SecureString.SetAt(Int32, Char) 方法

定义

将指定索引位置上的现有字符替换为其他字符。Replaces the existing character at the specified index position with another character.

public:
 void SetAt(int index, char c);
public void SetAt (int index, char c);
[System.Runtime.ExceptionServices.HandleProcessCorruptedStateExceptions]
public void SetAt (int index, char c);
member this.SetAt : int * char -> unit
[<System.Runtime.ExceptionServices.HandleProcessCorruptedStateExceptions>]
member this.SetAt : int * char -> unit
Public Sub SetAt (index As Integer, c As Char)

参数

index
Int32

此安全字符串中的某个现有字符的索引位置。The index position of an existing character in this secure string

c
Char

替换现有字符的字符。A character that replaces the existing character.

属性

例外

已处置此安全字符串。This secure string has already been disposed.

此安全字符串是只读的。This secure string is read-only.

index 小于零,或者大于或等于此安全字符串的长度。index is less than zero, or greater than or equal to the length of this secure string.

保护或取消保护此安全字符串的值时出错。An error occurred while protecting or unprotecting the value of this secure string.

示例

下面的示例演示了 AppendCharInsertAtRemoveAtSetAt 和方法如何 Clear 影响对象的值 SecureStringThe following example demonstrates how the AppendChar, InsertAt, RemoveAt, SetAt, and Clear methods affect the value of a SecureString object.

using namespace System;
using namespace System::Security;

void main()
{
    String^ msg = L"   The current length of the SecureString object: {0}\n";
    SecureString ^ ss = gcnew SecureString;

    Console::WriteLine(L"1) Instantiate the SecureString object:");
    Console::WriteLine(msg, ss->Length );

    Console::WriteLine(L"2) Append 'a' to the value:");
    ss->AppendChar('a');
    Console::WriteLine(msg, ss->Length );

    Console::WriteLine(L"3) Append 'X' to the value:");
    ss->AppendChar('X');
    Console::WriteLine(msg, ss->Length);

    Console::WriteLine(L"4) Append 'c' to the value:");
    ss->AppendChar('c');
    Console::WriteLine(msg, ss->Length);

    Console::WriteLine(L"5) Insert 'd' at the end of the value:");
    ss->InsertAt(ss->Length, 'd');
    Console::WriteLine(msg, ss->Length);

    Console::WriteLine(L"6) Remove the last character ('d') from the value:");
    ss->RemoveAt(3);
    Console::WriteLine(msg, ss->Length);

    Console::WriteLine(L"7) Set the second character ('X') of the value to 'b':" );
    ss->SetAt(1, 'b');
    Console::WriteLine(msg, ss->Length );

    Console::WriteLine(L"8) Delete the value of the SecureString object:");
    ss->Clear();
    Console::WriteLine(msg, ss->Length);

    delete ss;
}

/*
This code example produces the following results:

This example demonstrates the effect of the AppendChar, InsertAt,
RemoveAt, SetAt, and Clear methods on the value of a SecureString
object. This example simulates the value of the object because the
actual value is encrypted.

1) The initial value of the SecureString object:
   SecureString = ""
   Length = 0

2) AppendChar: Append 'a' to the value:
   SecureString = "a"
   Length = 1

3) AppendChar: Append 'X' to the value:
   SecureString = "aX"
   Length = 2

4) AppendChar: Append 'c' to the value:
   SecureString = "aXc"
   Length = 3

5) InsertAt: Insert 'd' at the end of the value (equivalent
     to AppendChar):
   SecureString = "aXcd"
   Length = 4

6) RemoveAt: Remove the last character ('d') from the value:
   SecureString = "aXc"
   Length = 3

7) SetAt: Set the second character ('X') of the value to 'b':
   SecureString = "abc"
   Length = 3

8) Clear: Delete the value of the SecureString object:
   SecureString = ""
   Length = 0
*/
using System;
using System.Security;

class Example
{
    public static void Main()
    {
       string msg = "The curent length of the SecureString object: {0}\n";
       Console.WriteLine("1) Instantiate the SecureString object.");
       SecureString ss = new SecureString();
       Console.WriteLine(msg, ss.Length);

       Console.WriteLine("2) Append 'a' to the value.");
       ss.AppendChar('a');
       Console.WriteLine(msg, ss.Length);

       Console.WriteLine("3) Append 'X' to the value.");
       ss.AppendChar('X');
       Console.WriteLine(msg, ss.Length);

       Console.WriteLine("4) Append 'c' to the value.");
       ss.AppendChar('c');
       Console.WriteLine(msg, ss.Length);

       Console.WriteLine("5) Insert 'd' at the end of the value.");
       ss.InsertAt(ss.Length, 'd');
       Console.WriteLine(msg, ss.Length);

       Console.WriteLine("6) Remove the last character ('d') from the value.");
       ss.RemoveAt(3);
       Console.WriteLine(msg, ss.Length);

       Console.WriteLine("7) Set the second character of the value to 'b'.");
       ss.SetAt(1, 'b');
       Console.WriteLine(msg, ss.Length);

       Console.WriteLine("8) Delete the value of the SecureString object:");
       ss.Clear();
       Console.WriteLine(msg, ss.Length);

       ss.Dispose();
    }
}
// The example displays the following output:
//       1) Instantiate the SecureString object.
//       The curent length of the SecureString object: 0
//
//       2) Append 'a' to the value.
//       The curent length of the SecureString object: 1
//
//       3) Append 'X' to the value.
//       The curent length of the SecureString object: 2
//
//       4) Append 'c' to the value.
//       The curent length of the SecureString object: 3
//
//       5) Insert 'd' at the end of the value.
//       The curent length of the SecureString object: 4
//
//       6) Remove the last character ('d') from the value.
//       The curent length of the SecureString object: 3
//
//       7) Set the second character of the value to 'b'.
//       The curent length of the SecureString object: 3
//
//       8) Delete the value of the SecureString object:
//       The curent length of the SecureString object: 0
Imports System.Security

Module Example
    Public Sub Main()
       Dim msg As String = "The curent length of the SecureString object: {0}" + vbCrLf
       Console.WriteLine("1) Instantiate the SecureString object.")
       Dim ss As New SecureString()
       Console.WriteLine(msg, ss.Length)

       Console.WriteLine("2) Append 'a' to the value.")
       ss.AppendChar("a"c)
       Console.WriteLine(msg, ss.Length)

       Console.WriteLine("3) Append 'X' to the value.")
       ss.AppendChar("X"c)
       Console.WriteLine(msg, ss.Length)

       Console.WriteLine("4) Append 'c' to the value.")
       ss.AppendChar("c"c)
       Console.WriteLine(msg, ss.Length)

       Console.WriteLine("5) Insert 'd' at the end of the value.")
       ss.InsertAt(ss.Length, "d"c)
       Console.WriteLine(msg, ss.Length)

       Console.WriteLine("6) Remove the last character ('d') from the value.")
       ss.RemoveAt(3)
       Console.WriteLine(msg, ss.Length)

       Console.WriteLine("7) Set the second character of the value to 'b'.")
       ss.SetAt(1, "b"c)
       Console.WriteLine(msg, ss.Length)

       Console.WriteLine("8) Delete the value of the SecureString object:")
       ss.Clear()
       Console.WriteLine(msg, ss.Length)

       ss.Dispose()
    End Sub
End Module
' The example displays the following output:
'       1) Instantiate the SecureString object.
'       The curent length of the SecureString object: 0
'
'       2) Append 'a' to the value.
'       The curent length of the SecureString object: 1
'
'       3) Append 'X' to the value.
'       The curent length of the SecureString object: 2
'
'       4) Append 'c' to the value.
'       The curent length of the SecureString object: 3
'
'       5) Insert 'd' at the end of the value.
'       The curent length of the SecureString object: 4
'
'       6) Remove the last character ('d') from the value.
'       The curent length of the SecureString object: 3
'
'       7) Set the second character of the value to 'b'.
'       The curent length of the SecureString object: 3
'
'       8) Delete the value of the SecureString object:
'       The curent length of the SecureString object: 0

注解

索引从零开始;此实例中的第一个字符的索引位置为零。The index is zero-based; the first character in this instance is at index position zero.

如果实现使用保护机制(如加密),则安全字符串的值(如果有)不受保护; c 将分配给指定的索引位置,然后重新保护新的值。If the implementation uses a protection mechanism, such as encryption, the value of the secure string, if any, is unprotected; c is assigned to the specified index position; then the new value is re-protected.

适用于