I want to add newline character below. But the result is wrong. Teach me what is wrong.
test.txt(before)
------------------
2014-09
2014-10
2014-11
------------------
test.txt(after)
------------------
2014-09
2014-10
2014-11
------------------
I make a ruby script below, but the result is wrong.
f = File.open("test.txt","r+")
f.each{|line|
if line.include?("2014-10")
f.puts nil
end
}
f.close
the result
------------------
2014-09
2014-10
014-11
------------------
Reading and writing a file at the same time can get messy, same thing with other data structures like arrays. You should build a new file as you go along.
Some notes:
File.open because it will stop you from forgetting to call f.closeputs nil is the same as puts without argumentsdo ... end instead of { ... } for multi-line blocksFile.open(...).each can be replaced with File.foreachStringIO object which will respond to puts etc.Example:
require 'stringio'
file = 'test.txt'
output = StringIO.new
File.foreach(file) do |line|
if line.include? '2014-10'
output.puts
else
output << line
end
end
output.rewind
File.open(file, 'w') do |f|
f.write output.read
end
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