C# Online Compiler | .NET Fiddle

using System;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;

namespace ConsoleApp1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var value = 5555;
            using (var binaryFile = new FileStream("file.bin", FileMode.Create))
            {
                using (var binaryWriter = new BinaryWriter(binaryFile))
                {
                    binaryWriter.Write(value);
                }
            }

            using (var binaryFile = new FileStream("file.txt", FileMode.Create))
            {
                using (var streamWriter = new StreamWriter(binaryFile))
                {
                    streamWriter.Write(value);
                }
            }
            Console.WriteLine(string.Format("Zapisano do plików liczbę {0}..", value));

            using (var fs = new FileStream(@"file.bin", FileMode.Open, FileAccess.Read))
            {
                using (var binary = new BinaryReader(fs, Encoding.ASCII))
                {
					Console.WriteLine(string.Format("Binary: {0}", binary.ReadInt32()));
                }
            }

            using (var fs = new FileStream("file.txt", FileMode.Open, FileAccess.Read))
            {
                using (var binary = new BinaryReader(fs, Encoding.ASCII))
                {
                    var stringBuilder = new StringBuilder();
                    char character;
                    while (binary.BaseStream.Position != binary.BaseStream.Length && (character = binary.ReadChar()) != '\n') // czytam tylko do znaku końca linijki
                    {
                        stringBuilder.Append(character);
                    }
                    Console.WriteLine(string.Format("Characters: {0}", stringBuilder));

                    binary.BaseStream.Position = 0; // ustawiam pozycje streama na początek
                    Console.WriteLine(string.Format("Read characters[4] as int: {0}", binary.ReadInt32()));
                }
            }

        }
    }
}

 
using System;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
​
namespace ConsoleApp1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var value = 5555;
            using (var binaryFile = new FileStream("file.bin", FileMode.Create))
            {
                using (var binaryWriter = new BinaryWriter(binaryFile))
                {
                    binaryWriter.Write(value);
                }
            }
​
            using (var binaryFile = new FileStream("file.txt", FileMode.Create))
            {
                using (var streamWriter = new StreamWriter(binaryFile))