本人小菜鸟，最近学到使用标准库的排序函数qsort()。但是在测试时发现，常见的排序算法都能正常排序，但是使用qsort后总会有一个错误的逆序，太令人费解了？

以下是测试结果
新排序法02
Runtime is: 63.3284 ms.
新排序法
Runtime is: 9217.69 ms.
冒泡排序法
Runtime is: 35644.4 ms.
选择排序法
Runtime is: 33746.1 ms.
指针式选择排序法
Runtime is: 10347.1 ms.
C++标准库排序
Runtime is: 33.1877 ms.
99505 2147469257 2147469406 -1569897150 -1200968838 One Reverse order.                //只有标准库的qsort出现了一条随机的逆序错误。
           n-2项    n-1项        n项           n+1项

C:\Users\ZH11002\source\repos\TEST0002\x64\Debug\TEST0002.exe (进程 9308)已退出，代码为 0。
要在调试停止时自动关闭控制台，请启用“工具”->“选项”->“调试”->“调试停止时自动关闭控制台”。
按任意键关闭此窗口. . .

以下是代码

#include <iostream>
#include <stdio.h>
#include <bitset>
#include <stdlib.h>
#include <random>
#include <Windows.h>
#pragma warning(disable:4996)

constexpr auto NUM01 = 100000;

using namespace std;

int qsortnum(const void* a, const void* b) {
    int* aa = (int*)a;
    int* bb = (int*)b;
    return *aa - *bb;
}

int main()
{
    int* a = new int[NUM01];

    random_device rd;

    LARGE_INTEGER freq01;
    LARGE_INTEGER begintime01;
    LARGE_INTEGER endtime01;
    double microsecond01;


    QueryPerformanceFrequency(&freq01); // 获取时钟周期
    ///////////////////////////////////
    for (int i = 0; i < NUM01; i++) {
        a[i] = rd();
    }
    QueryPerformanceCounter(&begintime01); // 开始计时
    qsort(a, NUM01, sizeof(int), qsortnum);
    QueryPerformanceCounter(&endtime01);//结束计时
    microsecond01 = (double)(endtime01.QuadPart - begintime01.QuadPart) * 1e3 / (double)freq01.QuadPart;
    cout << "C++标准库排序" << endl;
    cout << "Runtime is: " << microsecond01 << " ms." << endl;

    for (int i = 0; i < NUM01 - 1; i++) {
        if (a[i] > a[i + 1]) {
            cout << i << " " << a[i - 1] << " " << a[i] << " " << a[i + 1] << " " << a[i + 2] << " One Reverse order." << endl;
        }
    }
    delete[] a;

}