Статья
11/18/2011

MemoryStream.Read Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Reads a block of bytes from the current stream and writes the data to a buffer.

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

Syntax

'Declaration
Public Overrides Function Read ( _
    <OutAttribute> buffer As Byte(), _
    offset As Integer, _
    count As Integer _
) As Integer

public override int Read(
    byte[] buffer,
    int offset,
    int count
)

Parameters

buffer
Type: array<System.Byte[]
When this method returns, contains the specified byte array with the values between offset and (offset + count - 1) replaced by the characters read from the current stream.

offset
Type: System.Int32
The zero-based byte offset in buffer at which to begin storing data from the current stream.

count
Type: System.Int32
The maximum number of bytes to read.

Return Value

Type: System.Int32
The total number of bytes written into the buffer. This can be less than the number of bytes requested if that number of bytes are not currently available, or zero if the end of the stream is reached before any bytes are read.

Exceptions

Exception	Condition
ArgumentNullException	buffer is nulla null reference (Nothing in Visual Basic).
ArgumentOutOfRangeException	offset or count is negative.
ArgumentException	offset subtracted from the buffer length is less than count.
ObjectDisposedException	The current stream instance is closed.

Remarks

This method overrides Read.

The offset parameter gives the offset of the first byte in buffer to which data from the current stream is written. The count parameter gives the maximum number of bytes to read from the current stream. The returned value is the actual number of bytes read, or zero if the end of the stream is reached.

If the read operation is successful, the current position within the stream advances by the number of bytes read. If an exception occurs, the current position within the stream remains unchanged.

The Read method will return zero only if the end of the stream is reached. In all other cases, Read always reads at least one byte from the stream before returning. By definition, if no data is available from the stream upon a call to Read, the Read method returns zero (the end of the stream is reached automatically). An implementation is free to return fewer bytes than requested even if the end of the stream has not been reached.

Use BinaryReader for reading primitive data types.

Caution:
If the byte array specified in the buffer parameter is the underlying buffer returned by the GetBuffer method, the array contents are overwritten, and no exception is thrown.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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