Index Struct in C# 8.0

C# 8.0 introduced a new predefined structure that is known as Index struct. This struct is used to represent a type that can be used as an index of a collection or sequence that starts from either start or end. It provides a new index style to access elements that is ^ operator. This operator is used to find the last elements of the specified collection or sequence. Also with the help of Index struct you are allowed to create a variable of the index type.

Example:

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// C# program to illustrate 
// the concept of index
using System;
  
namespace example {
  
class GFG {
  
    // Main Method
    static void Main(string[] args)
    {
  
        // Creating and initializing an array
        int[] num = new int[] {1, 2, 3, 4, 5, 6, 7};
  
        // Accessing the starting
        // elements of the array
        Console.WriteLine("Starting Elements");
        Console.WriteLine(num[1]);
        Console.WriteLine(num[2]);
        Console.WriteLine(num[3]);
  
        // Accessing the last
        // elements of the array
        Console.WriteLine("Last Elements");
        Console.WriteLine(num[^2]);
        Console.WriteLine(num[^3]);
        Console.WriteLine(num[^4]);
        Console.WriteLine();
  
        // Index as a variable
        Index i = ^1;
        Console.WriteLine("Index as a variable: " + num[i]);
    }
}
}

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Output:



Starting Elements
2
3
4
Last Elements
6
5
4

Index as a variable: 7

Constructor

Constructor Description
Index(Int32, Boolean) It is used to initialize a new Index with a specified index position and a value that indicates if the index is from the start or the end of a collection.

Properties

Property Description
End It is used to get an Index that points beyond the last element.
IsFromEnd It is used to get a value that indicates whether the index is from the start or the end.
Start It is used to get an Index that points to the first element of a collection.
Value It is used to get the index value.

Methods

Method Description
Equals() It is used to check whether the given index is equal to another index or not.
FromEnd(Int32) It is used to create an Index from the end of a collection at a specified index position.
FromStart(Int32) It is used to create an Index from the specified index at the start of a collection.
GetHashCode() It return the hash code for the given instance.

GetOffset(Int32) It is used to calculate the offset from the start of the collection using the given collection length.
ToString() It is used to return the string representation of the current Index instance.


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