what is the sum of 1 to n number code example

Example 1: sum of n natural numbers

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	int sum=0;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		sum+=i;
	}
		cout<<sum<<" ";
	cout<<endl;
	return 0;
}

Example 2: sum of all n integers

Sum of n integers 1 + 2 + 3 + ... + n = n * (n + 1) / 2