Write Method

FileStream.Write Method (Byte[], Int32, Int32)


Writes a block of bytes to the file stream.

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

public override void Write(
	byte[] array,
	int offset,
	int count


Type: System.Byte[]

The buffer containing data to write to the stream.

Type: System.Int32

The zero-based byte offset in array from which to begin copying bytes to the stream.

Type: System.Int32

The maximum number of bytes to write.

Exception Condition

array is null.


offset and count describe an invalid range in array.


offset or count is negative.


An I/O error occurred.

- or -

Another thread may have caused an unexpected change in the position of the operating system's file handle.


The stream is closed.


The current stream instance does not support writing.

This method overrides Write.

The offset parameter gives the offset of the byte in array (the buffer index) at which to begin copying, and the count parameter gives the number of bytes that will be written to the stream. If the write operation is successful, the current position of the stream is advanced by the number of bytes written. If an exception occurs, the current position of the stream is unchanged.


Use the CanWrite property to determine whether the current instance supports writing. For additional information, see CanWrite.

Do not interrupt a thread that is performing a write operation. Although the application may appear to run successfully after the thread is unblocked, the interruption can decrease your application's performance and reliability.

For a list of common file and directory operations, see Common I/O Tasks.

This code example is part of a larger example provided for the Lock method.

// Write the original file data.
if(fileStream.Length == 0)
    tempString = 
        lastRecordText + recordNumber.ToString();
        0, uniEncoding.GetByteCount(tempString));

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Return to top
© 2015 Microsoft