Debugging with pry and byebug in Ruby

Introduction

Debugging helps you find and fix mistakes in your code. Pry and Byebug let you pause your program and look inside to understand what is happening.

When your program is not working as expected and you want to see the values of variables step-by-step.

When you want to stop your program at a certain line to check what is going on.

When you want to try out code commands inside your program while it is paused.

When you want to understand why a loop or condition is not behaving correctly.

When you want to learn how your code flows by moving through it slowly.

Syntax

Ruby

require 'pry'

# Insert this line where you want to pause
binding.pry

# For byebug
require 'byebug'

# Insert this line where you want to pause
byebug

Use binding.pry or byebug inside your code where you want to pause.

Make sure you have installed the gems pry and byebug before using them.

Examples

This pauses the program before adding x and y. You can check the values of x and y in the Pry console.

Ruby

require 'pry'

x = 10
y = 20
binding.pry
sum = x + y
puts sum

This pauses inside the greet method so you can see the value of name before printing.

Ruby

require 'byebug'

def greet(name)
  byebug
  puts "Hello, #{name}!"
end

greet('Alice')

Sample Program

This program pauses inside the loop for each number. You can check the value of num before it prints double the number.

Ruby

require 'pry'

numbers = [1, 2, 3]

numbers.each do |num|
  binding.pry
  puts num * 2
end

Important Notes

When the program pauses, you can type variable names to see their values.

Type continue or c to resume the program after pausing.

Use debugging to learn and fix problems step-by-step, not just to find errors.

Summary

Debugging with Pry and Byebug lets you pause and explore your code while it runs.

Insert binding.pry or byebug where you want to stop and check variables.

This helps you understand your code better and fix mistakes easily.