Introduction To C# 11 And Its New Features

string message = """
    Writing a message
        to explain "Raw String Literals"
    which includes multiple lines
                with different indentation and
        also it contains 'single quote', "double quote",
        other special chars \n and white spaces.
    """;
Console.WriteLine(message);

string firstName = "Aaditya Kumar";
string lastName = "Ravi";
string message = $$"""
    My name is {{{firstName}} {{lastName}}}
    """;
Console.WriteLine(message);

var filler = "WELCOME";
Console.WriteLine($"You are {filler.
     ToLower()} to learn C# 11.");

int[] numbers = { 1, 2, 3 };
Console.WriteLine(numbers is [1, 2, 3]);  // True
Console.WriteLine(numbers is [1, 2, 4]);  // False
Console.WriteLine(numbers is [1, 2, 3, 4]);  // False
Console.WriteLine(numbers is [0 or 1, <= 2, >= 3]);  // True

Output

Each element of numbers array should match with a pattern or exact value specified in the list at the corresponding index to return True. The 0 position value of the array should match or satisfy the condition with the 0 position value of the list, 1st with 1st, and so on.

Numbers = {1,2,3} and [0 or 1, <=2, >=3], here 1 match with 0 or 1, 2 matches with <=2, 3 matches with >=3. Hence it returns True.

Example 2

Code

List<int> numbers = new() { 1, 2, 3 };
if (numbers is [var first, _, _])
{
    Console.WriteLine($"The first element of a three-item list is {first}.");
}

Output

Here, the numbers list is mapped with [var first, _, _], the 2nd and 3rd position is discarded because of the underscore ( _ ), and the first value is mapped with 1 of the numbers list. Hence the first equals to 1.

Example 3

Code

int[] numbers = { 1, 2, 3 };
if (numbers is [var first, .. var rest])
{
    Console.WriteLine(first);
}

Output

Here first is mapped with 1, and the remaining value is mapped with the rest variable due to slice pattern(..)

Example 4

Code

Console.WriteLine(new[] { 1, 2, 3, 4, 5 } is [> 0, > 0, ..]);  // True
Console.WriteLine(new[] { 1, 1 } is [_, _, ..]);  // True
Console.WriteLine(new[] { 0, 1, 2, 3, 4 } is [> 0, > 0, ..]);  // False

Output

4. Required Members

By adding the "required" modifier to properties and fields, constructors and callers can be compelled to initialize those values.

Example 1

Code

var stud = new Student() {
    Name = "Aaditya"
};
class Student {
    public required string Name {
        get;
        set;
    }
}

Output

Build Succeeded because we provided the value to the Name field while calling.

var stud = new Student() { Name = "Aaditya"};

If we don't provide the value to the required field, it gives an error at compile time.

Additionally, the System.Diagnostics.CodeAnalysis.SetsRequiredMembersAttribute can be used with constructors to indicate to the compiler that a constructor initializes all necessary members.

Example 2

Code

using System.Diagnostics.CodeAnalysis;
static void Main(string[] args) {
    Student stud = new Student("Aaditya");
}
class Student {
    public Student() {}
        [SetsRequiredMembers]
    public Student(string name) {
        Name = name;
    }
    public required string Name {
        get;
        set;
    }
}

Output

The build Succeeded, as shown in the above screenshot.

5. Auto Default Struct

As part of executing a constructor, the C# 11 compiler guarantees that all fields of a struct type are initialized to their default value. Consequently, the compiler automatically initializes any field or auto property that is not initialized by a constructor. Therefore, structs that do not explicitly assign all fields in the constructor will still compile, and any fields that are not explicitly initialized will be set to their default value. Whereas C# 10 or other previous versions used to throw errors.

Example 1:Code

static void Main(string[] args) {}
public struct Coords {
    public int X;
    public int Y;
    public Coords(int x, int y) {
        X = x;
        /* Y = y; here we commented Y=y assignment, still C# 11 compiles it and assign default value as
                  0. However C# 10 or previous version gave error at this point if all members of
                  struct is not assigned with some value*/
    }
}

When I change project C# version 11 to 10 (by right-clicking on the project and selecting .Net 6.0), it gives an error as Y is not assigned.

Conclusion

In conclusion, C# 11 introduces a wide range of new features and improvements that make writing code easier and more efficient. The above features are just a few enhancements in C# 11, making it a great programming language for modern development. If you're a C# developer, you'll definitely want to take advantage of these new features to write more robust, efficient, and maintainable code.