Ruby笔记

1.数组遍历方法总结

(1)

    array = (1..10).to_a 

(2)

    length = array.length 
    length.times do t 
    print "#{array[t]} " 
    end 
    puts "n" 

(3)

    length = array.length-1 
    for i in 0..length do 
    print "#{array[i]} " 
    end 
    puts "n" 

(4)
Ruby for i in array do print "#{i} " end puts "n"Ruby

(5)

    array.each{x print x," "} 
    puts "n" 

(6)

    length = array.length 
    i = 0 
    while i< length do 
    print "#{array[i]} " 
    i = i+1 
    end 
    puts "n" 

(7)

    length = array.length 
    i = 0 
    until i==length do 
    print "#{array[i]} " 
    i += 1 
    end 
    puts "n" 

(8)

    array.each_index do i 
    print "#{array[i]} " 

2.Ruby连接数据库
(1).mysql

    require 'mysql'  
    begin  
        db = Mysql.init  
        db.options(Mysql::SET_CHARSET_NAME, 'utf8')  
        db = Mysql.real_connect("127.0.0.1", "root", "123456", "test", 3306)  
        db.query("SET NAMES utf8")
        db.query("drop table if exists tb_test")  
        db.query("create table tb_test (id int,
        text LONGTEXT) ENGINE=MyISAM DEFAULT CHARSET=utf8")  
        db.query("insert into tb_test (id, text) values ( 
        1,'first line'),(2,'second line')")  
        printf "%d rows were inserted\n",db.affected_rows  
        rslt = db.query("select text from tb_test")  
        while row = rslt.fetch_row do  
            puts row[0]  
        end  
    rescue Mysql::Error => e  
            puts "Error code: #{e.errno}"  
            puts "Error message: #{e.error}"  
            puts "Error SQLSTATE: #{e.sqlstate}" if e.respond_to?("sqlstate")  
    ensure  
            db.close if db  
    end  

(2).redis

    #!/bin/ruby
    
    require 'redis'
    
    def writeToFile(file,content)
        fp = File.new(file,"a+") 
        if fp
            fp.syswrite(content)
        else
            puts "..."
        end
    end
    
    def connect(host)
        redis = Redis.new(:host => host,:port => 6379)
        redis.info.keys.each do |key|
            puts "#{key}:\t"+redis.info["#{key}"]
        end
    end
    
    connect("1.1.1.1")

(3).sqlite3

    require 'sqlite3'
    
    db = SQLite3::Database.new('test.db')
    
    db.execute("create table test(
                    ID integet not null,
                    Username varchar(20) null,
                    Password varchar(64) null)")
    db.execute("insert into test(ID.Username,Password) 
        values('0','admin','admin')")
    db.execute("select * from test")
    db.execute("update test set password='12345' where id=0")

3.Ruby socket
服务端：

    require 'socket'
    
    server = TCPServer.open('0.0.0.0', 8080)
    loop do
        Thread.start(server.accept) do |client|
            begin
                while true
                    puts "#{client.to_i} online"
                    data = client.read()
                    throw "empty" if data.empty?
                    #puts data.length
                    puts data
                end
            rescue Exception => e
                puts "#{client.to_i} offline"
            end
        end
    end

客户端：

    require 'socket'
    
    hostname = '127.0.0.1'
    port = 8080
    buf = 'test'
    s = TCPSocket.open(hostname, port)
    s.write buf
    sleep(1)
    s.close

4.ruby gem 文档
rubygems.org上main的gem文档访问起来太慢了，其实装了gem的机器本身就自带doc的功能
使用下列命令可以启动gem自带的文档

    gem server --port 1234

然后用浏览器访问http://localhost:1234就可以查看相关的gem文档。

5.ruby改变控制台输出内容的颜色

     puts "\033[1m前景色\033[0m\n"  
    puts "   \033[30mBlack (30)\033[0m\n"  
    puts "   \033[31mRed (31)\033[0m\n"  
    puts "   \033[32mGreen (32)\033[0m\n"  
    puts "   \033[33mYellow (33)\033[0m\n"  
    puts "   \033[34mBlue (34)\033[0m\n"  
    puts "   \033[35mMagenta (35)\033[0m\n"  
    puts "   \033[36mCyan (36)\033[0m\n"  
    puts "   \033[37mWhite (37)\033[0m\n"  
    puts ''   
    puts "\033[1m背景色\033[0m\n"  
    puts "   \033[40m\033[37mBlack (40), White Text\033[0m\n"  
    puts "   \033[41mRed (41)\033[0m\n"  
    puts "   \033[42mGreen (42)\033[0m\n"  
    puts "   \033[43mYellow (43)\033[0m\n"  
    puts "   \033[44mBlue (44)\033[0m\n"  
    puts "   \033[45mMagenta (45)\033[0m\n"  
    puts "   \033[46mCyan (46)\033[0m\n"  
    puts "   \033[47mWhite (47)\033[0m\n"  
    puts ''  
    puts "\033[1m其他\033[0m\n"  
    puts "   Reset (0)"  
    puts "   \033[1mBold (1)\033[0m\n"  
    puts "   \033[4mUnderlined (4)\033[0m\n"  

6.一些比较特别的包
Ruby json gem
https://rubygems.global.ssl.fastly.net/gems/json-1.8.3.gem
树莓派wiringpi gpio包
http://pi.gadgetoid.com/article/wiringpi-as-a-ruby-gem

7.安装rvm的正确姿势
参考自:http://rvm.io/rvm/install
首先添加gpg公钥:

    gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3

安装稳定版本的rvm

    curl -sSL https://get.rvm.io | bash -s stable --ruby