![read a filereturn a single line>> f.gets=> "aaa\n"return the whole file after current position>> f.read=> "aaa\nbbb\nccc"returns file as an array of lines>> f.readlines=> ["aaa\n", "bbb\n", "ccc"]](https://image.slidesharecdn.com/5filesio-100208132725-phpapp01/85/5-Files-Io-6-320.jpg)
![use any enumerable method>> f.map {|line| line.chomp + "... "}=> ["ddd... ", "eee... ", "fff4th letter to 6th... "]>> f.any? {|line| line =~ /ddd\n/ }=> false>> f.rewind=> 0>> f.any? {|line| line =~ /ddd\n/ }=> true](https://image.slidesharecdn.com/5filesio-100208132725-phpapp01/85/5-Files-Io-9-320.jpg)
![directories>> d = Dir.new("/Users/liahhansen/s/dir")=> #<Dir:/Users/liahhansen/s/dir>>> d.entries=> [".", "..", "abc.rb", "anothersubdir", "def.rb", "ghi.rb", "subdirectory"]](https://image.slidesharecdn.com/5filesio-100208132725-phpapp01/85/5-Files-Io-15-320.jpg)
![iterate over files in directory>> ruby_files = Dir["*.rb"]=> ["abc.rb", "def.rb", "ghi.rb"]>> ruby_files.map do |file| "rb_" + file end=> ["rb_abc.rb", "rb_def.rb", "rb_ghi.rb"]](https://image.slidesharecdn.com/5filesio-100208132725-phpapp01/85/5-Files-Io-17-320.jpg)
5 Files Io
- 2. IO: Input/OutputIO class is the basis for all input and output in RubyIO objects represent readable and/or writable connections to disk files, keyboards & screens File is a subclass of IO and allows for reading and writing files in ruby
- 3. common modes for opening I/O ports "r" Read-only, starts at beginning of file (default) "r+" Read-write, starts at beginning of file "w" Write-only, truncates existing file to zero length or creates a new file for writing "w+" Read-write, truncates existing file to zero length or creates a new file for reading and writing
- 4. open a fileCreating the file object opens the file: >> f = File.new("abc.rb")=> #<File:abc.rb>
- 5. open file – with a blockFile.open is synonomous with File.new, except that it can take a block:>> File.open(“abc.rb", "r+") do |f| f << "hello" end => #<File:abc.rb (closed)>
- 6. read a filereturn a single line>> f.gets=> "aaa\n"return the whole file after current position>> f.read=> "aaa\nbbb\nccc"returns file as an array of lines>> f.readlines=> ["aaa\n", "bbb\n", "ccc"]
- 7. position & rewind>> f.rewind=> 0>> f.pos=> 0>> f.gets=> "aaa\n">> f.pos=> 4
- 8. iterate over linesFile objects are enumerable:>> f.each {|line| puts line}aaabbbccc
- 9. use any enumerable method>> f.map {|line| line.chomp + "... "}=> ["ddd... ", "eee... ", "fff4th letter to 6th... "]>> f.any? {|line| line =~ /ddd\n/ }=> false>> f.rewind=> 0>> f.any? {|line| line =~ /ddd\n/ }=> true
- 10. write to a file“r+” argument>> g = File.new("def.rb", "r+")=> #<File:def.rb>>> g.read=> "ddd\neee\nfff">> g.puts "4th letter to 6th”>> g.rewind>> g.read=> "ddd\neee\nfff4th letter to 6th\n"
- 11. Exercise: Using gem faker to create test dataDirections:Create a yaml file with 50 fake names and addresses.Write spec
- 12. Make it passcreating test datasudo gem install faker>> require 'faker’>> Faker::Name.name=> "Matteo Kuhic">> Faker::Address.street_address=> "6413 Timmothy Brook">> Faker::Address.city=> "Gleichnerhaven">> Faker::Address.us_state=> "Florida">> Faker::Address.zip_code=> "40554-7199"
- 13. final product:name: Matteo Kuhic street_address: 6413 Timmothy Brook city: Gleichnerhaven state: Florida zip_code: 40554-7199
- 14. Live Codingmarkdown to textile conversion, with files
- 15. directories>> d = Dir.new("/Users/liahhansen/s/dir")=> #<Dir:/Users/liahhansen/s/dir>>> d.entries=> [".", "..", "abc.rb", "anothersubdir", "def.rb", "ghi.rb", "subdirectory"]
- 16. count files in directory>> i=0=> 0>> d.each {|x| i+=1; puts i}1234567
- 17. iterate over files in directory>> ruby_files = Dir["*.rb"]=> ["abc.rb", "def.rb", "ghi.rb"]>> ruby_files.map do |file| "rb_" + file end=> ["rb_abc.rb", "rb_def.rb", "rb_ghi.rb"]
- 18. HomeworkChapters:12Exercises:make index for directory