Program 93:To print sum of digits in string

Program 93:To print sum of digits in string

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
main()
{
int i,j=0,temp,sum=0,n;
char str1[100],str2[100]={0};
printf("Enter a string\n");
gets(str1);

for(i=0;i<strlen(str1);i++)
{
    if(str1[i]>='0'&&str1[i]<='9')
    {
        str2[j]=str1[i];
        j++;
    }
    
}
temp=atoi(str2);//To convert string to integer
printf("The digits present in string is %d\n",temp);
while(temp>0)
{
    n=temp%10;
    sum+=n;
    temp=temp/10;
}
printf("The sum of digits is %d\n",sum);

}

Explanation:

1. This program starts with initializing :
   • temp → To store only digits from string temporarily as a number integer format
   • i,j,n→Used as helping variable
   • sum → To store output sum
   • str1 →To store input string
   • str2  →To store digits in string format

2. printf("Enter a string\n");
   gets(str1);
   

   Taking input from user.Let it be "he123"

3. for(i=0;i<strlen(str1);i++)
   {
       if(str1[i]>='0'&&str1[i]<='9')
       {
           str2[j]=str1[i];
           j++;
       }
       
   }

   The above for loop traverse from 0 to length of string which here is 5(he123).
   Each time it iterates from 0 it checks whether the character lies in between 0 and 9 and if it is ,then that character which lies in between 0 and 9 is stored in str2 one by one
4. Finally all the digits are stored in str2 in string format 

5. temp=atoi(str2);

   atoi will convert string to integer and that is stored in temp=123

6. while(temp>0)
   {
       n=temp%10;
       sum+=n;
       temp=temp/10;
   }
   printf("The sum of digits is %d\n",sum);

   Now temp will have 123 in("he123").The above forloop will get us sum of the digits.If you would like to understand how that works see this Program 8:Sum of all Digits
7. Finally sum of 123 is 6

 Output: