C# FileInfo
last modified July 5, 2023
In this article we use FileInfo to work with files in C#.
FileInfo
FileInfo provides properties and instance methods for the creation,
copying, deletion, moving, and opening of files. It aids in the creation of
FileStream objects.
There is a similar class called File in .NET. While
FileInfo is an instance of a file representing the file,
File is a utility class for working with any file.
sky borrow war ocean cup cloud water read book look
In several examples, we use this text file.
C# FileInfo simple example
We have a simple example with FileInfo.
var fi = new FileInfo("words.txt");
Console.WriteLine(fi.Name);
Console.WriteLine(fi.FullName);
bool ro = fi.IsReadOnly;
if (ro)
{
Console.WriteLine("readonly file");
}
else
{
Console.WriteLine("not a readonly file");
}
We create a FileInfo object, passing a text file to its
constructor. Then we print its three properties.
Console.WriteLine(fi.Name); Console.WriteLine(fi.FullName);
We print its name and fullname.
bool ro = fi.IsReadOnly;
if (ro)
{
Console.WriteLine("readonly file");
}
else
{
Console.WriteLine("not a readonly file");
}
We determine whether the file is readonly.
$ dotnet run words.txt /home/jano/Documents/prog/csharp/fileinfo/First/words.txt not a readonly file
C# FileInfo create text file
The CreateText method creates a StreamWriter that
writes a new text file.
var fi = new FileInfo("colours.txt");
using StreamWriter sw = fi.CreateText();
sw.WriteLine("red");
sw.WriteLine("yellow");
sw.WriteLine("white");
sw.WriteLine("brown");
We create a new text file colours.txt. We write four lines into the
file.
using StreamWriter sw = fi.CreateText();
The StreamWriter class implements the IDisposable
interface; therefore, we use the using statement to close the
resources when we are done.
C# FileInfo read file
The OpenText creates a StreamReader with UTF8 encoding
that reads from an existing text file.
var fi = new FileInfo("words.txt");
using StreamReader sr = fi.OpenText();
string? s = string.Empty;
while ((s = sr.ReadLine()) != null)
{
Console.WriteLine(s);
}
In the example, we read a file line by line.
$ dotnet run sky borrow war ocean cup cloud water read book look
C# FileInfo delete file
The Delete method deletes a file.
var fi = new FileInfo("/etc/hostname");
try
{
fi.Delete();
} catch (UnauthorizedAccessException e)
{
Console.WriteLine("failed to delete file");
Console.WriteLine(e.Message);
}
In the example, we try to delete a system file. Since we do not have enough permissions, an exception is thrown.
$ dotnet run failed to delete file Access to the path '/etc/hostname' is denied.
C# FileInfo copy file
The CopyTo copies an existing file to a new file, disallowing the
overwriting of an existing file.
var fi = new FileInfo("words.txt");
fi.CopyTo("words2.txt");
The example creates a copy of the words.txt file.
C# FileInfo Directory
The Directory gets an instance of the parent directory.
var fi = new FileInfo("/etc/hostname");
var di = fi.Directory;
Console.WriteLine(di?.FullName);
Console.WriteLine(di?.LastAccessTime);
Console.WriteLine(di?.Root);
The example prints the file's parent directory fullname, last access time and root directory.
$ dotnet run /etc 6/30/2022 11:46:07 AM /
Source
FileInfo class - language reference
In this article we have used FileInfo to work with files.
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