Python 判斷是否為None

Python的None代表空，不含任何值，相當於其他語言(e.g. Java, C#, php)的null。Python判斷變數是否為None的方式如下。

使用is None判斷是為None；
使用is not None判斷不為None。

a = None
if a is not None:
    print("a is not None")
else:
    print("a is None")


b = 1
if b is not None:
    print("b is not None")
else:
    print("b is None")


print(a is None)  # True
print(b is not None)  # True

印出結果

a is None
b is not None
True
True

• Null in Python: Understanding Python's NoneType Object