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如何：向字符串写入字符

  • 项目

下面的代码示例从字符数组以同步或异步方式向字符串写入字符。

示例：在控制台应用中以同步方式编写字符

下面的示例使用 StringWriter 将五个字符同步写入 StringBuilder 对象。

using System;
using System.IO;
using System.Text;

public class CharsToStr
{
    public static void Main()
    {
        StringBuilder sb = new StringBuilder("Start with a string and add from ");
        char[] b = { 'c', 'h', 'a', 'r', '.', ' ', 'B', 'u', 't', ' ', 'n', 'o', 't', ' ', 'a', 'l', 'l' };

        using (StringWriter sw = new StringWriter(sb))
        {
            // Write five characters from the array into the StringBuilder.
            sw.Write(b, 0, 5);
            Console.WriteLine(sb);
        }
    }
}
// The example has the following output:
//
// Start with a string and add from char.



Imports System.IO
Imports System.Text

Public Class CharsToStr
    Public Shared Sub Main()
        Dim sb As New StringBuilder("Start with a string and add from ")
        Dim b() As Char = {"c", "h", "a", "r", ".", " ", "B", "u", "t", " ", "n", "o", "t", " ", "a", "l", "l"}

        Using sw As StringWriter = New StringWriter(sb)
            ' Write five characters from the array into the StringBuilder.
            sw.Write(b, 0, 5)
            Console.WriteLine(sb)
        End Using
    End Sub
End Class
' The example has the following output:
'
' Start with a string and add from char.

示例：在 WPF 应用中以同步方式编写字符

下一个示例是 WPF 应用背后的代码。 在窗口加载时，示例从 TextBox 控件异步读取所有字符，并将其存储在数组中。 随后，它以异步方式将每个字母或空格字符写入单独的 TextBlock 控件行。

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

请参阅