System.IO Namespace - .NET Framework API Documentation

Provides types that allow reading and writing files and data streams, and types that represent streams and file system objects.

Classes

File
Provides static methods for the creation, copying, deletion, moving, and opening of files, and provides properties for creating and accessing elements of a file.

Class
Directory
Provides static methods for the creation, moving, and enumeration of directories and subdirectories.

Class
Stream
Abstract base class and a foundation for the Stream derived classes.

Class
FileInfo
Provides properties and instance methods for the creation, deletion, moving, and opening of files, and aids in their creation.

Class
DirectoryInfo
Provides properties and instance methods for the creation, moving, and enumeration of directories and subdirectories.

Class
Path
Provides properties and methods for creating, manipulating, and querying paths in a cross-platform manner.

Class
MemoryStream
Creates a seekable, readable and writable Stream based on memory.

Class
FileStream
Exposes a Stream around a file, supporting both synchronous and asynchronous operations.

Class
TextReader
Abstract base class for all TextReaders, which read sequences of characters.

Class
StreamReader
Implements a TextReader that reads characters from a byte stream in a particular encoding.

Class
TextWriter
Abstract base class for TextWriters, which write sequences of characters.

Class
StreamWriter
Implements a TextWriter for writing characters to a Stream in a particular encoding.

Class

Interfaces

IDisposable
Provides a mechanism for releasing unmanaged resources.

Interface

Enums

FileMode
Specifies how the operating system should open a file.

Enum
FileAccess
Specifies the permitted access to an object that is accessed by using the FileStream object.

Enum
FileShare
Defines constants that control the type of access allowed to an object that represents a file.

Enum
SeekOrigin
Specifies the starting point for a stream seek operation.

Enum

Exceptions

IOException
Represents errors that occur during file or stream operations.

Class
DirectoryNotFoundException
The exception that is thrown when the code tries to access a directory that does not exist.

Class
FileNotFoundException
The exception that is thrown when the code tries to access a file that does not exist.

Class
PathTooLongException
The exception that is thrown when a specified file or directory name or the a combination of file/directory names exceeds the system-defined maximum length.

Class

Example Usage

Reading a Text File

            
using System;
using System.IO;

public class Example
{
    public static void Main(string[] args)
    {
        try
        {
            // Specify the path to a text file.
            string path = @"C:\Users\Public\Documents\MyFile.txt";

            // Create a StreamReader.
            using (StreamReader sr = new StreamReader(path))
            {
                string line;
                // Read and display lines from the file until the end of the file is reached.
                while ((line = sr.ReadLine()) != null)
                {
                    Console.WriteLine(line);
                }
            }
        }
        catch (Exception e)
        {
            // Let the user know what went wrong.
            Console.WriteLine("The file could not be read:");
            Console.WriteLine(e.Message);
        }
    }
}
            
        

Writing to a Text File

            
using System;
using System.IO;

public class Example
{
    public static void Main(string[] args)
    {
        try
        {
            // Specify the path to a text file.
            string path = @"C:\Users\Public\Documents\MyFile.txt";

            // Create a StreamWriter.
            using (StreamWriter sw = new StreamWriter(path))
            {
                sw.WriteLine("This is the first line.");
                sw.WriteLine("This is the second line.");
                sw.WriteLine("This is the third line.");
            }

            Console.WriteLine("Successfully wrote to the file.");
        }
        catch (Exception e)
        {
            // Let the user know what went wrong.
            Console.WriteLine("The file could not be written:");
            Console.WriteLine(e.Message);
        }
    }
}
            
        