Function pointers and callback Functions

1. pointer type to function

Define the pointer type to the function:

// The Void type indicates any type

Typedef void (* FP) (void); // defines the pointer type of the function that points to the returned void type. You need to input a void type parameter.

FP; // define the variable fp

Fp = math. sin; // assign the variable FP to the sin function.

// The method for calling the function pointer is as follows:

Void main ()

{

FP ();

(* FP )();

}

// A good example of using function pointers is: Message ing table

 

2. Call back)

Local service functions or callback functions are often used when different modules call each other. Pointers to functions are often used.

Service (void (* FP) (void ),......)

The above function uses a pointer to the function, used to call when the external module completes the work.

When you call a function from another place, you know that the interface of the local module is service (). In this function, you can input a function from another place. When the service is completed locally, this function will be called from other places, which is equivalent to notifying a program from another place.