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StringReader.ReadLineAsync Method ()

.NET Framework (current version)

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

Namespace:   System.IO
Assembly:  mscorlib (in mscorlib.dll)

public override Task<string> ReadLineAsync()

Return Value

Type: System.Threading.Tasks.Task<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.

Exception Condition

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

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.5
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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