Hints

checkpoint 模块

def checkpoint():

while True:

res = input("Confirm to Continue? (Y/N) \n")

if res == 'Y' or res == 'y':

return True

else:

print('Cancelled')

break

Print 换行符

"\r" 是将光标移到一行的开始,所以\r之后的内容会覆盖掉上次打印的内容

"\n" 结尾换行

"\t" 制表符 表示中间加一个tab

r"xy\nz" 字符串前加字母r表示后面字符串中不进行转义 => 'xyz'

"\b" 退格符,将光标前移,覆盖

Dict 字典推导式

import random

>>>dic={k:random.randint(4,9) for k in ["a","b","c","d"]}

>>>dic

{'a': 7, 'b': 7, 'c': 5, 'd': 8}

String with Multilines:

s = """ this is a very

long string if I had the

energy to type more and more ..."""

Split multilines string one by one:

• s.splitlines()

["this is a very", "long string if I had the", "energy to type more and more ..."]

Try and Exception#

try:

print(v)

except Exception as e:

print("Error code %d - %s" % (10,e))

>>>Error code 10 - name 'v' is not defined

自定义异常用raise抛出异常

def Fnc():

try for i in range(5):

print (i)

if i > 3:

rasie Exception ("Not much left")

except Expection as Err

print (Err)

continue

try..except..else没有捕获到异常，执行else语句

try..except..finally不管是否捕获到异常，都执行finally语句

ReCall Variable 变量 in String

method-1:

>>> vars_in_string = "Angela {} is {} years old.".format(variable1, variable2)

>>> print("Number {:03d} is here.".format(11))

Number 011 is here.

>>> 'A formatted number - {:.4f}'.format(.2)

'A formatted number - 0.2000'

method-2:

f-string syntax

>>> vars_in_string = f"Eric {variable1} is {variable2} years old."

method-3:

>>> vars_in_string = "Eric %s is %d years old." % (variable1, variable2)

Join&Split#

"1.2.3.4".split(".") == ['1', '2', '3', '4']

".".join(['1', '2', '3', '4']) == "1.2.3.4"

网页处理用 Requests

res=requests.get("http://www.google.ie")

系统文件处理用 OS

os.rename(old, new)

os.getcwd()

os.listdir()

os.environ()

系统环境处理用 sys

sys.argv[0]

sys.stderr()

sys.exit()

NOT > AND > OR

# NOT 优于 AND 优于 OR