python学习笔记（四）字符串及字符串操作

字符串

　　字符串可以存任意类型的字符串，比如名字，一句话等等。

字符串还有很多内置方法，对字符串进行操作，常用的方法如下：

name1='hello world'
print(name.capitalize())#首写字母大写
print(name1.capitalize())#首写字母大写Hello world
print(name1.center(50,'-'))#50个-，把name1放中间-------------------hello world--------------------
print(name.endswith('u'))#是否以x结尾 False
print(name1.endswith('d'))#是否以x结尾 True
print(name.expandtabs(30))#补入	的次数my                             name is {name},age is{age}.
print(name1.find('n'))#查找字符串的索引5(	代表3个字符)
print(name.format(name='niuniu',age=18))#这个是格式字符串my      name is niuniu,age is18.
print(name.format_map({'name':'niuniu','age':19}))#这个也是格式化字符串，后面跟的是一个字典，字典在后面也会写
#my      name is niuniu,age is19.
print('abA123'.isalnum())#是否包含数字和字母 True
print('abA'.isalpha())#是否有英文字母True

name = 'My 	 name is {name},age is{age}.'
print('122'.isdigit())#是否有数字True
print('aa'.isidentifier())#是否是一个合法的变量名True
print('aa'.islower())#是否是小写字母True
print('AA'.isupper())#是否是大写字母True
print('Loadrunner Book'.istitle())#是不是一个标题，判断首字母是否大写True
print('+'.join(['hehe','haha','ee']))#拼接字符串 hehe+haha+ee
print(name.lower())#变成小写my      name is {name},age is{age}.
print(name.upper())#变成大写MY      NAME IS {NAME},AGE IS{AGE}.
print('
mysql 
'.lstrip())#默认去掉左边的空格和换行
print('
mysql 
'.rstrip())#默认去掉右边的空格和换行
print('
mysql 
'.strip())#默认去掉两边的空格和换行
p=str.maketrans('abcdefg','1234567')#前面的字符串和后面的字符串做映射
print('cc ae gg'.translate(p))#输出按照上面maketrans做映射后的字符串33 15 77

new_p=str.maketrans('1234567','abcdefg')
print('cc ae gg'.translate(new_p))
print('mysql is db.'.replace('mysql','oracle',1))#替换字符串oracle is db.
print('mysql is db.mysql is db.mysql is db.'.replace('mysql','oracle',2))#替换字符串oracle is db.oracle is db.mysql is db.
print('mysql is is db'.rfind('is'))#返回最右边字符的下标 9
print('1+2+3+4'.split('+'))#切割字符串，返回一个list ['1', '2', '3', '4']
print('1+2+3
1+2+3+4'.splitlines())#按照换行符分割['1+2+3', '1+2+3+4']
print('Abcdef'.swapcase())#大小写反转aBCDEF