Reg EX
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The document discusses regular expressions (regex or regexp), which allow for matching and manipulation of textual data. It covers using regex to scan for patterns, replace parts of strings, and split strings. It also details regex syntax, characters that need escaping, and common regex patterns. Examples are provided for using regex with Ruby methods like .match, =~, .scan, .split, .gsub, and gsub with a block.
![CHARACTERS THAT NEED TO BE
ESCAPED
. | ( ) [ ] { } + ^ $ * ?](https://image.slidesharecdn.com/regex-110304182921-phpapp02/85/Reg-EX-6-320.jpg)
![REGEX BASICS
• [abc] A single character: a, b or c
• [^abc] Any single character but a, b, or c
• [a-z] Any single character in the range a-z
• [a-zA-Z] Any single character in the range a-z or A-Z
• ^ Start of line
• $ End of line
• A Start of string
• z End of string](https://image.slidesharecdn.com/regex-110304182921-phpapp02/85/Reg-EX-7-320.jpg)
![SCAN
>> numbers = "one two three"
=> "one two three"
>> numbers.scan(/w+/)
=> ["one", "two", "three”]](https://image.slidesharecdn.com/regex-110304182921-phpapp02/85/Reg-EX-12-320.jpg)
![SPLIT WITH REGULAR
EXPRESSIONS
>> "one twotthree".split(/s/)
=> ["one", ”two", "three"]](https://image.slidesharecdn.com/regex-110304182921-phpapp02/85/Reg-EX-13-320.jpg)
Reg EX
- 1. REGULAR EXPRESSIONS /regex will find me/
- 2. WHAT ARE REGULAR EXPRESSIONS • Regular expressions allow matching and manipulation of textual data. • Abbreviated as regex or regexp, or alternatively, just patterns
- 3. REGULAR EXPRESSIONS IN RUBY
- 4. USING REGULAR EXPRESSIONS • Scan a string for multiple occurrences of a pattern. • Replace part of a string with another string. • Split a string based on a matching separator.
- 5. REGULAR EXPRESSION SYNTAX • Regular expressions are put between two forward slashes (/match_me/) • They are escaped with a backward slash ().
- 6. CHARACTERS THAT NEED TO BE ESCAPED . | ( ) [ ] { } + ^ $ * ?
- 7. REGEX BASICS • [abc] A single character: a, b or c • [^abc] Any single character but a, b, or c • [a-z] Any single character in the range a-z • [a-zA-Z] Any single character in the range a-z or A-Z • ^ Start of line • $ End of line • A Start of string • z End of string
- 8. REGEX BASICS CONT... • . Any single character • s Any whitespace character • S Any non-whitespace character • d Any digit • D Any non-digit • w Any word character (letter, number, underscore) • W Any non-word character • b Any word boundary character
- 9. REGEX BASICS CONT... • (...) Capture everything enclosed • (a|b) a or b • a? Zero or one of a • a* Zero or more of a • a+ One or more of a • a{3} Exactly 3 of a • a{3,} 3 or more of a • a{3,6} Between 3 and 6 of a
- 10. REGEX: .MATCH >> category = "power tools" => "power tools" >> puts "on Sale" if category.match(/power tools/) on Sale >> puts "on Sale" if /power tools/.match(category) on Sale
- 11. REGEX: =~ >> category = "shoes" => "shoes" >> puts "15 % off" if category =~ /shoes/ 15 % off >> puts "15 % off" if /shoes/ =~ category 15 % off >> /pants/ =~ category => nil >> /shoes/ =~ category => 0 >> category = "women's shoes” >> /shoes/ =~ category => 8 8th character
- 12. SCAN >> numbers = "one two three" => "one two three" >> numbers.scan(/w+/) => ["one", "two", "three”]
- 13. SPLIT WITH REGULAR EXPRESSIONS >> "one twotthree".split(/s/) => ["one", ”two", "three"]
- 15. GSUB WITH A BLOCK "one twotthree".gsub(/(w+)/) do |w| puts w end one two three
- 16. TITLE CASE Capitalize All Words of a Sentence: >> full_name.gsub(/bw/){|s| s.upcase} => "Yukihiro Matsumoto"