Ok I know one way of using the formula n*(n+1)/2) and have used it to calculate the sum already but I just wanted to know how I can access many numbers in a loop and add them together. Here is what I did so far.

Code:

#include <iostream>
using namespace std;
int main (){
int num, num1, sum;
cout<<"Please enter a number\n";
cin>>num;
cout <<"Please enter the number to which you want to count\n";
cin>>num1;
for (; num<=num1; num++)
cout<<num<< ","; //I do get the numbers but from here
//I want to know what I can do so that I can add each
// of these numbers together?
do (sum=num+num);//I want to add them like 0+1+2+...
//tried using loops but couldn't get it
while (num<=sum);
cout<<sum;//but this does not work so any help is appreciated
return 0;
}