Question

Write a function called alter_sum(n)that returns the alternating sum of all the numbers from 1 to n so that the first number is added, the second number is subtracted, the third number added, the fourth subtracted, and so on: 1-2+3-4+5-6+7… until you reach n. If n is 0 or less then return 0.

Answer 1

code in c++

#include <iostream>

using namespace std;

// creating function
int alter_sum(int n)
{
    // if n is less than or equal to 0 return 0
    if(n<=0) 
    return 0;

    int sum=0;           //initializing int sum to 0

    // calculating alternate sum
    for (int i = 1; i <= n; i++)
    {
        if(i%2!=0)           //if i is odd then add it to sum        
        sum+=i;
        else                 //if i is even then subtract it from sum
        sum-=i;
    }
    return sum;    
}

int main()
{
    // testing our function
    cout<<alter_sum(5);

}

ss for reference: