CODEWITHSUNDEEP
c++
JASON
JASON

Reputation: 7491

why the while body is executed?

I have the following program:

int main() {
  int i;
  while (cin >> i) {
    cout << abs(i) << endl;
  }
  return 0;
}

(where abs is defined by int abs(int val))

when I input a non-int number, for example, -1.2, it will give the following output:

$ -1.2
1

My question is: why the while body gets executed? I think the condition should fail as soon as I input a non-int value and the program should terminate. Thanks!

Upvotes: 2

Views: 72

Answers (2)

James Hurley
James Hurley

Reputation: 762

Your program only reads one integer, not any more than that. If you use cin to read an int value the operator will only read an int, so using a decimal will make it only read up to the dot. Entering -55.365, for example, would really only send -55.

Upvotes: 2

Some programmer dude
Some programmer dude

Reputation: 409166

Because the input operator reads -1, and stops at the dot. Next time through the loop the input operator sees the dot and sets the fail flag, terminating the loop.

Upvotes: 2

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