Dir operations for directories in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Ruby code using Dir.entries?

Consider the following Ruby code snippet that lists entries in the current directory. What will it output?

Ruby

puts Dir.entries(".").sort

A Only files in the current directory sorted alphabetically

B Only directories in the current directory sorted alphabetically

C An array of all files and directories excluding '.' and '..' sorted alphabetically

D An array of all files and directories including '.' and '..' sorted alphabetically

💡 Hint

Dir.entries returns all entries including special ones '.' and '..'.

Dir.entries returns all entries in the directory including '.' (current directory) and '..' (parent directory). Sorting them alphabetically will include these special entries.

❓ Predict Output

intermediate

What does Dir.glob("*.rb") return?

Given a directory with files: test.rb, example.py, script.rb, and README.md, what will Dir.glob("*.rb") return?

Ruby

p Dir.glob("*.rb")

A ["test.rb", "script.rb"]

B ["test.rb", "example.py", "script.rb"]

C ["README.md"]

D An empty array []

💡 Hint

Dir.glob with '*.rb' matches files ending with .rb only.

Dir.glob("*.rb") returns an array of filenames in the current directory that match the pattern '*.rb'. Only test.rb and script.rb match.

🔧 Debug

advanced

Why does this code raise an error?

This Ruby code tries to change directory and list files but raises an error. Identify the cause.

Ruby

Dir.chdir("nonexistent_dir")
puts Dir.entries(".")

A It raises Errno::ENOENT because the directory 'nonexistent_dir' does not exist

B It raises TypeError because Dir.chdir expects a block

C It raises NoMethodError because Dir.entries is called incorrectly

D It raises ArgumentError because Dir.chdir requires absolute path

💡 Hint

Check if the directory exists before changing into it.

Dir.chdir raises Errno::ENOENT if the directory does not exist. The error is due to trying to change into a non-existing directory.

📝 Syntax

advanced

Which option correctly creates a new directory named 'data'?

Select the Ruby code that correctly creates a directory named 'data' in the current working directory.

A Dir.make('data')

B Dir.mkdir('data')

C Dir.create('data')

D Dir.new('data')

💡 Hint

The method to create a directory is mkdir.

Dir.mkdir('data') creates a new directory named 'data'. Other methods do not exist or do not create directories.

🚀 Application

expert

How many entries will this code print?

Given a directory containing 3 files and 2 subdirectories (excluding '.' and '..'), what will this Ruby code print?

Ruby

entries = Dir.entries(".") - ['.', '..']
puts entries.size

A 7

B 3

C 5

D 2

💡 Hint

Dir.entries includes '.' and '..', which are removed here.

Dir.entries returns all entries including '.' and '..'. Removing these two leaves the actual files and directories. Since there are 3 files and 2 directories, total is 5.