BinaryWriter Class

Definition

Namespace:

System.IO

Assembly:

System.Runtime.dll

Source:

BinaryWriter.cs

Writes primitive types in binary to a stream and supports writing strings in a specific encoding.

public ref class BinaryWriter : IAsyncDisposable, IDisposable

public class BinaryWriter : IAsyncDisposable, IDisposable

type BinaryWriter = class
    interface IAsyncDisposable
    interface IDisposable

Public Class BinaryWriter
Implements IAsyncDisposable, IDisposable

Inheritance

Object

BinaryWriter

Implements

IDisposable IAsyncDisposable

Examples

The following code example demonstrates how to store and retrieve application settings in a file.

using System;
using System.IO;
using System.Text;

class ConsoleApplication
{
    const string fileName = "AppSettings.dat";

    static void Main()
    {
        WriteDefaultValues();
        DisplayValues();
    }

    public static void WriteDefaultValues()
    {
        using (var stream = File.Open(fileName, FileMode.Create))
        {
            using (var writer = new BinaryWriter(stream, Encoding.UTF8, false))
            {
                writer.Write(1.250F);
                writer.Write(@"c:\Temp");
                writer.Write(10);
                writer.Write(true);
            }
        }
    }

    public static void DisplayValues()
    {
        float aspectRatio;
        string tempDirectory;
        int autoSaveTime;
        bool showStatusBar;

        if (File.Exists(fileName))
        {
            using (var stream = File.Open(fileName, FileMode.Open))
            {
                using (var reader = new BinaryReader(stream, Encoding.UTF8, false))
                {
                    aspectRatio = reader.ReadSingle();
                    tempDirectory = reader.ReadString();
                    autoSaveTime = reader.ReadInt32();
                    showStatusBar = reader.ReadBoolean();
                }
            }

            Console.WriteLine("Aspect ratio set to: " + aspectRatio);
            Console.WriteLine("Temp directory is: " + tempDirectory);
            Console.WriteLine("Auto save time set to: " + autoSaveTime);
            Console.WriteLine("Show status bar: " + showStatusBar);
        }
    }
}

open System.IO
open System.Text

let fileName = "AppSettings.dat"

let writeDefaultValues () =
    use stream = File.Open(fileName, FileMode.Create)
    use writer = new BinaryWriter(stream, Encoding.UTF8, false)
    writer.Write 1.250F
    writer.Write @"c:\Temp"
    writer.Write 10
    writer.Write true

let displayValues () =
    if File.Exists fileName then
        use stream = File.Open(fileName, FileMode.Open)
        use reader = new BinaryReader(stream, Encoding.UTF8, false)
        let aspectRatio = reader.ReadSingle()
        let tempDirectory = reader.ReadString()
        let autoSaveTime = reader.ReadInt32()
        let showStatusBar = reader.ReadBoolean()

        printfn $"Aspect ratio set to: {aspectRatio}"
        printfn $"Temp directory is: {tempDirectory}"
        printfn $"Auto save time set to: {autoSaveTime}"
        printfn $"Show status bar: {showStatusBar}"

writeDefaultValues ()
displayValues ()

Imports System.IO

Module Module1
    Const fileName As String = "AppSettings.dat"

    Sub Main()
        WriteDefaultValues()
        DisplayValues()
    End Sub

    Sub WriteDefaultValues()
        Using writer As BinaryWriter = New BinaryWriter(File.Open(fileName, FileMode.Create))
            writer.Write(1.25F)
            writer.Write("c:\Temp")
            writer.Write(10)
            writer.Write(True)
        End Using
    End Sub

    Sub DisplayValues()
        Dim aspectRatio As Single
        Dim tempDirectory As String
        Dim autoSaveTime As Integer
        Dim showStatusBar As Boolean

        If (File.Exists(fileName)) Then

            Using reader As BinaryReader = New BinaryReader(File.Open(fileName, FileMode.Open))
                aspectRatio = reader.ReadSingle()
                tempDirectory = reader.ReadString()
                autoSaveTime = reader.ReadInt32()
                showStatusBar = reader.ReadBoolean()
            End Using

            Console.WriteLine("Aspect ratio set to: " & aspectRatio)
            Console.WriteLine("Temp directory is: " & tempDirectory)
            Console.WriteLine("Auto save time set to: " & autoSaveTime)
            Console.WriteLine("Show status bar: " & showStatusBar)
        End If
    End Sub

End Module

Remarks

The BinaryWriter class provides methods that simplify writing primitive data types to a stream. For example, you can use the Write method to write a Boolean value to the stream as a one-byte value. The class includes write methods that support different data types.

When you create a new instance of the BinaryWriter class, you provide the stream to write to, and optionally specify the type of encoding and whether to leave the stream open after disposing the BinaryWriter object. If you do not specify an encoding type, UTF-8 is used.

Important

This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the "Using an Object that Implements IDisposable" section in the IDisposable interface topic.

A derived class can override the methods of this class to give unique character encodings.

Constructors

BinaryWriter()	Initializes a new instance of the BinaryWriter class that writes to a stream.
BinaryWriter(Stream)	Initializes a new instance of the BinaryWriter class based on the specified stream and using UTF-8 encoding.
BinaryWriter(Stream, Encoding)	Initializes a new instance of the BinaryWriter class based on the specified stream and character encoding.
BinaryWriter(Stream, Encoding, Boolean)	Initializes a new instance of the BinaryWriter class based on the specified stream and character encoding, and optionally leaves the stream open.

Fields

Null	Specifies a BinaryWriter with no backing store.
OutStream	Holds the underlying stream.

Properties

BaseStream

Gets the underlying stream of the BinaryWriter.

Methods

Close()	Closes the current BinaryWriter and the underlying stream.
Dispose()	Releases all resources used by the current instance of the BinaryWriter class.
Dispose(Boolean)	Releases the unmanaged resources used by the BinaryWriter and optionally releases the managed resources.
DisposeAsync()	Asynchronously releases all resources used by the current instance of the BinaryWriter class.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
Flush()	Clears all buffers for the current writer and causes any buffered data to be written to the underlying device.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
Seek(Int32, SeekOrigin)	Sets the position within the current stream.
ToString()	Returns a string that represents the current object. (Inherited from Object)
Write(Boolean)	Writes a one-byte Boolean value to the current stream, with 0 representing false and 1 representing true.
Write(Byte)	Writes an unsigned byte to the current stream and advances the stream position by one byte.
Write(Byte[])	Writes a byte array to the underlying stream.
Write(Byte[], Int32, Int32)	Writes a region of a byte array to the current stream.
Write(Char)	Writes a Unicode character to the current stream and advances the current position of the stream in accordance with the Encoding used and the specific characters being written to the stream.
Write(Char[])	Writes a character array to the current stream and advances the current position of the stream in accordance with the Encoding used and the specific characters being written to the stream.
Write(Char[], Int32, Int32)	Writes a section of a character array to the current stream, and advances the current position of the stream in accordance with the Encoding used and perhaps the specific characters being written to the stream.
Write(Decimal)	Writes a decimal value to the current stream and advances the stream position by sixteen bytes.
Write(Double)	Writes an eight-byte floating-point value to the current stream and advances the stream position by eight bytes.
Write(Half)	Writes a two-byte floating-point value to the current stream and advances the stream position by two bytes.
Write(Int16)	Writes a two-byte signed integer to the current stream and advances the stream position by two bytes.
Write(Int32)	Writes a four-byte signed integer to the current stream and advances the stream position by four bytes.
Write(Int64)	Writes an eight-byte signed integer to the current stream and advances the stream position by eight bytes.
Write(ReadOnlySpan<Byte>)	Writes a span of bytes to the current stream.
Write(ReadOnlySpan<Char>)	Writes a span of characters to the current stream, and advances the current position of the stream in accordance with the Encoding used and perhaps the specific characters being written to the stream.
Write(SByte)	Writes a signed byte to the current stream and advances the stream position by one byte.
Write(Single)	Writes a four-byte floating-point value to the current stream and advances the stream position by four bytes.
Write(String)	Writes a length-prefixed string to this stream in the current encoding of the BinaryWriter, and advances the current position of the stream in accordance with the encoding used and the specific characters being written to the stream.
Write(UInt16)	Writes a two-byte unsigned integer to the current stream and advances the stream position by two bytes.
Write(UInt32)	Writes a four-byte unsigned integer to the current stream and advances the stream position by four bytes.
Write(UInt64)	Writes an eight-byte unsigned integer to the current stream and advances the stream position by eight bytes.
Write7BitEncodedInt(Int32)	Writes a 32-bit integer in a compressed format.
Write7BitEncodedInt64(Int64)	Writes out a number 7 bits at a time.

Extension Methods

ConfigureAwait(IAsyncDisposable, Boolean)

Configures how awaits on the tasks returned from an async disposable will be performed.

See also

• Encoding
• How to: Read and Write to a Newly Created Data File
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File