Integer returned as sum of digits?

Question

Here is what I'm supposed to write:

• a function, countDigits, which will take an integer as a parameter and return the sum of its digits (you must use a for loop). For instance, the number 123 would return 6 (1 + 2 + 3)

• a main function which will count numbers starting at one, and ending when the total digits (for all the numbers) exceeds 1,000,000. So, if you want the total digits for the number 5, you would add:

  • 1 = 1
  • 2 = 2 + 1
  • 3 = 3 + 3
  • 4 = 6 + 4
  • 5 = 10 + 5, so 15 would be the total digit count.

• your program will print both the number and the digit count before it exceeds 1,000,000. This is easiest with a while loop.

I've written the code for the function countDigits, which is:

def countDigits():
    value=int(input('Enter Integer: '))
    str_num= str(value)
    total = 0
    for ch in str_num:
        total += int(ch)
    print(total)

However, I'm stuck as to how to write the main function. Can anyone point me in the right direction?

EDIT

Here is my revised countDigits function:

def countDigits(value):
    str_num= str(value)
    total = 0
    for ch in str_num:
        total += int(ch)
    print(total)

Answer 1

a one-liner:

factorial_digit_sum = lambda x: sum( sum(map(int, str(a))) for a in range(1,x+1) )

If you EVER write real code like this, Guido will hunt you down. Was kind of a fun brain teaser to golf, though.

For a real answer:

def countDigits(number):
    return sum(map(int, str(number)))

def main():
    total = 0
    count = 1
    while total <= 1000000:
        total += countDigits(count)
    total -= countDigits(count) # you want the number BEFORE it hits 1000000
    print("Summing the digits of {}! yields {}".format(count, total))

main()

The problem in your code is that your countDigits function requests user input. You should change that to accepting the integer as a parameter. It also print s the result instead of return ing it.

Answer 2

As @Blorgbeard mentioned in the comments, change countDigits to accept an integer as input. Also, return the total from it.

In the main function, read input, call countDigits and add them in a while loop until the total is greater than 1,000,000

def countDigits(value):
    str_num= str(value)
    total = 0
    for ch in str_num:
        total += int(ch)
    return total

grandTotal = 0
while ( grandTotal < 1000000 ):
  value=int(input('Enter Integer: '))
  grandTotal += countDigits(value)