如何将一个数组中的字符添加到 C# 中的一个空数组中？

Question

In the code below, I have copied the first 5 characters of my string [] items to the char itemnames. I want to now add the new shortened strings to my empty array. I'm getting the error that "Index was outside the bounds of the array" Any idea why?

using System;

namespace new_assignment_george
{
class Program
{
    static void separate_prices(string[] items, string[] item_names, double[] item_prices)
    {
        char[] itemnames = new char[5];
        int x = 0;
        foreach (string i in items)
        {
            items[x].CopyTo(0, itemnames, 0, 5);
            item_names[x] = itemnames.ToString();
            Console.WriteLine(item_names[x]);
            x = x + 1;
        }


    }

    static void Main(string[] args)
    {
        string[] items = { "Widget 15.50", "Thingy 50.99", "Ratchet25.00", "Clanger115.49", "Fracker75.25" };
        string[] item_names = { };
        double[] item_prices = { };

        Program myprogram = new Program();

        separate_prices(items, item_names, item_prices);
    }
}

}

Answer 1

You need to specify the size for the two arrays so that the indexes are available to be populated. you can set that like following so that you have same size of arrays for item names and prices:

 string[] item_names = new string[items.Length];
 double[] item_prices = new double[item.Length];

Currently you have declared these arrays without specifying the size so those indexes which are accessed wouldn't be available to be used.

Now we have item_names and item_prices arrays of same size which we have in items array.

Answer 2

In addition to what Ehsan said, you should not be using char array here. This code is incorrect: item_names[x] = itemnames.ToString();

Here is the working code:

using System;
using System.Linq;

namespace new_assignment_george
{
class Program
{
    static void separate_prices(string[] items, string[] item_names, double[] item_prices)
    {
        int i=0;
        foreach (string item in items)
        {
            item_names[i++] = item.Substring(0,5);
        }
    }

    static void Main(string[] args)
    {
        string[] items = { "Widget 15.50", "Thingy 50.99", "Ratchet25.00", "Clanger115.49", "Fracker75.25" };
        string[] item_names = new string[items.Count()];
        double[] item_prices = new double[items.Count()];
        separate_prices(items, item_names, item_prices);
        foreach(string s in item_names)
        {
            Console.WriteLine(s);
        }
    }
}
}