#349 Ruby File Handling
Reviewing common file operations with ruby
Notes
Create and Write to File
Use either
File.new
or
File.open
File.newopens the file at the given path according to the given mode; creates and returns a new File object for that file.File.openusesFile.newbut also accepts a block
Examples:
f = File.new(filename, 'w')
f.write 'content'
f.close
# or
File.open(filename, 'w') do |f|
f.write 'content'
end
Read File
Files support IO#read
to read the content.
Example:
content = File.read(filename)
# or
f = File.open('t.txt')
content = f.read
Append to File
Use the append mode when opening the file
Example:
File.open('t.txt', 'a') do |file|
file.write(content)
end
Delete File
Use File.delete
aliased to File.unlink:
File.delete('t.txt')
Example
See example.rb
#!/usr/bin/env ruby
def create_file_new(filename, content)
puts "# creating file using File.new: #{filename}"
f = File.new(filename, 'w')
f.write(content)
f.close
end
def create_file_open(filename, content)
puts "# creating file using File.open: #{filename}"
File.open(filename, 'w') do |file|
file.write(content)
end
end
def append_to_file(filename, content)
puts "# appending to file: #{filename}"
File.open(filename, 'a') do |file|
file.write(content)
end
end
def read_file(filename)
puts "# reading file: #{filename}"
File.read(filename)
end
def delete_file(filename)
puts "# deleting file: #{filename}"
File.delete(filename)
end
filename = 'example.txt'
create_file_new(filename, "Using File.new: Hello World!\n")
puts read_file(filename)
create_file_open(filename, "Using File.open: Hello World!\n")
puts read_file(filename)
append_to_file(filename, "Appended content to the file.\n")
puts read_file(filename)
delete_file(filename)
Run:
$ ruby example.rb
# creating file using File.new: example.txt
# reading file: example.txt
Using File.new: Hello World!
# creating file using File.open: example.txt
# reading file: example.txt
Using File.open: Hello World!
# appending to file: example.txt
# reading file: example.txt
Using File.open: Hello World!
Appended content to the file.
# deleting file: example.txt