数据类型转换
#int----->str
s = 1
i = str(s)
print(i)
#str----->int
s = '123'
i = int(s)
print(i)
#int------->bool
i = 3
b = bool(i)
print(b)# s = '' ------>Fasle
#非空字符串都是True
#s = "0" --------->True字符串的索引与切片
切片：顾头不顾尾
s = 'ABCDLSESRF'
s1 = s[0]
print(s1)
s2 = s[2]
print(s2)
s3 = s[0:3] #顾头不顾定
print(s3)
s4 = s[-1]
print(s4)
s5 = s[0:]
print(s5)
s6 = s[:]
print(s6)
s7 = s[0:5:2]
print(s7)
s8 = s[3::-1]
print(s8)
s9 = s[3::-2]
print(s9)
s10 = s[-1::-1]
print(s10)
s10 = s[::-1]
print(s10)
A
C
ABC
F
ABCDLSESRF
ABCDLSESRF
ACL
DCBA
DB
FRSESLDCBA
FRSESLDCBA
字符串操作
s = 'alexusir'
s1 = s.capitalize() #首字母大写
print(s1)
Alexusirs2 = s.upper() #全部字母大写
print(s2)
############
ALEXUSIRs3 = s.lower() #全部字母小写
print(s3)
alexusir
s4 = s.swapcase() #字母大小写翻转
print(s4)
aLEXUSIR每个隔开（特殊字符或者数字）的单词的字母大写
s = 'alex open user'
s5 = s.title()
print(s5)
###########
Alex Open User居中和填充
s = 'alexUser'
s6 = s.center(20,'#') #居中和填充
print(s6)
######alexUser######table 键位
s = 'all\tuser'
s7 = s.expandtabs() #table键
print(s7)
all user字符长度
s = '123dfjlasjflasjfklasjf地方'
s8 = len(s)
print(s8)
24判断字符串中以什么开头和结尾
s = 'alexWUsir'
s9 = s.startswith('alex')
print(s9)
True
s = 'alexWUsir'
s9 = s.startswith('alex')
print(s9)
s10 = s.startswith('U',5)
print(s10)
True
True前缩进后缩进
s = ' string '
s12 = s.strip()
print(s12)
string
username = input('请输入姓名： ').strip()
if username == "tim":
print('gogogogo')计数
s = 'alexaa wusiral'
s10 = s.count('al')
print(s10)
2split
s = 'cis h3 c'
s11 = s.split()
print(s11)
s = 'cis:h3:c'
s12 = s.split(':')
print(s12)
['cis', 'h3', 'c']
['cis', 'h3', 'c']
format的三种玩法，格式化输出
s = '我叫{},今年{},爱好{},再说一下我叫{}'.format('tim',22,'girl','tim')
print(s)
s = '我叫{0},今年{1},爱好{2},再说一下我叫{0}'.format('tim',22,'girl','tim')
print(s)
s = '我叫{name},今年{age},爱好{hobby},再说一下我叫{name}'.format(name='tim',hobby='girl',age=33)
print(s)
我叫tim,今年22,爱好girl,再说一下我叫tim
我叫tim,今年22,爱好girl,再说一下我叫tim
我叫tim,今年33,爱好girl,再说一下我叫tim字符串替换
s = 'skdfjlasdfjlasdfjlsdfjls'
s13 = s.replace('jl','xxxxxxxxxxxxxxx')
print(s13)
s14 = s.replace('jl','xxxxxxxxxxxxxxx',1)
print(s14)
skdfxxxxxxxxxxxxxxxasdfxxxxxxxxxxxxxxxasdfxxxxxxxxxxxxxxxsdfxxxxxxxxxxxxxxxs
skdfxxxxxxxxxxxxxxxasdfjlasdfjlsdfjls
