1.25 迷一样的字符串 =================== .. image:: http://image.iswbm.com/20200804124133.png 示例一 .. code:: python # Python2.7 >>> a = "Hello_Python" >>> id(a) 32045616 >>> id("Hello" + "_" + "Python") 32045616 # Python3.7 >>> a = "Hello_Python" >>> id(a) 38764272 >>> id("Hello" + "_" + "Python") 32045616 示例二 .. code:: python >>> a = "MING" >>> b = "MING" >>> a is b True # Python2.7 >>> a, b = "MING!", "MING!" >>> a is b True # Python3.7 >>> a, b = "MING!", "MING!" >>> a is b False 示例三 .. code:: python # Python2.7 >>> 'a' * 20 is 'aaaaaaaaaaaaaaaaaaaa' True >>> 'a' * 21 is 'aaaaaaaaaaaaaaaaaaaaa' False # Python3.7 >>> 'a' * 20 is 'aaaaaaaaaaaaaaaaaaaa' True >>> 'a' * 21 is 'aaaaaaaaaaaaaaaaaaaaa' True