Vs2012编译时指示索引数组溢出，求指教

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace sl_15102004
{
    class Program
    {

        static void Main(string[] args)
        {
            int[] a=new int[5]{1,2,3,4,5};
            int[] b=new int[a.Length ];
            int[] c= new int[a.Length];

            b= a;
            Console.WriteLine("输出b数组数据：");
            foreach (int i in b)
            {
                Console.WriteLine(i);
            }
            for (int i = 0; i <= a.Length; i++)
            {
                c[i] = a[i];
            }
            Console.WriteLine("输出c数组数据：");
            foreach (int i in c)
            {
                Console.WriteLine(i);
            }

            Console.WriteLine("改变a数组的第2个数据的值，请输入新的值：");
            a[1] = Console.Read();

            Console.WriteLine("输出a数组的数据：");
            foreach (int i in a)
            {
                Console.WriteLine(i);
            }
            Console.WriteLine("输出b数组数据：");
            foreach (int i in b)
            {
                Console.WriteLine(i);
            }
            Console.WriteLine("输出c数组数据：");
            foreach (int i in b)
            {
                Console.WriteLine(i);
            }
            Console.ReadLine();
        }
    }
}