StringBuilder.EnsureCapacity(Int32) Method

Reference

Definition

Namespace:: System.Text

Assemblies:: mscorlib.dll, System.Runtime.dll

Assemblies:: netstandard.dll, System.Runtime.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: StringBuilder.cs

Source:: StringBuilder.cs

Source:: StringBuilder.cs

Source:: StringBuilder.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Ensures that the capacity of this instance of StringBuilder is at least the specified value.

public:
 int EnsureCapacity(int capacity);

public int EnsureCapacity(int capacity);

member this.EnsureCapacity : int -> int

Public Function EnsureCapacity (capacity As Integer) As Integer

Parameters

capacity: Int32

The minimum capacity to ensure.

Returns

Int32

The new capacity of this instance.

Exceptions

ArgumentOutOfRangeException

capacity is less than zero.

-or-

Enlarging the value of this instance would exceed MaxCapacity.

Examples

The following example demonstrates the EnsureCapacity method.

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));
    }
}
/*
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
*/

open System.Text

let sb1 = StringBuilder "abc"
let sb2 = StringBuilder("abc", 16)

printfn $"a1) sb1.Length = {sb1.Length}, sb1.Capacity = {sb1.Capacity}"
printfn $"a2) sb2.Length = {sb2.Length}, sb2.Capacity = {sb2.Capacity}"
printfn $"a3) sb1.ToString() = \"{sb1}\", sb2.ToString() = \"{sb2}\""
printfn $"a4) sb1 equals sb2: {sb1.Equals sb2}"

printfn "\nEnsure sb1 has a capacity of at least 50 characters."
sb1.EnsureCapacity 50 |> ignore

printfn $"\nb1) sb1.Length = {sb1.Length}, sb1.Capacity = {sb1.Capacity}"
printfn $"b2) sb2.Length = {sb2.Length}, sb2.Capacity = {sb2.Capacity}"
printfn $"b3) sb1.ToString() = \"{sb1}\", sb2.ToString() = \"{sb2}\""
printfn $"b4) sb1 equals sb2: {sb1.Equals sb2}"

printfn "\nSet the length of sb1 to zero."
printfn "Set the capacity of sb2 to 51 characters."
sb1.Length <- 0
sb2.Capacity <- 51

printfn $"\nc1) sb1.Length = {sb1.Length}, sb1.Capacity = {sb1.Capacity}"
printfn $"c2) sb2.Length = {sb2.Length}, sb2.Capacity = {sb2.Capacity}"
printfn $"c3) sb1.ToString() = \"{sb1}\", sb2.ToString() = \"{sb2}\""
printfn $"c4) sb1 equals sb2: {sb1.Equals sb2}"

// 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

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 
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

Remarks

If the current capacity is less than the capacity parameter, memory for this instance is reallocated to hold at least capacity number of characters; otherwise, no memory is changed.

Applies to

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