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

Reads count bytes from the stream with index as the starting point in the byte array.

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

public virtual int Read (
	byte[] buffer,
	int index,
	int count
)
public int Read (
	byte[] buffer, 
	int index, 
	int count
)
public function Read (
	buffer : byte[], 
	index : int, 
	count : int
) : int

Parameters

buffer

The buffer to read data into.

index

The starting point in the buffer at which to begin reading into the buffer.

count

The number of characters to read.

Return Value

The number of characters read into buffer. This might be less than the number of bytes requested if that many bytes are not available, or it might be zero if the end of the stream is reached.

Exception typeCondition

ArgumentException

The buffer length minus index is less than count.

ArgumentNullException

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

ArgumentOutOfRangeException

index or count is negative.

ObjectDisposedException

The stream is closed.

IOException

An I/O error occurs.

BinaryReader does not restore the file position after an unsuccessful read.

The following table lists examples of other typical or related I/O tasks.

To do this...

See the example in this topic...

Create a text file.

How to: Write Text to a File

Write to a text file.

How to: Write Text to a File

Read from a text file.

How to: Read Text from a File

Append text to a file.

How to: Open and Append to a Log File

File.AppendText

FileInfo.AppendText

Get the size of a file.

FileInfo.Length

Get the attributes of a file.

File.GetAttributes

Set the attributes of a file.

File.SetAttributes

Determine if a file exists.

File.Exists

Read from a binary file.

How to: Read and Write to a Newly Created Data File

Write to a binary file.

How to: Read and Write to a Newly Created Data File

The following code example shows how to write binary data using memory as a backing store, and then verify that the data was written correctly.

using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        const int arrayLength = 1000;

        // Create random data to write to the stream.
        byte[] dataArray = new byte[arrayLength];
        new Random().NextBytes(dataArray);

        BinaryWriter binWriter = new BinaryWriter(new MemoryStream());

        // Write the data to the stream.
        Console.WriteLine("Writing the data.");
        binWriter.Write(dataArray, 0, arrayLength);

        // Create the reader using the stream from the writer.
        BinaryReader binReader = 
            new BinaryReader(binWriter.BaseStream);

        // Set Position to the beginning of the stream.
        binReader.BaseStream.Position = 0;

        // Read and verify the data.
        byte[] verifyArray = new byte[arrayLength];
        if(binReader.Read(verifyArray, 0, arrayLength) != arrayLength)
        {
            Console.WriteLine("Error writing the data.");
            return;
        }
        for(int i = 0; i < arrayLength; i++)
        {
            if(verifyArray[i] != dataArray[i])
            {
                Console.WriteLine("Error writing the data.");
                return;
            }
        }
        Console.WriteLine("The data was written and verified.");
    }
}

import System.*;
import System.IO.*;

class BinaryRW
{   
    public static void main(String[] args)
    {
        final int arrayLength = 1000;

        // Create random data to write to the stream.
        ubyte dataArray[] = new ubyte[arrayLength];
        new Random().NextBytes(dataArray);

        BinaryWriter binWriter = new BinaryWriter(new MemoryStream());

        // Write the data to the stream.
        Console.WriteLine("Writing the data.");
        binWriter.Write(dataArray, 0, arrayLength);

        // Create the reader using the stream from the writer.
        BinaryReader binReader = new BinaryReader(binWriter.get_BaseStream());

        // Set Position to the beginning of the stream.
        binReader.get_BaseStream().set_Position(0);

        // Read and verify the data.
        ubyte verifyArray[] = new ubyte[arrayLength];
        if ( binReader.Read(verifyArray, 0, arrayLength) != arrayLength ) {
            Console.WriteLine("Error writing the data.");
            return;
        }
        for(int i=0;i < arrayLength;i++) {
            if ( verifyArray[i] != dataArray[i] ) {
                Console.WriteLine("Error writing the data.");
                return;
            }
        } 
        Console.WriteLine("The data was written and verified.");
    } //main
} //BinaryRW

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

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