IRB for interactive exploration in Ruby - Step-by-Step Execution

Concept Flow - IRB for interactive exploration

Start IRB

↓

Prompt user input

↓

Evaluate input code

↓

Display result

↓

Wait for next input

Loop back to Prompt user input↓

Exit IRB on command

↩Loop back to Prompt user input

IRB starts and waits for your code input, runs it, shows the result, then waits again until you exit.

Execution Sample

Ruby

irb(main):001:0> 2 + 3
=> 5
irb(main):002:0> puts 'Hi!'
Hi!
=> nil

This shows typing code in IRB, it runs and shows the output immediately.

Execution Table

Step	User Input	Evaluation	Output	Next Action
1	2 + 3	Calculate sum	5	Prompt next input
2	puts 'Hi!'	Print string	Hi!	Prompt next input
3	exit	Exit command	Session ends	Stop IRB

💡 User types 'exit' to end the IRB session

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
_ (last result)	nil	5	nil	nil

Key Moments - 3 Insights

Why does IRB show '=> 5' after I type '2 + 3'?

IRB evaluates your expression and shows the result with '=>'. This is shown in execution_table step 1 under Output.

Why does 'puts' print output but return nil?

'puts' prints text to the screen but returns nil, so IRB shows 'Hi!' as output and '=> nil' as the return value, seen in execution_table step 2.

How do I stop IRB?

Typing 'exit' or pressing Ctrl+D ends the session, as shown in execution_table step 3.

Visual Quiz - 3 Questions

Look at the execution table, what is the output after step 1?

A nil

B 2 + 3

C 5

D Hi!

💡 Hint

Check the Output column in execution_table row 1

At which step does IRB stop running?

A Step 3

B Step 2

C Step 1

D Never stops

💡 Hint

Look at the Next Action column in execution_table

If you type 'puts "Hello"' in IRB, what will the return value be?

A "Hello"

B nil

C puts

D Error

💡 Hint

See execution_table step 2 and variable_tracker for 'puts' behavior

Concept Snapshot

IRB lets you type Ruby code and see results instantly.
Type code, press Enter, see output with '=>'.
Use 'exit' to leave IRB.
Useful for quick testing and learning Ruby.

Full Transcript

IRB is an interactive Ruby shell. You start it and get a prompt. You type Ruby code, press Enter, and IRB runs it immediately. It shows the result with a '=>' sign. For example, typing '2 + 3' shows '=> 5'. If you use 'puts', it prints text but returns nil, so IRB shows the printed text and then '=> nil'. You keep typing commands and seeing results until you type 'exit' to stop IRB. This makes it easy to explore Ruby code step by step.