python - 在 python 中使用负数

Question

我是编程概念类(class)的学生。该实验室由助教管理，今天在实验室他给了我们一个真正简单的小程序来构建。这是一个乘以加法的地方。无论如何，他让我们使用 absolute 以避免用底片破坏 prog。我很快就把它搞定了，然后和他争论了 10 分钟，说这是糟糕的数学。原来，4 * -5 不等于 20，它等于 -20。他说他真的不在乎这个，而且无论如何让前卫处理底片太难了。所以我的问题是我该怎么做。

这是我提交的程序:

#get user input of numbers as variables

numa, numb = input("please give 2 numbers to multiply seperated with a comma:")

#standing variables
total = 0
count = 0

#output the total
while (count< abs(numb)):
    total = total + numa
    count = count + 1

#testing statements
if (numa, numb <= 0):
    print abs(total)
else:
    print total

我想不用绝对值，但每次我输入负数时，我都会得到一个大胖鹅蛋。我知道有一些简单的方法可以做到，我就是找不到。

Answer 1

也许你会用一些效果来完成这个

text = raw_input("please give 2 numbers to multiply separated with a comma:")
split_text = text.split(',')
a = int(split_text[0])
b = int(split_text[1])
# The last three lines could be written: a, b = map(int, text.split(','))
# but you may find the code I used a bit easier to understand for now.

if b > 0:
    num_times = b
else:
    num_times = -b

total = 0
# While loops with counters basically should not be used, so I replaced the loop 
# with a for loop. Using a while loop at all is rare.
for i in xrange(num_times):
    total += a 
    # We do this a times, giving us total == a * abs(b)

if b < 0:
    # If b is negative, adjust the total to reflect this.
    total = -total

print total

或者也许

a * b