你的代码错在 if new_user and new_new_user in user,程序会先计算and,and以后的值肯定不在user里,所以都是false,这样的功能请参考下方
user = ['a', 'b', 'c', 'd', 'e']
new_user = ['z', 'x', 'C', 'v', 'b', 'n']
for i in new_user:
if i.lower() in user:
print('在')
else:
print('不在')
user = ['a', 'b', 'c', 'd', 'e']
new_user = ['z', 'x', 'C', 'v', 'b', 'n']
for i in new_user:
if i.lower() in user:
print(i,'在','user里面',end='\t')
else:
print(i,'不在','user里面',end='\t')