StringBuilder.Length 屬性

定義

命名空間:

System.Text

組件:

netstandard.dll, System.Runtime.dll

來源:

StringBuilder.cs

取得或設定當前 StringBuilder 物件的長度。

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

public int Length { get; set; }

member this.Length : int with get, set

Public Property Length As Integer

屬性值

Int32

這個實例的長度。

例外狀況

ArgumentOutOfRangeException

集合運算指定的值小於零或大於 MaxCapacity。

範例

以下範例展示了該 Length 性質。

using System;
using System.Text;

StringBuilder sb1 = new("abc");
StringBuilder sb2 = new("abc", 16);

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

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

Console.WriteLine();
Console.WriteLine($"b1) sb1.Length = {sb1.Length}, sb1.Capacity = {sb1.Capacity}");
Console.WriteLine($"b2) sb2.Length = {sb2.Length}, sb2.Capacity = {sb2.Capacity}");
Console.WriteLine($"b3) sb1.ToString() = \"{sb1}\", sb2.ToString() = \"{sb2}\"");
Console.WriteLine($"b4) sb1 equals sb2: {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($"c1) sb1.Length = {sb1.Length}, sb1.Capacity = {sb1.Capacity}");
Console.WriteLine($"c2) sb2.Length = {sb2.Length}, sb2.Capacity = {sb2.Capacity}");
Console.WriteLine($"c3) sb1.ToString() = \"{sb1}\", sb2.ToString() = \"{sb2}\"");
Console.WriteLine($"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: True (False on .NET Framework)

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: True (False on .NET Framework)
//       
//       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: True (False on .NET Framework)
'       
'       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

備註

物件的 StringBuilder 長度由其物件數量 Char 決定。

與 屬性 String.Length 相同， Length 屬性表示目前字串物件的長度。 與 String.Length 唯讀的屬性不同，屬性 Length 允許你修改儲存到 StringBuilder 物件的字串長度。

若指定長度小於當前長度，則將當前 StringBuilder 物件截斷至指定長度。 若指定長度大於當前長度，則當前物件字串值 StringBuilder 末尾會填充 Unicode NULL 字元（U+0000）。

若指定長度大於當前容量，則 Capacity 增加至大於或等於指定長度。