Python 范围问题

Question

我正在编写一个程序，它需要确定数字的范围，就像我在 user_input 'a' 中输入 15 这样它应该打印从 'a' 到 'b' 的范围，但不幸的是我无法工作谁能帮我解决这个问题。这是我的代码:

a = int(raw_input("How many did you say you're going to count down? "))
b = int(raw_input("When are you actually going to stop? "))
i = 0
for i in range(a, b):
    i = i + 1
    print i 

我希望它像这样工作:

How many did you say you're going to count down? 15
When are you actually going to stop? 8
15
14
13
12
11
10
9
8

或

How many did you say you're going to count down? 6
When are you actually going to stop? 4
6
5
4

Answer 1

循环可以是:

a = int(raw_input("How many did you say you're going to count down? "))
b = int(raw_input("When are you actually going to stop? "))

for i in range(a, b-1, -1):
    print i 

(假设计数减少)。

你必须知道的是:

1. for 循环会为您做递减(不需要像 C 中那样的 i = i-1)。
2. range(a, b-1, -1) 是一个列表(在 Python 2 中)，从 a 到 b-1(不包括在内)，按 -1 的步骤进行。例如，您可以尝试在 Python shell 中执行 print range(10, 5, -1)。您还可以检查 range(5, 11, 2) 的输出，以更好地理解 range() 的作用。