Here is a simple loop program to add numbers between 2 inputted numbers.
#include"iostream.h"
#include"conio.h"
void main()
{
clrscr();
int num1,num2,sum=0;
cout<<"Enter 1st number :: ";
cin>>num1;
cout<<"\nEnter 2nd number :: ";
cin>>num2;
for(int i=num1;i<=num2;i++)
{
sum=sum+i;
cout<<"\nSum of the numbers is "<
}