Question

Write a function named "sum_from_to" that takes two integer arguments, call them "first" and "last", and returns as its value the sum of all the integers between first and last inclusive. Thus, for example:

cout << sum_from_to(4,7) << endl;  //will print 22 because 4+5+6+7 = 22

cout << sum_from_to(-3,1) << endl; //will print -5 'cause (-3)+(-2)+(-1)+0 +1 = -5

cout << sum_from_to(7,9) << endl;  //will print 22 because 7+8+9 = 24

cout << sum_from_to(9,9) << endl;  //will print 9

Answer 1

#include<bits/stdc++.h>
using namespace std;
int sum_from_to(int first, int last)
{
    int s=first;
    while(first<last)
    {
        first=first+1;
        s=s+first;
    }
    return s;
}
int main()
{
    cout << sum_from_to(4,7) << endl;  //will print 22 because 4+5+6+7 = 22


cout << sum_from_to(-3,1) << endl; //will print -5 'cause (-3)+(-2)+(-1)+0 +1 = -5


cout << sum_from_to(7,9) << endl;  //will print 22 because 7+8+9 = 24


cout << sum_from_to(9,9) << endl;  //will print 9
}