有没有更有效的比较字符串的方法？

Question

I am creating a program that stores 3 film objects in an array . As part of it there is a method that searches for films that have the same 2 actors supplied by the user. The actual actors in the object are simply stored as variables ( _actor1 and _actor2 ). This is my code:

static void sameActors(string actor1, string actor2)
    {
        foreach (Film i in filmLibrary)
        {
            //check if both actors are in the film
            if ((i.getActor1() == actor1 && i.getActor2() == actor2) || (i.getActor1() == actor2 && i.getActor2() == actor1))
            {
                foreach (Film j in filmLibrary)
                {
                    //makes sure that it does not compare to itself
                    if (i.getName() != j.getName())
                    {
                        //checks if films have same actors
                        if ((actor1.Equals(j.getActor1()) && actor2.Equals(j.getActor2())) || (actor2.Equals(j.getActor1()) && actor2.Equals(j.getActor2())))
                        {
                            Console.WriteLine(i.getName() + " and " + j.getName() + " both share the same actors.");
                        }
                    }
                }
            }
        }
        menu();
    }

The code does the job, but to me there is a lot of thinking to do if you are first looking at the code. Is there a more efficient way?

Also, when this code is executed, it will compare twice, so once it will say " Movie 1 and Movie 2 have the same actors. " and then it will say " Movie 2 and Movie 1 have the same actors. " What's the best way to prevent this?

Answer 1

I can't imagine what getActor1() does. Why would you have a fixed number in the function name?

The approach I would take is to store it in a set that supports faster lookups, using either a Dictionary<> or Set<> . I would store the actors there and then the search should be significant faster. It has the added benefit where it can store any number of actors (since you never know how many actors a movie might have).

But, again, it's hard to know why you did it this way so I don't know if that meets your requirements.

Answer 2

I'll elaborate on where I think Jonathan Wood was going. I'm going to include some code that's going to suggest a slightly better model for your data and then also include a solution using LINQ . For starters, I think your actors should exist as a collection within your film. In this way you are not confining your data, and then you allow for a more elegant use of the data.

In this example, I define my Film object, seed 4 films, then create a Dictionary-based index of films to films where actors intersect, excluding itself. Lastly, I report the list using a bit more LINQ to format the movies. In this example there is no restriction on the number of actors per film, and each film can be related to 0 or many other films.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Film> films = new List<Film>() {
                new Film() {
                    Title = "Terminator",
                    Actors = new List<string>() {
                        "Arnold Schwarzenegger",
                        "Michael Biehn",
                        "Linda Hamilton"
                    }
                },
                new Film() {
                    Title = "Aliens",
                    Actors = new List<string>() {
                        "Sigourney Weaver",
                        "Carrie Henn",
                        "Michael Biehn"
                    }
                },
                new Film() {
                    Title = "Avatar",
                    Actors = new List<string>() {
                        "Sam Worthington",
                        "Zoe Saldana",
                        "Sigourney Weaver"
                    }
                },
                new Film() {
                    Title = "Star Wars",
                    Actors = new List<string>() {
                        "Mark Hamill",
                        "Harrison Ford",
                        "Carrie Fisher"
                    }
                }
            };

            var filmIndex = films.ToDictionary(
                f => f.Title, 
                m => films
                    .Where(f => f.Title != m.Title && 
                        f.Actors
                        .Intersect(m.Actors)
                        .Any())
                    .Select(t => t.Title));

            foreach (var film in filmIndex)
            {
                Console.WriteLine(string.Format("Movie: {0} has same actors as {1}.", 
                    film.Key, 
                    film.Value.Any() ? film.Value.Aggregate((i, j) => i + ", " + j) : "no other film"));
            }

            Console.ReadKey();
        }
    }

    class Film
    {
        public string Title { get; set; }
        public IEnumerable<string> Actors { get; set; }
    }
}