str的用法简单整理

Posted 2020-10-18 清欢

#字符串的索引和切片
‘‘‘
s = ‘AbcdeF‘    #s[首：尾：步长]
‘‘‘
# s1 = s[-2]
# print(s1)
#切片 ：顾头不顾尾。
# s1 = s[0:4]
# print(s1)
# s2 = s[0:-1]
# print(s2)
# s3 = s[:]
# print(s3)
# s4 = s[0:]
# print(s4)
# s5 = s[:-1]
# print(s5)
# s6 = s[0:0]
# print(s6)
# s7 = s[0:5]
# print(s7)
# s8 = s[0:4:2]
# print(s8)
# s9 = s[5:2:-1]      #逆向输出
# print(s9)
# s1 = s[3::-1]
# print(s1)
# s2 = s[3::-2]
# print(s2)
# s3 = s[-1::-1]
# print(s3)
# s4 = s[::-1]
# print(s4)
# if s3 == s4:
#     print(0)
‘‘‘
s = ‘aleX‘
#首字母大写
s1 = s.capitalize()
print(s1)
‘‘‘     #1,首字母大写
‘‘‘
s2 = s.upper()      #全大写
sq = s.lower()      #全小写
print(s2,sq)
‘‘‘     #2,全大写，全小写
‘‘‘
s3 = s.swapcase()
print(s3)
‘‘‘     #3,大小写反转
‘‘‘
s = ‘aq-ex*e 3 go2n-wusir‘
s4 = s.title()
print(s4)
‘‘‘     #4,每个隔开（特殊字符或者数字）的单词首字母大写。
‘‘‘
s = ‘alexWUsir‘
s5 = s.center(21,‘。‘)
print(s5)
‘‘‘     #5,居中，空白填充。
‘‘‘
s = ‘alexaaaa\tsir‘
s6 = s.expandtabs()
print(s6)
‘‘‘     #6，自动填八位，满八位，填16位。

‘‘‘
s = ‘alex二哥‘
#公共方法
l = len(s)
print(l)
‘‘‘     #7，字符串长度。
‘‘‘
s = ‘alexWUsir‘
s7 =s.startswith(‘alex‘)
s71 = s.startswith(‘x‘,3,5)
print(s7,s71)
‘‘‘     #8，以什么开头
‘‘‘
find 通过元素找索引，找不到返回-1

index通过元素找索引，找不到报错


s = ‘alexWUsir‘
s8 = s.find(‘A‘)
# s81 = s.index(‘A‘)   直接报错
print(type(s8))
‘‘‘     #9，查找索引
‘‘‘
s = ‘alexWUsir%‘
s9 = s.strip(‘%‘)
print(s9)
s = ‘ *a%lexWUsi* r%‘
s91 = s.lstrip(‘ %*‘)
print(s91)
# username = input(‘请输入名字：‘).strip()
# if username ==‘春哥‘:
#     print(‘恭喜春哥发财‘)
‘‘‘     #10,strip 默认删除前后空格,lstrip 左
‘‘‘
s = ‘alexaa wusirl‘
s10 = s.count(‘e‘)
print(s10)
‘‘‘     #11,count 查看某字符串s10在s里面的个数。
# split   str ---->list


‘‘‘
s = ‘;alex;wusir;taibai‘
l = s.split(‘a‘)
print(l)
‘‘‘     #12,分割，str转list



‘‘‘
s = ‘我叫{}，今年{}，爱好{}，再说一下我叫{}‘.format(‘太白‘,36,‘girl‘,‘太白‘)
print(s)
name = input(‘请输入名字：‘)
s = ‘我叫{0}，今年{1}，爱好{2}，再说一下我叫{0}‘.format(name,36,‘girl‘)
print(s)
name = input(‘请输入名字：‘)
s = ‘我叫{name}，今年{age}，爱好{hobby}，再说一下我叫{name}‘.format(age=18,name=name,hobby=‘girl‘)
print(s)
‘‘‘     #13,format的三种玩法 格式化输出
‘‘‘
s = ‘你好漂亮你好我们再见‘
s11 = s.replace(‘你好‘,‘再见‘,2)
print(s11)
‘‘‘     #14,replace 替换原来str中的某个元素，可以加次数。