reading-notes

Reading Notes for Codefellows!

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Code 401 ASP.NET

Reading 03

(All My Notes are attributed/sourced from the Resources directly preceding them.)

File and Stream I/O

Author: Microsoft Docs

Article Source

File and stream I/O (input/output) refers to the transfer of data either to or from a storage medium.

• System.IO namespace in C# enables reading and writing to datastreams and files.
• Commonly used file and directory classes:
  • File
  • FileInfo
  • Directory
  • DirectoryInfo
  • Path
• The Stream abstract class supports reading and writing bytes.
• Streams involve 3 fundamental operations:
  • Reading
  • Writing
  • Seeking
• Commonly used Stream classes:
  • FileStream
  • IsolatedStorageFileStream
  • MemoryStream
  • BufferedStream
  • NetworkStream
  • PipeStream
  • CryptoStream
• System.IO provides several reader and writer classes. Examples of commonly used classes below:
  • BinaryReader / BinaryWriter
  • StreamReader / StreamWriter
  • StringReader / StringWriter
  • TextReader / TextWriter
• System.IO provides Compression and Decompression classes to help with the transfer of data
• Commonly used Compression classes:
  • ZipArchive
  • ZipArchiveEntry
  • ZipFile
  • ZipFileExtensions
  • DeflateStream
  • GZipStream
• Isolated Storage is a way to keep your application within the control of a computer’s security policy.
• Commonly used Isolated Storage classes:
  • IsolatedStorage
  • IsolatedStorageFile
  • IsolatedStorageFileStream

How to: Write text to a file

Author: Microsft Docs

Article Source

• Below are common methods used to write to a text file
  • StreamWriter
  • File
  • Path

Example: Synchronously write text with StreamWriter

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {

        // Create a string array with the lines of text
        string[] lines = { "First line", "Second line", "Third line" };

        // Set a variable to the Documents path.
        string docPath =
          Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        // Write the string array to a new file named "WriteLines.txt".
        using (StreamWriter outputFile = new StreamWriter(Path.Combine(docPath, "WriteLines.txt")))
        {
            foreach (string line in lines)
                outputFile.WriteLine(line);
        }
    }
}
// The example creates a file named "WriteLines.txt" with the following contents:
// First line
// Second line
// Third line

Example: Synchronously append text with StreamWriter

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {

        // Set a variable to the Documents path.
        string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        // Append text to an existing file named "WriteLines.txt".
        using (StreamWriter outputFile = new StreamWriter(Path.Combine(docPath, "WriteLines.txt"), true))
        {
            outputFile.WriteLine("Fourth Line");
        }
    }
}
// The example adds the following line to the contents of "WriteLines.txt":
// Fourth Line

Example: Asynchronously write text with StreamWriter

using System;
using System.IO;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        // Set a variable to the Documents path.
        string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        // Write the specified text asynchronously to a new file named "WriteTextAsync.txt".
        using (StreamWriter outputFile = new StreamWriter(Path.Combine(docPath, "WriteTextAsync.txt")))
        {
            await outputFile.WriteAsync("This is a sentence.");
        }
    }
}
// The example creates a file named "WriteTextAsync.txt" with the following contents:
// This is a sentence.

Example: Write and append text with the File class

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        // Create a string with a line of text.
        string text = "First line" + Environment.NewLine;

        // Set a variable to the Documents path.
        string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        // Write the text to a new file named "WriteFile.txt".
        File.WriteAllText(Path.Combine(docPath, "WriteFile.txt"), text);

        // Create a string array with the additional lines of text
        string[] lines = { "New line 1", "New line 2" };

        // Append new lines of text to the file
        File.AppendAllLines(Path.Combine(docPath, "WriteFile.txt"), lines);
    }
}
// The example creates a file named "WriteFile.txt" with the contents:
// First line
// And then appends the following contents:
// New line 1
// New line 2

How to: Read and write to a newly created data file

Author: Microsoft Docs

Article Source

• BinaryWriter and BinaryReader are used for writing data that is not character strings.

The following example shows how to create an empty file stream, write data to it, and read data from it.

using System;
using System.IO;

class MyStream
{
    private const string FILE_NAME = "Test.data";

    public static void Main()
    {
        if (File.Exists(FILE_NAME))
        {
            Console.WriteLine($"{FILE_NAME} already exists!");
            return;
        }

        using (FileStream fs = new FileStream(FILE_NAME, FileMode.CreateNew))
        {
            using (BinaryWriter w = new BinaryWriter(fs))
            {
                for (int i = 0; i < 11; i++)
                {
                    w.Write(i);
                }
            }
        }

        using (FileStream fs = new FileStream(FILE_NAME, FileMode.Open, FileAccess.Read))
        {
            using (BinaryReader r = new BinaryReader(fs))
            {
                for (int i = 0; i < 11; i++)
                {
                    Console.WriteLine(r.ReadInt32());
                }
            }
        }
    }
}


// The example creates a file named "Test.data" and writes the integers 0 through 10 to it in binary format.
// It then writes the contents of Test.data to the console with each integer on a separate line.

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