ArraySegment<T> 结构
定义
重要
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分隔一维数组的一部分。
generic <typename T>
public value class ArraySegment : System::Collections::Generic::ICollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::IList<T>, System::Collections::Generic::IReadOnlyCollection<T>, System::Collections::Generic::IReadOnlyList<T>generic <typename T>
public value class ArraySegmentpublic struct ArraySegment<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.IReadOnlyList<T>public readonly struct ArraySegment<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.IReadOnlyList<T>[System.Serializable]
public struct ArraySegment<T>[System.Serializable]
public struct ArraySegment<T> : System.Collections.Generic.ICollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.Generic.IReadOnlyList<T>type ArraySegment<'T> = struct
interface ICollection<'T>
interface seq<'T>
interface IEnumerable
interface IList<'T>
interface IReadOnlyCollection<'T>
interface IReadOnlyList<'T>[<System.Serializable>]
type ArraySegment<'T> = struct[<System.Serializable>]
type ArraySegment<'T> = struct
interface IList<'T>
interface ICollection<'T>
interface IReadOnlyList<'T>
interface IReadOnlyCollection<'T>
interface seq<'T>
interface IEnumerable[<System.Serializable>]
type ArraySegment<'T> = struct
interface IList<'T>
interface ICollection<'T>
interface seq<'T>
interface IEnumerable
interface IReadOnlyList<'T>
interface IReadOnlyCollection<'T>type ArraySegment<'T> = struct
interface IList<'T>
interface ICollection<'T>
interface IReadOnlyList<'T>
interface IReadOnlyCollection<'T>
interface seq<'T>
interface IEnumerablePublic Structure ArraySegment(Of T)
Implements ICollection(Of T), IEnumerable(Of T), IList(Of T), IReadOnlyCollection(Of T), IReadOnlyList(Of T)Public Structure ArraySegment(Of T)类型参数
- T
数组段中元素的类型。
- 继承
- 属性
- 实现
示例
下面的代码示例将 ArraySegment<T> 结构传递给方法。
using namespace System;
namespace Sample
{
public ref class SampleArray
{
public:
static void Work()
{
// Create and initialize a new string array.
array <String^>^ words = {"The", "quick", "brown",
"fox", "jumps", "over", "the", "lazy", "dog"};
// Display the initial contents of the array.
Console::WriteLine("The first array segment"
" (with all the array's elements) contains:");
PrintIndexAndValues(words);
// Define an array segment that contains the entire array.
ArraySegment<String^> segment(words);
// Display the contents of the ArraySegment.
Console::WriteLine("The first array segment"
" (with all the array's elements) contains:");
PrintIndexAndValues(segment);
// Define an array segment that contains the middle five
// values of the array.
ArraySegment<String^> middle(words, 2, 5);
// Display the contents of the ArraySegment.
Console::WriteLine("The second array segment"
" (with the middle five elements) contains:");
PrintIndexAndValues(middle);
// Modify the fourth element of the first array
// segment
segment.Array[3] = "LION";
// Display the contents of the second array segment
// middle. Note that the value of its second element
// also changed.
Console::WriteLine("After the first array segment"
" is modified,the second array segment"
" now contains:");
PrintIndexAndValues(middle);
Console::ReadLine();
}
static void PrintIndexAndValues(ArraySegment<String^>^ segment)
{
for (int i = segment->Offset;
i < (segment->Offset + segment->Count); i++)
{
Console::WriteLine(" [{0}] : {1}", i,
segment->Array[i]);
}
Console::WriteLine();
}
static void PrintIndexAndValues(array<String^>^ words)
{
for (int i = 0; i < words->Length; i++)
{
Console::WriteLine(" [{0}] : {1}", i,
words[i]);
}
Console::WriteLine();
}
};
}
int main()
{
Sample::SampleArray::Work();
return 0;
}
/*
This code produces the following output.
The original array initially contains:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
The first array segment (with all the array's elements) contains:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
The second array segment (with the middle five elements) contains:
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
After the first array segment is modified, the second array segment now contains:
[2] : brown
[3] : LION
[4] : jumps
[5] : over
[6] : the
*/
using System;
public class SamplesArray {
public static void Main() {
// Create and initialize a new string array.
String[] myArr = { "The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog" };
// Display the initial contents of the array.
Console.WriteLine( "The original array initially contains:" );
PrintIndexAndValues( myArr );
// Define an array segment that contains the entire array.
ArraySegment<string> myArrSegAll = new ArraySegment<string>( myArr );
// Display the contents of the ArraySegment.
Console.WriteLine( "The first array segment (with all the array's elements) contains:" );
PrintIndexAndValues( myArrSegAll );
// Define an array segment that contains the middle five values of the array.
ArraySegment<string> myArrSegMid = new ArraySegment<string>( myArr, 2, 5 );
// Display the contents of the ArraySegment.
Console.WriteLine( "The second array segment (with the middle five elements) contains:" );
PrintIndexAndValues( myArrSegMid );
// Modify the fourth element of the first array segment myArrSegAll.
myArrSegAll.Array[3] = "LION";
// Display the contents of the second array segment myArrSegMid.
// Note that the value of its second element also changed.
Console.WriteLine( "After the first array segment is modified, the second array segment now contains:" );
PrintIndexAndValues( myArrSegMid );
}
public static void PrintIndexAndValues( ArraySegment<string> arrSeg ) {
for ( int i = arrSeg.Offset; i < (arrSeg.Offset + arrSeg.Count); i++ ) {
Console.WriteLine( " [{0}] : {1}", i, arrSeg.Array[i] );
}
Console.WriteLine();
}
public static void PrintIndexAndValues( String[] myArr ) {
for ( int i = 0; i < myArr.Length; i++ ) {
Console.WriteLine( " [{0}] : {1}", i, myArr[i] );
}
Console.WriteLine();
}
}
/*
This code produces the following output.
The original array initially contains:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
The first array segment (with all the array's elements) contains:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
The second array segment (with the middle five elements) contains:
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
After the first array segment is modified, the second array segment now contains:
[2] : brown
[3] : LION
[4] : jumps
[5] : over
[6] : the
*/
open System
// Print functions.
let printIndexAndValues (myArr: string []) =
for i = 0 to myArr.Length - 1 do
printfn $" [{i}] : {myArr[i]}"
printfn ""
let printIndexAndValuesSeg (arrSeg: ArraySegment<string>) =
for i = arrSeg.Offset to arrSeg.Offset + arrSeg.Count - 1 do
printfn $" [{i}] : {arrSeg.Array[i]}"
printfn ""
// Create and initialize a new string array.
let myArr = [| "The"; "quick"; "brown"; "fox"; "jumps"; "over"; "the"; "lazy"; "dog" |]
// Display the initial contents of the array.
printfn "The original array initially contains:"
printIndexAndValues myArr
// Define an array segment that contains the entire array.
let myArrSegAll = ArraySegment<string>(myArr)
// Display the contents of the ArraySegment.
printfn "The first array segment (with all the array's elements) contains:"
printIndexAndValuesSeg myArrSegAll
// Define an array segment that contains the middle five values of the array.
let myArrSegMid = ArraySegment<string>(myArr, 2, 5)
// Display the contents of the ArraySegment.
printfn "The second array segment (with the middle five elements) contains:"
printIndexAndValuesSeg myArrSegMid
// Modify the fourth element of the first array segment myArrSegAll.
myArrSegAll.Array[3] <- "LION"
// Display the contents of the second array segment myArrSegMid.
// Note that the value of its second element also changed.
printfn "After the first array segment is modified, the second array segment now contains:"
printIndexAndValuesSeg myArrSegMid
(*
This code produces the following output.
The original array initially contains:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
The first array segment (with all the array's elements) contains:
[0] : The
[1] : quick
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
[7] : lazy
[8] : dog
The second array segment (with the middle five elements) contains:
[2] : brown
[3] : fox
[4] : jumps
[5] : over
[6] : the
After the first array segment is modified, the second array segment now contains:
[2] : brown
[3] : LION
[4] : jumps
[5] : over
[6] : the
*)
Public Class SamplesArray
Public Shared Sub Main()
' Create and initialize a new string array.
Dim myArr As String() = {"The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog"}
' Display the initial contents of the array.
Console.WriteLine("The original array initially contains:")
PrintIndexAndValues(myArr)
' Define an array segment that contains the entire array.
Dim myArrSegAll As New ArraySegment(Of String)(myArr)
' Display the contents of the ArraySegment.
Console.WriteLine("The first array segment (with all the array's elements) contains:")
PrintIndexAndValues(myArrSegAll)
' Define an array segment that contains the middle five values of the array.
Dim myArrSegMid As New ArraySegment(Of String)(myArr, 2, 5)
' Display the contents of the ArraySegment.
Console.WriteLine("The second array segment (with the middle five elements) contains:")
PrintIndexAndValues(myArrSegMid)
' Modify the fourth element of the first array segment myArrSegAll.
myArrSegAll.Array(3) = "LION"
' Display the contents of the second array segment myArrSegMid.
' Note that the value of its second element also changed.
Console.WriteLine("After the first array segment is modified, the second array segment now contains:")
PrintIndexAndValues(myArrSegMid)
End Sub
Public Shared Sub PrintIndexAndValues(arrSeg As ArraySegment(Of String))
Dim i As Integer
For i = arrSeg.Offset To (arrSeg.Offset + arrSeg.Count - 1)
Console.WriteLine(" [{0}] : {1}", i, arrSeg.Array(i))
Next i
Console.WriteLine()
End Sub
Public Shared Sub PrintIndexAndValues(myArr as String())
Dim i As Integer
For i = 0 To (myArr.Length - 1)
Console.WriteLine(" [{0}] : {1}", i, myArr(i))
Next i
Console.WriteLine()
End Sub
End Class
'This code produces the following output.
'
'The original array initially contains:
' [0] : The
' [1] : quick
' [2] : brown
' [3] : fox
' [4] : jumps
' [5] : over
' [6] : the
' [7] : lazy
' [8] : dog
'
'The first array segment (with all the array's elements) contains:
' [0] : The
' [1] : quick
' [2] : brown
' [3] : fox
' [4] : jumps
' [5] : over
' [6] : the
' [7] : lazy
' [8] : dog
'
'The second array segment (with the middle five elements) contains:
' [2] : brown
' [3] : fox
' [4] : jumps
' [5] : over
' [6] : the
'
'After the first array segment is modified, the second array segment now contains:
' [2] : brown
' [3] : LION
' [4] : jumps
' [5] : over
' [6] : the
注解
ArraySegment<T> 是数组的包装器，用于分隔该数组中的元素范围。 多个 ArraySegment<T> 实例可以引用相同的原始数组，并且可以重叠。 原始数组必须是一维数组，并且必须具有从零开始的索引。
注意
ArraySegment<T> 从 .NET Framework 4.6 开始实现 IReadOnlyCollection<T> 接口;在早期版本的 .NET Framework 中，ArraySegment<T> 结构未实现此接口。
每当数组的元素在不同的段中操作时，ArraySegment<T> 结构都很有用。 例如：
可以将仅表示数组的一部分作为参数的 ArraySegment<T> 对象传递给方法，而不是调用相对昂贵的方法（如 Copy）来传递数组的一部分副本。
在多线程应用中，可以使用 ArraySegment<T> 结构让每个线程只对数组的一部分进行操作。
对于基于任务的异步操作，可以使用 ArraySegment<T> 对象来确保每个任务对数组的不同段进行操作。 以下示例将数组划分为包含最多 10 个元素的单个段。 段中的每个元素都乘以其段号。 结果显示，使用 ArraySegment<T> 类以这种方式操作元素会更改其基础数组的值。
using System; using System.Collections.Generic; using System.Threading.Tasks; public class Example { private const int segmentSize = 10; public static async Task Main() { List<Task> tasks = new List<Task>(); // Create array. int[] arr = new int[50]; for (int ctr = 0; ctr <= arr.GetUpperBound(0); ctr++) arr[ctr] = ctr + 1; // Handle array in segments of 10. for (int ctr = 1; ctr <= Math.Ceiling(((double)arr.Length)/segmentSize); ctr++) { int multiplier = ctr; int elements = (multiplier - 1) * 10 + segmentSize > arr.Length ? arr.Length - (multiplier - 1) * 10 : segmentSize; ArraySegment<int> segment = new ArraySegment<int>(arr, (ctr - 1) * 10, elements); tasks.Add(Task.Run( () => { IList<int> list = (IList<int>) segment; for (int index = 0; index < list.Count; index++) list[index] = list[index] * multiplier; } )); } try { await Task.WhenAll(tasks.ToArray()); int elementsShown = 0; foreach (var value in arr) { Console.Write("{0,3} ", value); elementsShown++; if (elementsShown % 18 == 0) Console.WriteLine(); } } catch (AggregateException e) { Console.WriteLine("Errors occurred when working with the array:"); foreach (var inner in e.InnerExceptions) Console.WriteLine("{0}: {1}", inner.GetType().Name, inner.Message); } } } // The example displays the following output: // 1 2 3 4 5 6 7 8 9 10 22 24 26 28 30 32 34 36 // 38 40 63 66 69 72 75 78 81 84 87 90 124 128 132 136 140 144 // 148 152 156 160 205 210 215 220 225 230 235 240 245 250open System open System.Threading.Tasks // Create array. let arr = Array.init 50 (fun i -> i + 1) // Handle array in segments of 10. let tasks = Array.chunkBySize 10 arr |> Array.mapi (fun m elements -> let mutable segment = ArraySegment<int>(arr, m * 10, elements.Length) task { for i = 0 to segment.Count - 1 do segment[i] <- segment[i] * (m + 1) } :> Task) try Task.WhenAll(tasks).Wait() let mutable i = 0 for value in arr do printf $"{value, 3} " i <- i + 1 if i % 18 = 0 then printfn "" with :? AggregateException as e -> printfn "Errors occurred when working with the array:" for inner in e.InnerExceptions do printfn $"{inner.GetType().Name}: {inner.Message}" // The example displays the following output: // 1 2 3 4 5 6 7 8 9 10 22 24 26 28 30 32 34 36 // 38 40 63 66 69 72 75 78 81 84 87 90 124 128 132 136 140 144 // 148 152 156 160 205 210 215 220 225 230 235 240 245 250Imports System.Collections.Generic Imports System.Threading.Tasks Module Example Private Const SegmentSize As Integer = 10 Public Sub Main() Dim tasks As New List(Of Task) ' Create array. Dim arr(49) As Integer For ctr As Integer = 0 To arr.GetUpperBound(0) arr(ctr) = ctr + 1 Next ' Handle array in segments of 10. For ctr As Integer = 1 To CInt(Math.Ceiling(arr.Length / segmentSize)) Dim multiplier As Integer = ctr Dim elements As Integer = If((multiplier - 1) * 10 + segmentSize > arr.Length, arr.Length - (multiplier - 1) * 10, segmentSize) Dim segment As New ArraySegment(Of Integer)(arr, (ctr - 1) * 10, elements) tasks.Add(Task.Run( Sub() Dim list As IList(Of Integer) = CType(segment, IList(Of Integer)) For index As Integer = 0 To list.Count - 1 list(index) = list(index) * multiplier Next End Sub )) Next Try Task.WaitAll(tasks.ToArray()) Dim elementsShown As Integer = 0 For Each value In arr Console.Write("{0,3} ", value) elementsShown += 1 If elementsShown Mod 18 = 0 Then Console.WriteLine() Next Catch e As AggregateException Console.WriteLine("Errors occurred when working with the array:") For Each inner As Exception In e.InnerExceptions Console.WriteLine("{0}: {1}", inner.GetType().Name, inner.Message) Next End Try End Sub End Module ' The example displays the following output: ' 1 2 3 4 5 6 7 8 9 10 22 24 26 28 30 32 34 36 ' 38 40 63 66 69 72 75 78 81 84 87 90 124 128 132 136 140 144 ' 148 152 156 160 205 210 215 220 225 230 235 240 245 250
但是，请注意，尽管 ArraySegment<T> 结构可用于将数组划分为不同的段，但段并不完全独立于彼此。 Array 属性返回整个原始数组，而不是数组的副本;因此，对 Array 属性返回的数组所做的更改对原始数组进行了更改。 如果这是不可取的，则应对数组的副本执行操作，而不是表示数组一部分的 ArraySegment<T> 对象。
Equals 方法和相等运算符在比较两个 ArraySegment<T> 对象时测试引用相等性。 若要将两个 ArraySegment<T> 对象视为相等，它们必须满足以下所有条件：
引用相同的数组。
从数组中的同一索引开始。
具有相同数量的元素。
如果要在 ArraySegment<T> 对象中按其索引检索元素，则必须将其强制转换为 IList<T> 对象，并使用 IList<T>.Item[] 属性对其进行检索或修改。 请注意，F# 中不需要这样做。 以下示例检索 ArraySegment<T> 对象中的元素，该元素分隔字符串数组的节。
using System;
using System.Collections.Generic;
public class Example
{
public static void Main()
{
String[] names = { "Adam", "Bruce", "Charles", "Daniel",
"Ebenezer", "Francis", "Gilbert",
"Henry", "Irving", "John", "Karl",
"Lucian", "Michael" };
var partNames = new ArraySegment<string>(names, 2, 5);
// Cast the ArraySegment object to an IList<string> and enumerate it.
var list = (IList<string>) partNames;
for (int ctr = 0; ctr <= list.Count - 1; ctr++)
Console.WriteLine(list[ctr]);
}
}
// The example displays the following output:
// Charles
// Daniel
// Ebenezer
// Francis
// Gilbert
open System
let names =
[| "Adam"; "Bruce"; "Charles"; "Daniel"
"Ebenezer"; "Francis"; "Gilbert"
"Henry"; "Irving"; "John"; "Karl"
"Lucian"; "Michael" |]
let partNames = ArraySegment<string>(names, 2, 5)
// Enumerate over the ArraySegment object.
for part in partNames do
printfn $"{part}"
// The example displays the following output:
// Charles
// Daniel
// Ebenezer
// Francis
// Gilbert
Imports System.Collections.Generic
Module Example
Public Sub Main()
Dim names() As String = { "Adam", "Bruce", "Charles", "Daniel",
"Ebenezer", "Francis", "Gilbert",
"Henry", "Irving", "John", "Karl",
"Lucian", "Michael" }
Dim partNames As New ArraySegment(Of String)(names, 2, 5)
' Cast the ArraySegment object to an IList<String> and enumerate it.
Dim list = CType(partNames, IList(Of String))
For ctr As Integer = 0 To list.Count - 1
Console.WriteLine(list(ctr))
Next
End Sub
End Module
' The example displays the following output:
' Charles
' Daniel
' Ebenezer
' Francis
' Gilbert
构造函数
| ArraySegment<T>(T[]) |
初始化 ArraySegment<T> 结构的新实例，该实例分隔指定数组中的所有元素。 |
| ArraySegment<T>(T[], Int32, Int32) |
初始化 ArraySegment<T> 结构的新实例，该实例分隔指定数组中元素的指定范围。 |
属性
| Array |
获取包含数组段分隔的元素范围的原始数组。 |
| Count |
获取由数组段分隔的范围中的元素数。 |
| Empty |
表示空数组段。 此字段为只读。 |
| Item[Int32] |
获取或设置指定索引处的元素。 |
| Offset |
获取由数组段分隔的范围中第一个元素相对于原始数组的开头的位置。 |
方法
| CopyTo(ArraySegment<T>) |
将此实例的内容复制到同一类型的指定目标数组段 |
| CopyTo(T[]) |
将此实例的内容复制到同一类型 |
| CopyTo(T[], Int32) |
从指定的目标索引开始，将此实例的内容复制到同一类型 |
| Equals(ArraySegment<T>) |
确定指定的 ArraySegment<T> 结构是否等于当前实例。 |
| Equals(Object) |
确定指定的对象是否等于当前实例。 |
| GetEnumerator() |
返回可用于循环访问数组段的枚举数。 |
| GetHashCode() |
返回当前实例的哈希代码。 |
| Slice(Int32) |
从指定索引处开始的当前数组段形成切片。 |
| Slice(Int32, Int32) |
形成从指定索引处开始的当前数组段的指定长度的切片。 |
| ToArray() |
将此数组段的内容复制到新数组中。 |
运算符
| Equality(ArraySegment<T>, ArraySegment<T>) |
指示两个 ArraySegment<T> 结构是否相等。 |
| Implicit(T[] to ArraySegment<T>) |
定义类型 |
| Inequality(ArraySegment<T>, ArraySegment<T>) |
指示两个 ArraySegment<T> 结构是否不相等。 |
显式接口实现
| ICollection<T>.Add(T) |
在所有情况下引发 NotSupportedException 异常。 |
| ICollection<T>.Clear() |
在所有情况下引发 NotSupportedException 异常。 |
| ICollection<T>.Contains(T) |
确定数组段是否包含特定值。 |
| ICollection<T>.CopyTo(T[], Int32) |
从指定的数组索引开始，将数组段的元素复制到数组。 |
| ICollection<T>.IsReadOnly |
获取一个值，该值指示数组段是否为只读。 |
| ICollection<T>.Remove(T) |
在所有情况下引发 NotSupportedException 异常。 |
| IEnumerable.GetEnumerator() |
返回循环访问数组段的枚举数。 |
| IEnumerable<T>.GetEnumerator() |
返回循环访问数组段的枚举数。 |
| IList<T>.IndexOf(T) |
确定数组段中特定项的索引。 |
| IList<T>.Insert(Int32, T) |
在所有情况下引发 NotSupportedException 异常。 |
| IList<T>.Item[Int32] |
获取或设置指定索引处的元素。 |
| IList<T>.RemoveAt(Int32) |
在所有情况下引发 NotSupportedException 异常。 |
| IReadOnlyList<T>.Item[Int32] |
获取数组段的指定索引处的元素。 |
