Program debugging

Question

The program output should look like this:

Enter an even number: 23
The number is not a positive even number.
Enter an even number: -6
The number is not a positive even number.
Enter an even number: 4

20 20.25 20.50 20.75 21
The sum is 102.5

program doesn't run properly. the odd/ even numbers are identified, but the loop to increment the variables (20 + 1 / (even number entered)) does not work right.

#include <iostream>

int main(int argc, char *argv[])
{

    float val, sum, incr;
    int num;

    cout << "Enter an even number: ";
    cin >> num;

    if (num % 2 != 0)
        cout << "The number " << num << " is not a positive even number." << endl;
    else
        cout << num << " is even!" << endl << endl;


    incr = 1 / num;

    for (val = 20.0F; val <= 21.0; val += incr)
    {
        cout << val;
        sum += val;
    }

    cout << "The sum is " << sum << endl;

    return 0;

}

Answer 1

If you divide one integer 1 between another num the result is an integer that as chris said is 0.

You should do:

incr = 1.0F / (float)num;

And for exiting for wrong introduced values you should return from main

#include <iostream>

int main() {
    float val, sum, incr;
    int num; 

    cout << "Enter an even number: ";
    cin >> num;
    if (num < 0 || num % 2 != 0){
        cout << "The number " << num << " is not a positive even number." << endl;
        return -1;
    }
    else {
        cout << num << " is even!" << endl << endl;
    }

    incr = 1.0 / num;
    for (val = 20.0F; val <= 21.0; val += incr) {
        cout << val << " ";
        sum += val;
    }
    cout << "The sum is " << sum << endl;
    return 0;
}