需要计算偶数位上的数字之和.会是什么错误呢?

Question

需要计算偶数位置上的数字。我写了一个函数，但我不知道错误是什么?例如，在数字55443352中，5 + 4 + 3 + 5 = 17。这是预料之中的。

`def cnt_sum(one):
sum = 0
tmp = one
i=0
while tmp //= 10:
i = i + 1 
while one:
if (i==%2 == 0)
sum +=one%10
one/=10
return sum
cnt_sum(55443352)`

请帮我弄清楚……

while tmp // = 10:
^
SyntaxError: invalid syntax

Answer 1

除非使用海象操作符(3.8+)，否则不能在那里赋值temp:

In [98]: while temp = temp // 10:
...:     print(temp)
...:
File "<ipython-input-98-38590cf2c5e0>", line 1
while temp = temp // 10:
^
SyntaxError: invalid syntax

带海象操作符:

In [99]: while temp := temp // 10:
...:     print(temp)
...:
10
1

否则你可以这样做:

In [99]: while temp:
...:     print(temp)
...:     temp //= 10
...:
100
10
1

地板运算符的位置取决于你是否也得到了temp的第一个值。

Answer 2

贴出的代码有很多错误

代码可以简化为:

def cnt_sum(number):
sum_ = 0                  # don't use sum as a variable name (conflicts with built-in function(
str_number = str(number)  # number as string
for i, v in enumerate(str_number):
# enumerate is Pythonic method for iterating through a list of values with the index
if i % 2 == 0:
# We're on an even index
sum_ += int(v)   # add digit at this index (need int since we have a lit of character digits)
return sum_

可以进一步简化为

def cnt_sum(number):
return sum(int(v) for i, v in enumerate(str(number)) if i % 2 == 0)

输出

cnt_sum(55443352)# result is 17