subtraction and division using srand

[sttip]

Hi,

I'm a student taking a beginner's c++ course. I am trying to write a program that performes simple math operations on random numbers. I am using the
srand(int(time( 0))); function to generate the random numbers. I have two variables that I'm using to perform the operations upon. I was wondering if there was a way to tell one of the variables to be less than the other so that negative answers are not generated during subtraction and division. Here is a snippet:

srand(int(time(0)));
   vara = 1 + rand() % (1000 - 1 + 1);
   varb = 1 + rand() % (1000 - 1 + 1);
   answera = 0;
   cout << "What is " << vara << '-' << varb << '?' << endl; 
   cin >> response;
   answera = vara - varb;

Don't know how far off I am....like I said just a beginner. Any advice would be helpful.

[mac11]

I was wondering if there was a way to tell one of the variables to be less than the other so that negative answers are not generated during subtraction and division.

I would just compare the numbers before doing the subtraction and swap them if the second one turns out to be larger. (New code in bold)

srand(int(time(0)));
   vara = 1 + rand() % (1000 - 1 + 1);
   varb = 1 + rand() % (1000 - 1 + 1);
   answera = 0;
   
[B]    if( varb > vara ) // if b is larger swap a and b
    {
        int tmp = vara;
        vara = varb;
        varb = tmp;    
    }[/B]

   cout << "What is " << vara << '-' << varb << '?' << endl; 
   cin >> response;
   answera = vara - varb;

[AdrianH]

Hi,

I'm a student taking a beginner's c++ course. I am trying to write a program that performes simple math operations on random numbers. I am using the
srand(int(time( 0))); function to generate the random numbers. I have two variables that I'm using to perform the operations upon. I was wondering if there was a way to tell one of the variables to be less than the other so that negative answers are not generated during subtraction and division. Here is a snippet:

srand(int(time(0)));
   vara = 1 + rand() % (1000 - 1 + 1);
   varb = 1 + rand() % (1000 - 1 + 1);
   answera = 0;
   cout << "What is " << vara << '-' << varb << '?' << endl; 
   cin >> response;
   answera = vara - varb;

Don't know how far off I am....like I said just a beginner. Any advice would be helpful.

The formula you gave: "vara = 1 + rand() % (1000 - 1 + 1);" You don't need the - 1 + 1 as they cancel each other out.

So what you have is vara and varb being assigned a value between 1 and 1000.

If you just want one to be always greater than the other, just check after you generate the numbers and swap them if they are reverse of what you want.


Adrian

[sttip]

The formula you gave: "vara = 1 + rand() % (1000 - 1 + 1);" You don't need the - 1 + 1 as they cancel each other out.

So what you have is vara and varb being assigned a value between 1 and 1000.

If you just want one to be always greater than the other, just check after you generate the numbers and swap them if they are reverse of what you want.


Adrian

Thank you for swap suggestion. I wrote the srand statement from reading directions in textbook. Maybe I misunderstood. Thanks for help.