如何在C中按降序对结构数组进行排序

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

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

// 比较函数，按照年龄降序排序
int compare(const void* a, const void* b) {
    const struct Person* p1 = (const struct Person*)a;
    const struct Person* p2 = (const struct Person*)b;
    
    if (p1->age < p2->age) {
        return 1;
    } else if (p1->age > p2->age) {
        return -1;
    } else {
        return 0;
    }
}

int main() {
    // 定义结构体数组
    struct Person people[] = {
        {"Alice", 25},
        {"Bob", 30},
        {"Charlie", 20}
    };
    int numPeople = sizeof(people) / sizeof(struct Person);
    
    // 使用qsort函数进行排序
    qsort(people, numPeople, sizeof(struct Person), compare);
    
    // 打印排序结果
    for (int i = 0; i < numPeople; i++) {
        printf("Name: %s, Age: %d\n", people[i].name, people[i].age);
    }
    
    return 0;
}