c# - 如何从可用数字中获取随机数？

Question

我有一个表，我试图从中获取随机数:

//Fruits
id  |  FruitName
----------------
2   |  Banana
3   |  Apple
4   |  Orange
6   |  Grape
7   |  Plum
8   |  Lime
10  |  Kiwi

问题是因为不一致(注意:ids 1、5、9缺失)，写下面的语句是行不通的(即使写得正确):

Random.Next(someLinq.id).First(), (samelinq.id).Last())

我如何从可用数字中获得随机数？

Answer 1

您可以简单地使用项目的数量作为最大随机数，然后通过索引选择一个随机项目:

var random = new Random();
var items = new List<int> {2, 3, 4, 6, 7, 8, 10};
var randomItem = items[random.Next(items.Count)];

或者，在您的情况下(假设您正在获取包含 Id 属性的 Fruit 项目列表):

var items = new List<Fruit>
{
    new Fruit {Id = 2, Name = "Banana"},
    new Fruit {Id = 3, Name = "Apple"},
    new Fruit {Id = 4, Name = "Orange"},
    new Fruit {Id = 6, Name = "Grape"},
    new Fruit {Id = 7, Name = "Plum"},
    new Fruit {Id = 8, Name = "Lime"},
    new Fruit {Id = 10, Name = "Kiwi"}
};

var random = new Random();
var randomItem = items[random.Next(items.Count)];

Console.WriteLine("Randomly chose fruit: Id = {0}, Name = {1}", 
    randomItem.Id, randomItem.Name);