Python字符串字母大小写变换

说明：

字符串就是一系列字符，在Python中用引号括起来的都是字符串，引号可以是单引号，也可以是双引号，比如：“This is a book.”  ‘This is an apple.’

接下来简单说明下关于字符串大小写的变换。

操作：

casefold() 所有字母小写
lower() 所有字母小写
upper() 所有字母大写
capitalize() 所有字母小写
title() 所有首字母大写，其余字母小写
swapcase() 大小写字母替换
这几个方法都是生成新的字符串，不对原字符串内容进行修改。

demo = 'tHis iS a GOod boOK.'

print(demo.casefold())

print(demo.lower())

print(demo.upper())

print(demo.capitalize())

print(demo.title())

print(demo.swapcase())

输出：

this is a good book.

this is a good book.

THIS IS A GOOD BOOK.

This is a good book.

This Is A Good Book.

ThIS Is A goOD BOok.