【指针进阶三】实现C语言快排函数qsort&回调函数

#include<stdio.h>
void Swap(int* a, int* b)
{
	int temp = *a;
	*a = *b;
	*b = temp;
}

void Quick_sort(int* arr, int begin, int end)
{
	if (begin >= end)
	{
		return;
	}

	int keyi = begin;
	int left = begin, right = end;
	while (left < right)
	{
		while (left < right && arr[right] >= arr[keyi])
		{
			right--;
		}
		while (left < right && arr[left] <= arr[keyi])
		{
			left++;
		}
		Swap(&arr[left], &arr[right]);
	}
	int meeti = left;
	Swap(&arr[keyi], &arr[meeti]);

	Quick_sort(arr, begin, meeti-1);
	Quick_sort(arr, meeti+1, end);
	
}

void Print(int* arr, int sz)
{
	for (int i = 0; i < sz; i++)
	{
		printf("%d\t", arr[i]);
	}
}

int main()
{
	int arr[5] = { 12,43,5,23,6 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	Quick_sort(arr, 0,sz-1);
	Print(arr, sz);
	return 0;
}

#include<stdio.h>
#include<string.h>
typedef struct stu
{
	char name[20];
	int age;
}stu;

void Swap(stu* a,stu* b)
{
	stu temp = *a;
	*a = *b;
	*b = temp;
}

void Quick_sort(stu* ps, int begin, int end)
{
	if (begin >= end)
	{
		return;
	}
	int keyi = begin;
	int left = begin, right = end;
	while (left < right)
	{
		while (left < right && strcmp(ps[right].name, ps[keyi].name) >= 0)
		{
			right--;
		}
		while (left < right && strcmp(ps[left].name, ps[keyi].name) <= 0)
		{
			left++;
		}
		Swap(&ps[left], &ps[right]);
	}
	int meeti = left;
	Swap(&ps[keyi], &ps[meeti]);

	Quick_sort(ps, begin, meeti - 1);
	Quick_sort(ps, meeti+1, end);
}

void Print(stu* ps, int sz)
{
	for (int i = 0; i < sz; i++)
	{
		printf("%s\n", ps[i].name);
	}
}

int main()
{
	stu s[3] = { {"张三",18},{"李四",20},{"王五",19} };
	int sz = sizeof(s) / sizeof(s[0]);
	Quick_sort(s,0,sz-1);
	Print(s, sz);
	return 0;
}

#include<stdio.h>
#include<stdlib.h>
//以qsort库函数实现整型数组排序为例
int main()
{
	int arr[5] = { 12,43,5,23,6 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	qsort(arr, sz, sizeof(arr[0]), cmp);
	//arr:数组名,也是数组首元素的地址,数值上等于首元素中4个字节中地址最低的那个字节的地址
	//sz:数组arr的元素个数
	//sizeof(arr[0]):每一个数组元素所占的字节数
	//cmp_int:回调函数-比较数组元素的函数,根据调用者的需要自行实现
	Print(arr, sz);
	return 0;
}

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

int cmp_int(const void* e1, const void* e2)
{
    //比较两个整型元素
	//void*是无具体类型的指针
	//void*的指针可以接收任意类型的地址,类似垃圾桶
	//void*的指针没有具体类型,不能+1-1(因为不知道加多少)

	//升序:
	return *(int*)e1 - *(int*)e2;

	//降序:
	//return *(int*)e2 - *(int*)e1;
}


void Print(int* arr, int sz)
{
	for (int i = 0; i < sz; i++)
	{
		printf("%d\t", arr[i]);
	}
}

void test1()
{
	int arr[6] = { 14,35,4,42,6,12 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	qsort(&arr[0], sz, sizeof(arr[0]), cmp_int);
	Print(arr, sz);
}


int main()
{
	test1();

	return 0;
}

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

typedef struct stu
{
	char name[20];
	int age;
}stu;

int cmp_struct_by_name(const void* e1, const void* e2)
{
	return strcmp(((stu*)e1)->name, ((stu*)e2)->name);//妙哉之处
}

void Print(stu* ps, int sz)
{
	for (int i = 0; i < sz; i++)
	{
		printf("%s\n", ps[i].name);
	}
}


void test2()
{
	stu s[3] = { {"zhangsan",18},{"lisi",20},{"wangwu",19} };
	int sz = sizeof(s) / sizeof(s[0]);
	qsort(s,sz,sizeof(s[0]),cmp_struct_by_name);
	Print(s, sz);
}

int main()
{
	test2();

	return 0;
}

void Swap(char* buff1,char* buff2,int width)
{
	if (buff1 != buff2)
	{
		//way1
		//while (width--)
		//{
		//	char temp = *buff1;
		//	*buff1 = *buff2;
		//	*buff2 = temp;
		//	buff1++;
		//	buff2++;
		
		//way2
		for (int i = 0; i < width; i++)
		{
			char temp = *(buff1+i);
	        *(buff1+i) = *(buff2+i);
	        *(buff2+i) = temp;
		}
	}
}

void bubble_sort(void* base, int sz, int width, int(*cmp)(const void*, const void*))
{
	int flag = 1;
	//趟数
	for (int i = 0; i < sz-1; i++)
	{
		for (int j = 0; j < sz - 1 - i; 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;
	}
}