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Java

Posted by Ene Catalin
Ene Catalin
1,931 Points

How does the sumDigits method work?

The program calculates the sum of the digits of an integer, but I don't understand how the sumDigits method works:

Imgur

Brendan Whiting
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points

Ar you familiar with the modulus operator?

Ene Catalin
Ene Catalin
1,931 Points

Yes, I'm familiar with it

1 Answer

Brendan Whiting
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points

Here's how it works:

  • initializes a sum variable set a 0
  • finds the value of the last digit with n % 10. Modulus returns the remainder of a division, so the remainder of dividing by ten will return any value from 0-9 that's in the last position. So if n was 176, 176 / 10 would give us 17 remainder 6, so that would give us the number 6
  • we add that number to the sum
  • we divide the original number by 10 so that we can move on to the next digit. So 170 divided by 10 gives us 17, and now in the next iteration, 17 % 10 will gives us 7. So this will keep running until we've summed up all the digits
Ene Catalin
Ene Catalin
1,931 Points

Thanks a lot!