generating random numbers within a range

Hello Everyone

I'm hoping smeone can help me here - I can't see the wood for the trees. I have a requirement to generate random numbers of all types, optionally between a range. I'm OK with integer and smaller numbers, in fact the code I wrote is extremely similar to the stuff on the FAQ. Where I come unstuck is generating doubles, floats and long longs between ranges as % seems to do some truncation. I have tried something like this...

r=(drand48()*(end-start+1))+start;

when end and start can be the end and start of the range, or DBL_MIN and DBL_MAX.

When I do this I don't seem to get a good spread of values, or maybe I'm just misinterpreting the output.

Can anyone enlighten me?

Many thanks in advance

tucky

I wonder what your teacher will think if you hand in this :D

Code:

---

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

double rand_mid(int low, int high)
{
  return (double)(low+rand()%(high-low+1));
}

int main(void)
{
  double x;
  int i;
  srand(time(NULL));
  for(i=0; i<10; i++){
    x = rand_mid(1, 100);
    printf("A random number from 0 to 99.9: %f\n", x);
  }
return 0;
}

---

It's a normal integer rand() generator, except the output is a double ;p I actually haven't had a need to create random doubles or floats, I'll have to give this some thought.

-Prelude

Code:

---

#include <stdlib.h>

inline double drand(double low, double high)
{
    return ((double)rand() * (high - low)) / (double)RAND_MAX + low;
}

---

Of course, this limits you to a maximum of RAND_MAX numbers between low and high.

Teacher? This is for a utility at work.

I'll give the code a try - thanks for the help