IO

Description

This namespace contains classes to perform File I/O operations.

Namespace	Class
System.IO	`class File`
System.IO	`class DriveInfo`
System.IO	`class FileStream`
System.IO	`class Directory`
System.IO	`class FileNotFoundException`
System.IO	`class StreamWriter`
System.IO	`class FileInfo`
System.IO	`class StreamReader`
System.IO	`class DirectoryInfo`
System.IO	`class BinaryWriter`
System.IO	`class BinaryReader`

Classes

File

Static class that manipulates file.
All methods of this class are static methods.
For doing one action is good but for doing multiple actions at once it's better to use FileInfo class

System.IO.File.Method();

Methods:

Method	Description
`static FileStream Create( string path )`	Create / overwrites a file at the specified path.
`static bool Exists( string path )`	Determines whether the file exists in the disk or not.
`static void Copy( string sourceFile, string destFile )`	Copies the source file to the destination location.
`static void Move( string sourceFile, string destFile )`	Moves the source file to the destination location.
`static void Delete( string path )`	Deletes the specified file permanently.
`static void WriteAllLines( string path, IEnumerable<string> contents)`	Creates / overwrites a file; writes specified lines of content to the file; and close the file.
`static string[] ReadAllLines( string path )`	Reads file content as text and returns all lines.
`static string ReadAllText( string path )`	Reads file content as text and returns the same.
`static void WriteAllText( string path, string contents )`	Creates / overwrites a file; writes specified content to the file; and close the file.

FileInfo

Represents a file and provides methods to manipulate the file.
For doing multiple actions at onces is good but for doing one action it's better to use File class

FileInfo referenceVariable = new FileInfo("Your File Path Here");

Properties:

Property	Description
`bool Exists`	Determines whether the file exists in the disk or not.
`string FullName`	Represents full path (including file name and extension) of the file.
`string Name`	Represents only name of the file (without path).
`string DirectoryName`	Represents only path of the file (without file name).
`string Extension`	Represents only file extension (without file name).
`DateTime CreationTime`	Represents date and time of file creation.
`DateTime LastWriteTime`	Represents date and time of last modification of the file.
`DateTime LastAccessTime`	Represents date and time of last access of the file.
`long Length`	Represents file size (in the form of number of bytes).

Methods:

Method	Description
`FileInfo CopyTo(string destFilePath, bool overwrite)`	Copies the file into the new destination path. It returns an object of `FileInfo` class, representing the new file.
`void MoveTo(string destFilePath)`	Moves the file into the new destination path (must be in the same drive).
`void Delete()`	Deletes the file permanently.
`FileStream Create()`	Creates the file at the specified path and returns an object of `FileStream` with 'Create' mode to write data.
`FileStream Open(FileMode mode, FileAccess access)`	Opens the file with the specified mode and access, returns a `FileStream` object that can write/read file data.
`FileStream OpenRead()`	Opens the file in 'Read' mode and returns a `FileStream` object that can read the file data.
`FileStream OpenWrite()`	Opens the file in 'OpenOrCreate' mode and returns a `FileStream` object to write the file data.
`StreamWriter CreateText()`	Opens the file in 'Create' mode and returns a `StreamWriter` object to write text to the file.
`StreamWriter AppendText()`	Opens the file in 'Append' mode and returns a `StreamWriter` object to write appended text to the file.
`StreamReader OpenText()`	Opens the file in 'Open' mode and returns a `StreamReader` object that can read text from the file.

DirectoryInfo

Class that represents a directory (folder) on the disk and performs manipulations on directories.

DirectoryInfo referenceVariable = new DirectoryInfo("Directory Path Here");

Properties:

Property	Description
`bool Exists`	Determines whether the directory exists in the disk or not.
`string FullName`	Represents full path of the directory.
`string Name`	Represents only name of the directory (without path).
`DirectoryInfo Parent`	Represents parent directory of the current directory.
`DirectoryInfo Root`	Represents root (drive) of the directory.
`DateTime CreationTime`	Represents date and time of directory creation.
`DateTime LastWriteTime`	Represents date and time of last modification of the directory.
`DateTime LastAccessTime`	Represents date and time of last access of the directory.

Methods:

Method	Description
`void Create()`	Create the directory at the current path.
`DirectoryInfo CreateSubDirectory(string path)`	Creates a sub directory at the current path with specified name.
`void Delete(bool recursive)`	`true`: Deletes the directory including sub directories. `false`: Deletes directory only if empty.
`DirectoryInfo[] GetDirectories()`	Returns `DirectoryInfo[]` that represents sub directories of current directory.
`DirectoryInfo[] GetDirectories(string searchPattern)`	Returns `DirectoryInfo[]` that represents sub directories that match with specified search pattern.
`FileInfo[] GetFiles()`	Returns `FileInfo[]` that represents files of current directory.
`FileInfo[] GetFiles(string searchPattern)`	Returns `FileInfo[]` that represents files that match with specified search pattern.
`void MoveTo(string destDirName)`	Moves the current directory to the specified location in the same drive.

DriveInfo

Class that represents a drive and performs manipulations on drives.
You can read both fixed / removable drives.

DriveInfo referenceVariable = new DriveInfo("Your Drive Name Here");

Properties:

Property	Description
`string Name`	Represents name of the drive.
`string DriveType`	Represents type of drive either 'Fixed' or 'Removable'.
`string VolumeLabel`	Represents label of the drive (set by user).
`DirectoryInfo RootDirectory`	Represents root directory of the drive.
`long TotalSize`	Represents total size (bytes) of the drive.
`long AvailableFreeSpace`	Represents total free space (bytes) of the drive.

FileStream

Class that performs file I/O operations.
Writes / reads data in byte[ ] format.
For multiple file operation on one single file, this class is good, but for single operation like only read or only write the StreamReader and StreamWriter classes are better

FileStream referenceVariable = new FileStream( "File Path", FileMode.Create, FileAccess.Write );

Example:

// => FileStream for Writing
FileStream fileStream = new FileStream(filePath, FileMode.Create, FileAccess.Write);
//FileStream fileStream = File.Create(filePath);
//FileStream fileStream = File.Open(filePath, FileMode.Create, FileAccess.Write);
//FileStream fileStream = File.OpenWrite(filePath);
//FileStream fileStream = fileInfo.Create();
//FileStream fileStream = fileInfo.Open(FileMode.CreateNew, FileAccess.Write);
//FileStream fileStream = fileInfo.OpenWrite();

// => FileStream for Reading
FileStream fileStream2 = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.Read);
//FileStream fileStream2 = File.Open(filePath, FileMode.OpenOrCreate, FileAccess.Read);
//FileStream fileStream2 = File.OpenRead(filePath);
//FileStream fileStream2 = fileInfo.Open(FileMode.OpenOrCreate, FileAccess.Read);
//FileStream fileStream2 = fileInfo.OpenRead();

// => Creating and Writing to a File
// Create content
string content = "Dog is one of the domestic animal";
byte[] bytes = System.Text.Encoding.ASCII.GetBytes(content);

// Write
fileStream.Write(bytes, 0, bytes.Length);
fileStream.Close();

Methods:

Method	Description
`void Write(byte[] array, int offset, int count)`	Writes the specified no. of bytes specified by count, based on the byte[] specified by 'array' into the file, after the no. of bytes specified by 'offset'.
`int Read(byte[] array, int offset, int count)`	Reads the specified no. of bytes specified by count, into the byte[] specified by 'array' from the file, after the no. of bytes specified by 'offset'.
`void Close()`	Closes the file.

FileMode:

Mode	Description
`FileMode.CreateNew`	It specifies that the o/s should create a new file. If the file already exists, an IOException will be thrown.
`FileMode.Create`	It specifies that the o/s should create a new file. If the file already exists, it will be overwritten.
`FileMode.Open`	It specifies that the o/s should open an existing file. If the file doesn't exist, a FileNotFoundException will be thrown.
`FileMode.OpenOrCreate`	It specifies that the o/s should open an existing file. If the file doesn't exist, a new file will be created. It is useful for reading content of the file.
`FileMode.Append`	It specifies that the o/s should open an existing file and seek to the end of the file in order to write content at the end. It is useful with FileAccess.Write.

FileAccess:

Mode	Description
`FileAccess.Read`	It is used to read content from an existing file.
`FileAccess.Write`	It is used to write content to a file.
`FileAccess.ReadWrite`	It can be used for both read/write operations in a file.

StreamWriter

Class that writes text data into the file.
Internally uses FileStream.
Is a wrapper around the FileStream for writing strings

StreamWriter referenceVariable = new StreamWriter("File Path");

Example:

// 4 ways to create new object of StreamWriter
// StreamWriter streamWriter = new StreamWriter(filePath);
// StreamWriter streamWriter = new StreamWriter(fileStream);
// StreamWriter streamWriter = fileInfo.AppendText();
using (StreamWriter streamWriter = fileInfo.CreateText()) {
    streamWriter.WriteLine("Russia has population about 145,934,000");

    // some code here

    streamWriter.WriteLine("Germany has population about 83,783,000");
}

Methods:

Method	Description
`void Write(string content)`	Writes the specified string content to the file.
`void Close()`	Close the file.

StreamReader

Class that reads text data from the file.
Internally uses FileStream.
Is a wrapper around the FileStream for reading strings

StreamReader referenceVariable = new StreamReader("File Path");

Example:

// 3 ways to create object of StreamReader:
// StreamReader streamReader = new StreamReader(filePath);
// StreamReader streamReader = fileInfo.OpenText();

FileStream fileStream2 = new FileStream(filePath, FileMode.Open, FileAccess.Read);
using (StreamReader streamReader = new StreamReader(fileStream2)) {
    string content_from_file = streamReader.ReadToEnd();
    Console.WriteLine("\nFile read. File content is:");
    Console.WriteLine(content_from_file);
}

Methods:

Method	Description
`int Read(char[] buffer, int startIndex, int count)`	Reads the specified number of characters (using 'count') from the file into the specified buffer (char[]) and inserts the characters at the specified index of the buffer.
`string ReadToEnd()`	Reads complete content of the file in text format and returns the same as a string.
`string ReadLine()`	Reads a line from the file in text format and returns the same as a string.
`void Close()`	Closes the file.

BinaryWriter

Class that writes binary data into the file.
Internally uses FileStream.
For example, 65 is written as 1000001.

BinaryWriter referenceVariable = new BinaryWriter(fileStream);

Methods:

Method	Description
`void Write(...)`	Writes any type of value (only primitive types / string) into the file.
`void Close()`	Close the file.

BinaryReader

Class that reads binary data from the file.
Internally uses FileStream.

BinaryReader referenceVariable = new BinaryReader(fileStream);

Methods:

Method	Description
`ReadByte()`	Reads and returns a byte value from the file.
`ReadSByte(),` `ReadInt16(),` `ReadUInt16(),` `ReadInt32(),` `ReadUInt32(),` `ReadInt64(),` `ReadUInt64(),` `ReadSingle(),` `ReadDouble(),` `ReadDecimal(),` `ReadChar(),` `ReadString(),` `ReadBoolean()`	Reads and returns the specific type of value from the file.
`Close()`	Closes the file.

Method	Description
`static DirectoryInfo CreateDirectory(string path)`	Create a directory at the specified path.
`static void Delete(string path, bool recursive)`	true: Deletes the directory including subdirectories and all files. false: Deletes the directory only if it is empty.
`static bool Exists(string path)`	Determines whether the directory exists in the disk or not.
`static string[] GetDirectories(string path)`	Returns string[] that contains paths of subdirectories in the specified directory.
`static string[] GetDirectories(string path, string searchPattern)`	Returns string[] that contains paths of subdirectories that match the specified search pattern.
`static string[] GetFiles(string path)`	Returns string[] that contains paths of files in the specified directory.
`static string[] GetFiles(string path, string searchPattern)`	Returns string[] that contains paths of files that match the specified search pattern.
`static void Move(string sourceDir, string destDir)`	Moves the source directory to the specified destination location in the same drive.