list_a = [1,2,3,4] list_b = [3,4,5,6,7]
list_c = [a for a in list_a if a in list_b]
如果list_c=[] list_c 不是None
所以用下面的方式得不到真实的结果 :
if list_c is None:
if not list_c is None:
要用:
len(list_c)>0 ==0 来判断
list_a = [1,2,3,4] list_b = [3,4,5,6,7]
list_c = [a for a in list_a if a in list_b]
如果list_c=[] list_c 不是None
所以用下面的方式得不到真实的结果 :
if list_c is None:
if not list_c is None:
要用:
len(list_c)>0 ==0 来判断