managing File system

Managing the files
For many applications a common requirement is the ability to interact with the file system:
creation of new files
copying files
deleting files
moving files from one directory to another
The classes that are used to browse around the file system and perform the operations are File, FileInfo, Directory, DirectoryInfo, FileSystemInfo, Path
FileSystemInfo – Base class that represents any file system object
FileInfo and File – These classes represent a file on the file system
DirectoryInfo and Directory – These classes represent a folder on the file system
Path – contains static method that you can use to manipulate pathnames

.Net Classes that represent Files and Folders
Directory and File contain only static methods. You use these classes by supplying the path to the appropriate file system object. If you only want to do one operation on a folder or file then using these classes is more efficient, because it saves the overhead of instantiating a .NET class
DirectoryInfo and FileInfo implement the same public methods as Directory and File, but the members of these classes are not static. You need to instantiate these classes before each instance is associated with a particular folder or file. This means that these classes are more efficient if you’re performing multiple operations using the same object, because they read in the authentication and other information for the appropriate file system object on construction, and then do not need to read that information again.
string sourceFile = "...";
string destFile = "...";
bool overwrite = false;
File.Copy(sourceFile, destFile, overwrite);
string filePath = "...";
FileInfo file = new FileInfo(filePath);
string destPath = "...";
file.CopyTo(destPath);
//Copying fileFileInfo myF
ile = new FileInfo(@”C:\
Program Files\ReadMe.tx
t”);myFile.CopyTo(@”D:\Copies\ReadMe.txt”);

FileInfo and DirectoryInfo properties
You can use following properties

FileInfo and DirectoryInfo methods
You can also perform actions on the file system object using the following methods:
// displays the creation t
ime of a file, then chan
ges it and// displays i
t againFileInfo test = new FileInfo(@”C:\My

Example: A File Browser
that presents a simple user interface that allows you to browse around the file system, and view the creation time, last access time, last write time, and size of files

Example: A File Browser
Step 1. Create
textBoxInput
textBoxFolder
buttonDisplay
buttonUp
listBoxFiles
listBoxFolders
textBoxFileName
textBoxCreationTime
textBoxFileSize
textBoxLastAccessTime
textBoxLastWriteTime
Step 2. Indica

Example: A File Browser
Step 3. Add a
Step 4. Add ev
Stores the path of the folder whose contants are displayed in the list box
User clicks the Display button
User clicks on a file name in the Files list box
User clicks on a folder name in the Folders list box
User clicks on the Up button

Example: A File Browser
Step 5. Add t
//clear the contents of al
l controls protected voi
d ClearAllFields() {
listBoxFolders.Items.Clear(); listBoxF

Example: A File Browser
Step 5. Add t
//Display information for
a given file in the text
boxesprotected void Di
splayFileInfo(string fileFullName){FileInfo

Example: A File Browser
Step 5. Add t
//Display the contents of
a given folder in the tw
o list boxesprotected v
oid DisplayFolderList(string folderFullName

Example: A File Browser
Step 5. Add t
//Display button handlerpr
otected void OnDisplayBu
ttonClick(object sender
, EventArgs e){ string folderPath = textBo

Example: A File Browser
Step 5. Add t
//Event handler that is ca
lled when an item in the
Files list//box is sel
ectedprotected void OnListBoxFilesSelected(

Example: A File Browser
Step 5. Add t
//Event handler for the se
lection of a folder in t
he Folder listprotected
void OnListBoxFoldersSelected(object sende

Example: A File Browser
Step 5. Add t
//Event handler for Up but
tonprotected void OnUpBu
ttonClick(object sender
, EventArgs e){try { string folderPath = n

Reading and Writing to Files
Reading and writing to files is in principle very simple; however, it is not done through the DirectoryInfo or FileInfo objects. it is done through a number of classes that represent a generic concept called a stream.
A stream is an object used to transfer data.
The data can be transferred in one of two directions:
If the data is being transferred from some outside source into your program, then we talk about reading from the stream.
If the data is being transferred from your program to some outside source, then we talk about writing to the stream.

Actual hierarchy of stream-related classes in the System.IO namespace.

Streams
FileStream — This class is intended for reading and writing binary data in a binary file.
However, you can also use it to read from or write to any file.
StreamReader and StreamWriter — These classes are designed specifically for reading from and writing to text files.stream.

Reading and Writing Text Files
StreamReader Sr = new St
reaReader(@”c:\Documents\ReadMe.txt”);//spe
cif
y encoding (ASCII, Unicode, UTF8)StreamReader
sr
= new StreamReader(@”c:\Documents\ReadMe.txt
StreamReader. The simplest constructor takes just a file name

Reading and Writing Text Files
void SaveFile(){ Stream
Writer sw = new StreamWriter(chosenFile, fa
lse
, Encoding.Unicode); foreach (string line i
n t
extBoxContents.Lines) sw.WriteLine(line); s
StreamWriter. Write each line of the text box to a StreamWriter steram

Чтение и запись двоичных данных
string filePath = "...";
FileStream file = new FileStream(filePath);
...
BinaryReader reader = new BinaryReader(file);
...
BinaryWriter writer = new BinaryWriter(file);
При построении объектам BinaryReader и BinaryWriter предоставляется поток, подключенный к источнику данных, из которого нужно читать или в который необходимо писать
Когда использование объектов BinaryReader или BinaryWriter завершено, необходимо вызвать метод Close, чтобы флешировать поток и освободить любые ресурсы, связанные с потоком
Необходимо также закрыть объект FileStream, предоставляющий данные для объектов BinaryReader и BinaryWriter.

Чтение и запись двоичных данных
string destinationFilePath = @"C:\. . .\BinaryDataFile.bin";
byte[] dataCollection = { 1, 4, 6, 7, 12, 33, 26, 98, 82, 101 };
FileStream destFile = new FileStream(
destinationFilePath,
FileMode.Create
FileAccess.Write);
BinaryWriter writer = new BinaryWriter(destFile);
foreach (byte data in dataCollection)
{
writer.Write(data);
}
writer.Close();
destFile.Close();
Закрыть оба потока для сброса данных в файл
Запись каждого байта в поток
Коллекция байт
Создание объекта FileStream для взаимодействия с файловой системой
Создание объекта BinaryWriter, передавая объект FileStream как параметр

Чтение и запись двоичных данных
string sourceFilePath = @"C:\. . .\BinaryDataFile.bin";
FileStream sourceFile = new FileStream(
sourceFilePath,
FileMode.Open
FileAccess.Read);
BinaryReader reader = new BinaryReader(sourceFile);
int position = 0;
int length = (int)reader.BaseStream.Length;
byte[] dataCollection = new byte[length];
int returnedByte;
while ((returnedByte = reader.Read()) != -1)
{
dataCollection[position] = (byte)returnedByte;
position += sizeof(byte);
}
reader.Close();
sourceFile.Close();
Закрытие потоков для освобождения всех дескрипторов файлов
Создание объекта FileStream для взаимодействия с файловой системой
Создание объекта BinaryWriter, передавая объект FileStream как параметр
Если операции чтения из файла или записи в файл генерируют исключение, следует убедиться, что потоки и дескрипторы файлов освобождены

Reading and writing Text Files
We can use StreamReader and StreamWriter classes
string filePath = "...";
FileStream file = new FileStream(filePath );
...
StreamReader reader = new StreamReader(file);
...
StreamWriter writer = new StreamWriter(file);
Close()
Peek()
Read()
ReadBlock()
EndOfStream
ReadLine()
ReadToEnd()

Reading and Writing Text Files
string sourceFilePath = @"C:\. . .\TextDataFile.txt";
// Create a FileStream object so that you can interact with the file system
FileStream sourceFile = new FileStream(
sourceFilePath, // Pass in the source file path.
FileMode.Open, // Open an existing file.
FileAccess.Read);// Read an existing file.
StreamReader reader = new StreamReader(sourceFile);
StringBuilder fileContents = new StringBuilder();
// Check to see if the end of the file has been reached.
while (reader.Peek() != -1)
{
// Read the next character.
fileContents.Append((char)reader.Read());
}
// Store the file contents in a new string variable.
string data = fileContents.ToString();
// Always close the underlying streams release any file handles.
reader.Close();
sourceFile.Close();

Reading and Writing Text Files
string sourceFilePath = @"C:\. . .\TextDataFile.txt";
string data;
// Create a FileStream object so that you can
// interact with the file system.
FileStream sourceFile = new FileStream(
sourceFilePath, // Pass in the source file path.
FileMode.Open, // Open an existing file.
FileAccess.Read);// Read an existing file.
StreamReader reader = new StreamReader(sourceFile);
// Read the entire file into a single string variable.
data = reader.ReadToEnd();
// Always close the underlying streams release any file handles.
reader.Close();
sourceFile.Close();
Класс StreamReader

Reading and Writing Text Files
string destinationFilePath = @"C:\. . .\TextDataFile.txt";
string data = "Hello, this will be written in plain text";
// Create a FileStream object so that you can interact with the file
// system.
FileStream destFile = new FileStream(
destinationFilePath, // Pass in the destination path.
FileMode.Create, // Always create new file.
FileAccess.Write); // Only perform writing.
// Create a new StreamWriter object.
StreamWriter writer = new StreamWriter(destFile);
// Write the string to the file.
writer.WriteLine(data);
// Always close the underlying streams to flush the data to the file
// and release any file handles.
writer.Close();
destFile.Close();
StreamWriter