Match method and MatchData in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the match method do in Ruby?

The match method searches a string for a pattern using a regular expression and returns a MatchData object if it finds a match, or nil if it doesn't.

beginner

What is a MatchData object in Ruby?

A MatchData object holds details about the match found by the match method, including the matched string, captured groups, and position of the match.

intermediate

How can you access the entire matched string from a MatchData object?

You can use match_data[0] or match_data.to_s to get the full matched string from a MatchData object.

intermediate

What does match_data[1] return?

It returns the first captured group from the match, which is the part of the string matched inside the first set of parentheses in the regular expression.

beginner

What will "hello123".match(/(\d+)/) return?

It returns a MatchData object representing the digits "123" found in the string. You can access it with match_data[0] or match_data[1].

What does Ruby's match method return if no match is found?

A An empty MatchData object

B An empty string

C false

D nil

If the pattern is not found, match returns nil.

How do you get the first captured group from a MatchData object named m?

A m[0]

B m.group(0)

C m[1]

D m.first

m[1] returns the first captured group; m[0] is the entire match.

Which of these is true about MatchData?

A It stores the matched string and captured groups

B It is a string

C It is returned by <code>String#split</code>

D It is a boolean value

MatchData holds details about the match, including captured groups.

What does "abc123".match(/(\d+)/)[0] return?

A "123"

B "abc"

C nil

D "abc123"

It returns the matched digits "123" as a string.

If you want to check if a string contains digits using match, what should you check?

A If <code>match</code> returns an empty string

B If <code>match</code> returns a <code>MatchData</code> object

C If <code>match</code> returns false

D If <code>match</code> returns zero

A MatchData object means a match was found; nil means no match.

Explain how the match method works in Ruby and what kind of object it returns.

Think about what happens when you look for a pattern in a string.

Describe how to use a MatchData object to get the full matched string and captured groups.

Remember the numbering starts at zero for the full match.