一：基本使用
1 用途: 描述性质的数据,比如人的名字,单个爱好,地址
2 定义方式
name='egon' #name=str('egon')
x=str(1)
y=str(1.1)
z=str([1,2,3])
n=str({'a':1})
print(type(x))
print(type(y))
print(type(z))
print(type(n))
3 常用操作+内置的方法
优先掌握的操作(*****)：
1、按索引取值(正向取+反向取) ：只能取
msg='hello world'
print(type(msg[5]))
print(msg[-1])
msg[2]='A'
2、切片(顾头不顾尾，步长)
msg='hello world'
print(msg[1:5],type(msg[1:5]))
print(msg[6:-1])
print(msg[6:11])
print(msg[6:])
print(msg[6::2])
了解(**)
print(msg[0:])
print(msg[::-1])
msg='hello world'
print(msg[-3:-6:-1])
print(msg[6:9:-1])
3、长度len
msg='hello world'
print(len(msg))
4、成员运算in和not in
print('SB' in 'my name is alex,alex is SB')
print('alex' in 'my name is alex,alex is SB')
print('egon' not in 'my name is alex,alex is SB') # 推荐
print(not 'egon' in 'my name is alex,alex is SB')
5、移除空白strip
name=' e gon '
print(name.strip(' '))
print(name.strip())
name='****A*e*gon****'
print(name.strip('*'))
name='****egon****'
print(name.lstrip('*'))
print(name.rstrip('*'))
pwd=input('>>: ').strip() #pwd='123 '
if pwd == '123':
print('login successful')
msg='cccabcdefgccccc'
'c'
print(msg.strip('c'))
print('*-=egon *&^'.strip('-= *&^'))
6、切分split
msg='egon:18:male:180:160'
l=msg.split(':')
print(l)
print(l[3])
7、循环
msg='hello world'
for x in msg:
print(x)
需要掌握的操作(****)
1、strip,lstrip,rstrip
2、lower,upper
name='EoN'
print(name.lower())
name='egonN'
print(name.upper())
3、startswith,endswith
print('alex is SB'.startswith('alex'))
print('alex is SB'.endswith('B'))
4、format的三种玩法
print('my name is %s my age is %s' %('egon',18))
print('my name is {name} my age is {age}'.format(age=18,name='egon')) # 可以打破位置的限制,但仍能指名道姓地为指定的参数传值
print('my name is {} my age is {}'.format('egon',18))
print('my name is {0} my age is {1} {1} {1} {1}'.format('egon',18))
5、split,rsplit
info='egon:18:male'
print(info.split(':',1))
print(info.split(':',1)) #['egon','18:male']
print(info.rsplit(':',1)) #['egon:18','male']
6、join:只能将元素全为字符串的列表拼成一个大的字符串
info='egon:18:male'
l=info.split(':')
print(l)
new_info='-'.join(l)
print(new_info)
num=['a','b','c']
':'.join(num) #'a'+':'+'b'+':'+'c'
num=[1,2,'c']
':'.join(num) #1+':'+2+':'+'c'
7、replace
msg='my name is wupeiqi,wupeiqi is SB'
print(msg.replace('wupeiqi','Pig',1))
print(msg)
8、isdigit
print('111.1'.isdigit())
print('1111'.isdigit())
AGE=73
age=input('>>: ').strip() #age='asdfasdf'
if age.isdigit():
age=int(age)
if age > AGE:
print('too big')
elif age < AGE:
print('too small')
else:
print('you got it')
else:
print('必须输入数字啊傻叉')
其他操作（了解即可）(**)
1、find,rfind,index,rindex,count
msg='my name is alex,alex is hahaha'
print(msg.find('alex'))
print(msg.find('SB')) #找不到会返回-1
print(msg.index('alex'))
print(msg.index('SB')) # 找不到index会报错
print(msg.find('alex',0,3))
print(msg.count('alex'))
print(msg.count('alex',0,15))
2、center,ljust,rjust,zfill
print('info egon'.center(50,'-'))
print('info egon'.ljust(50,'-'))
print('info egon'.rjust(50,'-'))
print('info egon'.zfill(50))
3、expandtabs
print('a\tb\tc'.expandtabs(1))
4、captalize,swapcase,title
print('my name is egon'.capitalize())
print('my Name Is egon'.swapcase())
print('my name is egon'.title())
5、is数字系列
num1=b'4' #bytes
num2=u'4' #unicode,python3中无需加u就是unicode
num3='壹' #中文数字
num4='Ⅳ' #罗马数字
isdigit():bytes,unicode
print(num1.isdigit())
print(num2.isdigit())
print(num3.isdigit())
print(num4.isdigit())
isdecimal():unicode
print(num2.isdecimal())
print(num3.isdecimal())
print(num4.isdecimal())
isnumberic;unicode,中文,罗马
print(num2.isnumeric())
print(num3.isnumeric())
print(num4.isnumeric())
6、is其他
print('abasdf123123'.isalnum())
print('asdfasdf'.isalpha())
print('egon'.islower())
print('ABC'.isupper())
print(' '.isspace())
print('My Name Is Egon'.istitle())
二：该类型总结
1 存一个值or存多个值
只能存一个值
2 有序or无序
有序
3 可变or不可变
不可变
name='egon'
print(id(name))
name='alex'
print(id(name)