python之路：进击的小白

1.hello world

print("hello world")

2.变量定义的规则

• 变量名只能是 字母、数字或下划线的任意组合
• 变量名的第一个字符不能是数字
• 以下关键字不能声明为变量名
  ['and', 'as', 'assert', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'exec', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'not', 'or', 'pass', 'print', 'raise', 'return', 'try', 'while', 'with', 'yield']

3.字符编码-*-coding:utf-8-*-

在python2.0版本中，不声明字符编码则不支持中文

python3.0可以不声明默认是 -*-coding:utf-8-*-

4.注释：

单行注释: "#"

多行注释: " '''  "(3个单引号)

5.输入

name_input=input("用户名：")

password_input=input("密码")

• 密码可以密文(在linux环境中)

 #!/usr/bin/env python
 #-*-coding:utf--*-

 import getpass
 password_input=getpass.petpass("密码：")

6.模块

• os模块

 #!/usr/bin/env python
 # -*- coding: utf-8 -*-

 import os

 os.system("df -h") #调用系统命令

• sys模块

 #!/usr/bin/env python
 # -*- coding: utf-8 -*-

 import sys

 print(sys.argv)

 #输出
 $ python test.py helo world
 ['test.py', 'helo', 'world']  #把执行脚本时传递的参数获取到了

• Tab模块

 import sys
 import readline
 import rlcompleter

 if sys.platform == 'darwin' and sys.version_info[0] == 2:
     readline.parse_and_bind("bind ^I rl_complete")
 else:
     readline.parse_and_bind("tab: complete")  # linux and python3 on mac

 for mac

mac版本

 #!/usr/bin/env python
 # python startup file
 import sys
 import readline
 import rlcompleter
 import atexit
 import 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:
     pass
 atexit.register(readline.write_history_file, histfile)
 del os, histfile, readline, rlcompleter

 for Linux

linux版本

可以从网上找

7.格式化输出

 name_input = input('name:')
 age_input = int(input('age:'))
 job_input = input('job:')
 msg = '''
 Infomation of user %s
 --------------------
 Name:   %s
 Age :   %d
 Job :   %s
 -------END----------
 '''%(name_input,name_input,age_input,job_input)
 print(msg)
 print("姓名：",name_input)
 print("年龄:",age_input)
 print("职业:",job_input)

%s字符串
%d数字

8.for循环

 #!/usr/bin/env python
 #-*-coding:utf-8-*-
 num = 20
 counter = 0
 for i in range(10):
     if counter<3:
         guess_num = int(input("输入年龄："))
         if guess_num > num:
             print("猜大了")
         elif guess_num < num:
             print("猜小了")
         else:
             print("猜对了")
             break
     else:
         couter_confirm = input("还想继续吗？")
         if couter_confirm == 'y':
             counter = 0
             continue
         else:
             print("bay!")
             break
     counter +=1

猜年龄

break跳出本层循环

continue不向下循环从头开始循环