RUBY文件读写

11.读写

    标准输入流：gets 读文件 

              File.open("hello.rb","r") do |file|

               while line  = file.gets

                   puts line #打印出文件内容

               end

             end

    标准输出流：puts
    print
    两者的区别是puts会在参数后面添加回车换行，print不会添加
    printf("Number:%5.2f,\nString:%s\n",1.23,"hello") 这个语法跟c相同就不多说了
    %5.2f  匹配  1.23

    %s  匹配字符串

1.先写段代码看看    #p1    myFile = File.new("f:\\ruby\\mycode\\hello.rb","w");    myFile.puts "puts 'aa'"    myFile.puts "puts 'bb'"    myFile.close #只有close掉了内容才被写入文件里面。    windows中路径 "\\"        文件hello.rb写入上面两行代码    创建文件：File.new("hello.rb","w")    删除文件：File.delete("")    读取文件：File.open("hello.rb","r") do |file|                while line = file.gets   #标准输入流                   puts line                end              end    #读文件    print "Please input a file name:"    filename = gets    if filename &&!filename.empty?#文件存在        filename = filename[0,filename.length-1]        #去掉文件名后面的"\n"    else        print "the file name can't be null!"        exit(1)    end        if File.exist?(filename)        puts "=========#{filename}========="        File.open(filename,"r") do |file|             while line = file.gets                puts line             end        end        puts "=================="    else        puts "the program can't find the file #{filename}"    end    print "Press any key to contiue..."    gets            #写文件    puts "======================================"    puts "This program is about Ruby write file."    puts "======================================"    print "Please input file name: "    filename=gets    if filename&&!filename.empty?        filename=filename[0, filename.length-1]    else        puts "The file name can't been null!!"        exit 1;    end    file=nil    unless File.exist?(filename)#条件不成立的时候执行       puts "The system cannot find the file specified!"       print "[C] to create a new file and [E] to exit the program: "       option=gets       if option&&!option.empty?          option=option.chomp#去掉"\n"       else          puts "bye!"          exit 1;       end       case option.downcase       when "c" : file=File.new(filename, "w")       when "e" : exit 0       else          puts "Invalid arguments!! The program has stop. "          exit 0       end    else        file=File.new(filename, "w")    end    print "Now please input content: "    content=gets    file.print content    file.close    print "Press any key to continue...."    gets