Scan for all matches in Ruby - Step-by-Step Execution

Concept Flow - Scan for all matches

Start with string

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Apply scan method

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Find all matches

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Return array of matches

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Use matches as needed

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End

The scan method looks through the whole string and collects all parts that match a pattern, returning them as an array.

Execution Sample

Ruby

text = "I have 2 apples and 3 bananas"
numbers = text.scan(/\d+/)
puts numbers.inspect

This code finds all numbers in the text and prints them as an array.

Execution Table

Step	Action	Pattern Matched	Matches Found	Result
1	Start with string			"I have 2 apples and 3 bananas"
2	Apply scan with /\d+/	\d+	1	["2"]
3	Continue scan	\d+	2	["2", "3"]
4	No more matches			["2", "3"]
5	Return matches array			["2", "3"]

💡 No more matches found, scan ends and returns array of all matches.

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
text	"I have 2 apples and 3 bananas"	"I have 2 apples and 3 bananas"	"I have 2 apples and 3 bananas"	"I have 2 apples and 3 bananas"
numbers	nil	["2"]	["2", "3"]	["2", "3"]

Key Moments - 2 Insights

Why does scan return an array even if only one match is found?

Because scan always collects all matches into an array, even if there is only one match, as shown in rows 2 and 3 of the execution_table.

What happens if the pattern matches nothing in the string?

Scan returns an empty array, since no matches are found. This is implied in the exit_note when no matches remain.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'numbers' after step 3?

A ["2", "3"]

B ["3"]

C ["2"]

D nil

💡 Hint

Check the 'Matches Found' and 'Result' columns at step 3 in the execution_table.

At which step does scan find the first match?

A Step 4

B Step 1

C Step 2

D Step 5

💡 Hint

Look at the 'Pattern Matched' and 'Matches Found' columns in the execution_table.

If the string had no digits, what would 'numbers' be after scan?

A nil

B An empty array []

C Array with one empty string [""]

D The original string

💡 Hint

Refer to the key_moments answer about what happens when no matches are found.

Concept Snapshot

Ruby's scan method searches a string for all parts matching a pattern.
It returns an array of all matches found.
If no matches, it returns an empty array.
Useful to extract multiple pieces like numbers or words.
Syntax: string.scan(/pattern/)
Example: "abc123".scan(/\d+/) => ["123"]

Full Transcript

This visual execution shows how Ruby's scan method works step-by-step. Starting with a string, scan looks for all parts matching a pattern. Each match is collected into an array. The example finds all numbers in the string "I have 2 apples and 3 bananas". First, it finds "2", then "3", and then stops when no more matches remain. The variable 'numbers' changes from nil to an array containing the matches. Scan always returns an array, even if only one match is found or none at all. This helps extract multiple pieces of information from text easily.