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How are arrays used in C#?

Educative Answers Team

An array is a collection of data objects of the same type. An array creates one variable, rather than declaring multiple variables to store data.

That one variable is allocated to a contiguous memory space where all the data is stored. An array may be of type int, char, string and even an array itself.

The values stored in the array are referred to as elements and each element is present at a particular index of the array.

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Defining an array

The syntax to define an array is:

datatype[] arrayName;
  • datatype: The type of objects that will be stored in the array eg. int, char etc.

  • [ ]: Specifies that the declared variable points to an array

  • arrayName: Specifies the name of the array

Initializing an array

Defining an array does not initialize it. In order to store values in the array, we must initialize it first, the syntax of which is as follows:

data-type [ ] arrayName = new data-type [size];

Look at the following examples to get a better idea about array initialization:

  • Initializing an array of size 5 without assigning values
using System;

class HelloWorld
{
    static void Main()
    {
      int[] array = new int[5];
    }
}
  • Initializing an array of size 5 and assigning values
class HelloWorld
{
    static void Main()
    {
      int[] array = new int[5]{5,4,3,2,1}; 
    }
}
  • Initializing an array without specifying the size
class HelloWorld
{
    static void Main()
    {
        int[] array = {1,2,3,4,5}; 
    }
}

Note: If the new keyword is used, the array is initialized on the heap otherwise it is initialized on the stack.

Accessing array elements

The elements of an array can be accessed through their indices.

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Suppose we wish to access the fourth element 2. To do so, we will proceed as follows:

using System;
class HelloWorld
{
    static void Main()
    {
      int[] array = new int[5]{1,3,5,2,4};
      int x = array[3];
      Console.WriteLine(x);
    }
}

Another way of accessing array elements is by using the built-in GetValue() function.

using System;
class HelloWorld
{
    static void Main()
    {
      int[] array = new int[5]{1,3,5,2,4};
      int x = (int) array.GetValue(3);
      Console.WriteLine(x);
    }
}

Length of the array

The length or size of the array can be determined using the built-in Length function.

using System;

class HelloWorld
{
    static void Main()
    {
      int[] array = new int[5]{1,3,5,2,4};
      int length = array.Length;
      Console.WriteLine(length);
    }
}

Modifying array elements

The element stored at a particular index in the array can also be modified using the following syntax:

using System;
class HelloWorld
{
    static void Main()
    {
      int[] array = new int[5]{1,3,5,2,4};
      //Modifying the first element
      array[0] = 999;
      //Printing the entire array
      for (int i = 0; i < array.Length; i++)
      {
        Console.WriteLine(array[i]);
      }
    }
}

Arrays are one of the fundamental data structures in C#. The ability to store multiple items of the same data-type make them incredibly useful for complex programming problems.

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data structures
collection
array
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