Python是啥？
动态解释性的强类型定义语言。（看球不懂，慢慢理解...以下）
编程语言又有些撒子类型: 编译型、解释型
静态语言、动态语言
强类型定义语言、弱类型定义语言
编译型:（C/C++）
Complie: 有一个负责翻译的程序来对源代码进行转换，生成相对应的执行代码
Complier: 负责编译的程序
一次性把code转换成机器语言，然后写成可执行文件
解释型：（Java，Python）
如果说编译时一名书本翻译，解释更像一名同声传译
不断解释，不断执行... ...
动态类型语言：（Python Ruby）
运行期间才检查数据类型
静态类型语言：（C/C++,Java）
数据类型在编译时检查
强类型定义语言：
强制数据类型定义的语言
如没有强制转换，永远是同个数据类型
弱类型定义语言：
数据类型可以忽略的语言
一个变量可以赋予不同数据类型的值
小程序之 Hello World!
name = "你好，世界" # Python 3 可以写中文，但是不推荐
print(name)
小程序之 用户交互 （Interaction)
# user input
name = input("name:")
age = input("age:")
job = input("job:")
salary = input("salary：")
# 4 种格式化输出
# Practice 1 格式化输出 forget it
info = '''
-------- info of ''' + name +''' --------
Name: ''' + name + '''
Age; ''' + age + '''
Job: ''' + job + '''
Salary:''' + salary + '''
'''
print(info)
# Practice 2 格式化输出
# in shell, %s = $
info2 = '''
------- info of %s --------
Name: %s
Age; %s
Job: %s
Salary: %s
''' % (name,name,age,job,salary)
print(info)
# %s s represents string
# %d d only works for numbers Using int() to do transform for numerical variables
# %f f is floating numbers
# Practice 3 格式化输出 usually use this method
info3 = '''
-------- info of {_name} --------
Name:{_name}
Age:{_age}
Job:{_job}
Salary:{_salary}
'''.format(_name=name,
_age=age,
_job=job,
_salary=salary)
print(info3)
info4 = '''
-------- info of {0} --------
Name:{0}
Age:{1}
Job:{2}
Salary:{3}
'''.format(name, age, job, salary)
print(info4)
View Code
getpass： 输入密码时，如想不可见，可用它
但python自带IDE（Integrated Development Environment）终端不支持隐藏回显
用windows下的cmd就OK~
import getpass
_username = 'momo'
_password = 'abc123'
username = input("username:")
password = getpass.getpass("password:") #encrypt
# not working well in Pycharm but works in python
小程序之 猜年龄
流程: 1.定义一个年龄
2.用户去猜测
3.判断是否正确
---make only one guess---
if else：
age_of_oldboy = 56
# can only make one guess
guess_age =int(input("guess age:")) # input 默认是string, need to use int()
if guess_age == age_of_oldboy:
print("yes, you got it!")
elif guess_age > age_of_oldboy:
print("think smaller!")
else:
print("think bigger!")
View Code
---make only 3 guesses---
while：
age_of_oldboy = 56
count = 0
while count < 3: # make only 3 guesses
guess_age =int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes, you got it!")
break
elif guess_age > age_of_oldboy:
print("think smaller!")
else:
print("think bigger!")
count += 1
else:
print("you have tried too many times...fuck off")
View Code
while True：
age_of_oldboy = 56
count = 0
while True:
if count == 3: # only make 3 guesses
print("you have tried too many times...fuck off")
break
guess_age =int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes, you got it!")
break
elif guess_age > age_of_oldboy:
print("think smaller!")
else:
print("think bigger!")
count += 1
View Code
for：
age_of_oldboy = 56
for i in range(3): # make only 3 guesses
guess_age =int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes, you got it!")
break
elif guess_age > age_of_oldboy:
print("think smaller!")
else:
print("think bigger!")
else:
print("you have tried too many times...fuck off")
View Code
---keep guessing---
age_of_oldboy = 56
count = 0
while count < 3:
guess_age =int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes, you got it!")
break
elif guess_age > age_of_oldboy:
print("think smaller!")
else:
print("think bigger!")
count += 1
if count == 3:
countine_confirm = input("do you wanna keep guessing?")
if countine_confirm != 'n':
count = 0
View Code
★★★★★添补小知识★★★★★
1.comments
两种方法：# comments
'''comments'''/"""comments"""
PS： ''' comments'''可以print多行；
但是 ' 和 " 只能print单行
2.解释器
# !/usr/bin/ python
告诉操作系统执行这个脚本时，调用/usr/bin下的python解释器
# !/usr/bin/env python
防止python没装在默认的/usr/bin 路径里，会到env设置里查找python的安装路径，再调用对应的路径下的解释器程序
3.编码申明
#-*- coding uft-8 -*-
可变长的编码集
4.Define variables
# Good try
gf_of_oldboy = "Chen rong hua"
GFOfOldboy = "Chen rong hua" # called hump hhhhh 23333
__________name = "Chen rong hua"
# non sense
2name = ""
a
b
# Define constants(in Capital) eg. PIE
Important！！！
name = "Momo"
name2 = name
print("My name is",name,name2)
name = "PaoChe Ge"
print(name,name2) # name2 does not change
5. int(), str()
# convert string into integer
age = int(input("age:"))
# convert integer into string
print(str(age))
6. while, for 循环
while 循坏是地老天荒
例子：
# while True
count = 0
while True:
print("count:",count)
count = count + 1 # same as count += 1
if count == 1000:
break
# for
for i in range(10): # 0-10,0 gap
print('-----------',i)
for j in range(10):
print(j)
if j > 5:
break
continue VS. break
不往下走 不往下走
进入下一个loop 跳出整个loop
7.bytes类型 （字节数据类型）
文本总是Unicode， 由str类型表示
二进制数据由bytes类型表示 （视频，音频文件）
8bit = byte(字节）
1024 byte = 1kbyte
1024kbyte = 1mbyte
1024mb = 1gb
1024gb = 1T
string --> encode --> bytes
bytes --> decode --> string
eg.
>>> '€20'.encode('utf-8')
b'\xe2\x82\xac20' # b开头代表二进制
>>> b'\xe2\x82\xac20' . decode('utf-8)
'€20'
msg = "我爱北京天安门"
print(msg)
print(msg.encode(encoding="utf-8").decode(encoding="utf-8"))
8. 三元运算
result = 值1 if 条件 else 值2 （一句话搞定）
9.进制
