File Stream C#

using System;
using System.IO;
class FStream
{
    static void Main()
    {
        const string fileName = "data.dat";
        byte[] dataArray = new byte[100000];
        new Random().NextBytes(dataArray);
        using(FileStream fileStream = new FileStream(fileName, FileMode.Create))
        {
            for(int i = 0; i < dataArray.Length; i++)
            {
                fileStream.WriteByte(dataArray[i]);
            }
            fileStream.Seek(0, SeekOrigin.Begin);
            for(int i = 0; i < fileStream.Length; i++)
            {
                if(dataArray[i] != fileStream.ReadByte())
                {
                    Console.WriteLine("Error writing data.");
                    return;
                }
            }
            Console.WriteLine(fileStream.Name);
        }
    }
}