how to calculate the number of digits of an element inside of an array?(not the length of an array) and also calculate the sum of its digits

Question

suppose the array is a[]={123,34533,21123}.How do i calculate the length of element at index 1?I know i am doing it all wrong but i dont know how to approach this

#include<iostream>
using namespace std;
int main()
{
    int a[]={123,231,23},j=0,num,last_digit,sum;
    int size_of_array=sizeof(a)/4;
    int pos;
    cin>>pos;
    num=a[pos];

    for(int i=0;i<size_of_array;i++)
    {
       last_digit=num%10;
       sum=sum+last_digit;
       num=num/10;
    }
    cout<<sum;
}

Do you know how to compute the length of a regular integer variable? Just copy the array element into another `int` and do the same thing to it. — NathanOliver, Oct 29 '18 at 17:35
related/dupe: https://stackoverflow.com/questions/1489830/efficient-way-to-determine-number-of-digits-in-an-integer — NathanOliver, Oct 29 '18 at 17:36
actually i want to calculate sum of the digits of the element for which i need its length — Aayush peace, Oct 29 '18 at 17:46
It is unclear what you mean by "length" of an element. Do you mean the number of digits in the decimal representation of an `int`? Please clarify and [edit](https://stackoverflow.com/posts/53050894/edit) your question to include useful information and improve the chances of getting a good answer — alter_igel, Oct 29 '18 at 17:46
Do you to calculate the sum of digits of _every_ element in the array? Right now, your `for` loop looks promising but is doing the same thing many times in a row, and the body does not depend at all on `i`. Perhaps you want `num=a[i];` at the beginning of the loop? — alter_igel, Oct 29 '18 at 17:51

score 0 · Answer 1 · answered Oct 29 '18 at 17:59

"i want to calculate sum of the digits of the element for which i need its length "

Confusing. If you want to convert the element to a string and then take its length, you would do this:

    std::cout << "Length: " << std::to_string(a[i]).size() << std::endl;

Where i is the index into array a[].

However, if you want to calculate the sum of the digits, then I suppose you are trying to do this:

    int sumCell = 0;
    int cellValue = a[i];
    while(cellValue > 0) {
        sumCell = cellValue % 10;
        cellValue /= 10;
    }

Sum is in the variable sumCell.

Are you looking for one of these two solutions, or another?

The solution assumes that the cells' integers are non-negative. — Gardener, Oct 29 '18 at 18:02

score 0 · Answer 2 · edited Oct 29 '18 at 19:05

0

#include<iostream>
using namespace std;
int main()
{
    int a[] = { 123, 231, 23 }, j = 0, num, last_digit, sum = 0, count = 0;
    size_t size_of_array = sizeof(a) / 4;
    size_t index;
    cin >> index;
    num = a[index];

    while (num != 0) {
        last_digit = num % 10;
        sum = sum + last_digit;
        num = num / 10;
        count = count + 1;
    }
    cout << sum << endl;        //sum
    cout << count;              //number of digits
}

edited Oct 29 '18 at 19:05

OznOg

4,440
2
26
35

answered Oct 29 '18 at 18:00

Aayush peace

55
1
8

2

What's the purpose of `/4`, especially the value `4`? – Thomas Matthews Oct 29 '18 at 18:56
1

What happens when `sizeof(int) == 8`? – Thomas Matthews Oct 29 '18 at 18:57

score 0 · Answer 3 · answered Oct 29 '18 at 18:00

Just like an ordinary int

#include<iostream>

int main() {

    int a[]={123,231,23};
    size_t pos; // use size_t for index and size
    std::cin >> pos;
    int elm = a[pos];
    int cnt = 1;
    while ( elm /= 10) {
        ++cnt;
    }

    std::cout << cnt << std::endl;

    return 0;
}

Enter the index and get the length.

how to calculate the number of digits of an element inside of an array?(not the length of an array) and also calculate the sum of its digits

3 Answers3