Separate a Number's Digits

[rar]

In a test preparation exercise I just received, one question poses the problem of
If you are given a number, (ex. 13.23), print the sum of the number's digits.

So in this case, 1 + 3 + 2 + 3 = 9

Sample Input:
12.45
Sample Output:
12
(meaning 1 + 2 + 4 + 5 = 12)

[Tony]

Was there a question that you had about that?

[rar]

Nope, just letting you know!

[rar]

Sorry, I had to say it lol...I found my own idiocy amusing lol so I apologize.

My question was definitely:

How would you go about doing this in C?

[Tony]

Same way as in any other language. Division by powers of 10.

[Insectoid]

Another very messy way would be to convert the number to a string, take the first character, convert it to an integer. Do the same for the 2nd digit and add them. Repeat with the 3rd, and so on. This would be very slow though. Tony's way would be faster, cleaner, and all around a better solution. I would do it recursively.

[Tony]

insectoid @ Thu Nov 05, 2009 3:06 pm wrote:

convert the number to a string...

That would also defeat the purpose of the exercise.

[rar]

ok so...can you be more specific???

[Tony]

Do it on paper first, it's all math anyway.

Hint: you can shift numbers left/right with powers of 10.

12.34 * 10 = 123.4
12.34 / 10 = 1.234

[rar]

Right but then how would you get the later digits by themselves to add them?

[Tony]

code:

(int)1.234 == 1

[rar]

yes...so then would you go get rid of the one, multiply by 10 accordingly, and then cast the second digit in the same way?

[OneOffDriveByPoster]

Well, in general, you have to handle the digits in the non-fractional part too. You may want to consider division there.