/* 睹计 */

//qsort 把σ http://www2.lssh.tp.edu.tw/~hlf/class-1/lang-c/qsort.htm
//rand() 把σ http://dhcp.tcgs.tc.edu.tw/c/p005.htm
//RAND_MAX硂盽计琌rand()┮玻ネ程睹计﹚竡stdlib.h柑

// void qsort(void* base, size_t n, size_t size, int (*cmp)(const void*, const void*))皚膀娄е硉逼猭ㄧ计
   皚琌把计 basen 琌皚size 琌–じ程把计琌ㄧ计夹硂琌ゑ耕じㄧ计(  compare() ㄧ计

#include <stdio.h>
#include <stdlib.h> //ずΤqsort, rand(), RAND_MAX
#include <string.h>
#define SIZE 10

int compare_int (const void *a, const void *b)  //const絋玂把计肚秈ㄓぃ穦砆э->ぃ砆э->ぃ暗++or--单单
{
    const int *va = (const int *) a;
    const int *vb = (const int *) b;
    return *va-*vb;
    //return *((const int *)a) - *((const int *)b);  //ョр︽虏てΘ
}

int compare_double (const void *a, const void *b)  //夹非糶猭
{
    const double *da = (const double *) a;
    const double *db = (const double *) b;
    return (*da > *db) - (*da < *db);  //(*da > *db)籔(*da < *db)琌耞Αだ穦肚1┪琌0
    /*if(*da>*db) return 1;
    else if(*da<*db) return -1;
    else return 0;*/                   //ョ硂妓糶掄摨
}

int main(void)
{
    int data1[SIZE];
    double data2[SIZE];
    int i;

    for (i=0; i<SIZE; i++) {
        data1[i] = rand()%SIZE;
        data2[i] = (double) rand()/RAND_MAX;  //***рrand()锣传Θdouble
    }

    printf("original: ");
    for (i=0; i<SIZE; i++) {
        printf("%d ", data1[i]);
    }
    printf("\n");

    printf("  sorted: ");
    qsort(data1, SIZE, sizeof(int), compare_int);  //***
    for (i=0; i<SIZE; i++) {
        printf("%d ", data1[i]);
    }
    printf("\n");

    printf("original: ");
    for (i=0; i<SIZE; i++) {
        printf("%.2f ", data2[i]);
    }
    printf("\n");

    printf("  sorted: ");
    qsort(data2, SIZE, sizeof(double), compare_double);
    for (i=0; i<SIZE; i++) {
        printf("%.2f ", data2[i]);
    }
    printf("\n");

    return 0;
}


1. qsort((void*)a, SIZE, sizeof(a[0]), compare)
   * (void*)a...ex.int*double*array(癘拘砰竚)
   * void*...钡Α妓夹
   * SIZE...array计
   * sizeof(a[0])...–┬Τ
   * compare...qsort箇戳compare肚int,ぃ琌ㄤ戈篈

2. int compare_int (const void *a, const void *b)
{
    const int *va = (const int *) a;
    const int *vb = (const int *) b;
    return *va-*vb;
    //return *((const int *)a) - *((const int *)b);  //ョр︽虏てΘ
}
   * const絋玂把计肚秈ㄓぃ穦砆э->ぃ砆э->ぃ暗++or--单单
   * int -> 璝玥肚+   (把σint compare_double (const void *a, const void *b)ず)
            璝玥肚-
            璝单玥肚0
   * const int *va = (const int *)a ...р*a眏锣传Θint*vaず