Csharp/CSharp Tutorial/File Directory Stream/BinaryWriter

Binary Writer Reader

<source lang="csharp">using System; using System.Collections.Generic; using System.Text; using System.IO;

 class Program
 {
   static void Main(string[] args)
   {
     FileInfo f = new FileInfo("BinFile.dat");
     using (BinaryWriter bw = new BinaryWriter(f.OpenWrite()))
     {
       double aDouble = 1234.67;
       int anInt = 34567;
       string aString = "A, B, C";
       bw.Write(aDouble);
       bw.Write(anInt);
       bw.Write(aString);
     }
     using (BinaryReader br = new BinaryReader(f.OpenRead()))
     {
       Console.WriteLine(br.ReadDouble());
       Console.WriteLine(br.ReadInt32());
       Console.WriteLine(br.ReadString());
     }
   }
 }</source>

Commonly Used Output Methods Defined by BinaryWriter

Method Description void Write(sbyte val) Writes a signed byte. void Write(byte val) Writes an unsigned byte. void Write(byte[ ] buf) Writes an array of bytes. void Write(short val) Writes a short integer. void Write(ushort val) Writes an unsigned short integer. void Write(int val) Writes an integer. void Write(uint val) Writes an unsigned integer. void Write(long val) Writes a long integer. void Write(ulong val) Writes an unsigned long integer. void Write(float val) Writes a float. void Write(double val) Writes a double. void Write(char val) Writes a character. void Write(char[ ] buf) Writes an array of characters. void Write(string val) Writes a string using its internal representation, which includes a length specifier.

Move internal position for a BinaryWriter

<source lang="csharp">using System; using System.IO; public class MainClass {

   public static int Main(string[] args)
   {
   Console.WriteLine("***** Creating a file and writing binary data *****");
   FileStream myFStream = new FileStream("temp.dat", FileMode.OpenOrCreate,FileAccess.ReadWrite);
   
   BinaryWriter binWrit = new BinaryWriter(myFStream);
   binWrit.Write("Hello as binary info...");
   
   int myInt = 9;
   float myFloat = 9.8F;
   bool myBool = false;
   char[] myCharArray = {"H", "e", "l", "l", "o"};
   
   binWrit.Write(myInt);
   binWrit.Write(myFloat);
   binWrit.Write(myBool);
   binWrit.Write(myCharArray);
     
     binWrit.BaseStream.Position = 0;
   Console.WriteLine("Reading binary data...");
   BinaryReader binRead = new BinaryReader(myFStream);
   int temp = 0;
   while(binRead.PeekChar() != -1)
   {
     Console.Write(binRead.ReadByte());  
     temp = temp + 1;
     if(temp ==  5)
     {
       temp = 0;
       Console.WriteLine();
     }
   }
   binWrit.Close();
   binRead.Close();
   myFStream.Close();
       return 0;
   }

}</source>

***** Creating a file and writing binary data *****
Reading binary data...
2372101108108
111329711532
9810511097114
12132105110102
1114646469
000205204
2865072101
108108111

Use BinaryWriter to save data in binary format

<source lang="csharp">using System; using System.IO; class MainClass {

 public static void Main() 
 {
   FileStream outStream = File.Create("c:\\BinaryTest.dat");
   BinaryWriter bw = new BinaryWriter(outStream);
   bw.Write( (int) 3);
   bw.Write( (decimal) 4.5);
   string s = "Test String";
   bw.Write(s);
   bw.Flush();
   bw.Close();
   FileStream inStream = File.OpenRead("c:\\BinaryTest.dat");
   BinaryReader br = new BinaryReader(inStream);
   int i = br.ReadInt32();
   decimal d = br.ReadDecimal();
   string s2 = br.ReadString();
   Console.WriteLine(i);
   Console.WriteLine(d);
   Console.WriteLine(s2);
   br.Close();
 }

}</source>

3
4.5
Test String

Write and read back binary data

<source lang="csharp">using System; using System.IO;

class MainClass {

 public static void Main() { 
   BinaryWriter dataOut; 
   BinaryReader dataIn; 

   int i = 10; 
   double d = 1.56; 
   bool b = true; 

   try { 
     dataOut = new BinaryWriter(new FileStream("testdata", FileMode.Create)); 
   } 
   catch(IOException exc) { 
     Console.WriteLine(exc.Message + "\nCannot open file."); 
     return; 
   } 

   try { 
     Console.WriteLine("Writing " + i); 
     dataOut.Write(i);  

     Console.WriteLine("Writing " + d); 
     dataOut.Write(d); 

     Console.WriteLine("Writing " + b); 
     dataOut.Write(b); 

     Console.WriteLine("Writing " + 12.2 * 7.4); 
     dataOut.Write(12.2 * 7.4); 

   } 
   catch(IOException exc) { 
     Console.WriteLine(exc.Message + "\nWrite error."); 
   } 

   dataOut.Close(); 

   Console.WriteLine(); 

   try { 
     dataIn = new BinaryReader(new FileStream("testdata", FileMode.Open)); 
   } 
   catch(FileNotFoundException exc) { 
     Console.WriteLine(exc.Message + "\nCannot open file."); 
     return; 
   } 

   try { 
     i = dataIn.ReadInt32(); 
     Console.WriteLine("Reading " + i); 

     d = dataIn.ReadDouble(); 
     Console.WriteLine("Reading " + d); 

     b = dataIn.ReadBoolean(); 
     Console.WriteLine("Reading " + b); 

     d = dataIn.ReadDouble(); 
     Console.WriteLine("Reading " + d); 
   } 
   catch(IOException exc) { 
     Console.WriteLine(exc.Message + "Read error."); 
   } 

   dataIn.Close();  
 } 

}</source>

Writing 10
Writing 1.56
Writing True
Writing 90.28
Reading 10
Reading 1.56
Reading True
Reading 90.28

Write decimal, strings and char to a file using the BinaryWriter

<source lang="csharp">using System; using System.IO; static class MainClass {

   static void Main()
   {
       // Create a new file and writer.
       using (FileStream fs = new FileStream("test.bin", FileMode.Create))
       {
           using (BinaryWriter w = new BinaryWriter(fs))
           {
               // Write a decimal, two strings, and a char.
               w.Write(124.23M);
               w.Write("Test string");
               w.Write("Test string 2");
               w.Write("!");
           }
       }
       using (FileStream fs = new FileStream("test.bin", FileMode.Open))
       {
           using (StreamReader sr = new StreamReader(fs))
           {
               Console.WriteLine(sr.ReadToEnd());
               Console.WriteLine();
           }
       }
   }

}</source>

Test string 2! Test string

Write/Read int, float, char array and bool to a binary file using BinaryWriter

<source lang="csharp">using System; using System.IO; public class MainClass {

   public static int Main(string[] args)
   {
   Console.WriteLine("***** Creating a file and writing binary data *****");
   FileStream myFStream = new FileStream("temp.dat", FileMode.OpenOrCreate,FileAccess.ReadWrite);
   
   BinaryWriter binWrit = new BinaryWriter(myFStream);
   binWrit.Write("Hello as binary info...");
   
   int myInt = 9;
   float myFloat = 9.8F;
   bool myBool = false;
   char[] myCharArray = {"H", "e", "l", "l", "o"};
   
   binWrit.Write(myInt);
   binWrit.Write(myFloat);
   binWrit.Write(myBool);
   binWrit.Write(myCharArray);
     
     binWrit.BaseStream.Position = 0;
   Console.WriteLine("Reading binary data...");
   BinaryReader binRead = new BinaryReader(myFStream);
   int temp = 0;
   while(binRead.PeekChar() != -1)
   {
     Console.Write(binRead.ReadByte());  
     temp = temp + 1;
     if(temp ==  5)
     {
       temp = 0;
       Console.WriteLine();
     }
   }
   binWrit.Close();
   binRead.Close();
   myFStream.Close();
       return 0;
   }

}</source>

***** Creating a file and writing binary data *****
Reading binary data...
2372101108108
111329711532
9810511097114
12132105110102
1114646469
000205204
2865072101
108108111