Maintenance Ruby 3.3 gets fixes, but no new features. Switch to Ruby 4.0 →
IO#readlines
static VALUE
rb_io_readlines(int argc, VALUE *argv, VALUE io)
{
struct getline_arg args;
prepare_getline_args(argc, argv, &args, io);
return io_readlines(&args, io);
}
Reads and returns all remaining line from the stream; does not modify $_. See Line IO.
With no arguments given, returns lines as determined by line separator $/, or nil if none:
f = File.new('t.txt') f.readlines # => ["First line\n", "Second line\n", "\n", "Fourth line\n", "Fifth line\n"] f.readlines # => [] f.close
With only string argument sep given, returns lines as determined by line separator sep, or nil if none; see Line Separator:
f = File.new('t.txt') f.readlines('li') # => ["First li", "ne\nSecond li", "ne\n\nFourth li", "ne\nFifth li", "ne\n"] f.close
The two special values for sep are honored:
f = File.new('t.txt') # Get all into one string. f.readlines(nil) # => ["First line\nSecond line\n\nFourth line\nFifth line\n"] # Get paragraphs (up to two line separators). f.rewind f.readlines('') # => ["First line\nSecond line\n\n", "Fourth line\nFifth line\n"] f.close
With only integer argument limit given, limits the number of bytes in each line; see Line Limit:
f = File.new('t.txt') f.readlines(8) # => ["First li", "ne\n", "Second l", "ine\n", "\n", "Fourth l", "ine\n", "Fifth li", "ne\n"] f.close
With arguments sep and limit given, combines the two behaviors:
-
Returns lines as determined by line separator
sep. -
But returns no more bytes in a line than are allowed by the limit.
Optional keyword argument chomp specifies whether line separators are to be omitted:
f = File.new('t.txt') f.readlines(chomp: true) # => ["First line", "Second line", "", "Fourth line", "Fifth line"] f.close