Ruby：从文件读取+文件类方法

Posted 2021-02-26

=begin
'r' = Read from start (it must exist beforehand)
'w' = Start a new file, Write from the start but destroys any existing data (very distructive) 
'a' = Append / Write from end
'r+' = Read and write without being destructive
 
 
#File.new( 'file_name.extension', 'r|w|a|r+|w+|a+' )
file = File.new( 'file_example.txt', 'w' )
 
#You must close to free up the resources
file.close
 
#Open a file, pass a block of instructions, and it will open and close on its own
File.open( 'file_example.txt', 'r') do |file|
  #Read data from the file
end
 
=end
 
file = File.new("file_example.txt", "w")
#Various ways to print to a file
file.puts "Ruby"
file.print "programing
"
file.write "is"
file << "fun"
#Close method is required to actually save 
file.close
 
File.open("file_example.txt", "r") do |file|
  #While there is a new line
  while line = file.gets
    puts "** " + line.chomp.reverse + " **"
  end
end
 
File.open("file_example.txt", "r") do |file|
  file.each_line { |line| puts line.upcase }
end
 
 
### More File class methods ###
 
file = "file_example.txt"
 
#See if this file exists
puts File.exist?(file)
#Is this a file? 
puts File.file?(file)
#IS this a directory?
puts File.directory?(file)
#Readable?
puts File.readable?(file)
#Writable?
puts File.writable?(file)
#Executable?
puts File.executable?(file)
#File Size?
puts File.size(file)
#Just get me what's in the ned
full_path =  File.expand_path(file) 
puts File.basename(full_path)
#Find the extension
puts File.extname(file)
#Last time it was accessed
puts File.atime(file)
#Last modified time
puts File.mtime(file)
#Last status change time.  Read/Write/Owner/Group/or Permissions
puts File.ctime(file)