How to read a binary file in C#

The System.IO.BinaryReader class is used to read primitive .NET data types as binary in a specific encoding, including ASCII, Unicode, UTF32, UTF7, and UTF8 encoding. The Read overloaded method is used to write primitive data types to a stream. The Write method can write Boolean, Byte, Char, Decimal, Double, and Integer data types.  The BinaryReader also provides specific data type methods such as ReadString, ReadInt32, etc. 

Create a BinaryReader

The BinaryReader constructor has overloaded forms to support a stream and encoding.  The following code snippet creates BinaryWriter objects with a stream and character encoding format. 

BinaryReader binReader = new BinaryReader(File.Open(fileName, FileMode.Open)   
Encoding ascii = Encoding.ASCII; 
BinaryWriter bwEncoder = 
new BinaryWriter(new FileStream(fileName, FileMode.Create), ascii); 

Reading a Binary File

The Read overloaded method is used to write primitive data types to a stream. The Write method can write Boolean, Byte, Char, Decimal, Double, and Integer data types.  The BinaryReader also provides specific data type methods such as ReadString, ReadInt32, etc. 

The following code snippet reads various data types using their respective methods.

string authorName = binReader.ReadString();
int age = binReader.ReadInt32();
string bookTitle = binReader.ReadString();
bool mvp = binReader.ReadBoolean();
double price = binReader.ReadDouble();

Complete Code Sample

Here is a complete sample code that creates a binary file and adds data.

public class BinaryReadWriteClass  
{  
    public void WriteBinary()  
    {  
        try  
        {  
            Console.WriteLine("Binary Writer");  
            string authorName = "Mahesh Chand";  
            int age = 30;  
            string bookTitle = "ADO.NET Programming using C#";  
            bool mvp = true;  
            double price = 54.99;  
  
            string fileName = @"C:\temp\MC.bin";                  
            BinaryWriter bwStream = 
new BinaryWriter(new FileStream(fileName,FileMode.Create));  
  
            Encoding ascii = Encoding.ASCII;  
            BinaryWriter bwEncoder = 
new BinaryWriter(new FileStream(fileName, FileMode.Create), ascii);  
  
            using (BinaryWriter binWriter =  
                new BinaryWriter(File.Open(fileName, FileMode.Create)))  
            {  
                // Write string   
                binWriter.Write(authorName);  
                // Write string   
                // Write integer  
                binWriter.Write(age);  
                binWriter.Write(bookTitle);  
                // Write boolean  
                binWriter.Write(mvp);  
                // Write double   
                binWriter.Write(price);  
            }                
            Console.WriteLine("Data Written!");  
            Console.WriteLine();  
        }  
        catch (IOException ioexp)  
        {  
            Console.WriteLine("Error: {0}", ioexp.Message);  
        }  
    }  
}