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文章目录

1.qsort函数的介绍

2.qsort实现不同类型数据排序

3.qsort的模拟实现

1.qsort函数的介绍

void* base

size_t num

size_t width

int (compar)(const void,const void*)

2.qsort实现不同类型数据排序

define _CRT_SECURE_NO_WARNINGS

include<stdio.h>

include<stdlib.h>

include<string.h>

int cmp_int(const void e1, const void e2)
{

return (*(int*)e1 - *(int*)e2);

}
void test1()
{

int arr[] = {9，8，7，6，5，4，3，2，1，0};
int sz = sizeof(arr) / sizeof(arr[0]);
qsort(arr, sz, sizeof(arr[0]), cmp_int);
int i = 0;
for (i = 0; i < sz; i++)
{
    printf("%d ", arr[i]);
}

}

struct Stu
{

char name[20];
int age;

};

int cmp_stu_by_name(const void e1, const e2)
{

return strcmp(((struct Stu*)e1)->name, ((struct Stu*)e2)->name);

}

void test2()
{

struct Stu s[] = { {"zhangsan",20},{"lisi",21},"wangwu",19};
int sz = sizeof(s) / sizeof(s[0]);
qsort(s, sz, sizeof(s[0]), cmp_stu_by_name);
int i = 0;
for (i = 0; i < 3; i++)
{
    printf("%s %d ", s[i].name, s[i].age);
}

}

int main()
{

test1();
prinf("\n");
test2();
return 0;

}

int main()
{

int a = 10;
char* pa = &a;
return 0;

}

3.qsort的模拟实现

//交换
void Swap(char buf1, char buf2, int width)
{

int i = 0;
for (i = 0; i < width; i++)
{
    char tmp = *buf1;
    *buf1 = *buf2;
    *buf2 = tmp;
    buf1++;
    buf2++;
}

}

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++)
{
    //一趟排序
    int flag = 1;
    int j = 0;
    for (j = 0; j < sz - 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);
            flag = 0;
        }
    }
    if (flag == 1)
        break;
}

}
int cmp_int(const void e1, const void e2)
{

return (*(int*)e1 - *(int*)e2);

}

void test1()
{

int arr[] = { 9,8,7,6,5,4,3,2,1,0 };
int sz = sizeof(arr) / sizeof(arr[0]);
qsort(arr, sz, sizeof(arr[0]), cmp_int);
int i = 0;
for (i = 0; i < sz; i++)
{
    printf("%d ", arr[i]);
}

}

struct Stu
{

char name[20];
int age;

};

int cmp_stu_by_name(const void e1, const e2)
{

return strcmp(((struct Stu*)e1)->name, ((struct Stu*)e2)->name);

}

void test2()
{

struct Stu s[] = { {"zhangsan",20},{"lisi",21},"wangwu",19};
int sz = sizeof(s) / sizeof(s[0]);
 bubble_sort(s, sz, sizeof(s[0]), cmp_stu_by_name);
int i = 0;
for (i = 0; i < 3; i++)
{
    printf("%s %d ", s[i].name, s[i].age);
}

}
int main()
{

test1();
printf("\n");
test2();

return 0;

}

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