[이것이 C#이다] Chapter15: 연습문제 (LINQ)

1. 다음과 같은 배열이 있다고 할 때, Cost는 50이상,  MaxSpeed는 150 이상인 레코드만 조회하는 LINQ를 작성하세요.

class Car
    {
        public int Cost { get; set; }
        public int MaxSpeed { get; set; }
    }

    class MainApp
    {
        static void Main(string[] args)
        {
            // ...
            Car[] cars =
            {
                new Car(){Cost= 56, MaxSpeed= 120},
                new Car(){Cost= 70, MaxSpeed= 150},
                new Car(){Cost= 45, MaxSpeed= 180},
                new Car(){Cost= 32, MaxSpeed= 200},
                new Car(){Cost= 82, MaxSpeed= 280}
            };

            var selected = /* Cost가 50 이상, MaxSpeed는 150 이상인 레코드를 조회하는 LINQ */;

답)

var selected = from car in cars
                           where car.Cost >= 50 && car.MaxSpeed >= 150
                           select car;
            foreach (var car in selected) {
                Console.WriteLine($"Car's Cost: {car.Cost}, Car's MaxSpeed: {car.MaxSpeed}");
            }

Car's Cost: 70, Car's MaxSpeed: 150
Car's Cost: 82, Car's MaxSpeed: 280

 

2. 다음 코드에서 cars.Where( c => c.Cost < 60).OrderBy(c => c.Cost)와 동일한 결과를 반환하는 LINQ를 작성하세요.

class Car
        {
            public int Cost { get; set; }
            public int MaxSpeed { get; set; }
        }

        static void Main(string[] args)
        {
            Car[] cars =
            {
                new Car(){Cost= 56, MaxSpeed= 120},
                new Car(){Cost= 70, MaxSpeed= 150},
                new Car(){Cost= 45, MaxSpeed= 180},
                new Car(){Cost= 32, MaxSpeed= 200},
                new Car(){Cost= 82, MaxSpeed= 280}
            };

            var selected = cars.Where(c => c.Cost < 60).OrderBy(c => c.Cost);

답)

var selected = from car in cars
                           where car.Cost < 60
                           orderby car.Cost
                           select car;
            foreach (var car in selected) {
                Console.WriteLine($"Car's Cost: {car.Cost}, Car's MaxSpeed: {car.MaxSpeed}");
            }

Car's Cost: 32, Car's MaxSpeed: 200
Car's Cost: 45, Car's MaxSpeed: 180
Car's Cost: 56, Car's MaxSpeed: 120