sum of digits in c 2b 2b

1int x, s = 0;
2   cout << "Enter the number : ";
3   cin >> x;
4   while (x != 0) {
5      s = s + x % 10;
6      x = x / 10;
7   }

1// Method 1: Mathematical -> Sum up numbers from 1 to n 
2int sum(int n){
3	return (n * (n+1)) / 2;
4}
5
6// Method 2: Using a for-loop  -> Sum up numbers from 1 to n 
7int sum(int n){
8	int tempSum = 0; 
9  	for (int i = n; i > 0; i--){
10     	tempSum += i;  
11    }
12  	return tempSum; 
13}
14
15// Method 3: Using recursion -> Sum up numbers from 1 to n 
16int sum(int n){
17	return n > 0 ? n + sum(n-1) : 0; 
18}

1// sum the digits of an integer
2int getSum(long long n) {
3  int sum = 0;
4  int m = n;
5  while(n > 0) {    
6    m = n % 10;    
7    sum = sum + m;    
8    n = n / 10;    
9  } 
10  return sum;
11}

1//1
2	int n = 12345, sum = 0;
3    while(n) {
4        sum+=n%10;
5        n/=10;
6    }
7    cout << sum; //15
8//2
9	int n = 12345, sum = 0;
10    for (sum = 0; n > 0; sum += n % 10, n /= 10);
11    cout << sum; //15