StreamReader.Read Method (array<Char>[]()[], Int32, Int32)

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

Reads a maximum of count characters from the current stream into buffer, beginning at index.

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

Syntax

Public Overrides Function Read ( _
    buffer As Char(), _
    index As Integer, _
    count As Integer _
) As Integer
public override int Read(
    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.

Return Value

Type: System..::.Int32
The number of characters that have been read, or 0 if at the end of the stream and no data was read. The number will be less than or equal to the count parameter, depending on whether the data is available within the stream.

Exceptions

Exception Condition
ArgumentException

The buffer length minus index is less than count.

ArgumentNullException

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

ArgumentOutOfRangeException

index or count is negative.

IOException

An I/O error occurs, such as the stream is closed.

Remarks

This method overrides Read.

This method returns an integer so that it can return 0 if the end of the stream has been reached.

When using the Read method, it is more efficient to use a buffer that is the same size as the internal buffer of the stream, where the internal buffer is set to your desired block size, and to always read less than the block size. If the size of the internal buffer was unspecified when the stream was constructed, its default size is 4 kilobytes (4096 bytes). If you manipulate the position of the underlying stream after reading data into the buffer, the position of the underlying stream might not match the position of the internal buffer. To reset the internal buffer, call the DiscardBufferedData method; however, this method slows performance and should be called only when absolutely necessary.

This method returns after either the number of characters specified by the count parameter are read, or the end of the file is reached. ReadBlock is a blocking version of Read.

Version Notes

Windows Phone

StreamReader..::.Read may throw IndexOutOfRangeException if the stream state becomes corrupted. In Windows Phone, the stream state may become corrupted if multiple threads read from or write to a stream object without using synchronization.

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

See Also

Reference

StreamReader Class

Read Overload

System.IO Namespace