Simple C++ queston...

[Stormin]

I forgot how to generate random variables in C++. I think it is the rand() function but it doesnt seem to work. I need to produce a random number between 1 and 100. Can anyone help me? thanks.

 

[Schro]

If i recall correctly (and I may not...) The rand() function is defined as a random number between 0 and 1....

Consider some multiplication.....

i.e.: result of rand x 100 = a number 1-100 (round it if you please)

 

[BillLeeLee]

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

int main()
{
      srand((unsigned) time(NULL));

      std::cout << rand() % 100 + 1 << std::endl;

      return 0;
}

rand will generate numbers other than 0 and 1, so "rand() % 100 + 1" will generate a number between 1 and 100.

srand() is used so that the random generator uses a different seed every time the program is run.

 

[Lord of Shadows]

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

#define MAX 100
#define MIN 1
using namespace std;

int main (void)
{
	srand( time(NULL) );
	cout	<< rand() % (MAX + 1 - MIN) + MIN;

	return 0;
}

Pretty sure thats being scaled right, might want to check ranges. Anyway, srand sets the random seed to the current time (represented in seconds since 1970). (This ensures your random numbers dont repeat in order everytime you start the program) rand() returns a random int in the range of 0 to (2^15)-1. The mod function scales it down to the wanted range and then adds your min.

You may want to clean that up looks ugly to me, (Like find MAX+1-MIN and hardcode it in)

Looks like I took too long posting =)

 

[Stormin]

thanks a lot guys, you have been a big help!