为什么 qsort 不能正确地对动态分配的结构进行排序？

有必要按采集月份从小到大对所有记录进行分组。如果您决定不使用动态内存分配，那么它会按应有的方式从小到大排序，但是如果您更改代码，那么排序就不会那样工作。下面是按错误顺序排序的代码。

#include <stdio.h>
#include <stdlib.h>
#define COUNT_ITEMS 4

typedef struct Product {
    char name[256];
    int day;
    int month;
    int year;
    int cost;
    int count;
} Product;
void printinfo(const Product *prod)
{
    printf("Product name: %s\n", prod->name);
    printf("Date of purchase : %d.%d.%d\n", prod->day, prod->month, prod->year);
    printf("Product price: %d\n", prod->cost);
    printf("Number of products: %d\n", prod->count);
}

Product *prodRead() {
    Product *prod;
    prod = malloc(sizeof(Product));
    printf("Enter name of a Product:\n");
    scanf("%s", &prod->name);
    printf("Enter day, month(number), year of purchase through a space:\n");
    scanf("%d%d%d", &prod->day, &prod->month, &prod->year);
    printf("Enter cost of product:\n");
    scanf("%d", &prod->cost);
    printf("Enter number of product:\n");
    scanf("%d", &prod->count);
return prod;
}
int compMon(const void *a, const void *b) {
    const Product *partOne = (Product *)a;
    const Product *partTwo = (Product *)b;
    return ((*partOne).month > (*partTwo).month) - ((*partOne).month < (*partTwo).month);
}
int main() {
    Product *prod[COUNT_ITEMS];
    for (int i = 0; i < COUNT_ITEMS; i++) {
        prod[i]=prodRead();
        printf("\n");
    }
    qsort(prod, COUNT_ITEMS, sizeof(Product*), compMon);
    printf("Structura POSLE sortirovki \n");
    for (int i = 0; i < COUNT_ITEMS; i++) {
        printinfo(prod[i]);
        printf("\n");
    }
return 0;
}

输入数据（左）和输出数据（右）：

A                                    C   
10 11 2020                           6 6 2020
1000                                 600
2                                    1
B                                    A
5 5 2019                             10 11 2020
500                                  1000
3                                    2
C                                    D 
6 6 2020                             3 3 2018
600                                  200
1                                    2
D                                    B
3 3 2018                             5 5 2019
200                                  500
2                                    3