StringBuilder.Capacity 属性

获取或设置可包含在当前实例所分配的内存中的最大字符数。

**命名空间:**System.Text
**程序集:**mscorlib（在 mscorlib.dll 中）

语法

声明
Public Property Capacity As Integer
用法
Dim instance As StringBuilder
Dim value As Integer

value = instance.Capacity

instance.Capacity = value

public int Capacity { get; set; }

public:
property int Capacity {
    int get ();
    void set (int value);
}

/** @property */
public int get_Capacity ()

/** @property */
public void set_Capacity (int value)

public function get Capacity () : int

public function set Capacity (value : int)

属性值

可包含在当前实例所分配的内存中的最大字符数。

异常

异常类型	条件
ArgumentOutOfRangeException	为设置操作指定的值小于此实例的当前长度。 - 或 - 为设置操作指定的值大于最大容量。

备注

Capacity 不影响当前实例的字符串值。Capacity 可以减少，但是不能小于 Length。

StringBuilder 在需要时动态地分配更多的内存，并相应地增加 Capacity。出于性能的原因，StringBuilder 可能分配比所需更多的内存。分配的内存量是实现特定的。

示例

下面的代码示例演示了 Capacity 属性。

Imports System
Imports System.Text

Class Sample
   Public Shared Sub Main()
      Dim sb1 As New StringBuilder("abc")
      Dim sb2 As New StringBuilder("abc", 16)
      
      Console.WriteLine()
      Console.WriteLine("a1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity)
      Console.WriteLine("a2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity)
      Console.WriteLine("a3) sb1.ToString() = ""{0}"", sb2.ToString() = ""{1}""", _
                             sb1.ToString(),           sb2.ToString())
      Console.WriteLine("a4) sb1 equals sb2: {0}", sb1.Equals(sb2))
      
      Console.WriteLine()
      Console.WriteLine("Ensure sb1 has a capacity of at least 50 characters.")
      sb1.EnsureCapacity(50)
      
      Console.WriteLine()
      Console.WriteLine("b1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity)
      Console.WriteLine("b2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity)
      Console.WriteLine("b3) sb1.ToString() = ""{0}"", sb2.ToString() = ""{1}""", _
                             sb1.ToString(),           sb2.ToString())
      Console.WriteLine("b4) sb1 equals sb2: {0}", sb1.Equals(sb2))
      
      Console.WriteLine()
      Console.WriteLine("Set the length of sb1 to zero.")
      Console.WriteLine("Set the capacity of sb2 to 51 characters.")
      sb1.Length = 0
      sb2.Capacity = 51
      
      Console.WriteLine()
      Console.WriteLine("c1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity)
      Console.WriteLine("c2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity)
      Console.WriteLine("c3) sb1.ToString() = ""{0}"", sb2.ToString() = ""{1}""", _
                             sb1.ToString(),           sb2.ToString())
      Console.WriteLine("c4) sb1 equals sb2: {0}", sb1.Equals(sb2))
   End Sub 'Main
End Class 'Sample
'
'This example produces the following results:
'
'a1) sb1.Length = 3, sb1.Capacity = 16
'a2) sb2.Length = 3, sb2.Capacity = 16
'a3) sb1.ToString() = "abc", sb2.ToString() = "abc"
'a4) sb1 equals sb2: True
'
'Ensure sb1 has a capacity of at least 50 characters.
'
'b1) sb1.Length = 3, sb1.Capacity = 51
'b2) sb2.Length = 3, sb2.Capacity = 16
'b3) sb1.ToString() = "abc", sb2.ToString() = "abc"
'b4) sb1 equals sb2: False
'
'Set the length of sb1 to zero.
'Set the capacity of sb2 to 51 characters.
'
'c1) sb1.Length = 0, sb1.Capacity = 51
'c2) sb2.Length = 3, sb2.Capacity = 51
'c3) sb1.ToString() = "", sb2.ToString() = "abc"
'c4) sb1 equals sb2: False
'

using System;
using System.Text;

class Sample 
{
    public static void Main() 
    {
    StringBuilder sb1 = new StringBuilder("abc");
    StringBuilder sb2 = new StringBuilder("abc", 16);

    Console.WriteLine();
    Console.WriteLine("a1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity);
    Console.WriteLine("a2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity);
    Console.WriteLine("a3) sb1.ToString() = \"{0}\", sb2.ToString() = \"{1}\"", 
                           sb1.ToString(),       sb2.ToString());
    Console.WriteLine("a4) sb1 equals sb2: {0}", sb1.Equals(sb2));

    Console.WriteLine();
    Console.WriteLine("Ensure sb1 has a capacity of at least 50 characters.");
    sb1.EnsureCapacity(50);

    Console.WriteLine();
    Console.WriteLine("b1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity);
    Console.WriteLine("b2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity);
    Console.WriteLine("b3) sb1.ToString() = \"{0}\", sb2.ToString() = \"{1}\"", 
                           sb1.ToString(),       sb2.ToString());
    Console.WriteLine("b4) sb1 equals sb2: {0}", sb1.Equals(sb2));

    Console.WriteLine();
    Console.WriteLine("Set the length of sb1 to zero.");
    Console.WriteLine("Set the capacity of sb2 to 51 characters.");
    sb1.Length = 0;
    sb2.Capacity = 51;

    Console.WriteLine();
    Console.WriteLine("c1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity);
    Console.WriteLine("c2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity);
    Console.WriteLine("c3) sb1.ToString() = \"{0}\", sb2.ToString() = \"{1}\"", 
                           sb1.ToString(),       sb2.ToString());
    Console.WriteLine("c4) sb1 equals sb2: {0}", sb1.Equals(sb2));
    }
}
/*
This example produces the following results:

a1) sb1.Length = 3, sb1.Capacity = 16
a2) sb2.Length = 3, sb2.Capacity = 16
a3) sb1.ToString() = "abc", sb2.ToString() = "abc"
a4) sb1 equals sb2: True

Ensure sb1 has a capacity of at least 50 characters.

b1) sb1.Length = 3, sb1.Capacity = 51
b2) sb2.Length = 3, sb2.Capacity = 16
b3) sb1.ToString() = "abc", sb2.ToString() = "abc"
b4) sb1 equals sb2: False

Set the length of sb1 to zero.
Set the capacity of sb2 to 51 characters.

c1) sb1.Length = 0, sb1.Capacity = 51
c2) sb2.Length = 3, sb2.Capacity = 51
c3) sb1.ToString() = "", sb2.ToString() = "abc"
c4) sb1 equals sb2: False
*/

using namespace System;
using namespace System::Text;
int main()
{
   StringBuilder^ sb1 = gcnew StringBuilder( "abc" );
   StringBuilder^ sb2 = gcnew StringBuilder( "abc",16 );
   Console::WriteLine();
   Console::WriteLine( "a1) sb1->Length = {0}, sb1->Capacity = {1}", sb1->Length, sb1->Capacity );
   Console::WriteLine( "a2) sb2->Length = {0}, sb2->Capacity = {1}", sb2->Length, sb2->Capacity );
   Console::WriteLine( "a3) sb1 = \"{0}\", sb2 = \"{1}\"", sb1, sb2 );
   Console::WriteLine( "a4) sb1 equals sb2: {0}", sb1->Equals( sb2 ) );
   Console::WriteLine();
   Console::WriteLine( "Ensure sb1 has a capacity of at least 50 characters." );
   sb1->EnsureCapacity( 50 );
   Console::WriteLine();
   Console::WriteLine( "b1) sb1->Length = {0}, sb1->Capacity = {1}", sb1->Length, sb1->Capacity );
   Console::WriteLine( "b2) sb2->Length = {0}, sb2->Capacity = {1}", sb2->Length, sb2->Capacity );
   Console::WriteLine( "b3) sb1 = \"{0}\", sb2 = \"{1}\"", sb1, sb2 );
   Console::WriteLine( "b4) sb1 equals sb2: {0}", sb1->Equals( sb2 ) );
   Console::WriteLine();
   Console::WriteLine( "Set the length of sb1 to zero." );
   Console::WriteLine( "Set the capacity of sb2 to 51 characters." );
   sb1->Length = 0;
   sb2->Capacity = 51;
   Console::WriteLine();
   Console::WriteLine( "c1) sb1->Length = {0}, sb1->Capacity = {1}", sb1->Length, sb1->Capacity );
   Console::WriteLine( "c2) sb2->Length = {0}, sb2->Capacity = {1}", sb2->Length, sb2->Capacity );
   Console::WriteLine( "c3) sb1 = \"{0}\", sb2 = \"{1}\"", sb1, sb2 );
   Console::WriteLine( "c4) sb1 equals sb2: {0}", sb1->Equals( sb2 ) );
}

/*
This example produces the following results:

a1) sb1.Length = 3, sb1.Capacity = 16
a2) sb2.Length = 3, sb2.Capacity = 16
a3) sb1.ToString() = "abc", sb2.ToString() = "abc"
a4) sb1 equals sb2: True

Ensure sb1 has a capacity of at least 50 characters.

b1) sb1.Length = 3, sb1.Capacity = 51
b2) sb2.Length = 3, sb2.Capacity = 16
b3) sb1.ToString() = "abc", sb2.ToString() = "abc"
b4) sb1 equals sb2: False

Set the length of sb1 to zero.
Set the capacity of sb2 to 51 characters.

c1) sb1.Length = 0, sb1.Capacity = 51
c2) sb2.Length = 3, sb2.Capacity = 51
c3) sb1.ToString() = "", sb2.ToString() = "abc"
c4) sb1 equals sb2: False
*/

// This example demonstrates StringBuilder.EnsureCapacity
//                           StringBuilder.Capacity
//                           StringBuilder.Length
//                           StringBuilder.Equals
import System.*;
import System.Text.*;

class Sample
{
    public static void main(String[] args)
    {
        StringBuilder sb1 = new StringBuilder("abc");
        StringBuilder sb2 = new StringBuilder("abc", 16);

        Console.WriteLine();
        Console.WriteLine("a1) sb1.get_Length() = {0}, " 
            + "sb1.get_Capacity() = {1}", 
            System.Convert.ToString(sb1.get_Length()), 
            System.Convert.ToString(sb1.get_Capacity()));
        Console.WriteLine("a2) sb2.get_Length() = {0}, " 
            + "sb2.get_Capacity() = {1}", 
            System.Convert.ToString(sb2.get_Length()), 
            System.Convert.ToString(sb2.get_Capacity()));
        Console.WriteLine("a3) sb1.ToString() = \"{0}\", " 
            + "sb2.ToString() = \"{1}\"", sb1.ToString(), sb2.ToString());
        Console.WriteLine("a4) sb1 equals sb2: {0}", 
            System.Convert.ToString(sb1.Equals(sb2)));

        Console.WriteLine();
        Console.WriteLine("Ensure sb1 has a capacity of at least 50 " 
            + "characters.");
        sb1.EnsureCapacity(50);

        Console.WriteLine();
        Console.WriteLine("b1) sb1.get_Length() = {0}, " 
            + "sb1.get_Capacity() = {1}", 
            System.Convert.ToString(sb1.get_Length()), 
            System.Convert.ToString(sb1.get_Capacity()));
        Console.WriteLine("b2) sb2.get_Length() = {0}, " 
            + "sb2.get_Capacity() = {1}", 
            System.Convert.ToString(sb2.get_Length()), 
            System.Convert.ToString(sb2.get_Capacity()));
        Console.WriteLine("b3) sb1.ToString() = \"{0}\", " 
            + "sb2.ToString() = \"{1}\"", sb1.ToString(), sb2.ToString());
        Console.WriteLine("b4) sb1 equals sb2: {0}", 
            System.Convert.ToString(sb1.Equals(sb2)));

        Console.WriteLine();
        Console.WriteLine("Set the length of sb1 to zero.");
        Console.WriteLine("Set the capacity of sb2 to 51 characters.");
        sb1.set_Length(0);
        sb2.set_Capacity(51);

        Console.WriteLine();
        Console.WriteLine("c1) sb1.get_Length() = {0}, "
            + "sb1.get_Capacity() = {1}", 
            System.Convert.ToString(sb1.get_Length()), 
            System.Convert.ToString(sb1.get_Capacity()));
        Console.WriteLine("c2) sb2.get_Length() = {0}, " 
            + "sb2.get_Capacity() = {1}", 
            System.Convert.ToString(sb2.get_Length()), 
            System.Convert.ToString(sb2.get_Capacity()));
        Console.WriteLine("c3) sb1.ToString() = \"{0}\", " 
            + "sb2.ToString() = \"{1}\"", sb1.ToString(), sb2.ToString());
        Console.WriteLine("c4) sb1 equals sb2: {0}", 
            System.Convert.ToString(sb1.Equals(sb2)));
    } //main
} //Sample
/*
This example produces the following results:

a1) sb1.get_Length() = 3, sb1.get_Capacity() = 16
a2) sb2.get_Length() = 3, sb2.get_Capacity() = 16
a3) sb1.ToString() = "abc", sb2.ToString() = "abc"
a4) sb1 equals sb2: True

Ensure sb1 has a capacity of at least 50 characters.

b1) sb1.get_Length() = 3, sb1.get_Capacity() = 50
b2) sb2.get_Length() = 3, sb2.get_Capacity() = 16
b3) sb1.ToString() = "abc", sb2.ToString() = "abc"
b4) sb1 equals sb2: False

Set the length of sb1 to zero.
Set the capacity of sb2 to 51 characters.

c1) sb1.get_Length() = 0, sb1.get_Capacity() = 50
c2) sb2.get_Length() = 3, sb2.get_Capacity() = 51
c3) sb1.ToString() = "", sb2.ToString() = "abc"
c4) sb1 equals sb2: False
*/

平台

Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。

版本信息

.NET Framework

受以下版本支持：2.0、1.1、1.0

.NET Compact Framework

受以下版本支持：2.0、1.0

请参见

参考

StringBuilder 类
StringBuilder 成员
System.Text 命名空间