F# - 可变列表

List<'T> 类表示可以通过索引访问的强类型对象列表。

它是 List 类的可变对应项。 它与数组类似，因为它可以通过索引访问，但与数组不同的是，列表可以调整大小。 因此，您无需在声明时指定尺寸。

创建可变列表

列表是使用new关键字并调用列表的构造函数创建的。 下面的例子演示了这一点−

(* Creating a List *)
open System.Collections.Generic

let booksList = new List<string>()
booksList.Add("Gone with the Wind")
booksList.Add("Atlas Shrugged")
booksList.Add("Fountainhead")
booksList.Add("Thornbirds")
booksList.Add("Rebecca")
booksList.Add("Narnia")

booksList |> Seq.iteri (fun index item -> printfn "%i: %s" index booksList.[index])

当您编译并执行该程序时，它会产生以下输出 −

0: Gone with the Wind
1: Atlas Shrugged
2: Fountainhead
3: Thornbirds
4: Rebecca
5: Narnia

List(T) 类

List(T) 类表示可以通过索引访问的强类型对象列表。 它提供了搜索、排序和操作列表的方法。

下表提供了List(T)类的属性、构造函数和方法 −

属性

构造函数

Method

示例

(* Creating a List *)
open System.Collections.Generic

let booksList = new List<string>()
booksList.Add("Gone with the Wind")
booksList.Add("Atlas Shrugged")
booksList.Add("Fountainhead")
booksList.Add("Thornbirds")
booksList.Add("Rebecca")
booksList.Add("Narnia")

printfn"Total %d books" booksList.Count
booksList |> Seq.iteri (fun index item -> printfn "%i: %s" index booksList.[index])
booksList.Insert(2, "Roots")

printfn("after inserting at index 2")
printfn"Total %d books" booksList.Count

booksList |> Seq.iteri (fun index item -> printfn "%i: %s" index booksList.[index])
booksList.RemoveAt(3)

printfn("after removing from index 3")
printfn"Total %d books" booksList.Count

booksList |> Seq.iteri (fun index item -> printfn "%i: %s" index booksList.[index])

当您编译并执行该程序时，它会产生以下输出 −

Total 6 books
0: Gone with the Wind
1: Atlas Shrugged
2: Fountainhead
3: Thornbirds
4: Rebecca
5: Narnia
after inserting at index 2
Total 7 books
0: Gone with the Wind
1: Atlas Shrugged
2: Roots
3: Fountainhead
4: Thornbirds
5: Rebecca
6: Narnia
after removing from index 3
Total 6 books
0: Gone with the Wind
1: Atlas Shrugged
2: Roots
3: Thornbirds
4: Rebecca
5: Narnia