2016-12-16 38 views
-2

我在python控制檯中嘗試一些示例。並被困惑以下內容:什麼和python代表

>>> (1 and None) 
>>> (1 and None) == None 
True 
>>> (1 or None) == None 
False 
>>> (1 and 2) == 2 
True 
>>> (2 and 1) == 2 
False 
>>> (2 and 1) == 1 
True 

我很困惑爲什麼(1和None)不返回任何東西是行1?它應該是無?爲什麼(2和1)等於1但不是2。

+1

試試'print(1 and None)'。除非明確告知打印,否則Shell不打印'None'。 – JRodDynamite

+1

爲什麼'None'不顯示:http://stackoverflow.com/questions/39639342/none-is-not-displayed-as-i-expected-in-python-interactive-mode –

+1

請參閱文檔:https: //docs.python.org/3/library/stdtypes.html#truth-value-testing(4.1和4.2) –

回答