#建立一個222.rb文件并且輸入字符
file = File.open("222.rb","w+")
file.puts "123\nwadwa\n12124124\ndwdw"
file.close


#輸出222.rb的內容
File.open("222.rb","r+") do |file|
while line = file.gets
puts line
end
end


#直接用IO操作文件
IO.foreach("222.rb") do |line|
puts line if line =~/abc/ #輸出匹配到了'abc'的所在行
puts line if line !~/qwe/ #輸出沒有匹配到'qwe'的所在行
end



#輸出文件的絕對路徑
puts File.expand_path("222.rb")


#count chars from a file
file= File.new("222.rb")
w_count = 0
file.each_byte do |byte|
w_count += 1 if byte ==?1
end
puts "#{w_count}"


#create new file and write some words there
print "The file now is exist? --> " 
puts File.exist?("asd.txt")#判斷文件是否存在

file= File.new("asd.txt","w")
print "The file now is exist? --> " 
puts File.exist?("asd.txt")

file.write("hehe\nhahah")


#io.stream operation
require 'stringio'
ios = StringIO.new("abcdef\n ABC \n 12345")
ios.seek(5) #把偏移指針移到5（e字母所在位置）
ios.puts("xyz3") #從5開始覆寫原有數據
puts ios.tell #tell--Returns the current offset (in bytes) of ios. 
puts ios.string
puts ios.string.dump #忽略\n的轉義


#another example
require 'stringio'
ios = StringIO.new("abcdef\nq9ert \n 12345")
ios.seek(3)
ios.ungetc(?w) #replace the char at index 3
puts "Ptr = #{ios.tell}"
s1 = ios.gets #filte the "\n" 
s2 = ios.gets
puts s1
puts s2


#Ruby打開文件并寫入數據操作
txt = File.open("文件路徑","w+")
txt.puts '要寫入的文件內容'
txt.close
#從文件里讀取數據
num = File.readlines("文件路徑")[0].chomp
#打開文件的方法
system("notepad 文件路徑")