Infinite Loop

[rsh0117]

No idea you could do 1/(float)num and no I haven't heard of Debugging

[frema]

1 is an integer so the compiler returns the result as an integer. Therefore you need to do a cast. 1.0 will work or (float) 1/num or in c++ static_cast<float>(1)/num.

[rsh0117]

okay, so I did change 1/num to 1.0/num, and that fixed that. but this output
CSCE 1020 Lab 9 Randall Hall [e-mail]

Enter an even number: -6
The number is not a positive even number.
Enter an even number: 0
The number is not a positive even number.
Enter an even number: 23
The number is not a positive even number.
Enter an even number: 4
The number 4 is even!

-1.04596
The sum is -1.04596
corresponds to

/*
Randall Hall
CSCE 1020.302
Lab 09
[e-mail]

*/
#include <iostream>
int main() {
   float val, sum, incr;
   int num;

   cout << "CSCE 1020 Lab 9\tRandall Hall\[e-mail]" << endl;
   cout << "\n";
   do {
   cout << "Enter an even number: ";
   cin >> num;
   if(num % 2 == 0 && num > 0 && num != 0)
      cout << "The number " << num << " is even!" << endl << endl;
   else 
      cout << "The number is not a positive even number." << endl;
   } while (num % 2 !=0 || num <=0);
   sum = 0;
   incr = 1.0/(float)num;

   do {
   cout << val << " ";
   sum += val;
   val += incr;
   } while (val < 21.0 && val > 20.0); //if I do ||, it sends me back into an infinite loop
   cout << "" << endl;
   cout << "The sum is " << sum << endl;
   return 0;
}

[frema]

You should always initialize your variables. Some formatting would be nice, too.

It would also help commenting your code. What is it supposed to do?

// val is something, nobody knows

do{
	// something is printed
	cout << val << " ";
	// something is added to sum (initially zero) 
	sum += val;
	// something is increased by something else
	val += incr;
	// the loop lasts if something is smaller 
	// than 21 AND larger than 20  between 20 and 21 
	// (20.0 < val && val < 21.0) 
} while (val < 21.0 && val > 20.0);

With || the loop will last if something is smaller than 21 OR larger than 20 that is pretty much every possible number so it will never quit (val < 21.0 || 20.0 > val)