C#, Theory

C#. The Stream class. Operations (methods) of writing to a file stream

The Stream class. Operations (methods) of writing to a file stream. Examples

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1. Stream write operations. A brief overview

The following properties and methods (operations) are used to write to a stream:

  • property CanWrite – defines the ability of the stream to write;
  • method Write() – writes a sequence of bytes to the current stream;
  • method WriteByte() – writes a byte to the current stream.

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2. Property CanWrite. Example

You can use the CanWrite property to determine if the stream supports writing data. The general form of the property is as follows:

public abstract bool CanWrite { get; }

If the stream is writable, then the CanWrite property returns true. Otherwise, false is returned.

Example. The example creates a stream, which is associated with the file “myfile.txt”. It then uses the CanWrite property to determine if the stream supports writing.

using System;
using System.IO;

namespace ConsoleApp10
{
  class Program
  {
    static void Main(string[] args)
    {
      // 1. Create a stream and link it to the file "myfile.txt"
      Stream stream;

      using (stream = new FileStream("myfile.txt", FileMode.Create))
      {
        // 2. CanWrite property - determine if the stream is writeable
        if (stream.CanWrite)
          Console.WriteLine("Stream supports writing.");
        else
          Console.WriteLine("Stream does not support writing");

        // 3. Закрыть поток
        stream.Close();
      }
    }
  }
}

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3. The Write() method. Example

The Write() method is designed to write a sequence of bytes to the current stream. The general form of the method is as follows:

public abstract void Write(byte[] buffer, int offset, int count);

here

  • buffer – an array of bytes that are copied to the current stream;
  • offset – offset in the buffer array from which to start copying bytes into the current stream;
  • count – the number of bytes to be written to the current stream.

Example. The example writes a two-dimensional array of type int[] to a binary file. Then this array is read from the file for control.

using System;
using System.IO;

namespace ConsoleApp10
{
  class Program
  {
    static void Main(string[] args)
    {
      // Write array of strings to file
      using (FileStream fw = new FileStream("integers.dat", FileMode.Create, FileAccess.Write))
      {
        // Original array of integers
        int[,] AI = { { 2, 3, 5},
                      { 1, 8, 7 },
                      { 4, 2, 3 },
                      { -1, -2, 0 }
                    };

        // Additional variables
        byte[] AB;

        // First, write the dimension of the array 3*4
        // The number of rows
        int rows = AI.GetLength(0);
        AB = BitConverter.GetBytes(rows);
        fw.Write(AB, 0, AB.Length);

        // The number of columns
        int columns = AI.Length / AI.GetLength(0);
        AB = BitConverter.GetBytes(columns);
        fw.Write(AB, 0, AB.Length);

        // Cycle for writing numbers
        for (int i = 0; i < rows; i++)
          for (int j = 0; j < columns; j++)
          {
            // Write the number AI[i, j]
            AB = BitConverter.GetBytes(AI[i, j]);
            fw.Write(AB, 0, AB.Length);
          }
      }

      // Read array of strings from file
      using (FileStream fr = new FileStream("integers.dat", FileMode.Open, FileAccess.Read))
      {
        // The resulting array
        int[,] AI2;

        // Additional variables
        int rows, columns;
        byte[] AB;

        // Read the number of rows
        AB = new byte[sizeof(int)];
        fr.Read(AB, 0, AB.Length);
        rows = BitConverter.ToInt32(AB, 0);

        // Read the number of columns
        AB = new byte[sizeof(int)];
        fr.Read(AB, 0, AB.Length);
        columns = BitConverter.ToInt32(AB, 0);

        // Allocate memory for array of references
        AI2 = new int[rows, columns];

        // Цикл чтения чисел типа int
        for (int i = 0; i < rows; i++)
          for (int j = 0; j < columns; j++)
          {
            fr.Read(AB, 0, AB.Length);
            AI2[i, j] = BitConverter.ToInt32(AB, 0);
          }

        // Display the result
        Console.WriteLine("rows = {0}, columns = {1}", rows, columns);

        for (int i = 0; i < rows; i++)
        {
          for (int j = 0; j < columns; j++)
          {
            Console.Write("{0} ", AI2[i, j]);
          }
          Console.WriteLine();
        }
      }
    }
  }
}

The result of the program

rows = 4, columns = 3
2 3 5
1 8 7
4 2 3
-1 -2 0

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4. The WriteByte() method. Example

The WriteByte() method is designed to write to a stream (file) at the current position of one byte. According to the C# documentation, the general form of the WriteByte() method is as follows:

public virtual void WriteByte(byte value)

here value is the byte to write.

Example. The example combines the WriteByte() and ReadByte() methods. You need to write a string to a file using the WriteByte() method. This string is then read by the ReadByte() method.

using System;
using System.IO;

namespace ConsoleApp10
{
  class Program
  {
    static void Main(string[] args)
    {
      // Demonstration of a combination of the WriteByte() and ReadByte() methods
      using (FileStream fWrite = new FileStream("myfile.bin", FileMode.Create, FileAccess.Write))
      {
        // The line to write to the file
        string str = "bestprog.net";

        // The cycle of byte write - WriteByte() method
        foreach (char c in str)
          fWrite.WriteByte((byte)c);
      }

      // Reading a line from a file
      using (FileStream fRead = new FileStream("myfile.bin", FileMode.Open, FileAccess.Read))
      {
        // Additional variables
        string str2 = ""; // the resulting string
        int bt;

        // Cycle of byte reading from a file - the ReadByte() method
        while ((bt = fRead.ReadByte()) != -1)
          str2 += (char)bt; // add the read byte to the string as a character

        // Display the result
        Console.WriteLine(str2);
      }
    }
  }
}

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