TextReader.ReadBlockAsync Method

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

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)

Syntax

Public Overridable Function ReadBlockAsync ( _
    buffer As Char(), _
    index As Integer, _
    count As Integer _
) As Task(Of Integer)
public virtual Task<int> ReadBlockAsync(
    char[] buffer,
    int index,
    int count
)

Parameters

  • buffer
    Type: array<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.
  • 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.

Exceptions

Exception Condition
ArgumentNullException

buffer is nullNothingnullptra null reference (Nothing in Visual Basic).

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.

Remarks

The task does not complete until either the number of characters specified by the count parameter are read, or the end of the text has been reached.

Version Information

Windows Phone OS

Supported in: 8.1, 8.0

See Also

Reference

TextReader Class

System.IO Namespace

Other Resources

Quickstart: Text for Windows Phone