File class static methods in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this code using File.ReadAllText?

Consider a file named example.txt containing the text Hello World. What will the following C# code output?

C Sharp (C#)

string content = System.IO.File.ReadAllText("example.txt");
Console.WriteLine(content);

A Hello World

B example.txt

C System.IO.File

D FileNotFoundException

💡 Hint

File.ReadAllText reads the entire content of the file as a string.

The method File.ReadAllText reads all text from the file and returns it as a string. Since the file contains "Hello World", that is printed.

❓ Predict Output

intermediate

What does File.Exists return for a missing file?

What will the following code print if the file missing.txt does not exist?

C Sharp (C#)

bool exists = System.IO.File.Exists("missing.txt");
Console.WriteLine(exists);

A True

B False

C Throws FileNotFoundException

D null

💡 Hint

File.Exists returns a boolean indicating if the file is present.

If the file does not exist, File.Exists returns false without throwing an exception.

❓ Predict Output

advanced

What is the output of File.ReadAllLines with multiple lines?

Given a file data.txt with these lines:

Line1
Line2
Line3

What will the following code print?

C Sharp (C#)

string[] lines = System.IO.File.ReadAllLines("data.txt");
Console.WriteLine(lines.Length);

A 3

B 1

C 0

D Throws IOException

💡 Hint

File.ReadAllLines returns an array of lines from the file.

The file has 3 lines, so the array length is 3.

❓ Predict Output

advanced

What error does File.Delete throw if file is open and locked?

What exception will be thrown if you try to delete a file that is currently open and locked by another process?

C Sharp (C#)

System.IO.File.Delete("lockedfile.txt");

A UnauthorizedAccessException

B FileNotFoundException

C IOException

D No exception, file deleted

💡 Hint

Deleting a locked file causes an IO error.

When a file is locked by another process, File.Delete throws an IOException indicating the file cannot be accessed.

🧠 Conceptual

expert

Which File method creates a new file or overwrites existing one with text?

Which static method of the File class will create a new file or overwrite an existing file with the given string content?

A File.AppendAllText(path, content)

B File.OpenRead(path)

C File.Create(path)

D File.WriteAllText(path, content)

💡 Hint

One method writes text and replaces existing content.

File.WriteAllText writes the string to the file, creating it if missing or overwriting if it exists. AppendAllText adds to the end, Create returns a stream, and OpenRead opens for reading only.