Question

我无法理解这段代码是如何工作的，该程序能够读取文件，但最终多次打印同一行。

输出：

Track title is: c/music/1

Track file location is: c/music/1

Track title is: c/music/2 

Track file location is: c/music/2

Track title is: c/music/3

Track file location is: c/music/3

预期输出：

Track title is: Taco

Track file location is: c/music/1

Track title is: Burrito 

Track file location is: c/music/2

Track title is: Nacho

Track file location is: c/music/3

代码：

class Track
    attr_accessor :title, :file_location
end

def read_tracks music_file

    count = music_file.gets().to_i
  tracks = Array.new
  $i = 0

  while $i < count do
  track = read_track(music_file)
  tracks << track
  $i += 1
  end
    tracks
end


def read_track aFile

  track_title = aFile.gets
  track_file_location = aFile.gets
  track = Track.new
  track.title = track_title
  track.file_location = track_file_location

end



def print_tracks tracks
  $i = 0
  while $i < tracks.length do
    print_track(tracks)
    $i += 1
  end

end


def print_track tracks
  puts('Track title is: ' + tracks[$i].to_s)
    puts('Track file location is: ' + tracks[$i].to_s)
end


def main
  aFile = File.new("input.txt", "r") 
  if aFile  
    tracks = read_tracks(aFile)
    aFile.close
  else
    puts "Unable to open file to read!"
  end

  print_tracks(tracks)
end

main

输入文件示例：

5

Taco

c/music/1

Burrito

c/music/2

Nacho

c/music/3

Answer 1

尝试一下，将行处理为数组，然后对其进行处理：

lines = File.readlines('tracks.txt') # reads lines into array
lines.reject! { |e| e == "\n" } # removes empti lines
total_tracks = lines.shift.chomp.to_i # extract the first line from the array
lines.each_slice(2) { |e| puts e } # lines now contains only the pair track/directory
# adapt at your will

有关each_slice(2)的信息，请参见Enumerable#each_slice，它将数组中的元素分组。

Answer 2

问题出在方法 print_tracks 和 print_track 中。
这些方法应如下所示：

def print_tracks tracks
  $i = 0
  while $i < tracks.length do
    print_track(tracks[$i])
    $i += 1
  end    
end


def print_track track
  puts('Track title is: ' + track.title.to_s)
    puts('Track file location is: ' + track.file_location.to_s)
end

但是，如果您想使代码更好，请尝试如下操作：

def print_tracks(tracks)
  tracks.each do |track|
    puts "Track title is: #{track.title}"
    puts "Track file location is: #{track.file_location}"
    puts
  end
end

在这种情况下，整个代码将是：

class Track
  attr_accessor :title, :file_location
end

def read_tracks music_file
  count = music_file.gets().to_i
  tracks = Array.new
  i = 0

  while i < count do
    track = read_track(music_file)
    tracks << track
    i += 1
  end

  tracks
end

def read_track aFile
  track = Track.new
  track.title = aFile.gets
  track.file_location = aFile.gets
  track
end

def print_tracks(tracks)
  tracks.each do |track|
    puts "Track title is: #{track.title}"
    puts "Track file location is: #{track.file_location}"
    puts
  end
end

def main
  aFile = File.new("input.txt", "r").
  if aFile..
    tracks = read_tracks(aFile)
    aFile.close
  else
    puts "Unable to open file to read!"
  end

  print_tracks(tracks)
end

main

我已经使用示例文件input.txt测试了此代码：

3
Taco
c/music/1
Burrito
c/music/2
Nacho
c/music/3

我有输出：

Track title is: Taco
Track file location is: c/music/1

Track title is: Burrito
Track file location is: c/music/2

Track title is: Nacho
Track file location is: c/music/3

这正是您所期望的！

Ruby文件处理，读取后存储为数组

2 个答案: