file

• Ruby’s File.readlines method can be used in most common situations as a replacement for PHP’s file function.

  PHP

  $lines = file('/path/to/foobar');
  var_export($lines);
   
  // => array(0 => 'hello\n', 1 => 'there')

  Ruby

  lines = File.readlines('/path/to/foobar')
  p lines
   
  # => ['hello\n', 'there']

  Notice above that both PHP’s file function and Ruby’s File.readlines method both return the line separators at the end of each array element. The file function has a second optional argument, flags, that accepts constants like FILE_IGNORE_NEW_LINES. In Ruby, you’ll need to do this filtering yourself.

  A second important difference is that File.readlines has a second optional argument, separator, that defaults to \n. This is quite different from PHP, where PHP determines the separator based on the operating system or the auto_detect_line_endings runtime configuration option.

  Iterating Over Lines

  Often times you want to iterate over each line in a file and perform an operation using the line. You can use Ruby’s File.readlines to read the lines into an array and then iterate over that array. However, this can be costly when working with large files.

  A better solution for these circumstances is to open a File instance and then pass a block to the each_line method.

  Ruby

  File.open('/path/to/foobar') do |file|
   
    file.each_line do |line|
      puts line
    end
   
  end

  The snippet above will only read one line of the file into memory at a time, whereas File.readlines will load the entire file into an array.

  see also

  • readfile
  • fopen
  • fsockopen
  • popen
  • file_get_contents
  • include
  • stream_context_create

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