c语言qsort使用

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

#define NUM 3

typedef struct {
    int a;
    int b;
} Node;
Node nodes[] = {
    { 2, 3 },
    { 8, 3 },
    { 2, 9 }
};

void ShowNum(int *a)
{
    for (int i = 0; i < NUM; i++) {
        printf("%d ", a[i]);
    }
    printf("
");
}

void ShowStr(int **a)
{
    for (int i = 0; i < NUM; i++) {
        printf("%s
", a[i]);
    }
    printf("
");
}

void ShowStruct()
{
    for (int i = 0; i < NUM; i++) {
        printf("%d %d
", nodes[i].a, nodes[i].b);
    }
}

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

int CmpStr(const void *a, const void *b)
{
    return strcmp(*(char **)a, *(char **)b);
}

int CmpStruct(const void *a, const void *b)
{
    Node *pa = (Node *)a;
    Node *pb = (Node *)b;

    if (pa->a == pb->a) {
        return pa->b - pb->b;
    }
    return pa->a - pb->a;
}

int main()
{
    // 排序数字
    int values[] = {88, 56, 100};
    qsort(values, NUM, sizeof(int), CmpNum);
    ShowNum(values);

    // 排序字符串
    char *a[] = {"uhhkjhkj",
                 "dffgfg",
                 "kgyjhk"};
    qsort(a, NUM, sizeof(char *), CmpStr);
    ShowStr(a);

    // 排序结构体
    qsort(nodes, NUM, sizeof(Node), CmpStruct);
    ShowStruct();

    return 0;
}