下列程式代碼範例示範如何以同步或異步方式從字串讀取字元。
範例：同步讀取字元
這個範例會從字串同步讀取 13 個字元、將它們儲存在數位中，並加以顯示。 然後，此範例會讀取字串中其餘的字元，並將其儲存在陣列中，從第六個項目開始，並顯示數位的內容。
using System;
using System.IO;
public class CharsFromStr
{
public static void Main()
{
string str = "Some number of characters";
char[] b = new char[str.Length];
using (StringReader sr = new StringReader(str))
{
// Read 13 characters from the string into the array.
sr.Read(b, 0, 13);
Console.WriteLine(b);
// Read the rest of the string starting at the current string position.
// Put in the array starting at the 6th array member.
sr.Read(b, 5, str.Length - 13);
Console.WriteLine(b);
}
}
}
// The example has the following output:
//
// Some number o
// Some f characters
Imports System.IO
Public Class CharsFromStr
Public Shared Sub Main()
Dim str As String = "Some number of characters"
Dim b(str.Length - 1) As Char
Using sr As StringReader = New StringReader(str)
' Read 13 characters from the string into the array.
sr.Read(b, 0, 13)
Console.WriteLine(b)
' Read the rest of the string starting at the current string position.
' Put in the array starting at the 6th array member.
sr.Read(b, 5, str.Length - 13)
Console.WriteLine(b)
End Using
End Sub
End Class
' The example has the following output:
'
' Some number o
' Some f characters
範例：以異步方式讀取字元
下一個範例是 WPF 應用程式背後的程式代碼。 在視窗載入時，此範例會以異步方式從 TextBox 控件讀取所有字元，並將其儲存在陣列中。 然後，它會以異步方式將每個字母或空格符寫入控件的 TextBlock 個別行。
using System;
using System.Text;
using System.Windows;
using System.IO;
namespace StringReaderWriter
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private async void Window_Loaded(object sender, RoutedEventArgs e)
{
char[] charsRead = new char[UserInput.Text.Length];
using (StringReader reader = new StringReader(UserInput.Text))
{
await reader.ReadAsync(charsRead, 0, UserInput.Text.Length);
}
StringBuilder reformattedText = new StringBuilder();
using (StringWriter writer = new StringWriter(reformattedText))
{
foreach (char c in charsRead)
{
if (char.IsLetter(c) || char.IsWhiteSpace(c))
{
await writer.WriteLineAsync(char.ToLower(c));
}
}
}
Result.Text = reformattedText.ToString();
}
}
}
Imports System.IO
Imports System.Text
''' <summary>
''' Interaction logic for MainWindow.xaml
''' </summary>
Partial Public Class MainWindow
Inherits Window
Public Sub New()
InitializeComponent()
End Sub
Private Async Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
Dim charsRead As Char() = New Char(UserInput.Text.Length) {}
Using reader As StringReader = New StringReader(UserInput.Text)
Await reader.ReadAsync(charsRead, 0, UserInput.Text.Length)
End Using
Dim reformattedText As StringBuilder = New StringBuilder()
Using writer As StringWriter = New StringWriter(reformattedText)
For Each c As Char In charsRead
If Char.IsLetter(c) Or Char.IsWhiteSpace(c) Then
Await writer.WriteLineAsync(Char.ToLower(c))
End If
Next
End Using
Result.Text = reformattedText.ToString()
End Sub
End Class
