如何在ruby中输出循环到文本文件？

Question

我已经搜索了很多，大多数与此相关的文章都是关于php和python的。然而他们实际上并没有回答我的问题。当我打开文本文件时，我想看看那里的输出。我已经尝试过以下方法。代码运行时没有错误，但没有输出到文件“filename”。

def this()
  i = 0
  until i>=20
    i += 1
    next unless (i%2)==1
    puts i
  end
end 

filename = ARGV
script = $0
that = puts this
txt = File.open(filename,'w')
txt.write(that)
txt.close()*

Answer 1

def this(file)
  i = 0
  until i>=20
    i += 1
    next unless (i%2)==1
    # Normally 'puts' writes to the standard output stream (STDOUT)
    # which appears on the terminal, but it can also write directly
    # to a file ...
    file.puts i
  end
end

# Get the file name from the command line argument list. Note that ARGV
# is an array, so we need to specify that we want the first element
filename = ARGV[0]

# Open file for writing
File.open(filename, 'w') do |file|
  # call the method, passing in the file object
  this(file)
  # file is automatically closed when block is done
end

Answer 2

我认为你的代码序列有点不对劲。

你应该改为;

1. 做你想做的事，例如处理ARGV（这一步没问题）
2. 打开文件 - 这会返回文件处理程序
3. 将文件处理程序传递给this函数
4. 撰写内容
5. 关闭文件

示例：

def this(file)
  i = 0
  until i>=20
    i += 1
    next unless (i%2)==1
    file.puts(i)
  end
end 

# Main
begin
  file = File.open('hello.txt','w')
  this(file)
rescue IOError => e
  puts "oops"
ensure 
  file.close()
end

<强>输出：

  

1
  3
  5
  7
  9
  11
  13
  15
  17
  19

您还应该捕获潜在的IO错误，这是一种相当常见的做法。