python 2day

提示：扫一扫查出行
【扫一扫了解最新限行尾号】
复制提示

一优化

username='alex'

password=‘alex123’

可以写成

username，password =‘alex’，'alex123'

二.再次优化

for i in rang(10):

if i>3:break #后面没有写内容可以这么加

pass #代表占位符这个条件成立，不做任何事情

三定义常量

全是大写

MYSQL_CONNETCTION=192.168.1.1 #说明是常量就要大写

四安装模块命令

pip installl 模块

pip uninstalll 模块

五模块一般搁在哪个位置

找一个叫site-packages

找不到site-packages 找dist-packages

六布尔值

大写 TRUE FALSE

0==FALES

1==TRUE

name=['a','b','c']

print ('a' in name) #TRUE

print('bc' in name) #FALES

if a in name:

print("right")

name='a lex'
print(''in name)

七万恶的字符串拼接

name ='alex'

print("my name" + name + "and you ?"

八列表

列表的组成a = ["alex","abc"，9，"zj",6,7,8 ] alex abc 叫做元素用逗号隔开

ab =9 #可以存入一个变量

列表a = ["alex","abc",9,"zj",6,7,8,ab ] #但是打出来确实值

print(a)

=["alex","abc",9，"zj",6,7,8]

0 1 2

-3 -2 -1

从列表里取值

a[1]= "abc"

要想取出 abc 和9 要用作切片

a[1:3]="abc" 9 []虎头蛇尾

a[-3:]=6,7,8

列表里替换值

a= ["alex","abc"，9，"zj",6,7,8 ]

a[1]="abcd"

a= ["alex","abcd"，9，"zj",6,7,8 ]

列表里插入

a=["alex","abc"，9，"zj",6,7,8 ]

a.insert(2,"zj")

a=["alex","abc"，"zj",9，"zj",6,7,8 ]

列表里加入

a=["alex","abc"，"zj",9，"zj",6,7,8 ]

a.append("alex")

a=["alex","abc"，"zj",9，"zj",6,7,8 ,'alex'] #添加到最后

列表里删除

a=["alex","abc"，"zj",9，"zj",6,7,8 ,'alex']

a.remove("abc")

name=['a','b','c','d','e','f','g','o',3,3,3,4,5,6,7,45,43,3,2,34,1,23,3,3,3,]

name.pop(0)
print(name)

name=[b','c','d','e','f','g','o',3,3,3,4,5,6,7,45,43,3,2,34,1,23,3,3,3,]

练习

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:zj
name=['a','b','c','d','e','f','g','o']
name.insert(2,"abc",)
name.insert(3,"abcd")
#print(name[3:])
#name.remove('g')
#print(name)
#del name[2:4]
print(name)
#name[2]='abc(组长)'
print(name[0:9:2])
print(name)

九查看列表元素有几个count和所在的位置index

name1=['a','b','c','d','e','f','g','o',3,3,3,4,5,6,7,45,43,3,2,34,1,23,3,3,3,]
if 3 in name1:
count1= name1.count(3) #count 代表列表
weizhi=name1.index(3) #index 代表第几个位置
print(count1)
print(weizhi)
name1[weizhi]=999999999999999999999999999999999999999999999999999999
print(name1)
print("3[%s]is/are in name"%count1)思考：

name1=['a','b','c','d','e','f','g','o',3,3,3,4,5,6,7,45,43,3,2,34,1,23,3,3,3,]
for i in range(name1.count(3)):
weizhi=name1.index(3)
name1[weizhi]=99999999999999
print(name1)
十列表清空name1=['a','b','c','d','e','f','g','o',3,3,3,4,5,6,7,45,43,3,2,34,1,23,3,3,3,]

name2=name1.clear()# clear 代表把列表删除
print (name2)

十一添加小列表

name=['a','b','c','d','e','f','g','o',3,3,3,4,5,6,7,45,43,3,2,34,1,23,3,3,3,]
name1=['zhangsan','lisi',3,3,3,3,]
name.extend(name1) #extend 代表扩展添加小列表
print (name)十二小列表排序

name=['a','b','c','d','e','f','g','o',3,3,3,4,5,6,7,45,43,3,2,34,1,23,3,3,3,]
name.reverse()
print(name)
name.soft() # 2.7试用
print(name)

十三浅拷贝和深拷贝
浅拷贝：只拷贝第一层而列表中的列表确不拷贝列表中的[9,4,3,5]指的内存内存改随之也该（相当软连接）
深拷贝：完全克隆（硬链接） name3=copy.deepcopy(name)

练习

name=['a','b','c','d','e','f','g','o',[9,9,9,4,],5,6,7,45,43,9,2,34,9,23,3,3,3,]
for i in range(name.count(9)):
weizhi=name.index(9)
name[weizhi]=999999999999999print(name)

name=['a','b','c','d','e','f','g','o',[9,9,9,4,],5,6,7,45,43,9,34,34,9,23,34,34,34,]
for i in range(name.count(34)):
weizhi=name.index(34)
name.pop(weizhi)print(name)十四列表的长度

name=['a','b','c','d','e','f','g','o',[9,9,9,4,],5,6,7,45,43,9,34,34,9,23,34,34,34,]
#for i in range(name.count(34)):
# weizhi=name.index(34)
# name.pop(weizhi)print(len(name))十五元组
r = (1,2,3,4) 只能索引数读不能修改和添加十六字符串

username='abc'
a=input("your name" )
if a.strip()==username: .stip()去掉前后空格
print("ok")

name='alex','zj','jz'
print(name)
name1="alex,zj,jz"
print(name1)
name2=name1.split(",")
print(name2)

('alex', 'zj', 'jz')
alex,zj,jz
['alex', 'zj', 'jz']

name1="alex,zj,jz"name2=name1.split(",") # 出来是列表
print(name2)
name3=("/".join(name2)) # /分开
print(name3)

['alex', 'zj', 'jz']
alex/zj/jz

字符串首字母大写

name='a lex'
name1=name.capitalize()
print(name1)字符串添加变量

mes="hello {name} {age}"
mes1=mes.format(name='zj',age=33) #format()
print(mes1)

mes="hell{0}agee{1}"
mes1=mes.format('alex',33)
print(mes1)

字符串添加引用

name='alexalex'
name1=name.center(100,'*')
print(name1)

**********************************************alexalex**********************************************

字符串找索引

name='alexalex'
name1=name.find('x')
print(name1)结果
3字符串输入是否是数字
age=input("your age:")

if age.isdigit(): #isdigit 代表输入是不是数字
age=int(age)
else:
print("no")字符串判断是否有特殊字符结果是FALSE

name='3a$df'
name1=name.isalnum()
print(name1)

字符串判断是否是以字母结尾的结果是TRUE

name='3a$df'
name1=name.endswith('df')
print(name1)

字符串判断是否以字母开头的结果是FALSE

name='3a$df'
name1=name.startswith('df')
print(name1)

让字符串大写让字符串小写

name='3a$df'
name1=name.upper()
print(name1)
name2=name.lower()
print(name2)字典 {key:value} 架构

id_db= {
110102198107011111:{
'name':'alex',
'age':22,
'addr':'shandong'
},
1020239203902930239:{
'name':'abc',
'age':24,
'addr':'dongbei'
},
110102198107011110 :{
'name':'zj',
'age':23,
'addr':'beijing'
}
}

#print(id_db) #打印字典
#print(id_db[110102198107011110])
#id_db[110102198107011110]['name']='zhang'#修改值
#id_db[110102198107011111]['wife']='jjjjjj'#创建一个新的值
#del id_db[110102198107011111]['age'] #删除
#id_db[110102198107011111].pop('age')#删除
#a=id_db.get(110102198107011111)#获取key 值
#print(a)#dict2 ={'zjjdsjsjj':29399239239,
# 110102198107011110 :{
# 'name':'zj',
# 'age':23,
# 'addr':'beikikikiki'
# }
# }

#id_db.update(dict2) #更新字典存在相同的key 会覆盖没有key 会增加
#print(id_db.items())#把字典改成列表
#print(id_db.keys())#把所有的key 打印出来
#print(id_db.values())#把所有的value打印出来
#print(id_db)

#110102198107011110 in id_db#判断字典里有没有key
#print('aaa')#打印aa#print(id_db.setdefault(110102198107011110))##代表在id_db中是否有key ,有的话打印出来
#print(id_db.setdefault(1101021981070111101,'hahah'))##代表在id_db中没有key的话，生出新的key 和新的值
#print(id_db.fromkeys([1,2,3,4],'ddddd'))#列表里的key {1: 'ddddd', 2: 'ddddd', 3: 'ddddd', 4: 'ddddd'}
#print(id)