Regular Expressions Basics Lesson for Ada Academy

Transcript

1. REGULAR EXPRESSIONS Nell Shamrell @nellshamrell
2. What is a regular expression? It’s a pattern.
3. How do you make a regular expression? /RegularExpression/
4. What can you do with a regular expression?
5. Test Extract Change
6. Test Extract Change
7. Test Extract Change
8. Testing a String
9. “Use the force”
10. /force/ “Use the force”
11. =~
12. /force/ =~ “Use the force”
13. “Use the force” =~ /force/
14. /force/ =~ “Use the force” => 8
15. /dark side/ !~ “Use the force”
16. /dark side/ !~ “Use the force” => true
17. MatchData
18. match
19. string = “The force will be with you always.”
20. string = “The force will be with you always.” m = /force/.match(string)
21. string = “The force will be with you always.” m = /force/.match(string) => #<MatchData “force” >
22. What can you do with MatchData?
23. m = /force/.match(string)
24. m = /force/.match(string) m.to_s
25. m = /force/.match(string) m.to_s => “force”
26. m = /force/.match(string)
27. m = /force/.match(string) m.pre_match
28. m = /force/.match(string) m.pre_match => “The ”
29. m = /force/.match(string)
30. m = /force/.match(string) m.post_match
31. m = /force/.match(string) m.post_match => “ will be with you always ”
32. Email Validation
33. thing@thing.thing
34. Rubular
35. Alternation /nell | renee /
36. . * any single character character can appear any number of times
37. /.*/ Matches ANYTHING
38. Range [a-d] [1-4]
39. \w stands for any word character same as [a-zA-Z0-9_]
40. + character must appear one or more times
42. Extracting Strings
43. \d stands for any digit same as [0-9]
44. \d{3} looks for exactly 3 digits
45. ? makes a character optional
46. Changing a String
47. string = “Renee is presenting to the class right now. Renee is presenting on regular expressions.”
48. sub(/regex/, “text”)
49. string = “Renee is presenting to the class right now. Renee is presenting on regular expressions.”
50. string = “Renee is presenting to the class right now. Renee is presenting on regular expressions.” new = string.sub(/Renee/, “Nell”)
51. new = string.sub(/Renee/, “Nell”) => “Nell is presenting to the class right now. Renee is presenting on regular expressions.”
52. gsub(/regex/, “text”)
53. new = string.gsub(/Renee/, “Nell”)
54. => “Nell is presenting to the class right now. Nell is presenting on regular expressions.” new = string.gsub(/Renee/, “Nell”)
55. string.gsub!(/Renee/, “Nell”)
56. Welcome to the world of regular expressions!
57. https://gist.github.com/ nellshamrell/6938008 Resources
58. Contact Info Nell Shamrell @nellshamrell nellshamrell@gmail.com