BufferedStream.Read(Byte[], Int32, Int32) Method

Definition

Namespace:
System.IO
Assembly:
mscorlib.dll
Assembly:
System.IO.dll
Assembly:
netstandard.dll

Copies bytes from the current buffered stream to an array.

public:
 override int Read(cli::array <System::Byte> ^ array, int offset, int count);
public override int Read(byte[] array, int offset, int count);
override this.Read : byte[] * int * int -> int
Public Overrides Function Read (array As Byte(), offset As Integer, count As Integer) As Integer

Parameters

array
Byte[]

The buffer to which bytes are to be copied.

offset
Int32

The byte offset in the buffer at which to begin reading bytes.

count
Int32

The number of bytes to be read.

Returns

Int32

The total number of bytes read into array. This can be less than the number of bytes requested if that many bytes are not currently available, or 0 if the end of the stream has been reached before any data can be read.

Exceptions

ArgumentException

Length of array minus offset is less than count.

ArgumentNullException

array is null.

ArgumentOutOfRangeException

offset or count is negative.

IOException

The stream is not open or is null.

NotSupportedException

The stream does not support reading.

ObjectDisposedException

Methods were called after the stream was closed.

Examples

This code example is part of a larger example provided for the BufferedStream class.

// Receive data using the BufferedStream.
Console.WriteLine("Receiving data using BufferedStream.");
bytesReceived = 0;
startTime = DateTime.Now;

int numBytesToRead = receivedData.Length;

while (numBytesToRead > 0)
{
    // Read may return anything from 0 to numBytesToRead.
    int n = bufStream.Read(receivedData,0, receivedData.Length);
    // The end of the file is reached.
    if (n == 0)
        break;
    bytesReceived += n;
    numBytesToRead -= n;
}

bufferedTime = (DateTime.Now - startTime).TotalSeconds;
Console.WriteLine("{0} bytes received in {1} seconds.\n",
    bytesReceived.ToString(),
    bufferedTime.ToString("F1"));

// Receive data using the BufferedStream.
printfn "Receiving data using BufferedStream."
bytesReceived <- 0
let startTime = DateTime.Now

let mutable numBytesToRead = receivedData.Length

let mutable broken = false
while not broken && numBytesToRead > 0 do
    // Read may return anything from 0 to numBytesToRead.
    let n = bufStream.Read(receivedData,0, receivedData.Length)
    // The end of the file is reached.
    if n = 0 then
        broken <- true
    else
        bytesReceived <- bytesReceived + n
        numBytesToRead <- numBytesToRead - n

let bufferedTime = (DateTime.Now - startTime).TotalSeconds
printfn $"{bytesReceived} bytes received in {bufferedTime:F1} seconds.\n"

' Receive data using the BufferedStream.
Console.WriteLine("Receiving data using BufferedStream.")
bytesReceived = 0
startTime = DateTime.Now

Dim numBytesToRead As Integer = receivedData.Length
Dim n As Integer
Do While numBytesToRead > 0

    'Read my return anything from 0 to numBytesToRead
    n = bufStream.Read(receivedData, 0, receivedData.Length)
    'The end of the file is reached.
    If n = 0 Then
        Exit Do
    End If

    bytesReceived += n
    numBytesToRead -= n
Loop

bufferedTime = DateTime.Now.Subtract(startTime).TotalSeconds
Console.WriteLine("{0} bytes received in {1} " & _
    "seconds." & vbCrLf, _
    bytesReceived.ToString(), _
    bufferedTime.ToString("F1"))

Remarks

The Read method will return 0 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 0 (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.

Applies to

See also