如何实现qsort()来处理结构数组？

void qsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *));

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

// 定义一个结构体
struct Person {
    char name[20];
    int age;
};

// 自定义比较函数
int compare(const void *a, const void *b) {
    // 将void指针转换为结构体指针
    const struct Person *p1 = (const struct Person *)a;
    const struct Person *p2 = (const struct Person *)b;

    // 根据需要的排序规则进行比较
    return p1->age - p2->age;
}

int main() {
    struct Person people[] = {
        {"Alice", 25},
        {"Bob", 30},
        {"Charlie", 20}
    };
    int numPeople = sizeof(people) / sizeof(struct Person);

    // 使用qsort()对结构数组进行排序
    qsort(people, numPeople, sizeof(struct Person), compare);

    // 打印排序后的结果
    for (int i = 0; i < numPeople; i++) {
        printf("Name: %s, Age: %d\n", people[i].name, people[i].age);
    }

    return 0;
}