C#向數組添加數組

using System;

namespace ConsoleApp1
{
    class Program
    {
       /// <summary>
       /// 向數組添加數組
       /// </summary>
       /// <param name="arrayBorn">源數組</param>
       /// <param name="index">添加索引</param>
       /// <param name="value">添加數組</param>
       /// <returns></returns>
        static int[] AddNewArray(int[] arrayBorn,int index,int[] arrayAdd) 
        {
            if (index >= arrayBorn.Length)   //第一種情況：索引大於等於數組最大長度
            {
                index = arrayBorn.Length;
            }
            int[] arrayNew = new int[arrayBorn.Length + arrayAdd.Length];     //聲明一個新數組，長度為源數組+1          
            for (int i = 0;i < arrayNew.Length;i++)
            {
                if (index >= 0)
                {
                    if (i < index)
                    {
                        arrayNew[i] = arrayBorn[i];
                    }
                    else if (i == index)
                    {
                        for (int j = 0; j < arrayAdd.Length; j++)
                        {
                            arrayNew[i + j] = arrayAdd[j];
                        }
                        i = i + arrayAdd.Length - 1;    //注意：此時的索引需要減1，因為執行完此語句進入下次循環，i又會加1
                    }
                    else
                    {
                        arrayNew[i] = arrayBorn[i - arrayAdd.Length];
                    }
                }
                else    //第二種情況：索引小於0，一律視為等於0處理
                {
                    if (i == 0)
                    {
                        for (int j = 0; j < arrayAdd.Length; j++)
                        {
                            arrayNew[i + j] = arrayAdd[j];
                        }
                        i = i + arrayAdd.Length;
                    }
                    else
                    {
                        arrayNew[i] = arrayBorn[i - arrayAdd.Length];
                    }
                }
            }
            return arrayNew;
        }
        static void Main(string[] args)
        {
            int[] arrayInt = new int[] { 0,1,2,3,4,5,6,7,8,9};
            int[] arrayInt1 = new int[] { 4,3,2,1};
            Console.WriteLine("原數組元素：");
            foreach (int i in arrayInt)
            {
                Console.Write(i + " ");
            }
            Console.WriteLine();
            Console.WriteLine("要插入的數組：");
            foreach (int i in arrayInt1)
            {
                Console.Write(i + " ");
            }
            Console.WriteLine();
            arrayInt = AddNewArray(arrayInt,1, arrayInt1);
            Console.WriteLine("插入新元素的數組");
            foreach (int i in arrayInt)
            {
                Console.Write(i + " ");
            }
        }
    }
}