Uređivanje

Dijeli putem


SecureString.SetAt(Int32, Char) Method

Definition

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)

Parameters

index
Int32

The index position of an existing character in this secure string.

c
Char

A character that replaces the existing character.

Attributes

Exceptions

This secure string has already been disposed.

This secure string is read-only.

index is less than zero, or greater than or equal to the length of this secure string.

An error occurred while protecting or unprotecting the value of this secure string.

Examples

The 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 SecureStringExample
{
    public static void Main()
    {
       string msg = "The current 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 current length of the SecureString object: 0
//
//       2) Append 'a' to the value.
//       The current length of the SecureString object: 1
//
//       3) Append 'X' to the value.
//       The current length of the SecureString object: 2
//
//       4) Append 'c' to the value.
//       The current length of the SecureString object: 3
//
//       5) Insert 'd' at the end of the value.
//       The current length of the SecureString object: 4
//
//       6) Remove the last character ('d') from the value.
//       The current length of the SecureString object: 3
//
//       7) Set the second character of the value to 'b'.
//       The current length of the SecureString object: 3
//
//       8) Delete the value of the SecureString object:
//       The current length of the SecureString object: 0
Imports System.Security

Module Example
    Public Sub Main()
       Dim msg As String = "The current 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 current length of the SecureString object: 0
'
'       2) Append 'a' to the value.
'       The current length of the SecureString object: 1
'
'       3) Append 'X' to the value.
'       The current length of the SecureString object: 2
'
'       4) Append 'c' to the value.
'       The current length of the SecureString object: 3
'
'       5) Insert 'd' at the end of the value.
'       The current length of the SecureString object: 4
'
'       6) Remove the last character ('d') from the value.
'       The current length of the SecureString object: 3
'
'       7) Set the second character of the value to 'b'.
'       The current length of the SecureString object: 3
'
'       8) Delete the value of the SecureString object:
'       The current length of the SecureString object: 0

Remarks

The index is zero-based; the first character in this instance is at index position zero.

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.

Applies to