Use Library's qsort()

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
static int comp_double(const void *p1, const void *p2) {
  return *(double *) p1 < *(double *) p2;
}

int main(int ac, char **av) {
  printf("How many is random number generated? : ");
  int n = 0;
  scanf("%d", &n);
  double *randoms = (double *) malloc(n * sizeof(double));
  srand((unsigned int) time(NULL));
  for (int i = 0; i < n; i++)
    randoms[i] = (double) rand() / RAND_MAX;
  for (int i = 0; i < n; i++)
    printf("%g, ", randoms[i]);
  puts("");
  qsort(randoms, n, sizeof(double), comp_double);
  printf("1: %g\n2: %g\n", randoms[0], randoms[1]);
  return EXIT_SUCCESS;
}