Console.Write(binary[i]);
      }
      Console.WriteLine();
      Console.ReadKey();
    }
  }

Answer 1

您无法调整数组的大小，数组的长度始终是初始化期间指定的长度（在您的情况下为1）。

Answer 2

I think the problem is specifically in your expectation that you can update an array size "in the subsequent lines."

When you make the array here:

int[] binary = new int[size];

Then the size is set in stone

When you call something like: binary[size++] = 0; This will not actually increase the number of slots in your array. In fact, that code is only changing the index where you are looking to read or write values. I can see that your code is going to quickly go out of bounds of the array (if you ask for anything but binary[0]

It turns out this array is a tricky data type to use; arrays have a fixed size on creation. You want something that can grow! So you can either:

-Use an array, but declare that it's size is Math.Ciel(logbase2(yourNumber)) to make sure you will have enough space

-Use a data structure that can grow, like a string or list

-You can create a new array every time you need it bigger and assign it like:

binary = new int[++size];
binary[size-1]=whatever

Good luck, hope this helps!