如何像计算机科学家一样思考

Question

因此,正如标题所希望的那样,这是在所述书中的一个例子.我还是编程新手,调试困难.对此表示欢迎任何批评,特别是如果它显示更有效的编码方式; 请记住,我仍然是新手,所以如果你给我一个新的内置功能或某些东西,我很可能不知道你指的是什么.

因此,本练习的目的是编写一个函数,给它三个参数,以确定这三个参数是否形成一个三角形.这是我的代码:

def is_triangle(a,b,c):
    num_list = [a,b,c]
    biggest = max(num_list)
    other_two = num_list.remove(biggest)
    sum_of_two = sum(other_two)

    if sum_of_two > biggest:
        print 'Congrats, %d, %d, and %d form a triangle!' % (a,b,c)
    elif sum_of_two == biggest:
        print 'That forms a degenerate triangle!'
    else:
        print 'That does\'t make any sort triangle... >:['


def sides():
    side1 = raw_input('Please input side numero Juan: ')
    side2 = raw_input('Now side two: ')
    side3 = raw_input('...aaaannnd three: ')
    import time
    time.sleep(1)
    print 'Thanks >:]'
    side1 = int(side1)
    side2 = int(side2)
    side3 = int(side3)
    is_triangle(side1,side2,side3)

sides()

然而,每当我运行它时,我得到以下内容:

Traceback (most recent call last):
  File "A:/Python/is_triangle.py", line 27, in <module>
    sides()
  File "A:/Python/is_triangle.py", line 25, in sides
    is_triangle(side1,side2,side3)
  File "A:/Python/is_triangle.py", line 5, in is_triangle
    sum_of_two = sum(other_two)
TypeError: 'NoneType' object is not iterable

我的猜测是sum_of_two但是我不知道它有什么问题.有人可以帮我调试吗？

我花了一个小时用build_in函数重写它(以各种方式,or到处都是一堆).但它看起来很糟糕,我宁愿学会用这种方式写作.

Answer 1

问题在于remove修改基础列表 - 它不会返回新列表.将其更改为:

num_list.remove(biggest)
sum_of_two = sum(num_list)

要确切了解这种情况发生的原因,请在IDLE中尝试以下操作:

>>> x = [1,2,3,4,5]
>>> x.remove(1)
>>> x
[2,3,4,5]