TextReader.ReadAsync Method

July 28, 2014

Reads a specified maximum number of characters from the current text reader asynchronously and writes the data to a buffer, beginning at the specified index.

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

'Declaration
Public Overridable Function ReadAsync ( _
	buffer As Char(), _
	index As Integer, _
	count As Integer _
) As Task(Of Integer)

Parameters

buffer
Type: System.Char ()
When this method returns, contains the specified character array with the values between index and (index + count - 1) replaced by the characters read from the current source.
index
Type: System.Int32
The position in buffer at which to begin writing.
count
Type: System.Int32
The maximum number of characters to read. If the end of the text is reached before the specified number of characters is read into the buffer, the current method returns.

Return Value

Type: System.Threading.Tasks.Task(Of Int32)
A task that represents the asynchronous read operation. The value of the TResult parameter contains the total number of bytes read into the buffer. The result value can be less than the number of bytes requested if the number of bytes currently available is less than the requested number, or it can be 0 (zero) if the end of the text has been reached.

ExceptionCondition
ArgumentNullException

buffer is Nothing.

ArgumentOutOfRangeException

index or count is negative.

ArgumentException

The sum of index and count is larger than the buffer length.

ObjectDisposedException

The text reader has been disposed.

InvalidOperationException

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

The task completes after either the number of characters specified by the count parameter are read or the end of the file is reached.

Windows Phone OS

Supported in: 8.1, 8.0

Show:
© 2014 Microsoft