Attributes. Every file on the Windows File system stores a set of attributes. You can detect its visibility, whether it is a directory, and if it is read-only.
Note The Attributes property returns an enumerated constant that is encoded as enum flags. You can individually test these flags.
using System;
using System.IO;
class Program
{
static void Main()
{
// Get Attributes for file.
FileInfo info = new FileInfo("C:\\file.txt");
FileAttributes attributes = info.Attributes;
Console.WriteLine(attributes);
// Get Attributes for directory.
info = new FileInfo("C:\\");
attributes = info.Attributes;
Console.WriteLine(attributes);
}
}Archive
Hidden, System, Directory
Values, FileAttributes. There are many different flags on the FileAttributes enum. Some of them, such as ReadOnly, can be retrieved in other ways. This is true for many .NET methods.
Times. The Windows file system keeps track of a file's creation time, its last access, and its last write time. We can get this information with the FileInfo type.
Here We access the CreationTime, LastAccessTime and LastWriteTime properties. The program prints these values.
Detail You can also get the creation, last access, and last write times in Coordinated Universal Time.
using System;
using System.IO;
class Program
{
static void Main()
{
FileInfo info = new FileInfo("C:\\file.txt");
DateTime time = info.CreationTime;
Console.WriteLine(time);
time = info.LastAccessTime;
Console.WriteLine(time);
time = info.LastWriteTime;
Console.WriteLine(time);
}
}7/17/2010 9:48:48 AM
7/17/2010 9:48:48 AM
8/18/2010 4:48:27 PM
Directory. Every file on the file system is stored in a containing directory. You can quickly access this DirectoryInfo with the Directory property.
Info Alternatively, you can get just the name of the directory with the DirectoryName string property.
using System;
using System.IO;
class Program
{
static void Main()
{
// Get file info.
FileInfo info = new FileInfo("C:\\file.txt");
// Access parent directory.
DirectoryInfo dir = info.Directory;
Console.WriteLine(dir.Name);
// Get directory name.
string name = info.DirectoryName;
Console.WriteLine(name);
}
}C:\
C:\
Exists. You can create a FileInfo for a file that does not exist. To see if the file does not exist, you can test the result of the Exists property. It is true or false.
using System;
using System.IO;
class Program
{
static void Main()
{
// Get file info.
FileInfo info = new FileInfo("C:\\does-not-exist.txt");
bool exists = info.Exists;
Console.WriteLine(exists);
}
}False
Name, extension. Typically, you should use the Path type to get file name parts such as the name or extension. But the FileInfo type provides ways to get some of these parts as well.
using System;
using System.IO;
class Program
{
static void Main()
{
// Get file info.
FileInfo info = new FileInfo("C:\\file.txt");
string name = info.Name;
string fullName = info.FullName;
string extension = info.Extension; // Has period
Console.WriteLine(name);
Console.WriteLine(fullName);
Console.WriteLine(extension);
}
}file.txt
C:\file.txt
.txt
Length. How many bytes are in a file? The Length property on the FileInfo type provides a way to effectively determine this. It returns a figure in bytes.
using System;
using System.IO;
class Program
{
static void Main()
{
FileInfo info = new FileInfo("C:\\a");
long value = info.Length;
Console.WriteLine(value);
}
}5320683
MoveTo. You can use the FileInfo type to rename (move) a file. This should reduce copying in the file system over creating a duplicate file and deleting the original.
Also CopyTo and Replace provide parallel functionality to the MoveTo method. Instead of renaming, CopyTo makes a copy of the file.
And The Replace method allows you to copy a file to an existing location and also make a backup file.
using System.IO;
class Program
{
static void Main()
{
// Write the specified file with some text.
File.WriteAllText("C:\\test1.txt", "A");
// Create a FileInfo instance for the specified path.// ... Then move the specified file to a new file path.
FileInfo info = new FileInfo("C:\\test1.txt");
info.MoveTo("C:\\test2.txt");
}
}1. One file is created.
2. The file is renamed to a new name.
Text. If your FileInfo points to a text file, it is a good idea to use the AppendText, CreateText, and OpenText methods to acquire a StreamWriter or StreamReader instance.
Detail You should wrap these in the using-resource-acquisition statement. This improves resource usage.
using System;
using System.IO;
class Program
{
static void Main()
{
// This file will have a new line at the end.
FileInfo info = new FileInfo("C:\\file.txt");
using (StreamWriter writer = info.AppendText())
{
writer.WriteLine("Line");
}
// This file will have the word New in it.
info = new FileInfo("C:\\new.txt");
using (StreamWriter writer = info.CreateText())
{
writer.WriteLine("New");
}
// Get a StreamReader with OpenText.
using (StreamReader reader = info.OpenText())
{
Console.WriteLine(reader.ReadToEnd());
}
}
}New
Security. The FileInfo type provides a way to retrieve and store security information on the file system. This is most important for multi-user servers that have restricted information.
Encrypt. The Encrypt and Decrypt methods are not available on all Windows computers. If you choose to use them, you can wrap them in exception-handling.
Unhandled Exception: System.IO.IOException: The request is not supported.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.File.Encrypt(String path)
at System.IO.FileInfo.Encrypt()
at Program.Main() in C:\...Program.cs:line 10
ReadOnly, IsReadOnly. If you are trying to determine if a file is read-only, you can use the IsReadOnly method instead of the FileAttributes.ReadOnly constant.
FileStream. Sometimes, we deal with a non-text file and want to use types such as BinaryReader or BinaryWriter on a file. This is possible with a FileStream.
A summary. By providing these properties and methods, the FileInfo type makes it easy to get information from the file system about a file.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.