>>>print ('just to test it'.upper()) #所有字母都转换成大写
>>>JUST TO TEST IT
>>>print ('JUST TO TEST IT'.lower() )#所有字母都转换成小写
>>>just to test it
2. 对字符串中的字符(仅对字母有效)部分大小写转换:
>>>print ('JUST TO TEST IT'.capitalize()) #字符串的首字母转换成大写, 其余转换成小写
>>>Just to test it
>>>print ('JUST TO TEST IT'.title()) #字符串中所有单词的首字母转换成大写, 其余转换成小写
>>>Just To Test It
3. 判断字符串大小写函数:
>>>print ('JUST TO TEST IT'.isupper() )
>>>True
>>>print ('JUST TO TEST IT'.islower() )
>>>False
>>>print ('JUST TO TEST IT'.istitle() )
>>>False