Pattern Matchings

1-Conditional.cs

if (randomShape is Circle { Diameter: 10, Radius: < 5 and > 2, Area: <= 15 } c)
{
    Console.WriteLine($"This is my circle. Area: {c.Area}");
}
if (randomShape is not null)
{

}
if (randomShape is not Recatngle)
{

}
if (randomShape is not null and not Recatngle)
{

}

if (randomShape is Circle { Name: { Length: >= 0 } })
{

}
if (randomShape is Circle { Name.Length: >= 0 })
{

}

2-switch_case.cs

switch (randomShape)
{
    case Circle _:
        Console.WriteLine();
        break;
    case Recatngle r when r.Width == r.Height:
        Console.WriteLine("This is square.");
        break;
    default:
        break;
}

3.1-switch1.cs

var text = randomShape switch
{
    Circle { Diameter: 20 } c1 => "This is a special circle",
    Circle { Diameter: 10, Radius: < 5 and > 2, Area: <= 15 } c1 => "This is a very special circle",
    Circle _ => "This is a circle",
    Recatngle r when r.Width == r.Height => "This is a square",
    Recatngle r => "This is a rectangle",
    { Area: 100 } => "This is a shape with area 100",
    { Area: > 100 } => "This is a shape with begger than 100",
    _ => throw new NotImplementedException(),
};

3.2-switch2.cs

var text1 = randomShape.Area switch
{
    >= 100 and <= 200 => "Hi",
    _ => "Bye"
};

3.3- swicth_expression.cs

switch (fruit)
{
    case Apple apple when apple.Color == Color.Green:
        var food = MakeApplePieFrom(apple);
        break;
}

3.4-SwitchExpression.cs

public static string Display(this Person person)
{
    return (person?.Age < 50, IsYoung(person), IsBaby(person), person) switch
    {
        (_, _, _, Student p) => $"{p.Name} is a student and he studies {p.CourseOfStudy}.",// His birth year is {p.GetBirthYear()}",
        (_, _, _, Teacher { Age: 43 } p) => $"{p.Name} is same as me and he teaches {p.CourseOfTeach}",
        (_, true, _, Teacher p) => $"{p.Name} is a young teacher and he teaches {p.CourseOfTeach}",
        (true, _, _, Teacher p) => $"{p.Name} is a teacher and he teaches {p.CourseOfTeach}",
        (_, _, _, null) => "Null? kidding?",
        (_, _, _, { Age: 0, Name: var name }) => $"I don't know how old is '{name}'",
        (_, _, true, { } p) => $"{p.Name} is a baby. He is {p.Age}",
        (_, _, _, { } p) => $"{p.Name} is a person and he {p.Age} is",
        _ => $"What the f** is this?"
    };
    static bool IsYoung(Person p) => p?.Age > 40;
    static bool IsBaby(Person p) => p?.Age < 10;
}

4-Or_Disjunctive.cs

var isWeekEnd = DateTime.Now.DayOfWeek switch
{
    DayOfWeek.Sunday or DayOfWeek.Monday => true,
    _ => false
}

5-Positional.cs

var isWeekEnd = DateTime.Now.DayOfWeek switch
{
    DayOfWeek.Sunday or DayOfWeek.Monday => true,
    _ => false
}

6-Property.cs

if ((a is { } b) && (b is Student c and { Age: > 5 }))
{

}

7-ExtendedProperty.cs

if (person is Student and { Name.Length: > 5 })
{
}

98-best_practice.cs

static bool isEnglish(char c) => (c is (>= 'A' and <= 'Z') or (>= 'a' and <= 'z'));

99-Data.cs

using System;

internal readonly record struct Person(string Name, int Age);

internal abstract class Shape
{
    public abstract double Area { get; }

    public string Name { get; set; }
}

internal sealed class Circle : Shape
{
    public double Diameter { get; set; }
    public override double Area => this.Radius * Math.PI;
    public double Radius => this.Diameter / 2;
}

internal sealed class Recatngle : Shape
{
    public double Width { get; set; }
    public double Height { get; set; }
    public override double Area => this.Width * this.Height;
}