The “sum up the digits in an integer” problem was discussed in Loops in Python where it illustrated the use of a while loop and a for-loop. Now we want to solve this problem repeatedly. The user provides an integer and the program prints the sum of the digits in that integer; this process is repeated until the user enters -1 as input.
The program below wraps a while loop around the for-loop code (see Example 11 in Loops – Python). We could have also used the while loop code (Example 6 in Loops – Python).
# 03Loops example_06_summing up digits.py
n = int(raw_input('Please input an integer: ')) #To get the first integer
while n != -1:
sum = 0 #Use variable sum to store the sum of all the digits
for i in str(n): #Convert the integer into a string
sum = sum + int(i) #Convert the string into an integer and add
print sum
n = int(input('Please input an integer: ')) #Use input function to get another integer
print('The loop ends! Bye!') #Program ends
This nested loop example is discussed in the following video. Video Length: 4:33
