IO

=begin
#gets语句在sublime不可运行，在Dos窗口可运行
puts "Enter a value :"
val = gets
puts val

putc "hello"    # h

#打开、关闭文件
file = File.new("filename","r")
     #...处理文件
file.close

#File.open方法与new类似，但不同点在于File.open可与块相联
File.open("filename","mode") do |aFile|
    #...处理文件
end
=end

File.open("e:\\test.txt","r") do |file|        # "r"可省略
    while line = file.gets
        puts line
    end
end

#读文件
file = File.open("e:\\test.txt","r")
if file
    content = file.sysread(20)
    puts content
else
    puts "can't open txt"
end

#写文件
file = File.open("e:\\test.txt","w")
if file
    file.syswrite("modif")
else
    puts "can't open txt"
end

#读到字符串里
str = IO.read("e:\\test.txt")
puts str

#读到数组里
arr = IO.readlines("e:\\test.txt")
puts arr[0]

#each_byte  可以迭代字符串中每个字符
File.open("e:\\test.txt","r") do |file|        
    file.each_byte {|ch| putc ch;print "."}
end

#foreach与块相关联,逐行返回输出，不像方法 readlines，方法 foreach 不是返回一个数组
IO.foreach("e:\\test.txt"){|block| puts block}