Thread: forcing division with int result

Code:

num1 = rand();
num1 = rand() % 12 + 1;
num2 = rand(); // picks a second random number that will not be the first
num2 = rand() % 12 + 1;

I think it has been pointed out once to you that it is not necessary to call rand twice for each random number you want. (The red lines make no sense.)

So you want to draw two random numbers so that the first number is evenly divisible by second?

Firstly note that your comment is wrong. There is no guarantee that both numbers won't end up equal.

Secondly, since the first number may happen to be a prime (in addition to other complications), it might be easier to pick the result and the divider (num2) randomly, and then calculate the missing number (num1) using multiplication.

Code:

for (pro = 0; pro < numpro; pro++) //keeps a count until number of problems desired is reached
{
	srand((unsigned)time(0)); // allows for random number generation
	num1 = rand();
	num1 = rand() % 12 + 1;
	num2 = rand(); // picks a second random number that will not be the first
	num2 = rand() % 12 + 1;

	cout << "\n\n " << num1 << " / " << num2 << " = " ;
	cin >> ansr;
	total = num1/num2;
	{
		if (total == ansr) // verifies input answer is correct
		{
			right++;
			cout << "\n Correct!" << endl;
		}
		else if (total != ansr)
		{
			wrong++;
			cout << "\n Incorrect. The correct answer is: " << total << endl;
		}
	}

You don't need to indent such a ridiculous amount of tabs- The above will do just fine. It will just cause people to have to scroll.
Also note that you're missing a } at the end.

Code:

if (num1 + num2 = int)
    cin >> ansr;
else if (num1 + num2 !=int)
     srand((unsigned)time(0));
     num1 = rand();
     num1 = rand() % 12 + 1;
     num2 = rand();

I want to note to you that this code should be

Code:

if (num1 + num2 = int)
    cin >> ansr;
else if (num1 + num2 !=int)
     srand((unsigned)time(0));
num1 = rand();
num1 = rand() % 12 + 1;
num2 = rand();

Because only the first line is executed as part of the if. If you want the additional lines to be part of the if, as well, you need to use { and } around the else if.

Originally Posted by got1sleeve

It HAS been pointed out to me before but as I wrote in the reply that is how my professor wants it coded. Its not my option but thank you for pointing that out again.

OK, let's read that code.

Code:

num1 = rand();

OK, call rand() and assign the return to num1.

Code:

num1 = rand() % 12 + 1;

Call rand again, divide by 12 and take the remainder and add 1, then store in num1, erasing any previous contents.

Doesn't make sense, does it?
Either your teacher isn't thinking right or you are not understanding what your teacher means.

In your other thread you wrote:

Originally I wasn't using that buy monday my professor said he reccomends writing it out that way because the first one assigns a rand value to num1 and then the second line keeps it below 100.

Are you sure that he didn't mean:

Code:

num = rand(); //first line picks a random number
num = num % 100; //keeps it under 100

Otherwise that would really be strange.

Anyway, if you can't use my multiplication idea for some reason, you'll need to take into account that the first number has to be at least twice as big as the second one (if the numbers have to be different - better not accept 1 in the first place), and if the first number happens to be a prime, the second number can only be 1.

You can pick the first number randomly and then keep picking random numbers up to half the size of the first until they are evenly divisible (which can be checked using modulus).

Originally Posted by got1sleeve

It HAS been pointed out to me before but as I wrote in the reply that is how my professor wants it coded. Its not my option but thank you for pointing that out again.

Sorry you're wrong about that. That is not how your professor wants it coded. You get a lot of people misinterpreting what they've been told to do on here, claiming that they were told to do the most ridiculous of things. It's practically always a misunderstanding on behalf of the poster.

Calling rand unnecesarily is harmful as it shortens the length of the random sequence.
The only possible interpretation I can see of what your professor meant is what anon shows.

Code:

for (pro = 0; pro < numpro; pro++)
{
    srand((unsigned)time(0));

Calling srand in the loop? Does your prof want it written that way too?

If total and numpro are both integers, the result of the division will be truncated (to 0 or 1 if they are equal) before you get to cast it to double. Try casting one of them before dividing, or multiply by 100.0* first.

Code:

double percent = count * 100.0 / total;

You should still remove the srand call from the loop. srand should be called only once in your program. Otherwise, if you managed to answer within a second you'd be presented the exact same numbers again (because time would return the same value and for each seed rand() produces a deterministic sequence).

* 100.0 is interpreted as double and this will force intermediate result to be a double; 100 is an integer literal.