TextReader.ReadLineAsync Method

Definition

Namespace:

System.IO

Assembly:

System.Runtime.dll

Overloads

ReadLineAsync()	Reads a line of characters asynchronously and returns the data as a string.
ReadLineAsync(CancellationToken)	Reads a line of characters asynchronously and returns the data as a string.

ReadLineAsync()

Source:

TextReader.cs

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

public:
 virtual System::Threading::Tasks::Task<System::String ^> ^ ReadLineAsync();

public virtual System.Threading.Tasks.Task<string?> ReadLineAsync ();

abstract member ReadLineAsync : unit -> System.Threading.Tasks.Task<string>
override this.ReadLineAsync : unit -> System.Threading.Tasks.Task<string>

Public Overridable Function ReadLineAsync () As Task(Of String)

Returns

Task<String>

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

Exceptions

ArgumentOutOfRangeException

The number of characters in the next line is larger than Int32.MaxValue.

ObjectDisposedException

The text reader has been disposed.

InvalidOperationException

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

Remarks

The TextReader class is an abstract class. Therefore, you do not instantiate it in your code. For an example of using the ReadLineAsync method, see the StreamReader.ReadLineAsync method.

If the current TextReader represents the standard input stream returned by the Console.In property, the ReadLineAsync method executes synchronously rather than asynchronously.

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 ReadLine().

See also

• ReadLineAsync()
• ReadLineAsync()
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

ReadLineAsync(CancellationToken)

Source:

TextReader.cs

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

public:
 virtual System::Threading::Tasks::ValueTask<System::String ^> ReadLineAsync(System::Threading::CancellationToken cancellationToken);

public virtual System.Threading.Tasks.ValueTask<string?> ReadLineAsync (System.Threading.CancellationToken cancellationToken);

abstract member ReadLineAsync : System.Threading.CancellationToken -> System.Threading.Tasks.ValueTask<string>
override this.ReadLineAsync : System.Threading.CancellationToken -> System.Threading.Tasks.ValueTask<string>

Public Overridable Function ReadLineAsync (cancellationToken As CancellationToken) As ValueTask(Of String)

Parameters

cancellationToken

CancellationToken

The token to monitor for cancellation requests.

Returns

ValueTask<String>

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

Exceptions

ArgumentOutOfRangeException

The number of characters in the next line is larger than Int32.MaxValue.

ObjectDisposedException

The text 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

The TextReader class is an abstract class. Therefore, you do not instantiate it in your code. For an example of using the ReadLineAsync(CancellationToken) method, see the ReadLineAsync(CancellationToken) method.

If the current TextReader represents the standard input stream returned by the Console.In property, the ReadLineAsync(CancellationToken) method executes synchronously rather than asynchronously.

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 ReadLine().