python基础语法（1）

注释

1. 单行注释：#
2. 多行注释：(单引号，双引号在python中区别不大)

#~!@#!@#$（真正的注释）""" （虽然注释了，但是可以被当做字符串使用）~!@#!@#$"""'''~!@#!@#$'''

for 和 while循环

后跟else：
表示循环正常结束后，执行else后跟的东西

for i in range(100):    if i==50:        print "I have got to 50!"        continue    elif i>70:        break;    print ielse :    print "I have got to 100"i = 0while i < 10000000:    i = i + 1else:    print 'I have got to the round ',ifor i in range(100):    print ielse:    print 'The loop is done!'

导入模块

import moduleName1,moduleName2...From module import sayhiimport moduleName as newName 导入模块的路径：（优先级依次下降（在前面的路径下找到了模块，就不往下找了））import syssys.path(打印下面的内容) ['', '/usr/local/lib/python2.7/dist-packages/autopep8-1.2.4-py2.7.egg', '/usr/local/lib/python2.7/dist-packages/pep8-1.7.0-py2.7.egg', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages'] 默认把自己添加的模块文件放到下面的路径下： /usr/local/lib/python2.7/dist-packages

代码实例

tab.py(tab模块代码)

#!/usr/bin/env python # python startup file import sysimport readlineimport rlcompleterimport atexitimport os# tab completion readline.parse_and_bind('tab: complete')# history file histfile = os.path.join(os.environ['HOME'], '.pythonhistory')try:    readline.read_history_file(histfile)except IOError:    passatexit.register(readline.write_history_file, histfile)del os, histfile, readline, rlcompleter

录入信息

name = raw_input('what is your name?:').strip()if  len(name) == 0:    print 'Error: you must input sth as name.'age =raw_input('how old are you?:')job = raw_input('what is your job?')msg = """Information of %s as below:    Name : \033[42;1m%s \033[0m;    Age  : %s    Job  : %s """ %(name,name,age,job)if int(age) >=50:     print "You are too old, you can only work for ..." elif int(age) >=30 :    print "You are now in the middle age,so enjoy your life before getting too old.... "else:    if int(age) >=20:        print 'you are still very young!'    else:        print 'not adult'print msg

小登陆系统

#!/usr/bin/env pythonimport sysimport osusername = 'fdl'password = 'fdl123'locked = 0 retry_counter = 0while retry_counter <3 :    user = raw_input('Username:')    if len(user) ==0:        print 'Username cannot be empty!'        continue    passwd = raw_input('Password:')    if len(passwd) == 0:        print 'Password cannot be empty!'        continue    if locked == 0:#means the user is locekd         print 'Your username is locked!'        sys.exit()    else:        if user == username  and passwd == password:            sys.exit('Welcome %s login to our system!' % user )         else:            #retry_counter = retry_counter + 1            retry_counter += 1             print 'Wrong username or password, you have %s more chances!' % (3 - retry_counter  )else :    os.system("sed -i '6d' login.py")    os.system("sed -i '5a\locked = 0 ' login.py")

小爬虫爬取图片

#!/usr/bin/env python# coding=utf-8import reimport urllibdef getHtml(url):    page = urllib.urlopen(url)    html = page.read()    return html def getImg(html):    reg = r'src="(.+?\.jpg)" pic_ext'    imgre=re.compile(reg)    imglist=re.findall(imgre,html)    x=0    for imgurl in imglist:        urllib.urlretrieve(imgurl,'%s.jpg'%x)        x+=1html=getHtml("http://tieba.baidu.com/p/2460150866")print getImg(html)