C++ Loops forever

Question

I wrote the following loop as a part of a program for my CS homework, however regardless of the input, the program keeps looping at this exact point. What am I doing wrong?

#include <iostream>
using namespace std;

char choice;
do
{
  cout << "Type 'c' for characters or type 'n' for numbers: ";
  cin >> choice;
}while (choice != 'c' || choice != 'n');

Review the meaning of `||`. Try saying the expression out loud. — Drew Dormann, Mar 21 '18 at 20:54
Your condition always evaluates to `true` do to use of `||` operator. — Ron, Mar 21 '18 at 20:54
You cannot be 'c' and 'n' at same time, so it loops forever. — Afshin, Mar 21 '18 at 20:55
Possible duplicate of [Why non-equality check of one variable against many values always returns true?](https://stackoverflow.com/questions/26337003/why-non-equality-check-of-one-variable-against-many-values-always-returns-true) — Barmar, Mar 21 '18 at 21:14

Drew Dormann · Accepted Answer · 2018-03-21T21:14:23.603

3

A do-while statement loops as long as the while expression is true.

Your while expression is

choice != 'c' || choice != 'n'

In common English, that expression means

choice is not 'c' OR choice is not 'n'

That statement, logically, is always true. choice is always not one of those things.

In both English and C++, you would want to use and/&& in that expression.

edited Mar 21 '18 at 21:14

answered Mar 21 '18 at 21:10

Drew Dormann

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Oh I thought or was the way to achieve that effect. It makes more sense when you put it like that, thanks! – user9325564 Mar 21 '18 at 21:13

C++ Loops forever

1 Answers1