C-Program to print sum of digits in string

#include<stdio.h>

#include<string.h>

#include<stdlib.h>

int 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);

 return 0;

}