Ruby Cookbook

Recipe 1.1. Building a String from Parts Problem You want to iterate over a data structure, building a string from it as you do. Solution There are two efficient solutions. The simplest solution is to start with an empty string, a...

Recipe 1.2. Substituting Variables into Strings Problem You want to create a string that contains a representation of a Ruby variable or expression. Solution Within the string, enclose the variable or expression in curly bracket...

Recipe 1.3. Substituting Variables into an Existing String Problem You want to create a string that contains Ruby expressions or variable substitutions, without actually performing the substitutions. You plan to substitute values into the strin...

Recipe 1.4. Reversing a String by Words or Characters Problem The letters (or words) of your string are in the wrong order. Solution To create a new string that contains a reversed version of your original string, use the revers...

Recipe 1.5. Representing Unprintable Characters Problem You need to make reference to a control character, a strange UTF-8 character, or some other character that's not on your keyboard. Solution Ruby gives you a number of escaping m...

Recipe 1.6. Converting Between Characters and Values Problem You want to see the ASCII code for a character, or transform an ASCII code into a string. Solution To see the ASCII code for a specific character as an integer, use th...

Recipe 1.7. Converting Between Strings and Symbols Problem You want to get a string containing the label of a Ruby symbol, or get the Ruby symbol that corresponds to a given string. Solution To turn a symbol into a string, use ...

Recipe 1.8. Processing a String One Character at a Time Problem You want to process each character of a string individually. Solution If you're processing an ASCII document, then each byte corresponds to one character. Use String#each_byt...

Recipe 1.9. Processing a String One Word at a Time Problem You want to split a piece of text into words, and operate on each word. Solution First decide what you mean by "word." What separates one word from another? Only whitespace? Wh...

Recipe 1.10. Changing the Case of a String Problem Your string is in the wrong case, or no particular case at all. Solution The String class provides a variety of case-shifting methods: s = 'HELLO, I am not here. I WENT to tHe Ma...

Recipe 1.11. Managing Whitespace Problem Your string contains too much whitespace, not enough whitespace, or the wrong kind of whitespace. Solution Use strip to remove whitespace from the beginning and end of a string: " \tWhi...

Recipe 1.12. Testing Whether an Object Is String-Like Problem You want to see whether you can treat an object as a string. Solution Check whether the object defines the to_str method. 'A string'.respond_to? :to_str # => t...

Recipe 1.13. Getting the Parts of a String You Want Problem You want only certain pieces of a string. Solution To get a substring of a string, call its slice method, or use the array index operator (that is, call the [] method). Either...

Recipe 1.14. Handling International Encodings Problem You need to handle strings that contain nonASCII characters: probably Unicode characters encoded in UTF-8. Solution To use Unicode in Ruby, simply add the following to the begi...

Recipe 1.15. Word-Wrapping Lines of Text Problem You want to turn a string full of miscellaneous whitespace into a string formatted with linebreaks at appropriate intervals, so that the text can be displayed in a window or sent as an email...

Recipe 1.16. Generating a Succession of Strings Problem You want to iterate over a series of alphabetically-increasing strings as you would over a series of numbers. Solution If you know both the start and end points of your successi...

Recipe 1.17. Matching Strings with Regular Expressions Problem You want to know whether or not a string matches a certain pattern. Solution You can usually describe the pattern as a regular expression. The =~ operator tests a string ag...

Recipe 1.18. Replacing Multiple Patterns in a Single Pass Problem You want to perform multiple, simultaneous search-and-replace operations on a string. Solution Use the Regexp.union method to aggregate the regular expressions you want ...