Day1 初识Python

Posted 2020-07-26

（1）变量与赋值

name = "wanghuafeng"
age = 29
print(name, age)

a和b交换值

a = 3
b = 5
tmp = a
a = b
b = tmp
print(a, b)

（2）字符编码

ASCII码表（2**8=128个字符）

unicode：统一码、万国码

每一个字符最少用2个字节（16位）来存储，即2**16=65536

utf-8:是针对unicode的可变长度元编码。

它可以使用1~4个字节表示一个符号，根据不同的符号而变化字节长度。

（3）Pycharm修改文件模板

依次打开：File—>Settings—>Editor—>File and Code Templates—>Python Scripts

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

（4）多行打印

#！/usr/bin/env python
# -*- coding: utf-8 -*-
# Author: wanghuafeng
name = input("input your name:")
age = int(input("input your age:"))
job = input("input your job:")
#print("name is:", name + "\\nage is:", age + "\\njob is:", job)
msg = """
Information of user %s:
-------------------------
Name: %s
Age : %d
Job : %s
---------End-------------
""" % (name, name, age, job)
print(msg)

%d:整数

%f:浮点数

%s:字符串

（5）隐藏输入密码

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Author: WangHuafeng
import getpass
username = input("请输入用户名：")
password = input("请输入密码：")
print(username, password)

注意：Pycharm上输入密码时没有隐藏，Linux上可以隐藏。

（6）导入模块

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Author: WangHuafeng
import os
cmd_java = os.system("java -version")
print(cmd_java)

注意：导入模块或自己的python文件时不能加.py即：import Hello

（7）Linux上增加tab补全

新建文件tab.py

# 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

保存到/usr/lib/python2.7/dist-packages目录中

python命令行中输入：import tab

即可tab查看命令提示。