CSV library basics in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the CSV library in Ruby?

The CSV library helps read from and write to CSV (Comma-Separated Values) files easily, making it simple to handle tabular data.

beginner

How do you require the CSV library in a Ruby script?

Use require 'csv' at the top of your Ruby file to load the CSV library.

beginner

How do you read a CSV file line by line in Ruby?

Use CSV.foreach('filename.csv') do |row| ... end. Each row is an array of values from that line.

intermediate

How do you write an array of arrays to a CSV file in Ruby?

Use CSV.open('filename.csv', 'w') do |csv| data.each { |row| csv << row } end where data is an array of arrays.

intermediate

What does CSV.parse do?

CSV.parse reads CSV data from a string instead of a file, returning an array of rows.

Which Ruby command loads the CSV library?

A require 'csv'

B import csv

C include CSV

D load 'csv'

In Ruby, require 'csv' loads the CSV library.

What does CSV.foreach('file.csv') do |row| ... end do?

A Reads the CSV file line by line, yielding each row as an array

B Writes rows to the CSV file

C Parses CSV data from a string

D Deletes the CSV file

It reads the CSV file line by line and gives each row as an array to the block.

How do you write data to a CSV file in Ruby?

A CSV.delete('file.csv')

B CSV.read('file.csv')

C CSV.open('file.csv', 'w') { |csv| csv << ['data'] }

D CSV.parse('data')

Use CSV.open with write mode and add rows with <<.

What type of object is each row when reading CSV with CSV.foreach?

A String

B Array

C Hash

D Integer

Each row is an array of values from the CSV line.

Which method reads CSV data from a string instead of a file?

A CSV.foreach

B CSV.read

C CSV.open

D CSV.parse

CSV.parse reads CSV data from a string.

Explain how to read a CSV file line by line in Ruby using the CSV library.

Think about how to open and process each line easily.

Describe the steps to write multiple rows of data to a CSV file in Ruby.

Consider how to open a file for writing and add rows one by one.