Stream.Read Method
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| Read(Span<Byte>) |
When overridden in a derived class, reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read. |
| Read(Byte[], Int32, Int32) |
When overridden in a derived class, reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read. |
- Source:
- Stream.cs
- Source:
- Stream.cs
- Source:
- Stream.cs
When overridden in a derived class, reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.
public:
virtual int Read(Span<System::Byte> buffer);public virtual int Read(Span<byte> buffer);abstract member Read : Span<byte> -> int
override this.Read : Span<byte> -> intPublic Overridable Function Read (buffer As Span(Of Byte)) As IntegerParameters
A region of memory. When this method returns, the contents of this region are replaced by the bytes read from the current source.
Returns
The total number of bytes read into the buffer. This can be less than the size of the buffer if that many bytes are not currently available, or zero (0) if the buffer's length is zero or the end of the stream has been reached.
Remarks
Use the CanRead property to determine whether the current instance supports reading. Use the ReadAsync method to read asynchronously from the current stream.
Implementations of this method read a maximum of buffer.Length bytes from the current stream and store them in buffer. 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. Implementations return the number of bytes read. If more than zero bytes are requested, the implementation will not complete the operation until at least one byte of data can be read (if zero bytes were requested, some implementations may similarly not complete until at least one byte is available, but no data will be consumed from the stream in such a case). Read returns 0 only if zero bytes were requested or when there is no more data in the stream and no more is expected (such as a closed socket or end of file). 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
.NET 10 and other versions
| Product | Versions |
|---|---|
| .NET | Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10 |
| .NET Standard | 2.1 |
- Source:
- Stream.cs
- Source:
- Stream.cs
- Source:
- Stream.cs
When overridden in a derived class, reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.
public:
abstract int Read(cli::array <System::Byte> ^ buffer, int offset, int count);public abstract int Read(byte[] buffer, int offset, int count);abstract member Read : byte[] * int * int -> intPublic MustOverride Function Read (buffer As Byte(), offset As Integer, count As Integer) As IntegerParameters
- buffer
- Byte[]
An array of bytes. When this method returns, the buffer contains the specified byte array with the values between offset and (offset + count - 1) replaced by the bytes read from the current source.
- offset
- Int32
The zero-based byte offset in buffer at which to begin storing the data read from the current stream.
- count
- Int32
The maximum number of bytes to be read from the current stream.
Returns
The total number of bytes read into the buffer. This can be less than the number of bytes requested if that many bytes are not currently available, or zero (0) if count is 0 or the end of the stream has been reached.
Exceptions
The sum of offset and count is larger than the buffer length.
buffer is null.
offset or count is negative.
An I/O error occurs.
The stream does not support reading.
Methods were called after the stream was closed.
Examples
The following example shows how to use Read to read a block of data.
using namespace System;
using namespace System::IO;
public ref class Block
{
public:
static void Main()
{
Stream^ s = gcnew MemoryStream();
for (int i = 0; i < 100; i++)
{
s->WriteByte((Byte)i);
}
s->Position = 0;
// Now read s into a byte buffer.
array<Byte>^ bytes = gcnew array<Byte>(s->Length);
int numBytesToRead = (int) s->Length;
int numBytesRead = 0;
while (numBytesToRead > 0)
{
// Read may return anything from 0 to 10.
int n = s->Read(bytes, numBytesRead, 10);
// The end of the file is reached.
if (n == 0)
{
break;
}
numBytesRead += n;
numBytesToRead -= n;
}
s->Close();
// numBytesToRead should be 0 now, and numBytesRead should
// equal 100.
Console::WriteLine("number of bytes read: {0:d}", numBytesRead);
}
};
int main()
{
Block::Main();
}
using System;
using System.IO;
public class Block
{
public static void Main()
{
Stream s = new MemoryStream();
for (int i = 0; i < 122; i++)
{
s.WriteByte((byte)i);
}
s.Position = 0;
// Now read s into a byte buffer with a little padding.
byte[] bytes = new byte[s.Length + 10];
int numBytesToRead = (int)s.Length;
int numBytesRead = 0;
do
{
// Read may return anything from 0 to 10.
int n = s.Read(bytes, numBytesRead, 10);
numBytesRead += n;
numBytesToRead -= n;
} while (numBytesToRead > 0);
s.Close();
Console.WriteLine("number of bytes read: {0:d}", numBytesRead);
}
}
Imports System.IO
Public Class Block
Public Shared Sub Main()
Dim s As Stream = New MemoryStream()
For i As Integer = 0 To 121
s.WriteByte(CType(i, Byte))
Next i
s.Position = 0
' Now read s into a byte buffer that is padded slightly.
Dim bytes(s.Length + 10) As Byte
Dim numBytesToRead As Integer = s.Length
Dim numBytesRead As Integer = 0
Dim n As Integer
Do
' Read may return anything from 0 to 10.
n = s.Read(bytes, numBytesRead, 10)
' The end of the file is reached.
numBytesRead += n
numBytesToRead -= n
Loop While numBytesToRead > 0
s.Close()
Console.WriteLine("number of bytes read: {0:d}", numBytesRead)
End Sub
End Class
Remarks
Use the CanRead property to determine whether the current instance supports reading. Use the ReadAsync method to read asynchronously from the current stream.
Implementations of this 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. Implementations return the number of bytes read. If more than zero bytes are requested, the implementation will not complete the operation until at least one byte of data can be read (some implementations may similarly not complete until at least one byte is available even if zero bytes were requested, but no data will be consumed from the stream in such a case). Read returns 0 only if zero bytes were requested or when there is no more data in the stream and no more is expected (such as a closed socket or end of file). 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.
See also
Applies to
.NET 10 and other versions
| Product | Versions |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1 |
| UWP | 10.0 |
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