在 c# unity 中定义数组列表。

Question

I am trying to make an array list of integer values and run some basic math operations as seen below.

int dice1 = 4;
int dice2 = 3;
int dice3 = 6;
int dice4 = 4;
int dice 5 = 5;

ArrayList numbers = new  ArrayList();
        numbers[4] = dice5;
        numbers[3] = dice4;
        numbers[2] = dice3;
        numbers[1] = dice2;
        numbers[0] = dice1;

numbers[3] = numbers[3] * numbers[2];

However, the computer does not allow me to do this and produces an error "Operator "*" cannot be applied to operands of the type 'object' and 'object'". How do I fix this? I think that I have to define the array list as an array of integers... however I am not too sure. Please keep the answers simple as I am quite new to C# unity.

Thanks!

Answer 1

ArrayList stores everything as an 'object', basically the most basic type something can be in C#. You have a few options. If you want to keep using ArrayList, then you'll need to do cast the things you're multiplying, like:

numbers[3] = ((int)numbers[3]) * ((int)numbers[2])

Alternatively, you can ditch ArrayList and use the more modern List<> type. You need to add using System.Collections.Generic to the top, then your code will be like:

int dice1 = 4;
int dice2 = 3;
int dice3 = 6;
int dice4 = 4;
int dice5 = 5;

List<int> numbers = new List<int>(); //List contains ints only
    numbers[4] = dice5;
    numbers[3] = dice4;
    numbers[2] = dice3;
    numbers[1] = dice2;
    numbers[0] = dice1;

numbers[3] = numbers[3] * numbers[2]; //Works as expected

Finally, if you know that your collection will only have a certain number of things, you can use an array instead. Your code will now be:

int dice1 = 4;
int dice2 = 3;
int dice3 = 6;
int dice4 = 4;
int dice5 = 5;

int[] numbers = new int[5]; //Creates an int array with 5 elements
//Meaning you can only access numbers[0] to numbers[4] inclusive
    numbers[4] = dice5;
    numbers[3] = dice4;
    numbers[2] = dice3;
    numbers[1] = dice2;
    numbers[0] = dice1;

numbers[3] = numbers[3] * numbers[2]; //Works as expected

Answer 2

Avoid using array list

Use List<int> or int[]

Then the objects contained are typed instead of being object

Answer 3

您可以在一行中完成：

List<int> numbers = new List<int>{ 4, 3, 6, 4, 5 };

Answer 4

You need to parse the object to string then to int value then use it with * operator.But you firstly have to initialize the arraylist with null values then assign number values So that, use following code that I made clear changes for you.

int dice1 = 4;
    int dice2 = 3;
    int dice3 = 6;
    int dice4 = 4;
    int dice5 = 5;
    int capacity=5;
    ArrayList numbers = new ArrayList(capacity);
    for (int i = 0; i < capacity;i++ )
    {
        numbers.Add(null);
    }
    numbers[4] = dice5;
    numbers[3] = dice4;
    numbers[2] = dice3;
    numbers[1] = dice2;
    numbers[0] = dice1;

    numbers[3] = (int.Parse(numbers[3].ToString()) * int.Parse(numbers[2].ToString()));
    print(numbers[3]);