字符串类型

雨燕双飞 提交于 2020-01-13 04:15:36

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innot 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(****)

1strip,lstrip,rstrip

2lower,upper

 name='EoN'

 print(name.lower())

 

 name='egonN'

 print(name.upper())

 

3startswith,endswith

 print('alex is SB'.startswith('alex'))

 print('alex is SB'.endswith('B'))

 

4format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))

 

5split,rsplit

 info='egon:18:male'

 print(info.split(':',1))

 

 print(info.split(':',1)) #['egon','18:male']

 print(info.rsplit(':',1)) #['egon:18','male']

 

6join: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'

 

7replace

 msg='my name is wupeiqi,wupeiqi is SB'

 print(msg.replace('wupeiqi','Pig',1))

 print(msg)

 

8isdigit

 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)(**)

1find,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))

 

2center,ljust,rjust,zfill

 print('info egon'.center(50,'-'))

 print('info egon'.ljust(50,'-'))

 print('info egon'.rjust(50,'-'))

 print('info egon'.zfill(50))

 

3expandtabs

 print('a\tb\tc'.expandtabs(1))

 

4captalize,swapcase,title

 print('my name is egon'.capitalize())

 print('my Name Is egon'.swapcase())

 print('my name is egon'.title())

 

5is数字系列

num1=b'4' #bytes

num2=u'4' #unicode,python3中无需加u就是unicode

num3='' #中文数字

num4='' #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())

 

6is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)

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