System.IO Namespace
File
File Class
Represents a static class that provides methods for creating, copying, deleting, moving, and opening files. This class also helps in the creation of FileStream objects.
Methods
AppendAllLines(string path, IEnumerable contents)
Appends specified lines to a file, and then closes the file. If the file does not exist, it is created.
- path: The file to append the specified lines to.
- contents: The lines to append to the file.
public class Example
{
public static void Main()
{
string filePath = "myFile.txt";
string[] lines = { "First line.", "Second line." };
File.AppendAllLines(filePath, lines);
Console.WriteLine("Lines appended to file.");
}
}
ReadAllText(string path)
Opens a text file, reads all lines of the file, and then closes the file.
- path: The file to read.
public class Example
{
public static void Main()
{
string filePath = "myFile.txt";
string content = File.ReadAllText(filePath);
Console.WriteLine("File content:\n{0}", content);
}
}
WriteAllText(string path, string contents)
Creates a new file, writes the specified string to the file, and then closes the file. If the target file already exists, it is overwritten.
- path: The file to write to.
- contents: The string to write to the file.
public class Example
{
public static void Main()
{
string filePath = "newFile.txt";
string text = "This is the content written to the new file.";
File.WriteAllText(filePath, text);
Console.WriteLine("Content written to file.");
}
}
Exists(string path)
Determines whether the specified file exists.
- path: The file to check.
public class Example
{
public static void Main()
{
string filePath = "config.json";
if (File.Exists(filePath))
{
Console.WriteLine("Configuration file exists.");
}
else
{
Console.WriteLine("Configuration file not found.");
}
}
}
Directory
Directory Class
Represents a static class that provides methods for creating, moving, and enumerating through directories and subdirectories. This class also provides methods for reading and writing to files.
Methods
CreateDirectory(string path)
Creates all the directories and subdirectories in the specified path unless they already exist.
- path: The directory to create.
public class Example
{
public static void Main()
{
string dirPath = "MyNewApp/Data";
Directory.CreateDirectory(dirPath);
Console.WriteLine("Directory '{0}' created.", dirPath);
}
}
Delete(string path, bool recursive)
Deletes a specified directory and a specified reason. If the directory is not empty, this method will throw an exception unless recursive is true.
- path: The directory to delete.
- recursive: True to remove directories, subdirectories, and files in path; otherwise, false.
public class Example
{
public static void Main()
{
string dirPath = "TemporaryFiles";
// Ensure directory exists first for demonstration
Directory.CreateDirectory(dirPath);
File.WriteAllText(Path.Combine(dirPath, "temp.txt"), "temp content");
if (Directory.Exists(dirPath))
{
Directory.Delete(dirPath, true);
Console.WriteLine("Directory '{0}' deleted recursively.", dirPath);
}
}
}
Exists(string path)
Determines whether the given path refers to an existing directory on disk.
- path: The path to check.
public class Example
{
public static void Main()
{
string dirPath = "AppData/Settings";
if (Directory.Exists(dirPath))
{
Console.WriteLine("Settings directory exists.");
}
else
{
Console.WriteLine("Settings directory does not exist.");
}
}
}
Path
Path Class
Provides properties and methods, for creating, manipulating, and obtaining information about paths.
Properties
PathSeparator Property
Gets the directory separator character for the current platform.
using System.IO;
public class Example
{
public static void Main()
{
Console.WriteLine("Path separator: {0}", Path.PathSeparator);
}
}
DirectorySeparatorChar Property
Gets the directory separator character for the current platform.
using System.IO;
public class Example
{
public static void Main()
{
Console.WriteLine("Directory separator: {0}", Path.DirectorySeparatorChar);
}
}
Methods
Combine(string path1, string path2)
Combines two strings into a path. The result is valid on both the current platform and UNC servers.
- path1: The first path.
- path2: The second path.
public class Example
{
public static void Main()
{
string folder = "Documents";
string file = "report.docx";
string fullPath = Path.Combine(folder, file);
Console.WriteLine("Combined path: {0}", fullPath);
}
}
GetFileName(string path)
Returns the file name of the specified path string.
- path: The path string to return the file name from.
public class Example
{
public static void Main()
{
string filePath = "/Users/Me/Documents/report.docx";
string fileName = Path.GetFileName(filePath);
Console.WriteLine("File name: {0}", fileName);
}
}
Stream
Stream Class
Abstract base class for all streams. Provides the fundamental methods for working with streams, such as reading, writing, and seeking.
Properties
CanRead Property
Gets a value indicating whether the stream supports reading.
CanWrite Property
Gets a value indicating whether the stream supports writing.
CanSeek Property
Gets a value indicating whether the stream supports seeking.
Length Property
Gets the length in bytes of the stream.
Position Property
Gets or sets the current position within the stream.
Methods
Read(byte[] buffer, int offset, int count)
Reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.
- buffer: An array of bytes. When this method returns, the buffer contains the specified sequence of bytes.
- offset: The zero-based index in buffer at which to begin copying bytes.
- count: The maximum number of bytes to read.
Write(byte[] buffer, int offset, int count)
Writes a sequence of bytes to the current stream and advances the position within the stream by the number of bytes written.
- buffer: An array of bytes. This method copies count bytes from buffer to the current stream.
- offset: The zero-based index in buffer from which to begin copying bytes.
- count: The number of bytes to write.
Seek(long offset, SeekOrigin origin)
Sets the position within the current stream to the specified value.
- offset: A byte offset relative to the origin parameter.
- origin: A value of type SeekOrigin indicating the reference point to use for offset.
Flush()
Clears all buffers for this stream and causes any buffered data to be written to the underlying device.
FileInfo
FileInfo Class
Provides instance methods for the creation, deletion, moving, and opening of files, and aids in their creation, deletion, moving, and opening.
Constructors
FileInfo(string fileName)
Initializes a new instance of the FileInfo class for the specified file path.
- fileName: The name of the file.
Properties
Name Property
Gets the name of the file.
FullName Property
Gets the fully qualified path of the file or directory.
Exists Property
Gets a value indicating whether the specified file exists.
Length Property
Gets the size of the current file in bytes.
Methods
Open(FileMode mode)
Opens a FileStream object on the current file using the specified mode.
- mode: A FileMode value that specifies whether to create, open, append, or overwrite the file.
Delete()
Deletes this file.
MoveTo(string destFileName)
Moves a specified file to a new location, with the option to specify a new file name.
- destFileName: The name of the destination file.
DirectoryInfo
DirectoryInfo Class
Provides instance methods for the creation, deletion, moving, and enumeration of directories, and aids in their creation, deletion, moving, and opening.
Constructors
DirectoryInfo(string path)
Initializes a new instance of the DirectoryInfo class for the specified path.
- path: The path of the directory.
Properties
Name Property
Gets the name of the directory.
FullName Property
Gets the fully qualified path of the directory.
Exists Property
Gets a value indicating whether the specified directory exists.
Methods
Create()
Creates this directory.
Delete(bool recursive)
Deletes this directory, optionally with a parameter that indicates whether to remove directories, subdirectories, and files in this instance in error.
- recursive: True to remove directories, subdirectories, and files in path; otherwise, false.
GetFiles()
Gets a FileInfo array representing all the files in the current directory.
GetDirectories()
Gets a DirectoryInfo array representing the subdirectories in the current directory.
StreamReader
StreamReader Class
Implements a TextReader that reads characters from a byte stream in a particular encoding.
Constructors
StreamReader(string path)
Initializes a new instance of the StreamReader class for the specified file path.
- path: The complete file path to read.
StreamReader(Stream stream)
Initializes a new instance of the StreamReader class for the specified stream.
- stream: The stream to read from.
Methods
ReadLine()
Reads the next line of characters from the current stream and returns data as a string.
ReadToEnd()
Reads to the end of the stream and returns all characters that have been read.
StreamWriter
StreamWriter Class
Implements a TextWriter for writing characters to a stream in a particular encoding.
Constructors
StreamWriter(string path)
Initializes a new instance of the StreamWriter class for the specified file path.
- path: The complete file path to write to.
StreamWriter(Stream stream)
Initializes a new instance of the StreamWriter class for the specified stream.
- stream: The stream to write to.
Methods
WriteLine(string value)
Writes a string to the stream and followed by a line terminator.
- value: The string to write.
Write(string value)
Writes a string to the stream.
- value: The string to write.
Flush()
Clears all buffers for the current writer and causes any buffered data to be written to the underlying stream.
BinaryReader
BinaryReader Class
Reads primitive data types from a stream in binary format.
Constructors
BinaryReader(Stream input)
Initializes a new instance of the BinaryReader class using the specified stream and a UTF-8 encoding.
- input: The stream to read from.
Methods
ReadInt32()
Reads a 32-bit signed integer from the current stream and advances the stream position by four bytes.
ReadString()
Reads the next string from the current stream. The string is prefixed with the length, as a 32-bit integer, to read.
BinaryWriter
BinaryWriter Class
Writes primitive data types to a stream in binary format.
Constructors
BinaryWriter(Stream output)
Initializes a new instance of the BinaryWriter class using the specified stream and a UTF-8 encoding.
- output: The stream to write to.
Methods
Write(int value)
Writes a 32-bit signed integer to the current stream and advances the stream position by four bytes.
- value: The 32-bit signed integer to write.
Write(string value)
Writes a string to the current stream.
- value: The string to write.
Flush()
Clears all buffers for the current writer and causes any buffered data to be written to the underlying stream.
MemoryStream
MemoryStream Class
Creates a stream whose backing store is memory. This class cannot be inherited.
Constructors
MemoryStream()
Initializes a new instance of the MemoryStream class with an expandable capacity or a specific capacity.
MemoryStream(byte[] buffer)
Initializes a new instance of the MemoryStream class based on the specified byte array.
- buffer: The array of bytes from which to create the stream.
Methods
ToArray()
Creates a byte array, to the size of the stream.
FileStream
FileStream Class
Exposes a Stream around a file, supporting both synchronous and asynchronous read and write operations. This class cannot be inherited.
Constructors
FileStream(string path, FileMode mode)
Initializes a new instance of the FileStream class with the specified path and mode.
- path: The file to be opened.
- mode: A FileMode value that specifies whether to create, open, append, or overwrite the file.
Properties
CanSeek Property
Gets a value indicating whether the current stream supports seeking.
Methods
Close()
Closes the current FileStream and releases any resources such as file handles.