re = /(?i)\b([\w]{3}(?=[\w]*;))/m
str = 'd;dd;abc;def;ghi;jkl;ff,sd;cv;s;asdfasdf;s;asdf;asdfasdfad;trhegdas;sd;'
# Print the match result
str.scan(re) do |match|
puts match.to_s
end
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html