Challenge 1: Write and Read a File — Solution

File.open("diary.txt", "w") do |file|
  file.puts "Started learning Ruby today."
  file.puts "Exception handling makes a lot more sense now."
  file.puts "Excited for metaprogramming."
end

File.foreach("diary.txt").with_index(1) do |line, number|
  puts "#{number}: #{line.chomp}"
end

=begin
Output:
1: Started learning Ruby today.
2: Exception handling makes a lot more sense now.
3: Excited for metaprogramming.

Notes:
- File.open("diary.txt", "w") with a block writes three lines and
  automatically closes the file once the block finishes, per the
  chapter's warning about always preferring the block form.
- File.foreach("diary.txt") returns an Enumerator when chained with
  .with_index(1) (Chapter 4's Enumerator concept), pairing each line with
  a 1-based line number instead of the default 0-based index.
- line.chomp strips the trailing newline each line carries after being
  read from the file, so the printed output doesn't have a blank line
  after every entry.
=end