c# 12 - collection expression and lambda default

Collection expression 

C#12 provides a simpler and more consistency way to initialize collections for array, character and lists. Please review the example here:- 

// older ways to declare array int

int[] myintegers = new int[] { 1, 2, 3, 4, 5 };

// newer ways to to declare array int

int[] myintegersNew = [1,2,3,4,5];

// older ways to declare List<string>

List<string> myliststrings = new List<string> { "apple", "banana", "watermelon" };

// newer ways to to declare array int

List<string> myliststrings2 = ["apple", "banana", "watermelon"];

Lambda default and optional

With C#12, we can make use of default and optional parameters with lambda expression). For example,

var HelloWorld = (string greet = "hello", string user = "James") => $"{greet} {user}";

Console.WriteLine(HelloWorld());

Inline Array

First you need to use attribute and declare a struct with "[System.Runtime.CompilerServices.InlineArray(10)]". The underlying data type can be struct, class or just value type.  

You just have to initialize the type without needed to specifying size.

// declaring array of size 10

[System.Runtime.CompilerServices.InlineArray(10)]

public struct InlineArrayDemo

{

    private int _element;

}

// declaring array of size 10

[System.Runtime.CompilerServices.InlineArray(10)]

public struct InlineEmployeeDemo

{

    private Employee _element;

}

class Employee

{

    public string Name { get; set; }

    public string Id { get; set; }

}

Inline array variable cannot be used with Linq and doesn't not have length property like you get in array. 

Using simple inline array 

// create instance

var x = new InlineArrayDemo();

// update array [10] to 1

x[9] = 1;

// updating array higher than 10 results in compile time error

// x[11] = 1;

Using class inline array

var emp = new InlineEmployeeDemo();

emp[1] = new Employee { Id = "abc", Name = "Jeremy" };

Console.WriteLine(x[9]);

Console.WriteLine(emp[1].Name);

Looping through the inline array 

// looping through the inline array using foreach

foreach (var item in emp)

{

    Console.WriteLine(item?.Name); // throws null if object not initialize

}

for (int i = 0; i < 10; i++)

{

    Console.WriteLine(emp[i]?.Name);

}