Printing lines of a file in ruby

Question

I have literally just started using Ruby, and I'm looking for a possible alternative to using "gets" for file input... I'm trying to write a simple warmup program that will print out the longest line of a file, like so:

def findMax
  maxlength = 0

  while line = gets

    if line.length > maxlength then      
      maxlength = line.length
    end

  end

  return maxlength

end


def printLines num
  while line = gets
    if line.length == num
      puts line
    end
  end
end


printLines findMax

Pretty simple. Find the maximum length, and the use that to print out the longest line, nothing fancy yet. However, whenever I run it with ruby longest.rb < (file) , I get nothing. Is this because I can't use gets in the second while loop because it has nothing more to read? What can I do as an alternative? :)

Answer 1

假设您的文件名为foo.txt使用File#readlines将File#readlines所有行读取到数组中，然后使用Enumerable#sort_by按行的size （或length ）对行进行排序，并使用Array#last来选择排序后的最后一项排列

File.readlines("foo.txt").sort_by { |line| line.size }.last