12.5. Using the System.Array class

I mentioned that all array objects in C# are implicitly objects of the System.Array class. System.Array contains useful methods and properties which you can use. The Length property, ^[8] discussed earlier, is actually inherited from System.Array. Other methods can be used for creating, manipulating, searching, and sorting arrays.

^[8] If you are not sure of C# properties, just treat a property as a public field for now. See Chapter 20 for more information.

I shall introduce the following static methods in System.Array which can be useful for 1D arrays:

• public static void Reverse (Array array)

• public static void Sort (Array array)

• public static int IndexOf (Array array, Object value)

Check out the API documentation for more details.

Reverse() takes in a 1D array and reverses the sequence of the elements stored in it. Here is a simple example of its use:

 1: using System;
 2:
 3: public class TestClass{
 4:   public static void Main(){
 5:     string []Fruits ="apple","orange","banana","coconut"};
 6:     Array.Reverse(Fruits);
 7:
 8:     for (int i=0; i<4; i++)
 9:       Console.WriteLine(i + ":" + Fruits[i]);
10:   }
11: }

Output:

c:expt>test
0:coconut
1:banana
2:orange
3:apple

Likewise, Sort() takes in a 1D array and sorts the elements in order. Replacing line 6 of the program above with this statement:

6:     Array.Sort(Fruits);

results in this output:

c:expt>test
0:apple
1:banana
2:coconut
3:orange

IndexOf () takes in a 1D array and an object to be matched against the elements in the array. It returns the array index of the first match or -1 if no match is found. Examine the following program:

1: using System;
2: public class TestClass{
3:   public static void Main(){
4:     string []Fruits={"apple","orange","banana","coconut"};
5:     Console.WriteLine(Array.IndexOf(Fruits,"banana"));
6:   }
7: }

Output:

c:expt>test
2