Stream.Write Method

When overridden in a derived class, writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written.

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

public abstract void Write (
	byte[] buffer,
	int offset,
	int count
public abstract void Write (
	byte[] buffer, 
	int offset, 
	int count
public abstract function Write (
	buffer : byte[], 
	offset : int, 
	count : int



An array of bytes. This method copies count bytes from buffer to the current stream.


The zero-based byte offset in buffer at which to begin copying bytes to the current stream.


The number of bytes to be written to the current stream.

Exception typeCondition


The sum of offset and count is greater than the buffer length.


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


offset or count is negative.


An I/O error occurs.


The stream does not support writing.


Methods were called after the stream was closed.

For an example of creating a file and writing text to a file, see How to: Write Text to a File. For an example of reading text from a file, see How to: Read Text from a File. For an example of reading from and writing to a binary file, see How to: Read and Write to a Newly Created Data File.

Use the CanWrite property to determine whether the current instance supports writing.

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

The default implementation calls the asynchronous BeginWrite method.

The following example demonstrates how to use the Write method to copy an input stream to an output stream.

const int size = 4096;
byte[] bytes = new byte[4096];
int numBytes;
while((numBytes = input.Read(bytes, 0, size)) > 0)
    output.Write(bytes, 0, numBytes);

final int size = 4096;
ubyte bytes[] = new ubyte[4096];
int numBytes;
while (((numBytes = input.Read(bytes, 0, size)) > 0)) {
    output.Write(bytes, 0, numBytes);

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0