C语言回调函数

https://www.runoob.com/w3cnote/c-callback-function.html

回调函数：其实就是把一个函数当做参数传递给另一个函数，实现的方法是通过函数指针的方法；
特点：降低代码的耦合性；

1》不带参数的回调函数

在这里插入代码片
```#include<stdio.h>

int Callback_1() // Callback Function 1
{
    printf("Hello, this is Callback_1 ");
    return 0;
}

int Callback_2() // Callback Function 2
{
    printf("Hello, this is Callback_2 ");
    return 0;
}

int Callback_3() // Callback Function 3
{
    printf("Hello, this is Callback_3 ");
    return 0;
}

int Handle(int (*Callback)())
{
    printf("Entering Handle Function. ");
    Callback();
    printf("Leaving Handle Function. ");
}

int main()
{
    printf("Entering Main Function. ");
    Handle(Callback_1);
    Handle(Callback_2);
    Handle(Callback_3);
    printf("Leaving Main Function. ");
    return 0;
}
运行结果：

Entering Main Function.
Entering Handle Function.
Hello, this is Callback_1
Leaving Handle Function.
Entering Handle Function.
Hello, this is Callback_2
Leaving Handle Function.
Entering Handle Function.
Hello, this is Callback_3
Leaving Handle Function.
Leaving Main Function.

 

2》带参数的回调函数

```c
#include<stdio.h>

int Callback_1(int x) // Callback Function 1
{
    printf("Hello, this is Callback_1: x = %d ", x);
    return 0;
}

int Callback_2(int x) // Callback Function 2
{
    printf("Hello, this is Callback_2: x = %d ", x);
    return 0;
}

int Callback_3(int x) // Callback Function 3
{
    printf("Hello, this is Callback_3: x = %d ", x);
    return 0;
}

int Handle(int y, int (*Callback)(int))
{
    printf("Entering Handle Function. ");
    Callback(y);
    printf("Leaving Handle Function. ");
}

int main()
{
    int a = 2;
    int b = 4;
    int c = 6;
    printf("Entering Main Function. ");
    Handle(a, Callback_1);
    Handle(b, Callback_2);
    Handle(c, Callback_3);
    printf("Leaving Main Function. ");
    return 0;
}
运行结果：

Entering Main Function.
Entering Handle Function.
Hello, this is Callback_1: x = 2
Leaving Handle Function.
Entering Handle Function.
Hello, this is Callback_2: x = 4
Leaving Handle Function.
Entering Handle Function.
Hello, this is Callback_3: x = 6
Leaving Handle Function.
Leaving Main Function.