StringReader.ReadLineAsync StringReader.ReadLineAsync StringReader.ReadLineAsync StringReader.ReadLineAsync Method

定義

現在の文字列から文字の行を非同期的に読み取りし、データを文字列として返します。Reads a line of characters asynchronously from the current string and returns the data as a string.

public:
 override System::Threading::Tasks::Task<System::String ^> ^ ReadLineAsync();
[System.Runtime.InteropServices.ComVisible(false)]
public override System.Threading.Tasks.Task<string> ReadLineAsync ();
override this.ReadLineAsync : unit -> System.Threading.Tasks.Task<string>
Public Overrides Function ReadLineAsync () As Task(Of String)

戻り値

非同期の読み取り操作を表すタスク。A task that represents the asynchronous read operation. 値、TResultパラメーターが、文字列リーダーの次の行が含まれていますかnullすべての文字が読み取られた場合。The value of the TResult parameter contains the next line from the string reader, or is null if all the characters have been read.

例外

次の行に含まれる文字数が MaxValue を超えています。The number of characters in the next line is larger than MaxValue.

文字列リーダーは破棄されています。The string reader has been disposed.

リーダーは、前の読み取り操作によって現在使用されています。The reader is currently in use by a previous read operation.

次の例では、文字列から一度に 1 行を非同期的に読み込む方法を示します。The following example shows how to read one line at a time from a string asynchronously.

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

namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            ReadCharacters();
        }

        static async void ReadCharacters()
        {
            StringBuilder stringToRead = new StringBuilder();
            stringToRead.AppendLine("Characters in 1st line to read");
            stringToRead.AppendLine("and 2nd line");
            stringToRead.AppendLine("and the end");

            string readText;

            using (StringReader reader = new StringReader(stringToRead.ToString()))
            {
                while ((readText = await reader.ReadLineAsync()) != null)
                {
                    Console.WriteLine(readText);
                }
            }
        }
    }
}
// The example displays the following output:
//
// Characters in 1st line to read
// and 2nd line
// and the end
//
Imports System.IO
Imports System.Text

Module Module1

    Sub Main()
        ReadCharacters()
    End Sub

    Async Sub ReadCharacters()
        Dim stringToRead = New StringBuilder()
        stringToRead.AppendLine("Characters in 1st line to read")
        stringToRead.AppendLine("and 2nd line")
        stringToRead.AppendLine("and the end")

        Using reader As StringReader = New StringReader(stringToRead.ToString())
            Dim readText As String = Await reader.ReadLineAsync()
            While Not IsNothing(readText)
                Console.WriteLine(readText)
                readText = Await reader.ReadLineAsync()
            End While
        End Using
    End Sub
End Module
' The example displays the following output:
'
' Characters in 1st line to read
' and 2nd line
' and the end
'

適用対象