12.5 Using the System.Array class

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