我想要输出None而不是0

Question

def second_largest(numbers):
    first, second = 0,0
    for n in numbers:
        if n > first:
            first, second = n, first
        elif first > n > second:
            second = n
    return second
print(second_largest([2,2,2]))

如果没有第二大数字并且还有空列表，我想以None不输出0。

Answer 1

尝试将返回行更改为return second or None。

Answer 2

在return语句中稍作调整即可。查看以下代码：

def second_largest(numbers):
    first, second = 0,0
    for n in numbers:
        if n > first:
            first, second = n, first
        elif first > n > second:
            second = n
    return None if second ==0 else second
print(second_largest([2,2,2]))