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OracleBFile.Read Method

Note: This namespace, class, or member is supported only in version 1.1 of the .NET Framework.

Reads a sequence of bytes from the current OracleBFile stream and advances the position within the stream by the number of bytes read.

[Visual Basic]
Overrides Public Function Read( _
   ByVal buffer() As Byte, _
   ByVal offset As Integer, _
   ByVal count As Integer _
) As Integer
[C#]
public override int Read(
 byte[] buffer,
 int offset,
 int count
);
[C++]
public: int Read(
 unsigned char buffer __gc[],
 int offset,
 int count
);
[JScript]
public override function Read(
   buffer : Byte[],
 offset : int,
 count : int
) : int;

Parameters

buffer
An array of bytes. When this method returns, the buffer contains the specified byte array with the values between offset and (offset + count) replaced by the bytes read from the current source.
offset
The zero-based byte offset in buffer at which to begin storing the data read from the current stream.
count
The maximum number of bytes to be read from the current stream.

Return Value

The total number of bytes read into the buffer. This may be less than the number of bytes requested if that many bytes are not currently available, or zero (0) if the end of the file has been reached.

Exceptions

Exception Type Condition
ArgumentException The sum of offset and count is larger than the buffer length.
ArgumentNullException buffer is a null reference (Nothing in Visual Basic).
ArgumentOutOfRangeException offset or count is negative.
InvalidOperationException The connection with which a BFILE is associated is closed.
IOException An I/O error occurs.
ObjectDisposedException Methods were called after the stream was closed or disposed.

Remarks

The Read method read a maximum of count bytes from the current stream and store them in buffer beginning at offset. The current position within the stream is advanced by the number of bytes read; however, if an exception occurs, the current position within the stream remains unchanged. Read returns the number of bytes read. The return value is zero only if the position is currently at the end of the stream. Read will block until at least one byte of data can be read, in the event that no data is available. Read returns 0 only when the end of the file has been reached. Read is free to return fewer bytes than requested even if the end of the stream has not been reached.

Any attempt to access a closed OracleBFile using the Read or Seek methods reopens an OracleBFile stream automatically.

The following C# example assumes this schema in an Oracle table:

(col1 number, col2 BFILE)

The example demonstrates using the Read and Seek methods to access an OracleBFile object.

byte[] buffer = new byte[100];
OracleDataReader myReader = myCommand.ExecuteReader();
using (myReader) {
    if (myReader.Read()) {
            OracleBFile myBFile = myReader.GetOracleBFile(1);
        using (myBFile) {
            myBFile.Seek(0, SeekOrigin.Begin);
            myBFile.Read(buffer, 0, 100);
        }
    }
}

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

.NET Framework Security: 

See Also

OracleBFile Class | OracleBFile Members | System.Data.OracleClient Namespace

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