CODEWITHSUNDEEP
c++loopswhile-loopinputstreaminfinite-loop
HanzoSwitch
HanzoSwitch

Reputation: 1

Why is the loop endless?

I'm doing some homework and trying to make it safe from character input but somehow writing a character inside still breaks it because it makes the loop infinite. Can anyone suggest a way to fix it? Here's the code:

#include <iostream>
#include <cstdlib>
#include <ctime>
int main()
{
    srand( time( NULL ) );

    int given = 0;
    int imaginarynum = ( std::rand() % 99 ) + 1;
    int tries = 0;

    std::cout << "Hello! We'regoing to play an easy game! I'm goinng to think of a number between 1-100 and you'll have to guess it! " << std::endl;
    std::cout << given << " "<< imaginarynum;

    while(given < imaginarynum || given > imaginarynum)
    {
        std::cin >> given;
        bool error = std::cin.fail();
        std::cin.clear();
        std::cin.sync();

        while(error != false)
        {
            std::cout << "That's not a number!" << std::endl;
            std::cin >> given;
            bool error = std::cin.fail();
            std::cin.clear();
        }

        if (given < imaginarynum)
        {
            std::cout << "I thought of a bigger number! " << std::endl;
            std::cout << "Guess again!" << std::endl;
            tries = tries + 1;
        }else if (given > imaginarynum)
        {
            std::cout << "I thought of a smaller number! " << std::endl;
            std::cout << "Guess again!" << std::endl;
            tries = tries + 1;
        }
        else
        {`enter code here`
            tries = tries + 1;
            std::cout << "Good job! " << std::endl << "It took you: " << tries << " Tries!";
        }
    }

    return 0;
}

Upvotes: 0

Views: 112

Answers (1)

Vlad from Moscow
Vlad from Moscow

Reputation: 311068

The problem is that you are using two variables error

    while(error != false)
    {
        std::cout << "That's not a number!" << std::endl;
        std::cin >> given;
        bool error = std::cin.fail();
        std::cin.clear();
    }

Within the loop you declared a new variable. Substitute the declaration for an assignment statement

    while(error != false)
    {
        std::cout << "That's not a number!" << std::endl;
        std::cin >> given;
        error = std::cin.fail();
        std::cin.clear();
    }

And the second problem is that you need to clear the buffer. For example

#include <limits>

//...

std::cin.ignore( std::numeric_limits<std::streamsize>::max(), '\n' );

The loop will look the following way

    #include <limits>

    //...

    while(error != false)
    {
        std::cout << "That's not a number!" << std::endl;
        std::cin >> given;
        error = std::cin.fail();
        std::cin.clear();
        std::cin.ignore( std::numeric_limits<std::streamsize>::max(), '\n' );
    }

Upvotes: 5

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