static void Main(string[] args)
        {
            int[] arrayname = new int[5];/*arrayname is an array of 5 integer [5] mean in array [0],[1],[2],[3],[4],[5] because array starts with zero*/
            int i, j;


          /*initialize elements of array arrayname*/
            for (i = 0; i < 5; i++)
            {
                arrayname[i] = i + 100;
            }

             /*output each array element value*/
            for (j = 0; j < 5; j++)
            {
                Console.WriteLine("Element and output value [{0}]={1}",j,arrayname[j]);
            }
            Console.ReadKey();/*Obtains the next character or function key pressed by the user.
                                The pressed key is displayed in the console window.*/
        }

            /*arrayname is an array of 5 integer*/
            int[] arrayname = new int[5];
            int i, j;
            /*initialize elements of array arrayname*/
            for (i = 0; i < 5; i++)
            {
                arrayname[i] = i + 100;
            }

int[] terms = new int[10]; //create 10 empty index in array terms

//fill value = 400 for every index (run) in the array
//terms.Length is the total length of the array, it is equal to 10 in this case 
for (int run = 0; run < terms.Length; run++) 
{
    terms[run] = 400;
}

//print value from each of the index
for (int run = 0; run < terms.Length; run++)
{
    Console.WriteLine("Value in index {0}:\t{1}",run, terms[run]);
}

Console.ReadLine();

/ *输出: 索引0中的值:400 索引1中的值为400 索引2中的值为400 索引3中的值为400 索引4中的值为400 索引5中的值为400 索引6中的值为400 索引7中的值为400 索引8中的值为400 索引9中的值为400 * /

int[] terms = new int[400];

for(int runs = 0; runs < 400; runs++)
{
    terms[runs] = value;
}

你必须先分配数组:

int [] terms = new int[400]; // allocate an array of 400 ints
for(int runs = 0; runs < terms.Length; runs++) // Use Length property rather than the 400 magic number again
{
    terms[runs] = value;
}

下面是如何处理向数组中添加新数字和字符串的一种方法:

int[] ids = new int[10];
ids[0] = 1;
string[] names = new string[10];

do
{
    for (int i = 0; i < names.Length; i++)
    {
        Console.WriteLine("Enter Name");
        names[i] = Convert.ToString(Console.ReadLine());
        Console.WriteLine($"The Name is: {names[i]}");
        Console.WriteLine($"the index of name is: {i}");
        Console.WriteLine("Enter ID");
        ids[i] = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine($"The number is: {ids[i]}");
        Console.WriteLine($"the index is: {i}");
    }


} while (names.Length <= 10);