如何在Python中向后添加？

Question

我有一个数字，例如35。是否有做35+34+33.....+1 = 630的函数，我知道有累加，但更多用于数组而不是实数。

Answer 1

借助数学的力量，您可以高效地进行计算：

result = 35 * (35 + 1) // 2  # 630

Answer 2

There is not quite a built-in function that does exactly that, but you can combine the sum function with a range object.

result = sum(range(35, 0, -1))

The -1 in that expression makes the range count backwards, so the sum starts with 35 , it continues until it reaches 0 then stops (not including the 0 in the sum, though that does not matter here). Of course, the addition operator is associative and commutative, so the order does not matter theoretically. But this does what you asked, in the order you asked. There are, of course, also other ways to get the same result.

In a comment, you seem to say that you want to use the variable maxlen rather than the constant 35 . Then just use

result = sum(range(maxlen, 0, -1))