StreamReader.ReadToEndAsync Method

Definition

Namespace:

System.IO

Assembly:

System.Runtime.dll

Overloads

ReadToEndAsync()	Reads all characters from the current position to the end of the stream asynchronously and returns them as one string.
ReadToEndAsync(CancellationToken)	Reads all characters from the current position to the end of the stream asynchronously and returns them as one string.

ReadToEndAsync()

Source:

StreamReader.cs

Reads all characters from the current position to the end of the stream asynchronously and returns them as one string.

public:
 override System::Threading::Tasks::Task<System::String ^> ^ ReadToEndAsync();

public override System.Threading.Tasks.Task<string> ReadToEndAsync ();

override this.ReadToEndAsync : unit -> System.Threading.Tasks.Task<string>

Public Overrides Function ReadToEndAsync () As Task(Of String)

Returns

Task<String>

A task that represents the asynchronous read operation. The value of the TResult parameter contains a string with the characters from the current position to the end of the stream.

Exceptions

ArgumentOutOfRangeException

The number of characters is larger than Int32.MaxValue.

ObjectDisposedException

The stream has been disposed.

InvalidOperationException

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

Examples

The following example shows how to read the contents of a file by using the ReadToEndAsync() method.

using System;
using System.IO;

namespace ConsoleApplication
{
    class Program
    {
        static async Task Main()
        {
            await ReadCharacters();
        }

        static async Task ReadCharacters()
        {
            String result;
            using (StreamReader reader = File.OpenText("existingfile.txt"))
            {
                Console.WriteLine("Opened file.");
                result = await reader.ReadToEndAsync();
                Console.WriteLine("Contains: " + result);
            }
        }
    }
}

Imports System.IO

Module Module1

    Sub Main()
        ReadCharacters()
    End Sub

    Async Sub ReadCharacters()
        Dim result As String

        Using reader As StreamReader = File.OpenText("existingfile.txt")
            Console.WriteLine("Opened file.")
            result = Await reader.ReadToEndAsync()
            Console.WriteLine("Contains: " + result)
        End Using
    End Sub
End Module

Remarks

This method stores in the task it returns all non-usage exceptions that the method's synchronous counterpart can throw. If an exception is stored into the returned task, that exception will be thrown when the task is awaited. Usage exceptions, such as ArgumentException, are still thrown synchronously. For the stored exceptions, see the exceptions thrown by ReadToEnd().

ReadToEndAsync(CancellationToken)

Source:

StreamReader.cs

Reads all characters from the current position to the end of the stream asynchronously and returns them as one string.

public:
 override System::Threading::Tasks::Task<System::String ^> ^ ReadToEndAsync(System::Threading::CancellationToken cancellationToken);

public override System.Threading.Tasks.Task<string> ReadToEndAsync (System.Threading.CancellationToken cancellationToken);

override this.ReadToEndAsync : System.Threading.CancellationToken -> System.Threading.Tasks.Task<string>

Public Overrides Function ReadToEndAsync (cancellationToken As CancellationToken) As Task(Of String)

Parameters

cancellationToken

CancellationToken

The token to monitor for cancellation requests.

Returns

Task<String>

A task that represents the asynchronous read operation. The value of the TResult parameter contains a string with the characters from the current position to the end of the stream.

Exceptions

ArgumentOutOfRangeException

The number of characters is larger than Int32.MaxValue.

ObjectDisposedException

The stream reader has been disposed.

InvalidOperationException

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

OperationCanceledException

The cancellation token was canceled. This exception is stored into the returned task.

Remarks

If this method is canceled via cancellationToken, some data that has been read from the current Stream but not stored (by the StreamReader) or returned (to the caller) may be lost.

This method stores in the task it returns all non-usage exceptions that the method's synchronous counterpart can throw. If an exception is stored into the returned task, that exception will be thrown when the task is awaited. Usage exceptions, such as ArgumentException, are still thrown synchronously. For the stored exceptions, see the exceptions thrown by ReadToEnd().