complicated variable assignment

Question

I usually do my incrementation this way:

n=0
n=n+1 # and never do n+=1

Now there is code that I am trying to comprehend and I'm struggling to understand it.

sum=0
temp = num
while temp > 0:
    digit = temp % 10
    # below is the line I do not understand
    sum += digit ** power # what is happening here?. with power= len(str(num))
    temp //= 10

if num == sum:
   print num

This snippet is a piece to list the armstrong numbers.

In your case (and most cases), the line sum += digit ** power is equivalent to sum = sum + digit ** power. — javidcf
– javidcf, Commented May 30, 2018 at 13:25
Please provide the complete code. Also, num is not defined, please explain what num is. — Flaming_Dorito
– Flaming_Dorito, Commented May 30, 2018 at 13:32
@Flaming_Dorito the OP isn't asking to debug code, they're asking for someone to explain what n ** x means. Thus, an MCVe isn't necessary. — rst-2cv
– rst-2cv, Commented May 30, 2018 at 13:34
Possible duplicate of What does the ** maths operator do in Python? — Nick
– Nick, Commented May 30, 2018 at 13:35
@ResetACK OP might have been asking why we do that calculation and what it means in the calculation of the final answer. It wasn't clear. — Flaming_Dorito
– Flaming_Dorito, Commented May 30, 2018 at 13:47

rst-2cv · Accepted Answer · 2018-05-30 13:26:29Z

4

In python ** is the sign for exponent, so x ** 2 is x^2 (or x squared).

x += g is the same as x = x + g

sum += digit ** power == sum = sum + (digit ** power)

answered May 30, 2018 at 13:26

rst-2cv

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1 Comment

rst-2cv Over a year ago

As for being reluctant to use n += 1, it's up to you but that method is far easier to understand in my opinion than n = n + 1

OrionMD · Accepted Answer · 2018-09-28 10:57:50Z

2

while temp > 0:
    digit = temp % 10 
    sum += digit ** power
    temp //= 10

Take the last digit of temp
Add to sum the digit to the power of power
Delete the last digit of temp

edited Sep 28, 2018 at 10:57

answered May 30, 2018 at 13:28

OrionMD

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rst-2cv · Accepted Answer · 2018-05-30 14:19:48Z

0

suppose num = 34, then power becomes 2, so, for first iteration:

digit = 4
sum = 0 + 4 ** 2 # which is 0 + 16 = 16. Then adding to sum

so, digit ** power is digit to the power of 2

similarly, for second iteration:

digit = 3
sum = 16 + 3 ** 2 # which is  16 + 9 = 25

edited May 30, 2018 at 14:19

rst-2cv

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answered May 30, 2018 at 13:33

Mayank Mittal

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