Arrays in C#

Overview

• Fixed-Size Collection: An array is a fixed-size collection of elements, meaning the number of elements in an array is defined at the time of its creation and cannot be changed.
• Multiple Values: Arrays are used to store multiple values in a single variable, allowing for more organized and manageable code.
• Homogeneous Data Types: All elements in an array must be of the same data type.

Defining and Initializing Arrays

1. Defining an Array:

   • Example:

     // Defining an array with 5 elements
     string[] country = new string[5];

2. Defining and Initializing an Array:

   • Example:

     string[] country = { "Sri Lanka", "Singapore", "Italy", "Poland", "Canada" };

3. Initializing Elements in an Array:

   • Example:

     double[] height = { 87.1, 65.7, 12.7, 91.6 };
     int[] age = { 50, 27, 32, 49, 61 };

One-Dimensional vs. Two-Dimensional Arrays

One-Dimensional Array

• Description: A simple data structure that stores a collection of similar type data in a contiguous block of memory.

• Other Names: Called a single-dimensional array.

• Storage: Data will be stored as a list.

  Example:

  int age[] = new int[5];

Two-Dimensional Array

• Description: A type of array that stores multiple data elements of the same type in a matrix or table-like format with a number of rows and columns.

• Other Names: Called a multidimensional array.

• Storage: Data will be stored in a row-column format.

  Example:

  string name[][] = new string[5][8];

Array Methods

Here are some commonly used methods from the Array class:

1. Clone()

   • Description: Used to create a shallow copy of the array.
   • Example:

     int[] numbers = { 1, 2, 3 };
     int[] numbersClone = (int[])numbers.Clone();

2. Copy()

   • Description: Used to copy array elements into another array by specifying the starting index.
   • Example:

     int[] sourceArray = { 1, 2, 3 };
     int[] destinationArray = new int[3];
     Array.Copy(sourceArray, destinationArray, 3);

3. Empty<T>()

   • Description: Used to return an empty array.
   • Example:

     string[] emptyArray = Array.Empty<string>();

4. Finalize()

   • Description: Used to free resources and perform platform cleanup operations. (Not commonly used in typical array operations.)

5. Sort(Array)

   • Description: Used to sort all the elements of a one-dimensional array.
   • Example:

     int[] numbers = { 3, 1, 2 };
     Array.Sort(numbers);
     // numbers is now {1, 2, 3}

6. Reverse(Array)

   • Description: Used to reverse the sequence of elements in an array.
   • Example:

     int[] numbers = { 1, 2, 3 };
     Array.Reverse(numbers);
     // numbers is now {3, 2, 1}

7. IndexOf(Array, Object)

   • Description: Used to search for the specified object and return its first occurrence in a one-dimensional array.
   • Example:

     int[] numbers = { 1, 2, 3 };
     int index = Array.IndexOf(numbers, 2); // index will be 1

Array Class vs. ArrayList Class

Array Class:

• Description: A base class for language implementation that supports array operations. It provides methods for creating, manipulating, searching, and sorting array elements.

ArrayList Class:

• Description: Represents a resizable collection of elements that can contain elements of any data type. Unlike arrays, ArrayList can grow in size dynamically as elements are added.