Crashing and Wroung data

So what is happening is that I run this code and when I run the divide function it will sometimes crash or say that I entered a wrong answer when it’s correct. I know I need to check option while loop but I'm not too concerned with that at the moment. Please check the divide function and tell me what I need to revise.

Code:

---

bool check_flat(int x, int y) //checks that two numbers divide evenly to one another
{
    int int_check = x/y;
    double check_x = x;
    double check_y = y;
    double double_check = check_x/check_y;

    if (int_check < double_check)
        return (false);
    else
        return (true);
}


double dividing (int x, int y) //dividing fuction (this is giving me problems)
{
    bool flat = false;
    int first_number;
    int second_number;
    int greater_number;
    int lesser_number;
    while (flat == false) //when I mean flat I mean the two numbers divide evenly to one another, no decimals
    {
        first_number = rand() % (x - y + 1);
        second_number = rand() % (x - y + 1);

        if (first_number > second_number) //checks to find the bigger of the two numbers and then set one to greater_number and one to lesser_number
        {
            greater_number = first_number;
            lesser_number = second_number;
        }

        else
        {
            greater_number = second_number;
            lesser_number = first_number;
        }

        flat = check_flat(greater_number, lesser_number); //calls check_flat function
    }


int main()
{
    time_t seconds;
    time(&seconds);
    srand((unsigned int) seconds);

    int max;
    int min;
    int option;
    int difficulty;

    cout << "Math practice";
    cout << "What would you like to practice? \n"
        << "1. Adding \n"
        << "2. Subtracting \n"
        << "3. Multiplying \n"
        << "4. Dividing \n";
    cin >> option; //type of math problems

    cout << "Difficulty? \n"
        << "1. Very Easy (1-5) \n"
        << "2. Easy (1-10) \n"
        << "3. Medium (5-15) \n"
        << "4. Difficult (1-25) \n"
        << "5. Very Difficult (1-50) \n"
        << "6. Extremely Difficult (1-100) \n";

    cin >> difficulty; //range of numbers

    while ((difficulty < 1)||(difficulty > 6)) //checking difficulty
    {
        cout << "Enter a difficulty between 1 through 6 \n"
            << "1. Very Easy (1-5) \n"
            << "2. Easy (1-10) \n"
            << "3. Medium (5-15) \n"
            << "4. Difficult (1-25) \n"
            << "5. Very Difficult (1-50) \n"
            << "6. Extremely Difficult (1-100) \n";

        cin >> difficulty;
    }

    switch(difficulty) //sets max and min randoms to be generated
    {
        case 1: min = 1; max = 5; break;
        case 2: min = 1; max = 10; break;
        case 3: min = 5; max = 15; break;
        case 4: min = 1; max = 25; break;
        case 5: min = 1; max = 50; break;
        case 6: min = 1; max = 100; break;
    }

    for(int i = 10; i >= 1; i--) //generates 10 problems at a time
    {
        switch (option)
        {
          case 1: adding(min, max);break; //calls adding fuctions
          case 2: subtracting(min, max);break; //calls subtracting fuctions
          case 3: multiplying(min, max);break; //calls multiplying fuction
          case 4: dividing(min, max);break; //calls dividing fuction
        }
    }

    system("PAUSE"); //pauses system
}

---

So what is happening is that I run this code and when I run the divide function it will sometimes crash or say that I entered a wrong answer when it’s correct. I know I need to check option while loop but I'm not too concerned with that at the moment. Please check the divide function and tell me what I need to revise.

Thank you,

ShadowIII

Sorry about posting all my code a first. I didn't read all of the rules. I apologize. I hope this is slim enough.

first_number = rand() % (x - y + 1);
second_number = rand() % (x - y + 1);
x-y+1 will always be negative since x was min and y was max in main() and min - max < - 1 in every case available in switch(difficulty). I believe using negative numbers with % results in undefined behaviour which would account for the pattern of your problem quite nicely. Try making it y - x + 1, instead.

Quote:

---

Originally Posted by ShadowIII

So what is happening is that I run this code and when I run the divide function it will sometimes crash or say that I entered a wrong answer when it’s correct. I know I need to check option while loop but I'm not too concerned with that at the moment. Please check the divide function and tell me what I need to revise.


So what is happening is that I run this code and when I run the divide function it will sometimes crash or say that I entered a wrong answer when it’s correct. I know I need to check option while loop but I'm not too concerned with that at the moment. Please check the divide function and tell me what I need to revise.

Thank you,

ShadowIII

---

the % operator returns values of 0 to something.

Put a printout statement that shows the numbers that you are using:

Code:

---


        first_number = rand() % (x - y + 1);
        second_number = rand() % (x - y + 1);
        cout << "first_number = " << first_number << ", second_number = "
            << second_number << endl;

---

check_flat() divides one number by the other. If one of them is zero, ....

Regards,

Dave

Yay it works thank you.

You were right about the dividing by zero. so I changed it to this.

Code:

---

        first_number = rand() % (y - x) + 1;//no more zeros occure
        second_number = rand() % (y - x) + 1;

---

The reason I was getting wroung answers even when they were right.

Code:

---

    if (answer == (first_number / second_number)) //Sometimes the second number was great than the first
        cout << "Correct \n";
    else
        cout << "Wroung \n";

---

I changed it to this

Code:

---

    if (answer == (greater_number / lesser_number))
        cout << "Correct \n";
    else
        cout << "Wroung \n";

---

Thank you very much! :D