程序代码：

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

double values[] = { 40.3, 10.123, 100, 90.8, 20, 25 };

int compare (const void * a, const void * b)
{
  return ( *(double *)a - *(double *)b );
}

int main ()
{
  int n;
  qsort (values, 6, sizeof(double), compare);
  for (n=0; n<6; n++)
     printf ("%f ",values[n]);
  return 0;
}

程序代码：

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#define SIZE 20

int compare(const void * p1, const void * p2) {
    return *(double *)p1 - *(double *)p2;
}

int main(void) {
    double buffer[SIZE];
    int i;
    srand((unsigned)time(NULL));
    printf("before :\n");
    fflush(stdout);
    for(i = 0; i < SIZE; i++) {
        buffer[i] = rand() / 3.0;
        printf("%f\t", buffer[i]);
    }
    printf("\nafter :\n");
    qsort(buffer, SIZE, sizeof(double), compare);
    for(i = 0; i < SIZE; i++)
        printf("%f\t", buffer[i]);
    return 0;
}