• Articolo

StringBuilder.Capacity Property

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Gets or sets the maximum number of characters that can be contained in the memory allocated by the current instance.

Namespace:  System.Text
Assembly:  mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public Property Capacity As Integer

public int Capacity { get; set; }

Property Value

Type: System.Int32
The maximum number of characters that can be contained in the memory allocated by the current instance.

Exceptions

Exception Condition
ArgumentOutOfRangeException

The value specified for a set operation is less than the current length of this instance.

-or-

The value specified for a set operation is greater than the maximum capacity.

Remarks

Capacity does not affect the string value of the current instance. Capacity can be decreased as long as it is not less than Length.

The StringBuilder dynamically allocates more space when required and increases Capacity accordingly. For performance reasons, a StringBuilder might allocate more memory than needed. The amount of memory allocated is implementation-specific.

Examples

The following code example demonstrates the Capacity property.

Imports System.Text

Class Example
   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim sb1 As New StringBuilder("abc")
      Dim sb2 As New StringBuilder("abc", 16)

      outputBlock.Text &= vbCrLf
      outputBlock.Text += String.Format("a1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity) & vbCrLf
      outputBlock.Text += String.Format("a2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity) & vbCrLf
      outputBlock.Text += String.Format("a3) sb1.ToString() = ""{0}"", sb2.ToString() & vbCrLf = ""{1}""", _
                             sb1.ToString(), sb2.ToString())
      outputBlock.Text += String.Format("a4) sb1 equals sb2: {0}", sb1.Equals(sb2)) & vbCrLf

      outputBlock.Text &= vbCrLf
      outputBlock.Text &= "Ensure sb1 has a capacity of at least 50 characters." & vbCrLf
      sb1.EnsureCapacity(50)

      outputBlock.Text &= vbCrLf
      outputBlock.Text += String.Format("b1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity) & vbCrLf
      outputBlock.Text += String.Format("b2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity) & vbCrLf
      outputBlock.Text += String.Format("b3) sb1.ToString() = ""{0}"", sb2.ToString() & vbCrLf = ""{1}""", _
                             sb1.ToString(), sb2.ToString())
      outputBlock.Text += String.Format("b4) sb1 equals sb2: {0}", sb1.Equals(sb2)) & vbCrLf

      outputBlock.Text &= vbCrLf
      outputBlock.Text &= "Set the length of sb1 to zero." & vbCrLf
      outputBlock.Text &= "Set the capacity of sb2 to 51 characters." & vbCrLf
      sb1.Length = 0
      sb2.Capacity = 51

      outputBlock.Text &= vbCrLf
      outputBlock.Text += String.Format("c1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity) & vbCrLf
      outputBlock.Text += String.Format("c2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity) & vbCrLf
      outputBlock.Text += String.Format("c3) sb1.ToString() = ""{0}"", sb2.ToString() & vbCrLf = ""{1}""", _
                             sb1.ToString(), sb2.ToString())
      outputBlock.Text += String.Format("c4) sb1 equals sb2: {0}", sb1.Equals(sb2)) & vbCrLf
   End Sub 
End Class 
' The example displays the following output:
'       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 = 50
'       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 = 50
'       c2) sb2.Length = 3, sb2.Capacity = 51
'       c3) sb1.ToString() = "", sb2.ToString() = "abc"
'       c4) sb1 equals sb2: False

using System;
using System.Text;

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      StringBuilder sb1 = new StringBuilder("abc");
      StringBuilder sb2 = new StringBuilder("abc", 16);

      outputBlock.Text += "\n";
      outputBlock.Text += String.Format("a1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity) + "\n";
      outputBlock.Text += String.Format("a2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity) + "\n";
      outputBlock.Text += String.Format("a3) sb1.ToString() = \"{0}\", sb2.ToString() = \"{1}\"",
                             sb1.ToString(), sb2.ToString()) + "\n";
      outputBlock.Text += String.Format("a4) sb1 equals sb2: {0}", sb1.Equals(sb2)) + "\n";

      outputBlock.Text += "\n";
      outputBlock.Text += "Ensure sb1 has a capacity of at least 50 characters." + "\n";
      sb1.EnsureCapacity(50);

      outputBlock.Text += "\n";
      outputBlock.Text += String.Format("b1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity) + "\n";
      outputBlock.Text += String.Format("b2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity) + "\n";
      outputBlock.Text += String.Format("b3) sb1.ToString() = \"{0}\", sb2.ToString() = \"{1}\"",
                             sb1.ToString(), sb2.ToString()) + "\n";
      outputBlock.Text += String.Format("b4) sb1 equals sb2: {0}", sb1.Equals(sb2)) + "\n";

      outputBlock.Text += "\n";
      outputBlock.Text += "Set the length of sb1 to zero." + "\n";
      outputBlock.Text += "Set the capacity of sb2 to 51 characters." + "\n";
      sb1.Length = 0;
      sb2.Capacity = 51;

      outputBlock.Text += "\n";
      outputBlock.Text += String.Format("c1) sb1.Length = {0}, sb1.Capacity = {1}", sb1.Length, sb1.Capacity) + "\n";
      outputBlock.Text += String.Format("c2) sb2.Length = {0}, sb2.Capacity = {1}", sb2.Length, sb2.Capacity) + "\n";
      outputBlock.Text += String.Format("c3) sb1.ToString() = \"{0}\", sb2.ToString() = \"{1}\"",
                             sb1.ToString(), sb2.ToString()) + "\n";
      outputBlock.Text += String.Format("c4) sb1 equals sb2: {0}", sb1.Equals(sb2)) + "\n";
   }
}
/*
The example displays the following output:

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 = 50
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 = 50
c2) sb2.Length = 3, sb2.Capacity = 51
c3) sb1.ToString() = "", sb2.ToString() = "abc"
c4) sb1 equals sb2: False
*/

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.