模拟实现qsort库函数排序整型和结构体

代码：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
//使用qsort对整型数组进行排序
void print_arr(int arr[], int sz)
{
    for (int i = 0; i < sz; i++)
    {
        printf("%d ", arr[i]);
    }
    printf("\n");
}
int cmp_int(const* p1, const* p2)
{
    return *(int*)p1 - *(int*)p2;
}
//void test1()
//{
//    int arr[] = { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 };
//    int sz = sizeof(arr) / sizeof(arr[0]);
//    qsort(arr, sz, sizeof(arr[0]), cmp_int);
//    print_arr(arr, sz);
//}
//使用qsort对结构体进行排序
struct stu
{
    char name[20];
    int age;
};
int cmp_stu_by_name(const void* p1, const void* p2)//qsort内部的排序函数，对name进行排序
{
    return strcmp(((struct stu*)p1)->name, ((struct stu*)p2)->name);
}
int cmp_stu_by_age(const void* p1, const void* p2)//qsort内部的排序函数，对age进行排序
{
    return ((struct stu*)p1)->age - ((struct stu*)p2)->age;
}
void test2()
{
    struct stu arr[3] = { {"zhangsan", 20}, {"lisi", 35}, {"wangwu", 18} };
    int sz = sizeof(arr) / sizeof(arr[0]);
    qsort(arr, sz, sizeof(arr[0]), cmp_stu_by_name);
    for (int i = 0; i < sz; i++)
    {
        printf("%s, %d\n", arr[i].name, arr[i].age);
    }
}

//使用qsort实现冒泡排序
void Swap(char* buf1, char*buf2, size_t width)
{
    int i = 0;
    for (i = 0; i < width; i++)
    {
        char tmp = *buf1;
        *buf1 = *buf2;
        *buf2 = tmp;
        buf1++;
        buf2++;
    }
}
void bubble_sort(void* base, size_t sz, size_t width, int (*cmp)(const void* p1, const void* p2))
{
    int i = 0;
    for (i = 0; i < sz - 1; i++)
    {
        int j = 0;
        for (j = 0; j < sz - i - 1; j++)
        {
            if (cmp((char*)base + j * width, (char*)base + (j + 1) * width) > 0)
            {
                Swap((char*)base + j * width, (char*)base + (j + 1) * width, width);
            }
        }
    }
}

void test3()
{
    int arr[] = { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 };
    int sz = sizeof(arr) / sizeof(arr[0]);
    bubble_sort(arr, sz, sizeof(arr[0]), cmp_int);
    print_arr(arr, sz);
}
void test4()
{
    struct stu arr[3] = { {"zhangsan", 20}, {"lisi", 35}, {"wangwu", 18} };
    int sz = sizeof(arr) / sizeof(arr[0]);
    bubble_sort(arr, sz, sizeof(arr[0]), cmp_stu_by_age);
    for (int i = 0; i < sz; i++)
    {
        printf("%s, %d\n", arr[i].name, arr[i].age);
    }
}
//程序入口
int main()
{
    test4();
    return 0;
}

结果：