Consolidate and review the pointers and callback functions pointing to the function pointer array

One 、 A pointer to an array of function pointers

That is, the pointer points to an array , The elements of the array are all function pointers .

void test(const char* abcdef)
{
	printf("%s\n", abcdef);
}
int main()
{
	void (*p)(const char* abcdef) = test;// A function pointer 
	void (*parr[6])(const char* abcdef);// Function pointer array 
	void (*(*parr)[6])(const char* abcdef);// A pointer to an array of function pointers 
	return 0;
}

Two 、 Callback function

That is, pass the address of the function as a parameter to another function , When this pointer is used to call the function it points to , Let's just say this is a callback function .

Let's talk about bubble sorting first ：

#include<stdio.h>
void Bubble_sort(int* arr, int sz)
{
	int i = 0;
	for (i = 0; i < sz - 1; i++)// Bubble sort 
	{
		int j = 0;
		for (j = 0; j < sz - 1 - 0; j++)// Once in a bubble sort 
		{
			if (arr[j] > arr[j + 1])
			{
				int tmp = arr[j];
				arr[j] = arr[j + 1];
				arr[j + 1] = tmp;
			}
		}
	}
}
int main()
{
	int arr[10] = { 9,8,7,6,5,4,3,2,1,0 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	Bubble_sort(arr, sz);
	int i = 0;
	for (i = 0; i < sz; i++)
	{
		printf("%d ", arr[i]);
	}
	return 0;
}

qsort function , Sort any type of data ：

int cmp(const* e1, const* e2)
{
	return (*(int*)e1 - *(int*)e2);
}
int main()
{
	int arr[10] = { 9,8,7,6,5,4,3,2,1,0 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	//Bubble_sort(arr, sz);
	qsort(arr, sz, sizeof(arr[0]), cmp);
	int i = 0;
	for (i = 0; i < sz; i++)
	{
		printf("%d ", arr[i]);
	}
	return 0;
}

#include<string.h>
struct stu
{
	char name[20];
	int age;
};
int cmp_age(const void* e1, const void* e2)
{
	return (((struct stu*)e1)->age-((struct stu*)e2)->age);
}
void test2()
{
	struct stu s[] = { { "xiaohong",12 }, { "xiaolan",13 }, { "xiaohua",20 } };
	int sz = sizeof(s) / sizeof(s[0]);
	qsort(s, sz, sizeof(s[0]), cmp_age);
}
int main()
{
	//test1();
	test2();
	return 0;
}