1 static void Main(string[] args) 
 2 {
 3     int[] a = new int[]{ 1, 2, 3 };
 4     Test_1(a);
 5     Console.WriteLine(string.Join(",", a));
 6     Test_2(a);
 7     Console.WriteLine(string.Join(",", a));
 8     Console.ReadLine();
 9 }
10  
11 private static void Test_1(int[] a) 
12 {
13     a = new int[] { 100, 200, 300 };
14 }
15  
16 private static void Test_2(int[] a) 
17 {
18     a[1] = 10;
19 }

1 private static void Test_1(int[] b) 
2 {
3     b = new int[] { 100, 200, 300 };
4 }
5  
6 private static void Test_2(int[] c) 
7 {
8     c[1] = 10;
9 }