C# BinaryWriter

So far, we have only discussed classes that are used to write and read bytes or characters. But what if we want to read and write primitive data values like char, int, float, double or even String? To achieve that, C# provides us the BinaryWriter class, which allows us to create a stream, which can be used to write the primitive types values or String values in binary to a stream.

Some commonly used constructors of BinaryWriter

Constructors	Description
BinaryWriter(System.IO.Stream stream)	This constructor creates an object of the BinaryWriter based on the specified stream and using the default UTF-8 encoding.
FileStream(System.IO.Stream stream, System.Text.Encoding encoding)	The constructor created an object of the BinaryWriter class based on the specified Stream and character encoding.

Some commonly used write methods of BinaryWriter

Methods	Description
void Write(int value)	This method writes a signed int value to the stream.
void Write(uint s)	This method writes an unsigned int value to the stream.
void Write(char ch)	This method writes a character value to the stream.
void Write(char[] array)	This method writes a character array to the stream.
void Write(short s)	This method writes a signed short value to the stream.
void Write(ushort s)	This method writes an unsigned short value to the stream.
void Write(byte b)	This method writes an unsigned byte value to the stream.
void Write(sbyte sb)	This method writes an signed byte value to the stream.
void Write(byte[] array)	This method writes a byte array to the stream.
void Write(float f)	This method writes a float to the stream.
void Write(double d)	This method writes a double to the stream.
void Write(long l)	This method writes a long to the stream.
void Write(String str)	This method writes a String to the stream.
void Flush()	This method clears the buffer for the current writer stream by writing any buffered data to the stream.
void Close()	This method closes this stream and also frees any resources connected with this stream.

Example of BinaryWriter with default UTF-8 encoding.

In this example, we are going create an object of the BinaryWriter class and use it to write different types of primitive values and a String object to a file, by using the default UTF-8 encoding.

//C# Example of BinaryWriter by using the default UTF-8 encoding.


using System;
using System.IO;

class A
{
public static void Main(String[] ar)
{
	try
	{
		//Creating variables with primitives values
		int i = -10;
		uint ui = 9;
		char ch = 'C';
		short s = -99;
		ushort us = 99;
		float f = 89.9f;
		double d = 875.888;
		long l = 10000000000;
			
		//Creating a String object
		String str = "Keep smiling and think positive.";
	

		//Creating an object of FileStream to write to a file
		//We are going to use the FileMode Create to create a new file to write to it
		FileStream fs = new FileStream("D:\\File3.txt", FileMode.Create);


		//Creating an object of BinaryWriter to write to a file using FileStream 
		BinaryWriter bw = new BinaryWriter(fs);

		Console.WriteLine("Writing to the file using BinaryStream and default UTF-8 Encoding");

		//writing an int 
		bw.Write(i);

		//writing an uint 
		bw.Write(ui);

		//writing a char
		bw.Write(ch);

		//writing a short
		bw.Write(s);

		//writing a ushort
		bw.Write(us);

		//writing a float 
		bw.Write(f);

		//writing a double
		bw.Write(d);

		//writing a long
		bw.Write(l);

		//writing a String 
		bw.Write(str);
		
		
		Console.WriteLine("Data written successfully");
	
	
		//Calling the Flush() method to flush the buffered data to the file
		bw.Flush();
		
		//Closing the stream i.e. FileStream stream
		fs.Close();

		//Closing the stream i.e. BinaryWriter stream
		bw.Close();
	}
	catch(IOException e)
	{
		Console.WriteLine(e);
	}
}
}

Output is -:

Writing to the file using BinaryStream and default UTF-8 Encoding
Data written successfully

The program creates a file and writes its contents, which are shown below contents -:
```
öÿÿÿ	   Cÿc ÍÌ³BÉv¾Ÿ_‹@ äT    Keep smiling and think positive.
```
As you can see, the primitive values written to a file using BinaryWriter are encoded by the default UTF-8 encoding and therefore are not readable. This encoded data will be decoded back to its normal form when we read this data using the counterpart of BinaryWriter class i.e. the BinaryReader class(which is the topic of our next article).

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Example of BinaryWriter with a non-default Unicode encoding.

In this example, we are going create an object of the BinaryWriter class and use it to write different types of primitive values and a String object to a file, by using the non-default Unicode encoding.

//C# Example of BinaryWriter by using the non-default Unicode encoding.


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

class A
{
public static void Main(String[] ar)
{
	try
	{
		//Creating variables with primitives values
		int i = -10;
		uint ui = 9;
		char ch = 'C';
		short s = -99;
		ushort us = 99;
		float f = 89.9f;
		double d = 875.888;
		long l = 10000000000;
			
		//Creating a String object
		String str = "Keep smiling and think positive.";
	
	
		//Creating an object of Encoding type
		Encoding unicode = Encoding.Unicode;


		//Creating an object of FileStream to write to a file
		//We are going to use the FileMode Create to create a new file to write to it
		FileStream fs = new FileStream("D:\\File5.txt", FileMode.Create);


		//Creating an object of BinaryWriter to write to a file using FileStream 
		BinaryWriter bw = new BinaryWriter(fs, unicode);

		Console.WriteLine("Writing to the file using BinaryStream and non-default Unicode Encoding");

		//writing an int 
		bw.Write(i);

		//writing an uint 
		bw.Write(ui);

		//writing a char
		bw.Write(ch);

		//writing a short
		bw.Write(s);

		//writing a ushort
		bw.Write(us);

		//writing a float 
		bw.Write(f);

		//writing a double
		bw.Write(d);

		//writing a long
		bw.Write(l);

		//writing a String 
		bw.Write(str);
	
		
		Console.WriteLine("Data written successfully");
		
		
		//Calling the Flush() method to flush the buffered data to the file
		bw.Flush();
		
		//Closing the stream i.e. FileStream stream
		fs.Close();

		//Closing the stream i.e. BinaryWriter stream
		bw.Close();
	}
	catch(IOException e)
	{
		Console.WriteLine(e);
	}
}
}

Output is -:

Writing to the file using BinaryStream and non-default Unicode Encoding
Data written successfully

The program creates a file and writes its contents, which are shown below contents -:
```
öÿÿÿ	   C ÿc ÍÌ³BÉv¾Ÿ_‹@ äT   @K e e p   s m i l i n g   a n d   t h i n k   p o s i t i v e . 
```
As you can see the contents of the file, the primitive values written to the file using BinaryWriter are encoded by a non-default Unicode encoding and therefore they look a little different than the previous example which encoded values using the default UTF-8 encoding.

This encoded data will be decoded back to its normal form when we read this data using the counterpart of BinaryWriter class i.e. the BinaryReader class(which is the topic of our next article). So, please turn the page.

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