day06_08 字符串

1.0 双引号和单引号的区别

a = "Let's go"
print(a)
#>>>Let's go

2.0 重复输出字符串*

print('hello'*2)
#>>>hellohello

3.0 字符串索引

print('helloworld' [2:])
#>>>lloworld

4.0 判断in

print(123 in [23,45,123])
#>>>True

5.0 格式化字符串 %

print('%s is a good teacher'%'alex')
#>>>alex is a good teacher

6.0 字符串拼接+

a = '123'
b = 'abc'
c = a + b
print(c)
#>>>123abc 效率低,需要不停开辟内存空间

7.0 字符串拼接(此方法较好)

a = '123'
b = 'abc'
c = ''.join([a,b])
print(c)
#>>>123abc

7.1 拼接 ''.join()

a = '123'
b = 'abc'
d = 'miaomiao'
c = '------'.join([a,b,d])
print(c)
#>>>123------abc------miaomiao

8.0 字符串的内置方法

8.1 count(计算字符串的个数)

st = 'hello kitty'
print(st.count('l')) #统计元素个数
#>>>2

8.2 capitalize(将首字母大写)

st = 'hello kitty'
print(st.capitalize()) #首字母大写

8.3 center

st = 'hello kitty'
print(st.center(50,'-'))
#>>>-------------------hello kitty--------------------

8.4 endswith(判断是否以某个字符串结尾)

st = 'hello kitty'
print(st.endswith('ty'))
#>>>True

8.5 startwith(判断是否以某个字符串开头)

st = 'hello kitty'
print(st.startswith('he'))
#>>>True

8.6 expandtabs(可以把tab转换成XX个空格)

st = 'he\tllo kitty'
print(st.expandtabs(tabsize=10))
#>>>he        llo kitty

8.7 find(查找到第一个元素,并将索引值返回)

st = 'hello kitty'
print(st.find('t'))
#>>>8

8.8 format()

st = 'hello kitty{name} is {age}'
print(st.format(name='alex',age=37))
print(st.format_map({'name':'alex','age':22}))
#>>>hello kittyalex is 37
#>>>hello kittyalex is 22

8.9 index

st = 'hello kitty'
print(st.index('t'))
#>>>8

8.10 isalnum(查看是否是字符串,如果是特殊符号的话就为False)

st = 'abc345'
sr = '#123'
print(st.isalnum())
#>>>True
print(sr.isalnum())
#>>>False

8.11 isdigit(判断是否是整型数字)

print('1234'.isdigit())
#>>>True

　　

print('1234.123'.isdigit())
#>>>False

8.12 isnumeric(判断是否是数字,和isdigit一样)

print('1234'.isnumeric())
#>>>True

8.13 isidentifier(判断变量名是否规范)

print('34abc'.isidentifier())
#>>>False

8.14 islower(判断是否全是小写)

print('abc'.islower())
#>>>True

8.15 isupper(判断是否全是大写)

print('ABC'.isupper())
#>>>True

8.16 isspace(判断是否是空格)

print(' '.isspace())
#>>>True

8.17 istitle(判断是否首字母全都是大写)

print('My Title'.istitle())
#>>>True

8.18 lower(所有字母全都变小写)

print('My Title'.lower())
#>>>my title

8.19 upper(所有字母全都变成大写)

print('My Title'.upper())
#>>>MY TITLE

8.12 swapcase(大写变成小写,小写变成大写)

print('My Title'.swapcase())
#>>>mY tITLE

8.13 ljust 和 rjust

print('My Title'.ljust(50,'*'))
#>>>My Title******************************************
print('My Title'.rjust(50,'*'))
#>>>******************************************My Title

8.14 strip(去掉前面的空格)

print('   My Title\n'.strip())
#>>>My Title

8.14 lstrip

print('   My Title\n\n'.lstrip())
#>>>My Title
#>>>
#>>>

8.15 rstrip

print('   My Title\n\n'.rstrip())
#>>>   My Title

8.16 replace

print('My Title'.replace('Title','lesson'))
#>>>My lesson

8.16.2

print('My Title Title'.replace('itle','lesson',1))
#>>>My Tlesson Title

8.17 rfind

print('My Title Title'.rfind('T'))
#>>>9

8.18 split(以XX分割)

print('My Title Title'.split(' '))
#>>>['My', 'Title', 'Title']

print('My Title Title'.split('i'))
#>>>['My T', 'tle T', 'tle']

8.19 rsplit(只分割一次,以右为准)

print('My Title Title'.rsplit('i',1))
#>>>['My Title T', 'tle']