C#
File.Exists and Delete
Learn to check with File.Exists and delete with File.Delete.
Checking with File.Exists
The File.Exists method checks whether a file exists. It returns bool. Call: if (File.Exists("data.txt")) { ... }. If the file is missing, it returns false; no exception is thrown.
This is a standard pre-check in file operations. Calling Exists before ReadAllText prevents FileNotFoundException. In multi-threaded code, however, the file can be deleted between Exists and Read, so try/catch is still safer.
Deleting with File.Delete
The File.Delete method deletes a file. If the file is missing, no exception is thrown; it just continues. Call: File.Delete("old.txt");. Deleted files cannot be restored; use carefully.
Checking with Exists first is good practice, but since Delete does not throw when the file is missing, the check is not strictly required. To delete a directory use Directory.Delete; that is a separate topic.
Exercise Check, then delete
First create the file with File.WriteAllText("temp.txt", "data");. Then check with File.Exists("temp.txt") and print the result with Console.WriteLine. Finally delete the file with File.Delete("temp.txt"); and check again with File.Exists, printing the result.
Show example solution
First create with File.WriteAllText("temp.txt", "data");, then print Console.WriteLine(File.Exists("temp.txt"));, then File.Delete("temp.txt");, finally Console.WriteLine(File.Exists("temp.txt"));.
Example solution:
using System;
using System.IO;
class Program
{
static void Main()
{
File.WriteAllText("temp.txt", "data");
Console.WriteLine(File.Exists("temp.txt"));
File.Delete("temp.txt");
Console.WriteLine(File.Exists("temp.txt"));
}
}
Test yourself
-
Complete the Exists call
if (File.____("data.txt")) { Console.WriteLine("Yes"); }
Show answer
if (File.Exists("data.txt")) { Console.WriteLine("Yes"); }
-
File.Delete on a missing file?
File.Delete("missing.txt");
- Throws FileNotFoundException
- Returns false
- Does nothing, no error
- Creates the file
Show answer
Returns false — Correct. File.Delete does not throw on a missing file; it silently continues.
-
Match each method to its behavior
- Exists
- Checks presence
- Delete
- Removes
- ReadAllText
- Reads
- WriteAllText
- Writes
Next lesson: Summary - File I/O
