Python9-数据类型-day3

• 2020 年 1 月 20 日
• 筆記

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)    Alexusir

s2 = s.upper()    #全部字母大写  print(s2)  ############  ALEXUSIR

s3 = 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 = 'alltuser'  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)    2

 split

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