模拟实现冒泡排序qsort

• 调用函数库中的qsort

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

struct Stu
{
    char name[20];
    int age;
};

int cmp_int(const void*e1, const void*e2)
{
    return *(int*)e1 - *(int*)e2;
}

int cmp_stu_name(const void*e1, const void*e2)
{
    return strcmp((*(struct Stu*)e1).name, (*(struct Stu*)e2).name);
}

int main()
{
    int i = 0;
    int arr[] = {1,3,5,7,9,2,4,6,8,0};
    struct Stu arr2[] = { {"zhangsan",20}, {"lisi",45}, {"wangwu",12} };
    qsort(arr,sizeof(arr)/sizeof(arr[0]),sizeof(arr[0]),cmp_int);
    qsort(arr2, sizeof(arr2) / sizeof(arr2[0]), sizeof(arr2[0]), cmp_stu_name);

    for (i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
    {
        printf("%d ", arr[i]);
    }

    printf("\n------------------------------------\n");

    for (i = 0; i < sizeof(arr2) / sizeof(arr2[0]); i++)
    {
        printf("%s ", arr2[i].name);
    }

    return 0;

}

系统冒泡.png

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分析qsort函数：

void qsort( void *base, size_t num, size_t width, int (__cdecl *compare )(const void *elem1, const void *elem2 ) );

base----Start of target array----目标数组起始地址
num----Array size in elements----元素个数
width-----Element size in bytes----元素的大小（单位：字节）
compare----Comparison function----比较函数
elem1----Pointer to the key for the search----指针指向要比较的元素的地址
elem2--Pointer to the array element to be compared with the key--同上^_

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• 模拟实现qsort

#define _CRT_SECURE_N0_WARNINGS 1
#include<stdio.h>
#include <string.h>
#include<stdlib.h>


struct Stu
{
    char name[20];
    int age;
};

 //一个字节一个字节的交换
void Swap(char *buf1,char *buf2,int width)
{
    int i = 0;
    for (i = 0; i < width; i++)
    {
        char tmp = *(buf1 + i);
        *(buf1 + i) = *(buf2 + i);
        *(buf2 + i) = tmp;
    }
}

void bubble_sort(void *base, int sz, int width, int(*cmp)(const void*e1, const void*e2))
{
    int i = 0;
    for (i = 0; i < sz - 1; i++)
    {
        int j = 0;
        for (j = 0; j < sz - 1 - i; j++)
        {
            if (cmp((char*)base+j*width,(char*)base+(j+1)*width)>0)//传参 每个元素的地址
            {
                //交换
                Swap((char*)base + j*width, (char*)base + (j + 1)*width,width);
            }
        }
    }

}



int cmp_int(const void*e1, const void*e2)
{
    return *(int*)e1 - *(int*)e2;
}

int cmp_stu_name(const void*e1, const void*e2)
{
    return strcmp((*(struct Stu*)e1).name, (*(struct Stu*)e2).name);
}

int cmp_stu_age(const void*e1, const void*e2)
{
    return (((struct Stu*)e1)->age-((struct Stu*)e2)->age);
}


int main()
{
    int i = 0;
    int arr[] = {1,3,5,7,9,2,4,6,8,0};
    struct Stu arr2[] = { {"zhangsan",20}, {"lisi",45}, {"wangwu",12} };

    bubble_sort(arr,sizeof(arr)/sizeof(arr[0]),sizeof(arr[0]),cmp_int);
    for (i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
    {
        printf("%d ", arr[i]);
    }
    printf("\n------------------------------------\n");


    bubble_sort(arr2, sizeof(arr2) / sizeof(arr2[0]), sizeof(arr2[0]), cmp_stu_name);
    for (i = 0; i < sizeof(arr2) / sizeof(arr2[0]); i++)
    {
        printf("%s ", arr2[i].name);
    }
    printf("\n------------------------------------\n");


    bubble_sort(arr2, sizeof(arr2) / sizeof(arr2[0]), sizeof(arr2[0]), cmp_stu_age);
    for (i = 0; i < sizeof(arr2) / sizeof(arr2[0]); i++)
    {
        printf("%s ", arr2[i].name);
    }
    printf("\n------------------------------------\n");


    return 0;

}

模拟冒泡.png