Match operator (=~) in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Ruby code using =~?

Consider the following Ruby code snippet. What will it print?

Ruby

text = "hello world"
pattern = /world/
puts text =~ pattern

A nil

B true

C 6

D false

💡 Hint

The =~ operator returns the index of the first match or nil if no match.

The string "hello world" contains "world" starting at index 6, so text =~ /world/ returns 6.

❓ Predict Output

intermediate

What does this =~ expression return when no match?

What is the output of this Ruby code?

Ruby

text = "goodbye"
pattern = /hello/
puts text =~ pattern

A 0

B -1

C false

D nil

💡 Hint

If the pattern is not found, =~ returns nil.

Since "hello" is not in "goodbye", text =~ /hello/ returns nil.

🔧 Debug

advanced

Why does this =~ expression cause an error?

Look at this Ruby code. Why does it raise an error?

Ruby

text = nil
pattern = /test/
puts text =~ pattern

A NoMethodError because nil does not support =~

B SyntaxError due to missing quotes

C Returns nil because no match

D Returns false because nil is falsey

💡 Hint

Only strings or objects that implement =~ can use it.

Calling =~ on nil causes NoMethodError since nil does not have this method.

🧠 Conceptual

advanced

What is the value of 'index' after this code runs?

Given this Ruby code, what is the value of the variable index?

Ruby

index = "abracadabra" =~ /cad/

A 4

B nil

C 3

D 0

💡 Hint

Count characters starting at 0 to find where "cad" starts.

"abracadabra" has "cad" starting at index 4, so index is 4.

❓ Predict Output

expert

What is the output of this complex =~ usage?

What does this Ruby code print?

Ruby

text = "123abc456"
pattern = /\d{3}(?<letters>[a-z]{3})\d{3}/
match_pos = text =~ pattern
letters = $~[:letters]
puts "Position: #{match_pos}, Letters: #{letters}"

A Position: nil, Letters: abc

B Position: 0, Letters: abc

C Position: 0, Letters: nil

D Position: 3, Letters: abc

💡 Hint

The =~ operator sets the global match variable $~ with named captures.

The pattern matches starting at index 0. The named group 'letters' captures "abc". So output is "Position: 0, Letters: abc".