14 三元表达式、内置函数、面向过程编程

目录：三元表达式、内置函数、面向过程编程

一、三元表达式：

def func():
    if x>y:
        return x
    else:
        return y
res=func(1,2)

x=1
y=2
res=x if x>y else y
print(res)

二、内置函数

     重点掌握：

int             float             str            list             tuple           dict  set bool             bytes          
s=frozenset({1,2,3})  #不可变的集合
print（types(s))

s="print(‘hello')"
s="[1,2,3]"
l=eval(s)
print(l[0])

with open('a.txt',mode='rt',encoding='utf-8') as f:
    data = f.read()
    # print(data,type(data))  # '{"name":"egon","age":18}'

    dic = eval(data)
    print(dic['name'])

print("start===")
i=0
while i<3:
    print(i)
    i+=1
print("end===")

import base64         #解密
exec(base64.b64decode('cHJpbnQoInN0YXJ0Li4uIikKaSA9IDAKd2hpbGUgaSA8IDM6CiAgICBwcmludChpKQogICAgaSs9MQpwcmludCgnZW5kLi4uJykK'))

print(chr(65))
print(ord("A"))


l=[1,"a",3]
res1=l[::-1]
res1=list(reversed(l))    #反转
print(res1)



print(round(3.6))   #四舍五入

x="hello"
y=[1,2,3]
res=zip(x,y)    #拉链原理，一一对应，没有的则不要
print(res)
print(list(res))

m=__import__("time")

m.sleep(3)

面向对象需要学习的：

object
classmethod
staticmethod
property

hasattr
getattr
setattr
delattr

isinstance
issubclass

需要掌握的

max  min sorted  

# filter   #过滤
# names = ['egon','liusir_dsb',"housir_dsb"]
#
# print([name for name in names if name.endswith('dsb')])
#res=filter(lambda name:name.endswith("dsb"),names)
#print(res)
#print(list(res))


# map      #映射
# names = ['lxx', 'liusir', "housir"]
#
# # res = [name+"_sb" for name in names]
# # print(res)
#
# res = map(lambda x: x + "_sb", names)
# # print(res)
# print(list(res))

# reduce     #合并
from functools import reduce


res = reduce(lambda x, y: x + y, [1, 2, 3, 4, 5],100)
res = reduce(lambda x, y: x + y, [1, 2, 3, 4, 5])
res = reduce(lambda x, y: x + y, ["a",'b','c'])
print(res)

了解：

print(abs(-1))
# print(all([1, "aa", True]))
# print(any([0,"",True]))

# print(all(""))  # True
# print(any([]))  # False

# print(bin(11))
# print(oct(11))
# print(hex(11))

# print(callable(len))
# print(callable(10))

# aaaa = 1111111111
# def func():
#     x = 111111111
#     y = 2222222222222
#     print(globals())
#     print(locals())
#
# func()

# print(pow(10,2,3))  # 10 ** 2 % 3


# l = [1,2,3,4,5,6,7]
#
# s = slice(0,5,2)
# print(l[s])
#
#
# l1 = [11,222,333,444,555,666,777,88,999]
# print(l1[s])

三、面向过程编程：

  面向过程的核心是过程二字，过程指的是解决问题的步骤，即先干什么再干什么

  基于面向过程设计程序就好比在设计一条流水线，是一种机械式的思维方式

    优点：复杂的问题流程化，进而简单化

    缺点：可扩展性差，修改流水线的任意一个阶段，都会牵一发而动全身

  应用：扩展性要求不高的场景，典型案例如linux内核，git，httpd