I'm trying to solve a problem (as the title already state). I've actually learned that I can do it with modulo operator (%). But the first code that I wrote is using the while-loop, so I'm trying to finish the code.

This is the code

int main()
{
 char arr[1000000];
 int i = 0;
 int sum = 0;

    printf("type the number = ");
    scanf("%s", arr);

    while(arr[i] != '\0'){
        sum = arr[i]   sum;
        i  ;
}

printf("the total number is = %d", sum);

so the problem is it's actually printing out some huge amount of number.. I guess it's because of the array is in char, can someone help me how do I changed the value into int ?

CodePudding user response：

1. You need to substract from the digit code the code of '0'.

Here you have the both versions (I have added some logic to accept the numbers with & - at there beginning):

int sumdigitsStr(const char *num)
{
    int sum = 0;
    int first = 1;
    while(*num)
    {
        if(isdigit(*num)) {sum  = *num - '0'; first = 0;}
        else 
        if(first && (*num == '-' || *num == ' '))
        {
            first = 0;
            num  ;
            continue;
        }
        else
        { 
            sum = -1; break;
        } //error string contains non digits
        num  ;
    }
    return sum;
}

int sumdigits(long long num)
{
    int sum = 0;
    do
    {
        sum  = abs((int)(num % 10));
    }while((num = num / 10));
    return sum;
}

CodePudding user response：

#include<stdio.h>
int main()
{
int n;
    scanf("%d",&n);
    int d,sum=0;
    while(n!=0)
    {
        d = n%10;
        sum = sum   d;
        n = n/10;
        }
    printf("sum of digits is : %d",sum);
    return 0;
}