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-8-*-

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

#!/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

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

break跳出本层循环

continue不向下循环从头开始循环