How to generate a random number from within a range - C

Question

This is a follow on from a previously posted question:

http://stackoverflow.com/questions/822323/how-to-generate-a-random-number-in-c

I wish to be able to generate a random number from within a particular range, such as 1 to 6 to mimic the sides of a dice.

How would I go about doing this? I'm used to C# and it seems to be a lot more difficult in C to do this.

Thanks

Answer 1

#include <time.h>
#include <stdlib.h>

srand(time(NULL));
int N = 6;
int r = rand() % N;

Generates a number in the range 0 .. N - 1 inclusive. If you want the range to start with a number above zero, just shift it up by adding a constant.

For example:

int r = M + rand() % N;

Generates a random number in the range M .. M + N - 1 inclusive

Answer 2

Wouldn't you just do:

srand(time(NULL));
int r = ( rand() % 6 ) + 1;

% is the modulus operator. Essentially it will just divide by 6 and return the remainder... from 0 - 5

Answer 3

unsigned int
randr(unsigned int min, unsigned int max)
{
       double scaled = (double)rand()/RAND_MAX;

       return (max - min +1)*scaled + min;
}

See here for other options.