Function pointer and callback function

1. Callback function ： Functions called through function pointers , A function as a function parameter ,C Callback function in language can only be realized through function pointer .

Watch out! ： The callback function is called through the function pointer .

2. A function pointer —— Benefits of callback functions ：

（1） The caller who calls the callback function does not need to know how the callback function realizes its function , You only need to know that this function can realize some function , This should be API Interface .

（2） as everyone knows , The function name is also a pointer , Point to the entry address of the function , It's a pointer constant , This is similar to the array name . Since the function name itself is a pointer , So why define a function pointer ？ Aren't they both pointers ？

3. A function pointer - The use of callback functions

#include<stdio.h>

void CallBacksFunc1()
{
	printf("this is callbacksfunc1\n");
}


void CallBacksFunc2()
{
	printf("this is callbacksfunc2\n");
}


void CallBacksFunc3()
{
	printf("this is callbacksfunc3\n");
}

void Handle(void(*p)())// function Handle() Call the callback function through the function pointer .
 from Handle You can see from the parameter list of , The parameter of the function that calls the callback function is a function pointer , No specific function name is required , That is to say, there is no requirement to call any function , Only function types and parameter types are limited , As long as it is a function that conforms to the corresponding function type and parameter type , Its function name can be used as the parameter here .
 therefore , This is very convenient to achieve one thing , And it is very convenient to call different callback functions , Just use the function names of different callback functions .
{
	printf("Entering Handle\n");
	p();// Call the callback function through the function pointer 
	printf("Leaving Hande\n");
	

}

int main(int agrc, char* argv[])
{
	Handle(CallBacksFunc1);// Note that only the function name of the callback function is written here 
 The benefits of callback functions are reflected here , Switch to CallBackFunc2 It's called CallBackFunc2, But not right. Handle Modify the parameter list of the function . If Handle There are specific function names in the parameter list of , That would require several modifications .

	return 0;
}

in general , If you use the method of function pointer to call the callback function , You can save space , Between the designer of the calling function and the designer of the called function, the function pointer is used as API Interface , Design separately .

May refer to ：https://blog.csdn.net/weixin_41042404/article/details/86768240

https://blog.csdn.net/weixin_39939425/article/details/90298435

https://blog.csdn.net/wujiangguizhen/article/details/17153495

This is good https://www.jianshu.com/p/8c63d939285b