C++ count numbers

Question

I have this function:

int calc (int day, int month , int year)
{
    int cal;
    cal=day+month+year;
    cout<<cal;
}

Let say that the result of cal is 2008. What I want to do is to count each number separately.

Example:

2008=2+0+0+8=10

But I don't know how to do that. Any ideas?

Thanks

Edit:

Another Example:

day=20
Month=03
Year=1993

20+03+1993=2016

And 2+0+1+6=9

Have you tried anything or come up with any starting points or ideas? — chris, Mar 19 '13 at 04:11
This question doesn't really have anything to do with days or months or years, does it? — Beta, Mar 19 '13 at 04:12
x % 10 gives the least significant digit of a number. x / 10 gives the rest of that number without the least significant digit. — Jerry Coffin, Mar 19 '13 at 04:12
Yeah it does have days,months and years included in the source. — user1638487, Mar 19 '13 at 04:14
But all your question really boils down to is "How do I sum the digits of an integer?" Nothing to do with dates there. — chris, Mar 19 '13 at 04:17
The same way you do it in C or ObjC: http://stackoverflow.com/questions/4032702/objective-c-how-to-add-digits-in-a-number/4032721#4032721 — paxdiablo, Mar 19 '13 at 04:39

DotPi · Answer 1 · 2013-03-19T04:37:45.630

1

This is the way you take the sum of digits of any number.

The modulos divide (%) operator is used to extract the last digit. and a running sum is kept to keep the sum of digits. The divide operation at the end removes the last number from the digit so that in the next round of loop the second last number can be extracted by %.

Keep in mind that the number(num) is of integer type. Hence when you divide the number by 10, it keeps the integer part and discards any decimal part. Thus, 2008/10=200 and not 200.8. Also to clarify the % operator, 2008%10=8 as 8 is the remainder of dividing 2008 by 10.

num=2008;    //put any number here
sum=0;
while(num>=0)
{
       digit=num%10;
       sum+=digit;
       num=num/10;
}
cout<<sum;

edited Mar 19 '13 at 04:37

answered Mar 19 '13 at 04:16

DotPi

3,977
6
33
53

Can you give me a more detail example? I dont understand very well – user1638487 Mar 19 '13 at 04:24
When a decimal number is divided by 10, it is "shifted right" by one digit. The '%' operator returns the remainder from division. – Thomas Matthews Mar 19 '13 at 04:27
I have edited he post to try and give a better explanation. Please do a dry run of the code to gain an indepth understanding. – DotPi Mar 19 '13 at 04:33

C++ count numbers

Example:

Edit:

Another Example:

1 Answers1