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 结构 ArraySegment<T> 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> 是数组周围的包装器，该数组分隔该数组中的元素范围。 多个 ArraySegment<T> 实例可以引用同一原始数组，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>实现IReadOnlyCollection<T>从 .NET Framework 4.6 开始的 接口;在以前版本的 .NET Framework中， ArraySegment<T> 结构未实现此接口。
ArraySegment<T>每当数组的元素将在不同的段中操作时， 结构都很有用。 例如：
可以将仅表示数组的一部分的对象作为参数传递给 ArraySegment<T> 方法，而不是调用相对昂贵的方法（如 Copy 传递数组的一部分的副本）。
在多线程应用中，可以使用 ArraySegment<T> 结构让每个线程仅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
但请注意，尽管 ArraySegment<T> 结构可用于将数组划分为不同的段，但这些段并不完全相互独立。 属性 Array 返回整个原始数组，而不是数组的副本;因此，对属性返回 Array 的数组所做的更改将针对原始数组。 如果不需要此操作，则应对数组的副本而不是表示数组 ArraySegment<T> 的一部分的对象执行操作。
方法 Equals 以及相等和不相等运算符在比较两个 ArraySegment<T> 对象时测试引用相等性。 要使两个 ArraySegment<T> 对象被视为相等，它们必须满足以下所有条件：
引用同一数组。
从数组中的同一索引开始。
具有相同数量的元素。
如果要按元素在 对象中的 ArraySegment<T> 索引检索元素，则必须将其 IList<T> 强制转换为 对象，然后使用 IList<T>.Item[] 属性检索或修改它。 请注意，在 F# 中不需要这样做。 以下示例检索 对象中的 ArraySegment<T> 元素，该元素分隔字符串数组的一部分。
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，该结构用于分隔指定数组中的所有元素。 |
| ArraySegment<T>(T[], Int32, Int32) |
初始化 ArraySegment<T> 结构的新结构，该结构用于分隔指定数组中指定的元素范围。 |
属性
| Array |
获取原始数组，其中包含数组段分隔的元素范围。 |
| Count |
获取由数组段分隔的范围中的元素个数。 |
| 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的第一个元素的位置（相对于原始数组的开始位置）。 |
方法
| CopyTo(ArraySegment<T>) |
将此实例的内容复制到相同类型 |
| CopyTo(T[]) |
将此实例的内容复制到相同类型 |
| CopyTo(T[], Int32) |
从指定的目标索引开始，将此实例的内容复制到相同类型 |
| 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() |
返回一个可用于循环访问数组段的枚举器。 |
| GetHashCode() |
返回当前实例的哈希代码。 |
| Slice(Int32) |
从指定索引处开始，形成当前数组段的一个切片。 |
| Slice(Int32, Int32) |
从指定索引处开始，形成当前数组段的一个指定长度的切片。 |
| 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 |
| 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) |
在所有情况下都会引发 NotSupportedException 异常。 |
| ICollection<T>.Clear() |
在所有情况下都会引发 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一个数组中。 |
| ICollection<T>.IsReadOnly |
获取一个值，该值指示数组段是否为只读。 |
| ICollection<T>.Remove(T) |
在所有情况下都会引发 NotSupportedException 异常。 |
| IEnumerable.GetEnumerator() |
返回循环访问数组段的枚举器。 |
| IEnumerable<T>.GetEnumerator() |
返回循环访问数组段的枚举器。 |
| IList<T>.IndexOf(T) |
确定数组段中特定项的索引。 |
| IList<T>.Insert(Int32, T) |
在所有情况下都会引发 NotSupportedException 异常。 |
| IList<T>.Item[Int32] |
获取或设置指定索引处的元素。 |
| IList<T>.RemoveAt(Int32) |
在所有情况下都会引发 NotSupportedException 异常。 |
| IReadOnlyList<T>.Item[Int32] |
获取数组段的指定索引处的元素。 |
扩展方法
适用于
另请参阅
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