方法: 文字列からの文字の読み取りHow to: Read characters from a string

次のコード例は、文字列から同期的または非同期的に文字を読み取る方法を示しています。The following code examples show how to read characters synchronously or asynchronously from a string.

例:同期的に文字を読み取るExample: Read characters synchronously

この例では、文字列から同期的に 13 文字を読み取り、配列に格納し、これらを表示します。This example reads 13 characters synchronously from a string, stores them in an array, and displays them. 次に、この例では、文字列の残りの文字を読み取り、6 番目の要素で始まる配列に格納し、配列の内容を表示します。The example then reads the rest of the characters in the string, stores them in the array starting at the sixth element, and displays the contents of the array.

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
Imports System.IO

Public Class CharsFromStr
    Public Shared Sub Main()
        Dim str As String = "Some number of characters"
        Dim b(str.Length) 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

例:非同期的に文字を読み取るExample: Read characters asynchronously

次の例は WPF アプリの裏側にあるコードです。The next example is the code behind a WPF app. ウィンドウを読み込むと、TextBox コントロールから非同期的にすべての文字を読み取り、配列に格納します。On window load, the example asynchronously reads all characters from a TextBox control and stores them in an array. 次に、TextBlock コントロールの個別の行に各文字または空白文字が非同期で書き込まれます。It then asynchronously writes each letter or white-space character to a separate line of a TextBlock control.

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

関連項目See also