StringReader.ReadLineAsync Method


Reads a line of characters asynchronously from the current string and returns the data as a string.

 override System::Threading::Tasks::Task<System::String ^> ^ ReadLineAsync();
public override System.Threading.Tasks.Task<string> ReadLineAsync ();
public override System.Threading.Tasks.Task<string>? ReadLineAsync ();
public override System.Threading.Tasks.Task<string> ReadLineAsync ();
override this.ReadLineAsync : unit -> System.Threading.Tasks.Task<string>
override this.ReadLineAsync : unit -> System.Threading.Tasks.Task<string>
Public Overrides Function ReadLineAsync () As Task(Of String)



A task that represents the asynchronous read operation. The value of the TResult parameter contains the next line from the string reader, or is null if all the characters have been read.



The number of characters in the next line is larger than MaxValue.

The string reader has been disposed.

The reader is currently in use by a previous read operation.


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)

        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)
// 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()
    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)
                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

Applies to