python字符串的增删改查

Posted 2020-11-09

字符串增加

1. 直接 +

name = ‘de8ug‘

city = ‘beijing‘

info = name + ‘ ‘ + city

info

‘de8ug beijing‘

2. % 占位符替换

‘name: %s, place: %s‘%(name,city)                           

‘name: de8ug, place: beijing‘

3. {}format 变量替换{} 或者 参数赋值

‘name:{},place:{}‘.format(name,city)                        

‘name:de8ug,place:beijing‘

‘name:{nameA},place:{placeA}‘.format(nameA=name,placeA=city)  

‘name:de8ug,place:beijing‘

4. f-string

f‘name:{name},place:{city}‘

‘name:de8ug,place:beijing‘

5. ‘ lilei said "where is han×××" ‘
   或者 " lilei said ‘where is han××ב " #双引号内加单引号或者单引号内加双引号

删除字符串

name = ‘de8ug‘

name = ‘‘

name

‘‘

字符串修改

name = ‘de8ug‘

name.upper()  #大写

‘DE8UG‘

name.lower()  #小写

‘de8ug‘

name.capitalize() #首字母大写

‘De8ug‘

name = "python is cool"

name.title()  #标题大写

‘Python Is Cool‘

name.strip(‘python‘) #去掉python（开头和结尾的空格或者字符串去掉）

‘ is cool‘

email = ‘de8ug#foxmail.com‘

email.replace(‘#‘,‘@‘)    #email.replace(old,new)

‘[email protected]‘

email.split(‘#‘)        #去除分隔符，变成列表

[‘de8ug‘, ‘foxmail.com‘]

email.zfill(30)

‘0000000000000de8ug#foxmail.com‘

email.ljust(30,‘8‘)   #email.ljust(width.fillchar)  左对齐再填充

‘de8ug#foxmail.com8888888888888‘

email.rjust(20,‘*‘)   #右对齐再填充

‘***de8ug#foxmail.com‘

email.center(20,‘*‘)   #中间对齐再填充

‘*de8ug#foxmail.com**‘

字符串查

1.字符串.方法（）

‘de8ug‘.count(‘8‘)

1

name.isupper()  #判断是否为大写

False

name.islower()  #判断是否为小写

True

py = ‘python is cool‘

py.index(‘is‘)   #查询在哪个位置

7

py.index(‘o‘)

4

py.find(‘is‘)

7

py.find(‘isaaa‘)   #所有不存在为-1

-1

dir(py)  #看有哪些方法可用

[‘__add__‘,
 ‘__class__‘,
 ‘__contains__‘,
 ‘__delattr__‘,
 ‘__dir__‘,
 ‘__doc__‘,
 ‘__eq__‘,
 ‘__format__‘,
 ‘__ge__‘,
 ‘__getattribute__‘,
 ‘__getitem__‘,
 ‘__getnewargs__‘,
 ‘__gt__‘,
 ‘__hash__‘,
 ‘__init__‘,
 ‘__init_subclass__‘,
 ‘__iter__‘,
 ‘__le__‘,
 ‘__len__‘,
 ‘__lt__‘,
 ‘__mod__‘,
 ‘__mul__‘,
 ‘__ne__‘,
 ‘__new__‘,
 ‘__reduce__‘,
 ‘__reduce_ex__‘,
 ‘__repr__‘,
 ‘__rmod__‘,
 ‘__rmul__‘,
 ‘__setattr__‘,
 ‘__sizeof__‘,
 ‘__str__‘,
 ‘__subclasshook__‘,
 ‘capitalize‘,
 ‘casefold‘,
 ‘center‘,
 ‘count‘,
 ‘encode‘,
 ‘endswith‘,
 ‘expandtabs‘,
 ‘find‘,
 ‘format‘,
 ‘format_map‘,
 ‘index‘,
 ‘isalnum‘,
 ‘isalpha‘,
 ‘isdecimal‘,
 ‘isdigit‘,
 ‘isidentifier‘,
 ‘islower‘,
 ‘isnumeric‘,
 ‘isprintable‘,
 ‘isspace‘,
 ‘istitle‘,
 ‘isupper‘,
 ‘join‘,
 ‘ljust‘,
 ‘lower‘,
 ‘lstrip‘,
 ‘maketrans‘,
 ‘partition‘,
 ‘replace‘,
 ‘rfind‘,
 ‘rindex‘,
 ‘rjust‘,
 ‘rpartition‘,
 ‘rsplit‘,
 ‘rstrip‘,
 ‘split‘,
 ‘splitlines‘,
 ‘startswith‘,
 ‘strip‘,
 ‘swapcase‘,
 ‘title‘,
 ‘translate‘,
 ‘upper‘,
 ‘zfill‘]

my_name =input(‘name: ‘)

name: de8ug  

my_name

‘de8ug  ‘

len(my_name)   #可以包含空格

7

type(my_name)

str

my_name.strip()

‘de8ug‘

len(my_name.strip())

5

2. 切片查询

py = ‘python2 python3 python4 python8‘

py[3]

‘h‘

py[-2]

‘n‘

py[:6]

‘python‘

py.index(‘2‘)

6

py[:py.index(‘2‘)]

‘python‘

something = ‘abcdefg1234567‘

something[1:6:2]   #索引1到6 步长为2

‘bdf‘

something[4:]  #左边包括

‘efg1234567‘

something[:4]  #右边不包括

‘abcd‘

something[4::4]

‘e26‘

something[something.index(‘e‘):]

‘efg1234567‘

email = ‘[email protected]‘

email.split(‘@‘)   #去除分隔符，变成列表

[‘de8ug‘, ‘foxmail.com‘]

email.index(‘@‘)

5

email[:email.index(‘@‘)]

‘de8ug‘

email.find(‘@‘)

5

email[email.find(‘@‘)+1:]   #左边包括

‘foxmail.com‘