Array.Clear(Array, Int32, Int32) Array.Clear(Array, Int32, Int32) Array.Clear(Array, Int32, Int32) Method

定义

将数组中的某个范围的元素设置为每个元素类型的默认值。Sets a range of elements in an array to the default value of each element type.

public:
 static void Clear(Array ^ array, int index, int length);
public static void Clear (Array array, int index, int length);
static member Clear : Array * int * int -> unit

参数

array
Array Array Array

需要清除其元素的数组。The array whose elements need to be cleared.

index
Int32 Int32 Int32

要清除的一系列元素的起始索引。The starting index of the range of elements to clear.

length
Int32 Int32 Int32

要清除的元素数。The number of elements to clear.

异常

index 小于 array 的下限。index is less than the lower bound of array.

-or- length 小于零。length is less than zero.

-or- indexlength 大于 array 的大小。The sum of index and length is greater than the size of array.

示例

下面的示例使用Clear方法来重置一维二维数组中的整数值。The following example uses the Clear method to reset integer values in a one-dimensional, two-dimensional, and three-dimensional array.

using System;

class Example
{
    public static void Main()
    {
        Console.WriteLine("One dimension (Rank=1):");
        int[] numbers1 = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

        for (int i = 0; i < 9; i++)
        {
            Console.Write("{0} ", numbers1[i]);
        }
        Console.WriteLine();
        Console.WriteLine();

        Console.WriteLine("Array.Clear(numbers1, 2, 5)");
        Array.Clear(numbers1, 2, 5);

        for (int i = 0; i < 9; i++)
        {
            Console.Write("{0} ", numbers1[i]);
        }
        Console.WriteLine();
        Console.WriteLine();

        Console.WriteLine("Two dimensions (Rank=2):");
        int[,] numbers2 = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };

        for (int i = 0; i < 3; i++)
        {
            for (int j = 0; j < 3; j++)
            {
                Console.Write("{0} ", numbers2[i, j]);
            }
            Console.WriteLine();
        }

        Console.WriteLine();
        Console.WriteLine("Array.Clear(numbers2, 2, 5)");
        Array.Clear(numbers2, 2, 5);

        for (int i = 0; i < 3; i++)
        {
            for (int j = 0; j < 3; j++)
            {
                Console.Write("{0} ", numbers2[i, j]);
            }
            Console.WriteLine();
        }

        Console.WriteLine("Three dimensions (Rank=3):");
        int[, ,] numbers3 = {{{1, 2}, {3, 4}},
                             {{5, 6}, {7, 8}},
                             {{9, 10}, {11, 12}}};

        for (int i = 0; i < 2; i++)
        {
            for (int j = 0; j < 2; j++)
            {
                for (int k = 0; k < 2; k++)
                {
                    Console.Write("{0} ", numbers3[i, j, k]);
                }
                Console.WriteLine();
            }
            Console.WriteLine();
        }

        Console.WriteLine("Array.Clear(numbers3, 2, 5)");
        Array.Clear(numbers3, 2, 5);

        for (int i = 0; i < 2; i++)
        {
            for (int j = 0; j < 2; j++)
            {
                for (int k = 0; k < 2; k++)
                {
                    Console.Write("{0} ", numbers3[i, j, k]);
                }
                Console.WriteLine();
            }
            Console.WriteLine();
        }
    }
}
/*  This code example produces the following output:
 * 
 * One dimension (Rank=1):
 * 1 2 3 4 5 6 7 8 9
 * 
 * Array.Clear(numbers1, 2, 5)
 * 1 2 0 0 0 0 0 8 9
 * 
 * Two dimensions (Rank=2):
 * 1 2 3
 * 4 5 6
 * 7 8 9
 * 
 * Array.Clear(numbers2, 2, 5)
 * 1 2 0
 * 0 0 0
 * 0 8 9
 * 
 * Three dimensions (Rank=3):
 * 1 2
 * 3 4
 * 
 * 5 6
 * 7 8
 * 
 * Array.Clear(numbers3, 2, 5)
 * 1 2
 * 0 0
 * 
 * 0 0
 * 0 8
 */
Module Example
    Sub Main()
        Console.WriteLine(vbLf & "One dimension (Rank=1):")
        Dim numbers1() As Integer = {1, 2, 3, 4, 5, 6, 7, 8, 9}

        For i As Integer = 0 To 8
            Console.Write("{0} ", numbers1(i))
        Next 
        Console.WriteLine()

        Console.WriteLine(vbLf & "Array.Clear(numbers1, 2, 5)")
        Array.Clear(numbers1, 2, 5)

        For i As Integer = 0 To 8
            Console.Write("{0} ", numbers1(i))
        Next 
        Console.WriteLine()


        Console.WriteLine(vbLf & "Two dimensions (Rank=2):")
        Dim numbers2(,) As Integer = {{ 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 }}

        For i As Integer = 0 To 2
            For j As Integer = 0 To 2
                Console.Write("{0} ", numbers2(i, j))
            Next 
            Console.WriteLine()
        Next 

        Console.WriteLine(vbLf & "Array.Clear(numbers2, 2, 5)")
        Array.Clear(numbers2, 2, 5)

        For i As Integer = 0 To 2
            For j As Integer = 0 To 2
                Console.Write("{0} ", numbers2(i, j))
            Next 
            Console.WriteLine()
        Next 


        Console.WriteLine(vbLf & "Three dimensions (Rank=3):")
        Dim numbers3(,,) As Integer = {{{ 1, 2 }, { 3, 4 }}, _
                                       {{ 5, 6 }, { 7, 8 }}, _
                                       {{ 9, 10 }, { 11, 12 }}}

        For i As Integer = 0 To 1
            For j As Integer = 0 To 1
                For k As Integer = 0 To 1
                    Console.Write("{0} ", numbers3(i, j, k))
                Next 
                Console.WriteLine()
            Next 
            Console.WriteLine()
        Next 
        Console.WriteLine()
        
        Console.WriteLine("Array.Clear(numbers3, 2, 5)")
        Array.Clear(numbers3, 2, 5)

        For i As Integer = 0 To 1
            For j As Integer = 0 To 1
                For k As Integer = 0 To 1
                    Console.Write("{0} ", numbers3(i, j, k))
                Next 
                Console.WriteLine()
            Next 
            Console.WriteLine()
        Next 
    End Sub
End Module
' The example displays the following output:
'       One dimension (Rank=1):
'       1 2 3 4 5 6 7 8 9
'       
'       Array.Clear(numbers1, 2, 5)
'       1 2 0 0 0 0 0 8 9
'       
'       Two dimensions (Rank=2):
'       1 2 3
'       4 5 6
'       7 8 9
'       
'       Array.Clear(numbers2, 2, 5)
'       1 2 0
'       0 0 0
'       0 8 9
'       
'       Three dimensions (Rank=3):
'       1 2
'       3 4
'
'       5 6
'       7 8
'       
'       Array.Clear(numbers3, 2, 5)
'       1 2
'       0 0
'       
'       0 0
'       0 8

下面的示例定义了TimeZoneTime一个TimeZoneInfo包含字段和DateTimeOffset字段的结构。The following example defines a TimeZoneTime structure that includes a TimeZoneInfo field and a DateTimeOffset field. 然后, 它调用Clear方法以清除两元素值数组中的TimeZoneTime一个元素。It then calls the Clear method to clear one element in a two-element array of TimeZoneTime values. 方法TimeZoneInfo将已null清除元素的值设置为对象的默认值, 即, DateTimeOffset对象DateTimeOffset.MinValue的默认值为。The method sets the value of the cleared element to the default value of a TimeZoneInfo object, which is null, and the default value of a DateTimeOffset object, which is DateTimeOffset.MinValue.

using System;

public struct TimeZoneTime
{
   private DateTimeOffset dt;
   private TimeZoneInfo tz;
   
   public TimeZoneTime(DateTimeOffset dateTime, TimeZoneInfo timeZone)
   {
      dt = dateTime;
      tz = timeZone;
   }

   public DateTimeOffset DateTime 
   { get { return dt; } }
   
   public TimeZoneInfo TimeZone 
   { get { return tz; } }
}

public class Example
{
   public static void Main()
   {
      // Declare an array with two elements.
      TimeZoneTime[] timeZoneTimes = { new TimeZoneTime(DateTime.Now, TimeZoneInfo.Local),
                                       new TimeZoneTime(DateTime.Now, TimeZoneInfo.Utc) };   
      foreach (var timeZoneTime in timeZoneTimes)
         Console.WriteLine("{0}: {1:G}", 
                           timeZoneTime.TimeZone == null ? "<null>" : timeZoneTime.TimeZone.ToString(), 
                           timeZoneTime.DateTime);
      Console.WriteLine();
      
      Array.Clear(timeZoneTimes, 1, 1);
      foreach (var timeZoneTime in timeZoneTimes)
         Console.WriteLine("{0}: {1:G}", 
                           timeZoneTime.TimeZone == null ? "<null>" : timeZoneTime.TimeZone.ToString(), 
                           timeZoneTime.DateTime);
   }
}
// The example displays the following output:
//       (UTC-08:00) Pacific Time (US & Canada): 1/20/2014 12:11:00 PM
//       UTC: 1/20/2014 12:11:00 PM
//       
//       (UTC-08:00) Pacific Time (US & Canada): 1/20/2014 12:11:00 PM
//       <null>: 1/1/0001 12:00:00 AM
Public Structure TimeZoneTime
   Private dt As DateTimeOffset
   Private tz As TimeZoneInfo
   
   Public Sub New(dateTime As DateTimeOffset, timeZone As TimeZoneInfo)
      dt = dateTime
      tz = timeZone
   End Sub

   Public ReadOnly Property DateTime As DateTimeOffset
      Get
         Return dt
      End Get
   End Property
   
   Public ReadOnly Property TimeZone As TimeZoneInfo
      Get
         Return tz
      End Get
   End Property 
End Structure

Module Example
   Public Sub Main()
      ' Declare an array with two elements.
      Dim timeZoneTimes() As TimeZoneTime = { New TimeZoneTime(Date.Now, TimeZoneInfo.Local),
                                              New TimeZoneTime(Date.Now, TimeZoneInfo.Utc) }   
      For Each timeZoneTime In timeZoneTimes
         Console.WriteLine("{0}: {1:G}", 
                           If(timeZoneTime.TimeZone Is Nothing, "<null>", timeZoneTime.TimeZone), 
                           timeZoneTime.DateTime)
      Next
      Console.WriteLine()
      
      Array.Clear(timeZoneTimes, 1, 1)
      For Each timeZoneTime In timeZoneTimes
         Console.WriteLine("{0}: {1:G}", 
                           If(timeZoneTime.TimeZone Is Nothing, "<null>", timeZoneTime.TimeZone), 
                           timeZoneTime.DateTime)
      Next
   End Sub
End Module
' The example displays output like the following:
'       (UTC-08:00) Pacific Time (US & Canada): 1/20/2014 12:11:00 PM
'       UTC: 1/20/2014 12:11:00 PM
'       
'       (UTC-08:00) Pacific Time (US & Canada): 1/20/2014 12:11:00 PM
'       <null>: 1/1/0001 12:00:00 AM

注解

此方法将数组中的每个元素重置为元素类型的默认值。This method resets each element in an array to the element type's default value. 它将引用类型 (包括String元素) 的元素设置为null, 并将值类型的元素设置为下表中显示的默认值。It sets elements of reference types (including String elements) to null, and sets elements of value types to the default values shown in the following table.

类型Type Value
Boolean false
所有整型和浮点型数值类型All integral and floating point numeric types 0 (零)0 (zero)
DateTime DateTime.MinValue
其他值类型Other value types 类型字段的默认值Default value of the type's fields

已清除元素的范围在多维数组的行与行之间进行换行。The range of cleared elements wrap from row to row in a multi-dimensional array.

此方法仅清除元素的值;它不会删除元素本身。This method only clears the values of the elements; it does not delete the elements themselves. 数组具有固定的大小;因此, 无法添加或删除元素。An array has a fixed size; therefore, elements cannot be added or removed.

此方法是 O (n) 运算, 其中nlengthThis method is an O(n) operation, where n is length.

适用于