【leetcode】整数的各位积和之差

int subtractProductAndSum(int n) {
        int add = 0, mul = 1;
        while (n > 0) {
            int digit = n % 10;
            n /= 10;
            add += digit;
            mul *= digit;
        }
        return mul - add;
    }

int subtractProductAndSum(int n){
    char* arr = (char*)calloc(6,sizeof(int));
    sprintf(arr,"%d",n);
    int sum=0;
    int pro=1;
    for (int i=0; i<strlen(arr); i++)
    {
        sum+=(arr[i] - 0x30);
        pro*=(arr[i] - 0x30);
    }
    return pro-sum;
}