how to add to array after the new keyword in c# code example

Example 1: c# add to array

var Freds = new [] { "Fred", "Freddy" };
Freds = Freds.Concat(new [] { "Frederick" }).ToArray();

Example 2: append an array in c#

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