Histogram

#include <stdlib.h>
#include <stdio.h>
double uniform_rand(void) {
  return rand() / ((double) RAND_MAX + 1.);
}
double normal_rand_sub(void) {
  double z = 0.;
  int i;
  for (i = 0; i < 12; i++)
    z += uniform_rand();
  return z - 6.;
}
double normal_rand(double ave, double sd) {
  return sd * normal_rand_sub() + ave;
}
int main(void) {
  const int section = 101;
  int i, j, n = 3000, spec, freq[section];
  double ave = 50., sd = 10.;
  for (i = 0; i < section; i++)
    freq[i] = 0;
  for(i = 0; i < n; i++) {
    spec = (int) normal_rand(ave, sd);
    if (spec < 0) freq[0]++;
    else if (spec > section - 1) freq[section - 1]++;
    else freq[spec]++;
  }
  for (i = 0; i < section; i++) {
    printf("%3d - ", i);
    for (j = 0; j < freq[i]; j++)
      printf("*");
    puts("");
  }
  return 0;
}