C# Array Index

In this chapter you will learn:

Array Declaration with initialization
How ro assign value to an array
Set array element value by index(subscript)
Index out of range exception
What to do with IndexOutOfRangeException

Description

The general form for initializing a one-dimensional array is shown here:

type[ ] array-name = { val1, val2, val3, ..., valN };


using System; //  w w  w  .  java2  s  . com
class MainClass
{
  static void Main()
  {

    string[] languages = new string[]{"C#", "COBOL", "Java","java2s.com", "Visual Basic", "Pascal"};
    // Retrieve 5th item in languages array (Visual Basic)
    string language = languages[4];
    Console.WriteLine(language);  
  }
}

The code above generates the following result.

Assign value to array


using System; /*  w  w w.j  ava 2 s .co  m*/
 
class MainClass {  
  public static void Main() {  
    int[] sample = new int[10]; 
    int i;  
  
    for(i = 0; i < 10; i = i+1)  {
      sample[i] = i; 
    }
    for(i = 0; i < 10; i = i+1)  {
      Console.WriteLine("sample[" + i + "]: " + sample[i]);  
    }
  }  
}

The code above generates the following result.

Element by Index


/*  www  . java  2  s  . co m*/
using System; 
 
class MainClass {  
  public static void Main() {  
    int[] nums = new int[10]; 
    int avg = 0; 
 
    nums[0] = 99; 
    nums[1] = 10; 
    nums[2] = 100; 
    nums[3] = 18; 
    nums[4] = 78; 
    nums[5] = 23; 
    nums[6] = 63; 
    nums[7] = 9; 
    nums[8] = 87; 
    nums[9] = 49; 
 
    for(int i=0; i < 10; i++)  {
      avg = avg + nums[i]; 
    }
    avg = avg / 10; 
 
    Console.WriteLine("Average: " + avg); 
  }  
}

The code above generates the following result.

Index out of range exception

When reference an index behind the length of an array C# generates and throws IndexOfOfRange exception.

The following code generates the IndexOutOfRange exception.


using System;/*from w  ww.  j a  v a2s.  c  om*/

class Program
{
    static void Main(string[] args)
    {
        int[] intArray = new int[3];
        Console.WriteLine(intArray[10]);

    }
}

The output:

Catch IndexOutOfRangeException

An attempt to write to a nonexistent array element: IndexOutOfRangeException


using System;/*from  w  w w  .  j av a2  s .c  om*/

class MainClass
{

  public static void Main()
  {

    try
    {
      int[] intArray = new int[5];
      for (int i = 0; i <= intArray.Length; i++){
        intArray[i] = i;
        Console.WriteLine(intArray[i]);
      }
    }
    catch (IndexOutOfRangeException e)
    {
      Console.WriteLine("IndexOutOfRangeException occurred");
      Console.WriteLine("Message = " + e.Message);
      Console.WriteLine("Stack trace = " + e.StackTrace);
    }
  }
}

The code above generates the following result.

The for loop should be the following and <= should be <.

for (int i = 0; i < intArray.Length; i++){

Next chapter...

What you will learn in the next chapter:

Home »
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      C# Array

C# Arrays
C# Array Length
C# Array Rank

C# Array Index

C# Multidimensional Arrays
C# Array Initialization
C# Jagged Array
C# Array foreach loop
C# Array ForEach Action