Thread: randomizing?

Then argc == 4, argv[0] == "-cheats", argv[1] == "1", argv[2] == "-level", argv[3] == "99".

Actually, the program itself is in there, so it's

argc == 5, argv[0] == "myprog.exe", argv[1] == "-cheats", argv[2] == "1", argv[3] == "-level", argv[4] == "99".

Aaaaaaaagggggggggggg, When I read the FAQ I was totally lost. All your examples are great, but I still don't know how to incorporate them into my code or set the specific parameters for my program?

I don't understand this??

Originally Posted by sean_mackrory

1) Using srand, seed the generator once.
2) Determine the characteristics of the random numbers you need, and thus the corresponding parameters.
3) Call rand with those paramaters.

As I can see there are a lot of different ways of doing this and I got to here and I am stumped.

Code:

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

int main(int argc, char *argv[])
{
srand(time(0));
int x;
int guess;

do {
cout << "im thinking of a number between 1 and 10\n";
cout << "enter your guess please\n";

cin >> guess;

if (guess == x) {
cout << "you are correct\n";
}
else if (guess < x) {
cout << "guess a higher number\n";
}
else if (guess > x) {
cout << "your not supposed to guess this high\n";
}
else {
cout << "guess a lower number\n";
}
}while (guess != x);

system("pause");
return 0;
}

Did you see I quoted you? I don't understand what you just said. I would call rand if I knew how?!

rand() returns a number from 0 to RAND_MAX. Therefore ((double)rand() / (double)(RAND_MAX + 1)) is a number in the range [0, 1). If you multiply this by the (integer) range of values you want (i.e. if you want a number from 2 to 5, the range is (5 - 2) + 1 = 4), then you get an integral value in the range [0, range). Now add the 'lowest' value that you want, in this case 2, and you'll have a value in the range of [2, 6). Since it's getting converted into an integer, the 6) gets truncated to 5], so you end up with a number in the range [2,5] as desired. So the formula is,

Code:

randomValue = (((double)rand() / (double)(RAND_MAX + 1)) * (highestValue - lowestValue + 1)) + lowestValue;

Now you can plug that into your program and substitute your own 'parameters' or values for highestValue and lowestValue so that x is assigned a random number in the range that you want.

Here's an example in code form:

Code:

int getRandomValue(int lowBound, int highBound)
{
   //Find the number of possible values
   int range = highBound - lowBound + 1;

   //Get a random number from 0 to 1, excluding 1
   double random_multiplier = (double)rand() / (double)(RAND_MAX + 1);
   
   //Get a number from 0 to 'range', excluding 'range'
   int tempVal = (int)(random_multiplier * range);

   //Get a number from lowBound to highBound, including both
   int randomVal = tempVal + lowBound;

   return randomVal;
}

Hope this helps

You know, if you had taken a few moments of your own to LOOK AT THE FAQ, you would have your C++ version.

Quzah.

Code:

randomValue = (((double)rand() / (double) (RAND_MAX + 1)) * (10 - 1 +1)) + 1;

Like that?

Yes, that will get you a number from 1 to 10. In case you didn't see, I edited my post just a second ago to include a code example that explains a little better what it all does, hopefully it's a little more comprehensible.

>>When I read the FAQ I was totally lost.
Admittedly, so was I until about 5 minutes ago It seems Prelude holds us all to a higher standard than many of us are able to cope with.

Code:

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

int main(int argc, char *argv[])
{
 int x = (((double)rand() / (double) (RAND_MAX + 1)) * (10 - 1 +1)) + 1;
 int guess

 do {
 cout << "im thinking of a number between 1 and 10\n";
 cout << "enter your guess please\n";

 cin >> guess;

 if (guess == x) {
 cout << "you are correct\n";
 }
 else if (guess < x) {
 cout << "guess a higher number\n";
 }
 else if (guess > x) {
 cout << "your not supposed to guess this high\n";
 }
 else {
 cout << "guess a lower number\n";
 }
 }while (guess != x);

 system("pause");
 return 0;
}

Is that where it goes?

What now?

Is what where what goes?

Your logic is wrong also. It should be:

Code:

if guess < 1
    tell them to guess a number between 1 and 10
if guess > 10
    tell them to guess a number between 1 and 10
if guess == randomly selected number
    tell them they won
if guess < randomly selected number
    tell them to pick a larger number
if guess > randomly selected number
    tell them to pick a smaller number

On an aside, just so you stop asking: If your program works the way you think it should, then it's done. No need to keep asking if it's right if it does what it's supposed to.


Quzah.

>>Your logic is wrong also. It should be:
Huh? Looks ok to me...

>>int guess
You're missing a semicolon at the end, but other than that it looks like it should run to me. And as quzah said, the quickest way to find out if it's done is to see if it works

Code:

int x = (((double)rand() / (double) (RAND_MAX + 1)) * (10 - 1 +1)) + 1;

If the rand stuff is supposed to go where it is. No, my program doesn't do what its supposed becuase it doesn't generate a random number yet. So what do I need to add now?

Originally Posted by Hunter2

>>Your logic is wrong also. It should be:
Huh? Looks ok to me...

Look again:

Code:

if (guess == x) {
     cout << "you are correct\n";
}
else if (guess < x) {
     cout << "guess a higher number\n";
}
else if (guess > x) {
 cout << "your not supposed to guess this high\n";
 }
 else {
 cout << "guess a lower number\n";
 }
 }while (guess != x);

Ok, perhaps the "logic" is fine. It's the wording that's wrong. I read it as the output states, that they've guessed an out-of-range number. Because you see, if the random number is say 5, and I guess six, then it will tell me "your(sic) not supposed to guess this high", to which I would reply. "Yes I am. You said between 1 and 10."

Quzah.