BinaryWriter.Write Method

Definition

Namespace:

System.IO

Assemblies:

netstandard.dll, System.Runtime.dll

Writes a value to the current stream.

Overloads

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(Byte[], Int32, Int32)	Writes a region of a byte array to the current stream.
Write(UInt64)	Writes an eight-byte unsigned integer to the current stream and advances the stream position by eight bytes.
Write(UInt32)	Writes a four-byte unsigned integer to the current stream and advances the stream position by four bytes.
Write(UInt16)	Writes a two-byte unsigned integer to the current stream and advances the stream position by two 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(Single)	Writes a four-byte floating-point value to the current stream and advances the stream position by four bytes.
Write(SByte)	Writes a signed byte to the current stream and advances the stream position by one byte.
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(ReadOnlySpan<Byte>)	Writes a span of bytes to the current stream.
Write(Int64)	Writes an eight-byte signed integer to the current stream and advances the stream position by eight bytes.
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(Int16)	Writes a two-byte signed integer to the current stream and advances the stream position by two bytes.
Write(Half)	Writes a two-byte floating-point value to the current stream and advances the stream position by two bytes.
Write(Double)	Writes an eight-byte floating-point value to the current stream and advances the stream position by eight bytes.
Write(Decimal)	Writes a decimal value to the current stream and advances the stream position by sixteen bytes.
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(Byte[])	Writes a byte array to the underlying stream.
Write(Byte)	Writes an unsigned byte to the current stream and advances the stream position by one byte.
Write(Boolean)	Writes a one-byte Boolean value to the current stream, with 0 representing false and 1 representing true.
Write(Int32)	Writes a four-byte signed integer to the current stream and advances the stream position by four bytes.

Write(Char[], Int32, Int32)

Source:

BinaryWriter.cs

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.

C#

public virtual void Write(char[] chars, int index, int count);

Parameters

chars

Char[]

A character array containing the data to write.

index

Int32

The index of the first character to read from chars and to write to the stream.

count

Int32

The number of characters to read from chars and to write to the stream.

Exceptions

ArgumentException

The buffer length minus index is less than count.

ArgumentNullException

chars is null.

ArgumentOutOfRangeException

index or count is negative.

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Examples

The following code example shows how to read and write data using memory as a backing store.

C#

using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        char[] invalidPathChars = Path.InvalidPathChars;
        MemoryStream memStream = new MemoryStream();
        BinaryWriter binWriter = new BinaryWriter(memStream);

        // Write to memory.
        binWriter.Write("Invalid file path characters are: ");
        binWriter.Write(
            Path.InvalidPathChars, 0, Path.InvalidPathChars.Length);

        // Create the reader using the same MemoryStream
        // as used with the writer.
        BinaryReader binReader = new BinaryReader(memStream);

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

        // Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString());
        int arraySize = (int)(memStream.Length - memStream.Position);
        char[] memoryData = new char[arraySize];
        binReader.Read(memoryData, 0, arraySize);
        Console.WriteLine(memoryData);
    }
}

Remarks

For a list of common I/O tasks, see Common I/O Tasks.

See also

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

Write(Byte[], Int32, Int32)

Source:

BinaryWriter.cs

Writes a region of a byte array to the current stream.

C#

public virtual void Write(byte[] buffer, int index, int count);

Parameters

buffer

Byte[]

A byte array containing the data to write.

index

Int32

The index of the first byte to read from buffer and to write to the stream.

count

Int32

The number of bytes to read from buffer and to write to the stream.

Exceptions

ArgumentException

The buffer length minus index is less than count.

ArgumentNullException

buffer is null.

ArgumentOutOfRangeException

index or count is negative.

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Examples

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.

C#

using System;
using System.IO;

namespace BinaryRW
{
    class Program
    {
        static void Main(string[] args)
        {
            const int arrayLength = 1000;
            byte[] dataArray = new byte[arrayLength];
            byte[] verifyArray = new byte[arrayLength];

            new Random().NextBytes(dataArray);

            using (BinaryWriter binWriter = new BinaryWriter(new MemoryStream()))
            {
                Console.WriteLine("Writing the data.");
                binWriter.Write(dataArray, 0, arrayLength);

                using (BinaryReader binReader = new BinaryReader(binWriter.BaseStream))
                {
                    binReader.BaseStream.Position = 0;

                    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.");
        }
    }
}

Remarks

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(UInt64)

Source:

BinaryWriter.cs

Important

This API is not CLS-compliant.

Writes an eight-byte unsigned integer to the current stream and advances the stream position by eight bytes.

C#

[System.CLSCompliant(false)]
public virtual void Write(ulong value);

Parameters

value

UInt64

The eight-byte unsigned integer to write.

Attributes

CLSCompliantAttribute

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Remarks

BinaryWriter stores this data type in little endian format.

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(UInt32)

Source:

BinaryWriter.cs

Important

This API is not CLS-compliant.

Writes a four-byte unsigned integer to the current stream and advances the stream position by four bytes.

C#

[System.CLSCompliant(false)]
public virtual void Write(uint value);

Parameters

value

UInt32

The four-byte unsigned integer to write.

Attributes

CLSCompliantAttribute

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Remarks

BinaryWriter stores this data type in little endian format.

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(UInt16)

Source:

BinaryWriter.cs

Important

This API is not CLS-compliant.

Writes a two-byte unsigned integer to the current stream and advances the stream position by two bytes.

C#

[System.CLSCompliant(false)]
public virtual void Write(ushort value);

Parameters

value

UInt16

The two-byte unsigned integer to write.

Attributes

CLSCompliantAttribute

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Remarks

BinaryWriter stores this data type in little endian format.

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(String)

Source:

BinaryWriter.cs

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.

C#

public virtual void Write(string value);

Parameters

value

String

The value to write.

Exceptions

IOException

An I/O error occurs.

ArgumentNullException

value is null.

ObjectDisposedException

The stream is closed.

Examples

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

C#

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);
        }
    }
}

Remarks

Length-prefixed means that this method first writes the length of the string, in bytes, when encoded with the BinaryWriter instance's current encoding to the stream. This value is written as an unsigned integer. This method then writes that many bytes to the stream.

For example, the string "A" has a length of 1, but when encoded with UTF-16; the length is 2 bytes, so the value written in the prefix is 2, and 3 bytes are written to the stream, including the prefix.

For a list of common I/O tasks, see Common I/O Tasks.

See also

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

Write(Single)

Source:

BinaryWriter.cs

Writes a four-byte floating-point value to the current stream and advances the stream position by four bytes.

C#

public virtual void Write(float value);

Parameters

value

Single

The four-byte floating-point value to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Examples

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

C#

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);
        }
    }
}

Remarks

BinaryWriter stores this data type in little endian format.

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(SByte)

Source:

BinaryWriter.cs

Important

This API is not CLS-compliant.

Writes a signed byte to the current stream and advances the stream position by one byte.

C#

[System.CLSCompliant(false)]
public virtual void Write(sbyte value);

Parameters

value

SByte

The signed byte to write.

Attributes

CLSCompliantAttribute

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Remarks

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(ReadOnlySpan<Char>)

Source:

BinaryWriter.cs

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.

C#

public virtual void Write(ReadOnlySpan<char> chars);

Parameters

chars

ReadOnlySpan<Char>

A span of chars to write.

Write(ReadOnlySpan<Byte>)

Source:

BinaryWriter.cs

Writes a span of bytes to the current stream.

C#

public virtual void Write(ReadOnlySpan<byte> buffer);

Parameters

buffer

ReadOnlySpan<Byte>

The span of bytes to write.

Write(Int64)

Source:

BinaryWriter.cs

Writes an eight-byte signed integer to the current stream and advances the stream position by eight bytes.

C#

public virtual void Write(long value);

Parameters

value

Int64

The eight-byte signed integer to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Remarks

BinaryWriter stores this data type in little endian format.

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(Char[])

Source:

BinaryWriter.cs

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.

C#

public virtual void Write(char[] chars);

Parameters

chars

Char[]

A character array containing the data to write.

Exceptions

ArgumentNullException

chars is null.

ObjectDisposedException

The stream is closed.

IOException

An I/O error occurs.

Examples

The following code example shows how to read and write data using memory as a backing store.

C#

using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        char[] invalidPathChars = Path.InvalidPathChars;
        MemoryStream memStream = new MemoryStream();
        BinaryWriter binWriter = new BinaryWriter(memStream);

        // Write to memory.
        binWriter.Write("Invalid file path characters are: ");
        binWriter.Write(Path.InvalidPathChars);

        // Create the reader using the same MemoryStream
        // as used with the writer.
        BinaryReader binReader = new BinaryReader(memStream);

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

        // Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString());
        Console.WriteLine(binReader.ReadChars(
            (int)(memStream.Length - memStream.Position)));
    }
}

Remarks

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

See also

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

Write(Int16)

Source:

BinaryWriter.cs

Writes a two-byte signed integer to the current stream and advances the stream position by two bytes.

C#

public virtual void Write(short value);

Parameters

value

Int16

The two-byte signed integer to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Remarks

BinaryWriter stores this data type in little endian format.

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

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(Half)

Source:

BinaryWriter.cs

Writes a two-byte floating-point value to the current stream and advances the stream position by two bytes.

C#

public virtual void Write(Half value);

Parameters

value

Half

The two-byte floating-point value to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Examples

The following code example shows how to read and write Double data to memory by using the BinaryReader and BinaryWriter classes on top of the MemoryStream class. MemoryStream only reads and writes Byte data.

C#

using System;
using System.IO;

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

        // Create random data to write to the stream.
        Random randomGenerator = new Random();
        double[] dataArray = new double[arrayLength];
        for(i = 0; i < arrayLength; i++)
        {
            dataArray[i] = 100.1 * randomGenerator.NextDouble();
        }

        using(BinaryWriter binWriter =
            new BinaryWriter(new MemoryStream()))
        {
            // Write the data to the stream.
            Console.WriteLine("Writing data to the stream.");
            for(i = 0; i < arrayLength; i++)
            {
                binWriter.Write(dataArray[i]);
            }

            // Create a reader using the stream from the writer.
            using(BinaryReader binReader =
                new BinaryReader(binWriter.BaseStream))
            {
                try
                {
                    // Return to the beginning of the stream.
                    binReader.BaseStream.Position = 0;

                    // Read and verify the data.
                    Console.WriteLine("Verifying the written data.");
                    for(i = 0; i < arrayLength; i++)
                    {
                        if(binReader.ReadDouble() != dataArray[i])
                        {
                            Console.WriteLine("Error writing data.");
                            break;
                        }
                    }
                    Console.WriteLine("The data was written " +
                        "and verified.");
                }
                catch(EndOfStreamException e)
                {
                    Console.WriteLine("Error writing data: {0}.",
                        e.GetType().Name);
                }
            }
        }
    }
}

Remarks

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(Double)

Source:

BinaryWriter.cs

Writes an eight-byte floating-point value to the current stream and advances the stream position by eight bytes.

C#

public virtual void Write(double value);

Parameters

value

Double

The eight-byte floating-point value to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Examples

The following code example shows how to read and write Double data to memory by using the BinaryReader and BinaryWriter classes on top of the MemoryStream class. MemoryStream only reads and writes Byte data.

C#

using System;
using System.IO;

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

        // Create random data to write to the stream.
        Random randomGenerator = new Random();
        double[] dataArray = new double[arrayLength];
        for(i = 0; i < arrayLength; i++)
        {
            dataArray[i] = 100.1 * randomGenerator.NextDouble();
        }

        using(BinaryWriter binWriter =
            new BinaryWriter(new MemoryStream()))
        {
            // Write the data to the stream.
            Console.WriteLine("Writing data to the stream.");
            for(i = 0; i < arrayLength; i++)
            {
                binWriter.Write(dataArray[i]);
            }

            // Create a reader using the stream from the writer.
            using(BinaryReader binReader =
                new BinaryReader(binWriter.BaseStream))
            {
                try
                {
                    // Return to the beginning of the stream.
                    binReader.BaseStream.Position = 0;

                    // Read and verify the data.
                    Console.WriteLine("Verifying the written data.");
                    for(i = 0; i < arrayLength; i++)
                    {
                        if(binReader.ReadDouble() != dataArray[i])
                        {
                            Console.WriteLine("Error writing data.");
                            break;
                        }
                    }
                    Console.WriteLine("The data was written " +
                        "and verified.");
                }
                catch(EndOfStreamException e)
                {
                    Console.WriteLine("Error writing data: {0}.",
                        e.GetType().Name);
                }
            }
        }
    }
}

Remarks

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(Decimal)

Source:

BinaryWriter.cs

Writes a decimal value to the current stream and advances the stream position by sixteen bytes.

C#

public virtual void Write(decimal value);

Parameters

value

Decimal

The decimal value to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Remarks

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

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(Char)

Source:

BinaryWriter.cs

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.

C#

public virtual void Write(char ch);

Parameters

ch

Char

The non-surrogate, Unicode character to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

ArgumentException

ch is a single surrogate character.

Examples

The following code example shows how to read and write data using memory as a backing store.

C#

using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        int i = 0;
        char[] invalidPathChars = Path.InvalidPathChars;
        MemoryStream memStream = new MemoryStream();
        BinaryWriter binWriter = new BinaryWriter(memStream);

        // Write to memory.
        binWriter.Write("Invalid file path characters are: ");
        for(i = 0; i < invalidPathChars.Length; i++)
        {
            binWriter.Write(invalidPathChars[i]);
        }

        // Create the reader using the same MemoryStream
        // as used with the writer.
        BinaryReader binReader = new BinaryReader(memStream);

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

        // Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString());
        char[] memoryData =
            new char[memStream.Length - memStream.Position];
        for(i = 0; i < memoryData.Length; i++)
        {
            memoryData[i] = binReader.ReadChar();
        }
        Console.WriteLine(memoryData);
    }
}

Remarks

Because of data formatting conflicts, using this method with the following encodings is not recommended:

• UTF-7

• ISO-2022-JP

• ISCII

For a list of common I/O tasks, see Common I/O Tasks.

Unicode surrogate characters must be written out as pairs together in the same call, not individually. If you require support for surrogate pairs in your application, consider using a character array and the Write method overload.

See also

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

Write(Byte[])

Source:

BinaryWriter.cs

Writes a byte array to the underlying stream.

C#

public virtual void Write(byte[] buffer);

Parameters

buffer

Byte[]

A byte array containing the data to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

ArgumentNullException

buffer is null.

Examples

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.

C#

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);

        // 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 = binReader.ReadBytes(arrayLength);
        if(verifyArray.Length != 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.");
    }
}

Remarks

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(Byte)

Source:

BinaryWriter.cs

Writes an unsigned byte to the current stream and advances the stream position by one byte.

C#

public virtual void Write(byte value);

Parameters

value

Byte

The unsigned byte to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Examples

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.

C#

using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        int i = 0;

        // Create random data to write to the stream.
        byte[] writeArray = new byte[1000];
        new Random().NextBytes(writeArray);

        BinaryWriter binWriter = new BinaryWriter(new MemoryStream());
        BinaryReader binReader =
            new BinaryReader(binWriter.BaseStream);

        try
        {
            // Write the data to the stream.
            Console.WriteLine("Writing the data.");
            for(i = 0; i < writeArray.Length; i++)
            {
                binWriter.Write(writeArray[i]);
            }

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

            // Read and verify the data from the stream.
            for(i = 0; i < writeArray.Length; i++)
            {
                if(binReader.ReadByte() != writeArray[i])
                {
                    Console.WriteLine("Error writing the data.");
                    return;
                }
            }
            Console.WriteLine("The data was written and verified.");
        }

        // Catch the EndOfStreamException and write an error message.
        catch(EndOfStreamException e)
        {
            Console.WriteLine("Error writing the data.\n{0}",
                e.GetType().Name);
        }
    }
}

Remarks

Because of data formatting conflicts, using this method with the following encodings is not recommended:

• UTF-7

• ISO-2022-JP

• ISCII

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(Boolean)

Source:

BinaryWriter.cs

Writes a one-byte Boolean value to the current stream, with 0 representing false and 1 representing true.

C#

public virtual void Write(bool value);

Parameters

value

Boolean

The Boolean value to write (0 or 1).

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Examples

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

C#

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);
        }
    }
}

Remarks

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

Write(Int32)

Source:

BinaryWriter.cs

Writes a four-byte signed integer to the current stream and advances the stream position by four bytes.

C#

public virtual void Write(int value);

Parameters

value

Int32

The four-byte signed integer to write.

Exceptions

IOException

An I/O error occurs.

ObjectDisposedException

The stream is closed.

Examples

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

C#

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);
        }
    }
}

Remarks

BinaryWriter stores this data type in little endian format.

For a list of common I/O tasks, see Common I/O Tasks.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File