While loop not checking or condition

Question

I'm doing c++ practice exercises. The one question that I'm on is as follows...

Write a program that continues to ask the user to enter any number other than 5 until the user enters the number 5. Then tell the user "Hey! you weren't supposed to enter 5!" and exit the program.

★ Modify the program so that after 10 iterations if the user still hasn't entered 5 will tell the user "Wow, you're more patient then I am, you win." and exit.

#include <iostream>

using namespace std;

int main()
{
    int userNum;
    int numTimes = 0;

    do
    {
        cout << "Please enter a number: ";
        cin >> userNum;
        numTimes++;

    }while ((numTimes != 10) || (userNum != 5));
    {
        if (numTimes == 10)
        {
            cout << "Wow, you're more patient than I am, you win.\n";
        }
        else
        {
            cout << "Hey! you weren't supposed to enter 5!\n";
        }
    }
}

I can't seem to get the or condition of the while loop to work.

Offtopic: your brackets after while-loop are **extremely** confusing. Don't write confusing code. — , Jul 15 '19 at 07:33

Blaze · Answer 1 · 2019-07-15T07:34:57.370

Change this here

while ((numTimes != 10) || (userNum != 5));

To this

while ((numTimes != 10) && (userNum != 5));

Because you want it to stop as soon as just one condition turns false. The way you have it now with ||, it only stops if both conditions are true at the same time, so if the 10th number is 5. It won't stop if just a 5 is entered, or if it just reached 10. It wouldn't even stop if a 5 is entered after 10 numbers.

Remember, a || b is true even if just one of a and b are true. But since the conditional is confusing this way, why not split the logic like this?

int main()
{
    int userNum;

    for (int numTimes = 0; numTimes < 10; numTimes++){
        std::cout << "Please enter a number: ";
        std::cin >> userNum;

        if (userNum == 5) {
            std::cout << "Hey! you weren't supposed to enter 5!\n";
            return 0;
        }
    }

    std::cout << "Wow, you're more patient than I am, you win.\n";
}

Stack Danny · Accepted Answer · 2019-07-15T08:02:37.260

You are doing this in a confusing way, I would aim for expressiveness:

#include <iostream>

int main() {
    int userNum;
    int numTimes = 0;

    while (true) {
        std::cout << "Please enter a number: ";
        std::cin >> userNum;

        if (userNum == 5) {
            std::cout << "Hey! you weren't supposed to enter 5!\n";
            break;
        }

        ++numTimes;

        if (numTimes == 10) {
            std::cout << "Wow, you're more patient than I am, you win.\n";
            break;
        }
    }
}

break allows you to conveniently exit a loop. Please don't "abuse" this to overcomplicate or to accomplish weird tricks, though. No one likes spaghetti code.

Note how you shouldn't use namespace std;. Also try to use ++var over var++ as var++ unnecessarily copies the object.

Please enter a number: 5
Hey! you weren't supposed to enter 5!

Please enter a number: 12
Please enter a number: 45
Please enter a number: 12
Please enter a number: 0
Please enter a number: 9
Please enter a number: 1
Please enter a number: 2
Please enter a number: 3
Please enter a number: 4
Please enter a number: 1
Wow, you're more patient than I am, you win.

score 0 · Answer 3 · answered Jul 15 '19 at 07:30

The problem is with your condition. Your loop continues until the condition isnt met anymore.

while ((numTimes != 10) || (userNum != 5));

Forces the loop to continue until both conditions are false. If your numTimes == 10, then the userNum will be still < 5

while ((numTimes < 10) and (userNum != 5));

Is the correct condition

While loop not checking or condition

3 Answers3