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C# - How to Read and Write a Byte Array to File?

Learn, how to read and write a byte array into file using C# program?
Submitted by IncludeHelp, on November 17, 2017

Read and Write a Byte Array to File

To read and write a byte array to file in C#, we use the Read() and Write() methods of FileStream class.

Read() and Write() Methods - Syntax

void  Read (byte[] b, int offset, int count);
void  Write(byte[] b, int offset, int count);

Parameter(s)

• b : byte array
• offset : location of file
• count : Total bytes read/write to or from file.

C# program to read and write a byte array to file using FileStream class

using System;
using System.IO;

namespace ConsoleApplication1 {
  class Program {
    static void Main() {
      byte[] b1 = {10, 20, 24, 13, 15, 17};
      byte[] b2 = new byte[6];

      byte large = 0;
      FileStream f1;
      f1 = new FileStream("abc.txt", FileMode.Create, FileAccess.Write);

      f1.Write(b1, 0, 6);
      f1.Close();

      f1 = new FileStream("abc.txt", FileMode.Open, FileAccess.Read);

      f1.Read(b2, 0, 6);

      large = b2[0];
      for (int i = 1; i < b2.Length; i++) {
        if (large < b2[i])
          large = b2[i];
      }

      Console.WriteLine("Largest Item is : " + large);
      f1.Close();
    }
  }
}

Output

Largest Item is : 24

Explanation

In this program, we are performing read and write operation into file and find largest element from file.

In above program, we need to remember, when we use "FileStream" class then we need to include System.IO namespace in the program.

C# FileStream Class Program »